Dizziness in the Outpatient Care Setting

Review Article

Address correspondence to Dr Terry D. Fife, Barrow Dizziness in the Neurological Institute, 240 West Thomas Rd, Suite 301, Phoenix, AZ 85013, Outpatient Care Setting [email protected]. Relationship Disclosure: Terry D. Fife, MD, FAAN Dr Fife serves on the editorial boards of Barrow Quarterly and Neurology. Unlabeled Use of ABSTRACT Products/Investigational Purpose of Review: This article summarizes an approach to evaluating dizziness for Use Disclosure: Dr Fife discusses the the general neurologist and reviews common and important causes of dizziness unlabeled/investigational and vertigo. use of acetazolamide, Recent Findings: Improved methods of diagnosing patients with vertigo and venlafaxine, and zonisamide for the treatment of dizziness have been evolving, including additional diagnostic criteria and charac- vestibular migraine. terization of some common conditions that cause dizziness (eg, vestibular migraine, * 2017 American Academy benign paroxysmal positional vertigo, chronic subjective dizziness). Other uncommon of Neurology. causes of dizziness (eg, superior canal dehiscence syndrome, episodic ataxia type 2) have also been better clarified. Distinguishing between central and peripheral causes of vertigo can be accomplished reliably through history and examination, but imaging techniques have further added to accuracy. What has not changed is the necessity of obtaining a basic history of the patient’s symptoms to narrow the list of possible causes. Summary: Dizziness and vertigo are extremely common symptoms that also affect function at home and at work. Improvements in the diagnosis and management of the syndromes that cause dizziness and vertigo will enhance patient care and cost efficiencies in a health care system with limited resources. Clinicians who evaluate patients with dizziness will serve their patient population well by continuing to manage patients with well-focused workup and attentive care.

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INTRODUCTION ment, or a feeling of spatial misper- Dizziness accounts for 5% of outpa- ception. That is, the patient senses that tient clinic presentations, making it a balance is impaired because of poorer- very common symptom in clinical than-normal stability on his or her feet medicine.1 Meanwhile, dizziness may or a feeling that he or she might fall. be one of the most challenging symp- This sensation may result from dizzi- toms to which physicians can ascribe a ness but may be caused by many other mechanism and cause.2 conditions, ranging from orthopedic to Dizziness is a term used commonly neurodegenerative disorders, which by patients and physicians alike that will not be discussed in this article. broadly refers to a misperception of spatial orientation. Because dizziness is so APPROACH TO PATIENTS nonspecific a term, it may refer to ver- WITH DIZZINESS tigo (the illusion of movement, especially The effective history and directed ex- rotation), disequilibrium or imbalance, amination can determine the source lightheadedness, or near faintness. of dizziness in many cases. The history Unsteadiness or disequilibrium indi- should identify what is meant by cate a feeling of reduced balance when ‘‘dizziness,’’ whether it is constant or standing or walking, but without vertigo, intermittent, provoked or random, and lightheadedness, an illusion of move- how long it lasts if intermittent. The

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KEY POINT h Determining the history should also identify whether less helpful in narrowing the broad quality of dizziness is dizziness varies in certain circum- differential diagnosis. important but may not stances and if other symptoms accom- The quality-of-symptom approach be sufficient to make an pany the dizziness that might be clues to characterizing dizziness leads to 3,4 accurate diagnosis. to its nature and mechanism. many errors in diagnosis. In one Additional factors study by Hanley and O’Dowd,5 when including triggers, Clarifying ‘‘Dizziness’’ patients at an ambulatory clinic were duration, accompanying Dizziness may be caused by both given options to describe their dizzi- symptoms, and the benign and dangerous conditions, ness, 7.1% were unable to classify findings on examination so a careful history is important to im- their symptoms at all, and many are also needed to prove the diagnostic accuracy. When others chose multiple words simulta- narrow the range of the patient and clinician can come to neously to describe their sensation. possible causes. a clear and mutual understanding of While getting the patient to elaborate the patient’s description of dizziness, on the quality of the sensation is determining a clear cause is more helpful, more is needed to make a straightforward. However, substantial diagnosis (Case 2-1). limitations exist regarding how much the patient’s report of the quality of Narrowing the the sensation can be used to accurately Differential Diagnosis determine the mechanism, particularly What other symptoms or signs can in the acute care setting.3 Whether aidinnarrowingthepossiblemech- the patient states that he or she is spin- anisms and causes of the patient who ning or that the room is spinning is of experiences dizziness? As outlined in little importance. If the patient can Table 2-16, the patient’s descriptions identify clear rotational sensations, the of the timing, triggering events, and condition qualifies as vertigo, which associated symptoms are generally implies a greater likelihood of a vestib- more reliable than their descriptions ular mechanism. Other descriptions are of the quality of the dizziness.3

Case 2-1 A 46-year-old woman presented with a 4-month history of dizziness that she described as a constant feeling of instability; she sometimes felt as if she were spinning and at times felt that she could faint. Her symptoms had begun suddenly when at an out-of-town meeting while sitting at a table. She had begun to feel unstable and later became nauseated; she recalled a ‘‘topsy-turvy’’ spinninglike sensation that lasted the whole evening. She was alone and stayed in the hotel room, and eventually the spinning gave way to a constant swaying and floating feeling, which she continued to experience daily. She had not experienced any hearing loss, slurred speech, double vision, weakness, or numbness, and the nausea had not occurred since the initial onset of symptoms. Brain MRI was found to be normal on two occasions, and magnetic resonance angiography (MRA) of the head and neck, cardiac workup, and multiple blood tests were normal. At work, she had used all her vacation time and leave allowed by the Family and Medical Leave Act and was worried that she could no longer do her job as an information technology project manager. She was also reluctant to travel or drive. No abnormalities were found on examination. Continued on page 361

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Copyright © American Academy of Neurology. Unauthorized reproduction of this article is prohibited. Continued from page 360 KEY POINTS h The head impulse Comment. This case exemplifies a situation in which a patient probably test is a useful test of experienced a transient peripheral vestibular disturbance that caused vestibular function that spinning vertigo, but later a different form of dizziness became the can aid in the diagnosis predominant cause. This case shows that multiple descriptions of dizziness of vestibular disorders may be given by the patient; in this case, it was clarified that initially and requires no the patient experienced true vertigo but later experienced more of a special equipment. floating and swaying sensation. This could be due to poor compensation of unilateral vestibular loss but, more likely, the patient had a mild case h The head impulse test is of vestibular neuritis that created alarm and fear, and subsequently, done by grasping the chronic subjective dizziness related to anxiety ensued. patient’s head firmly on both sides, explaining the test to the patient, Useful Vestibular both sides, explaining the test to the and then making a Examination Techniques patient, and then making a very rapid very rapid but very Several examination techniques are but very small-amplitude turn of the small-amplitude turn helpful in evaluating the patient with head while the patient is instructed to of the head while the patient is instructed to vertigo and dizziness. These include look at the physician’s eye or some other look at the physician’s recognition of direction-fixed hori- fixed target. If the patient’s eyes never eye or some other zontal nystagmus and distinction from deviate from the target during or after fixed target. horizontal gazeYevoked nystagmus the head impulse, then vestibular func- h If the patient’s eyes (Table 2-1), head impulse testing, and tion related to the horizontal canal is never deviate from the the Dix-Hallpike maneuver (described normal or nearly normal in the ear on target during or after inthelatersectiononbenignparoxys- the side toward which the head is turned. the head impulse, then mal positional vertigo [BPPV]). If, however, the eyes moved with the vestibular function The head impulse (or head thrust) head and then must take a quick ex- related to the horizontal test is a simple test for detecting im- cursion or catch-up saccade back to the canal is normal or nearly paired vestibular function related to the target, then the test is abnormal on that normal in the ear on the horizontal semicircular canal. When the side. Head impulse testing remains ab- side toward which the head is turned quickly (1 Hz or more), normal for a lifetime once permanent head is turned. If, the only eye movement system that can unilateral or bilateral vestibular loss of however, the eyes moved move so quickly and with such short the horizontal canal has taken place. with the head and then latency is the vestibuloocular reflex. In Practical performance of the head must take a quick excursion or catch-up accordance with Ewald’s second law, impulse test takes a little experience, saccade back to the part of a set of principles by which the and so it is wise to perform the head target, then the test is vestibuloocular reflex works, turning impulse test in many patients, includ- abnormal on that side. the head rapidly stimulates the vestibu- ing healthy patients. One common mis- lar function on the side toward which take is to assume that a patient must the head is turned more than it inhibits make a large turn of the head, risking the other ear. The result is that if there neck injury. While it would be unwise to is loss of vestibular function on the side do this test in someone with a cervical to which the head is turned, the vesti- fracture, the risk of neck injury is negli- buloocular reflex is not able to drive the gible in most people. One problem with eyes in an equal and opposite direction, interpretation can be blinking or the in- so the eyes move with the head and ability of the patient to relax or to avoid then require a catch-up saccade to get moving his or her own head. Neverthe- back to the target the patient had in- less, the head impulse test is easily eval- tended to focus on. uated and interpreted in most patients. The head impulse test is done by A bit of gradation exists in how prom- grasping the patient’s head firmly on inent and consistently the catch-up

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TABLE 2-1 History and Examination of the Patient With Dizziness

Feature Response and Implied Mechanism or Cause Quality of dizziness Vertigo or clear spinning implies vestibular mechanism Near faintness (not floating) as a sole description implies cardiovascular/ hemodynamic cause Other descriptions far less clear as to mechanism Timing and duration Brief recurrent spells are seen with benign paroxysmal positional vertigo (BPPV), but do not totally exclude vascular, cardiac, psychological, or other mechanisms Recurrent spells of dizziness lasting 1 to 15 minutes may be seen with vertebrobasilar transient ischemic attacks, vestibular migraine, or sometimes with panic attacks Recurrent dizziness lasting hours may be seen with vestibular migraine or with Me´nie`re disease, the latter more likely if associated unilateral hearing loss or fluctuating hearing occurs Chronic ongoing dizziness nearly continuously for many weeks implies anxiety or migrainous mechanism but does not totally exclude other causes, including slow recovery from vestibular neuritis or brainstem/cerebellar lesions or drug toxicity Triggering Induced by rolling in bed, certain head positions, or looking up implies BPPV circumstances Dizziness worsened by head movement implies vestibular mechanism, whether central or peripheral Dizziness almost exclusively occurring when standing or walking and not when supine or recumbent implies hemodynamic mechanisms but is sometimes reported in those who have simple gait unsteadiness Dizziness triggered by vibration or loud sounds (Tullio phenomenon) may suggest superior canal dehiscence syndrome, a bony abnormality of the labyrinth Dizziness induced predominantly by seeing objects in motion implies visual vertigo (optokinetic motion sickness), a vestibular syndrome seen in several vestibular disorders Other associated Unilateral hearing loss with spinning vertigo implies labyrinthine cause symptoms Diplopia, dysarthria, or focal weakness or numbness with vertigo is not peripheral vestibular and implies central nervous system (CNS) vestibular mechanism Nausea is characteristic of vestibular causes (both central and peripheral) but may sometimes also occur with hemodynamic mechanisms Autophony is an unusual symptom in which the patient reports hearing or feeling his or her own voice, breathing, eye movements, or footsteps Dix-Hallpike maneuver Paroxysmal upbeating and torsional nystagmus after the Dix-Hallpike maneuver is characteristic of BPPV of the posterior canal and thus is highly diagnostic Nystagmus Spontaneous direction-fixeda nystagmus strongly supportive of a peripheral vestibular mechanism, particularly if it adheres to the Alexander lawb Spontaneous vertical or horizontal gazeYevoked nystagmus indicates a CNS process likely affecting the brainstem or cerebellum a Direction-fixed nystagmus means the nystagmus continues to beat in the same direction regardless of the direction of gaze. This distinguishes it from gaze-evoked nystagmus, where the nystagmus beats to the right in right gaze and to the left in left gaze, which indicates a CNS mechanism. b The Alexander law states that nystagmus is stronger with gaze in the direction of the fast phase and diminishes or abates with gaze in the direction opposite of the fast phase. The Alexander law is characteristic of peripheral vestibular disorders6 but may occasionally be seen where a vascular mechanism has caused peripheral vestibular ischemia as with the ischemia of the lateral pons affecting the vestibular nerve entry zone or the labyrinth itself (eg, the anterior inferior cerebellar artery syndrome).

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Copyright © American Academy of Neurology. Unauthorized reproduction of this article is prohibited. KEY POINT saccade is, with milder vestibular loss than 1%) may be affected. The direc- h Benign paroxysmal being harder to detect than severe loss. tional features of the nystagmus help positional vertigo is When in doubt, the test can be repeated to identify the side and semicircular caused when calcium 7 until the examiner feels comfortable canal affected (Table 2-2 ). carbonate debris erodes that it is either normal or not. Mechanism. The semicircular canals from the otoconia of the of the membranous labyrinth of the utricle and by the effect PRIMARY LABYRINTHINE CAUSES inner ear on each side detect angular of gravity finds its way OF VERTIGO AND DIZZINESS or turning movements of the head into the lumen of one of This section describes causes of diz- (Figure 2-2). Each labyrinth has three the semicircular canals (most commonly the zinessrelatedtoinnerearandpe- semicircular canals: anterior, poste- posterior canal), causing ripheral vestibular mechanisms. Most rior, and horizontal. The semicircular canals are roughly orthogonal, and excessive commonly, the character of the diz- endolymph movement this orientation maximizes their ability ziness in these disorders is spinning and excitation of the vertigo, but as described in the prior to detect all angular head acceleration ampulla, which causes section, the clinician should not over- movements. The ampulla of each canal positional vertigo. rely on the quality of dizziness but is the motion sensor containing a bend- also look at patterns that include able cupula that responds to any move- timing, triggering events, associated ment of endolymph as occurs during features, and the examination for nys- angular head acceleration. Stimulation tagmus to improve diagnostic accuracy. (or inhibition) of the structures creates a volley of neural activity in the ampul- Benign Paroxysmal lary nerve that is carried via the vestib- Positional Vertigo ular nerves to the brain. BPPV is the most common disorder Each labyrinth also has a saccule and causing recurrent vertigo. The lifetime a utricle that are sometimes referred prevalence of BPPV is 2.4%, and the to as the otolith organs (because they 1-year prevalence is about 1.6%. Most contain otoconia), and these struc- spells of BPPV last a few weeks but tures contain the sensory epithelium may last much longer or become a re- known as the macula. Their function is current condition lasting years. BPPV is to detect linear or translational accel- also an important health issue in older eration (Figure 2-2), including detec- people since the incidence increases tion of forces such as gravity or with age and may contribute to falling accelerating or stopping in a car. and its associated morbidity. BPPV is caused when the calcium car- BPPV is characterized by episodic bonate otoconia erode or parts of them vertigo usually lasting from 10 to become dislodged. This debris may then 30 seconds. The spells of vertigo are inappropriately end up within the lumen evoked by certain tilting positions of of one of the semicircular canals, where it the head, rolling over while supine, or inappropriately stimulates the ampulla, straightening up after bending over. causing transient positional vertigo and The Dix-Hallpike maneuver is a sim- nystagmus. The calcium carbonate crys- ple bedside examination technique tals are more than twice as dense (spe- that induces the vertigo and nystagmus cific gravity 2.7 g/cm3) as endolymph of the most common form of BPPV (specific gravity 1.0 g/cm3), so they sink (Figure 2-1). Most cases of BPPV (85%) or move in the fluid within the semicir- are related to involvement of the cular canal in response to gravity. posterior semicircular canal, but the The triggering event and the direction horizontal (15%) or, far less commonly, of nystagmus will vary depending on the anterior semicircular canals (less the canal where the calcium carbonate

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KEY POINT h Benign paroxysmal positional vertigo is diagnosed by the presence of recurrent attacks of positional dizziness lasting less than 1 minute that are provoked by lying down or turning while supine and are associated with characteristic nystagmus.

FIGURE 2-1 Dix-Hallpike maneuver. The Dix-Hallpike maneuver for detection of right posterior canal benign paroxysmal positional vertigo (A) and for the left posterior canal (B). The patient is taken from the sitting position (1) to the head hanging on the respective side being tested (2).

Reprinted with permission from Barrow Neurological Institute. B 2007, 2008 Barrow Neurological Institute, Phoenix, Arizona.

material is located. That is, each canal to the left, the nystagmus changes to a has its own pattern of paroxysmal burst of left-beating nystagmus. The rar- positional nystagmus. The posterior est form is the anterior canal type, which canal type is upbeating and torsional, is downbeating, sometimes with a minor with the top pole beating toward the torsional component (Table 2-2).8 In downward ear. The nystagmus of hori- some instances, more than one canal zontal (lateral) canal BPPV is horizontal may be simultaneously affected. The and changes direction as the head po- most common form is simultaneously sition is changed (paroxysmal direction- bilateral posterior canal type, and the changing positional nystagmus). For second most common is simultaneous example, when the patient is supine with involvement of the posterior and hori- the head turned to the right, there is a zontal canals on the same side. burst of right-beating nystagmus, and, Diagnosis. BPPV is diagnosed by conversely, when the head is then turned the presence of recurrent attacks of

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Copyright © American Academy of Neurology. Unauthorized reproduction of this article is prohibited. KEY POINT h TABLE 2-2 Directional Features of Variants of Benign Paroxysmal The nystagmus of Positional Vertigo by Canal Type posterior canal benign paroxysmal positional Type of Benign Paroxysmal Direction of Paroxysmal Nystagmusa vertigo is characteristic. Positional Vertigo (BPPV) (Fast Phase Direction) For left posterior canal Right posterior canal BPPV Upbeating, counterclockwise torsional benign paroxysmal positional vertigo, Left posterior canal BPPV Upbeating, clockwise torsional which is evoked by Right horizontal canal BPPVb Geotropic direction-changing Dix-Hallpike positioning horizontal nystagmus to the left, a burst of clockwise torsional and Apogeotropic direction-changing upbeating nystagmus horizontal nystagmus occurs. For right b Left horizontal canal BPPV Geotropic direction-changing posterior canal benign horizontal nystagmus paroxysmal positional Apogeotropic direction-changing vertigo evoked by the horizontal nystagmus Dix-Hallpike maneuver to the right, a burst Right anterior canal BPPV Downbeating, slight torsional component of counterclockwise Left anterior canal BPPV Downbeating, slight torsional component torsional and upbeat a The determination of clockwise or counterclockwise is made from the examiner’s viewpoint. The nystagmus occurs. horizontal or vertical direction is determined as from the patient’s viewpoint (eg, right beating refers to nystagmus with fast phase toward the patient’s right side). b Determination of the side affected in horizontal canal BPPV is based in part on the side that produces the most intense nystagmus.7 positional dizziness lasting less than an upright position to a head-hanging 1 minute that are provoked by lying position while the head remains turned down or turning while supine and are 45 degrees to the side being assessed. associated with characteristic nystag- Performing the Dix-Hallpike maneuver mus (Table 2-2).9 The history is gener- to the side affected by posterior canal ally adequate to make a presumptive BPPV results in a burst of torsional and diagnosis of BPPV, but observing charac- upbeat nystagmus that ensues after a teristic nystagmus upon examination short latency, which is usually approxi- confirms the diagnosis (Case 2-2). Oc- mately 2 to 15 seconds. The latency can casionally, patients with strong symp- occasionally be long enough that the toms or who are especially prone to nystagmus can be missed if the patient motion sickness report mild nausea and is not observed in the head-hanging floating dizziness for several hours after position for long enough. The direction the positional vertigo. However, most of the nystagmus as well as the side of patients are well between episodes. positioning help identify the affected Vertigo that continues for more than canal. For example, with BPPV affecting 2 minutes or that does not seem con- the left posterior semicircular canal, the sistently evoked by position changes nystagmus seen with the Dix-Hallpike should lead the clinician to consider maneuver to the left is clockwise tor- alternative causes. sional admixed with upbeat nystagmus. The Dix-Hallpike maneuver is used Meanwhile, with BPPV affecting the to diagnose the posterior canal type of right posterior semicircular canal, the BPPV (Figure 2-1). The maneuver is nystagmus with Dix-Hallpike position- performed by moving the head from ing to the right is counterclockwise

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FIGURE 2-2 Anatomy of the membranous labyrinth including the cochlea; the superior and inferior vestibular nerves; the anterior, horizontal, and posterior semicircular canals; and the otolith organs, the utricle, and saccule. The ampulla contains the structures to detect endolymph flow within each semicircular canal.

Reprinted with permission from Barrow Neurological Institute. B 2007, 2008 Barrow Neurological Institute, Phoenix, Arizona.

torsional and upbeating. By conven- lar canal. During performance of the tion, the direction of the nystagmus is Dix-Hallpike maneuver, if the head is defined by its fast phase. turned to the side enough, it is possi- The horizontal canal form of BPPV ble to elicit the horizontal direction- occurs when the calcium material changing nystagmus of the horizontal moves within the horizontal semicircu- form of BPPV. Nevertheless, the best

Case 2-2 A 67-year-old man came to the office for a neurologic consultation for vertigo that had begun 6 months prior to presentation. He recalled having a feeling of severe spinning that occurred when he would get out of bed but also occurred periodically when working on his car or around the house. The spells lasted less than 1 minute and never came on when he had been completely motionless. The spells initially abated after about 1 month after their onset, and he had been free of the vertigo until about 4 weeks ago, when it suddenly recurred upon trying to get up after working on the plumbing under his kitchen sink. Although he had not fallen, he periodically staggered and experienced intermittent dizziness when active. Examination was normal, but the Dix-Hallpike maneuver to the right side revealed an upbeating and counterclockwise torsional paroxysmal positional nystagmus that developed after a several-second latency and reproduced his symptoms. A canalith repositioning maneuver was performed, and upon repeating the maneuver, no further nystagmus or symptoms were present. Comment. This case is a classic example of benign paroxysmal positional vertigo of the posterior canal. Some patients may have an idea what side is more likely to cause the symptoms, but not all patients have deduced that it is triggered by position changes. Treatment is highly effective.

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Copyright © American Academy of Neurology. Unauthorized reproduction of this article is prohibited. KEY POINT method for inducing the nystagmus of terial is adherent to the cupula rather h Three forms of horizontal canal BPPV is to perform a than the more common canalolithiasis, benign paroxysmal supine head turn test, sometimes re- in which the calcium freely moves within positional vertigo occur 7 ferred to as the Pagnini-McClure supine the lumen of the semicircular canal. (one form for each head turn test (Figure 2-3). While the The least common form of BPPV canal). There is one type patient is supine, quickly turning the involves the anterior semicircular ca- of nystagmus for head to the right results in robust nal. When present, it produces parox- posterior canal benign right-beating nystagmus and, once ysmal downbeat positional nystagmus paroxysmal positional abated, quickly turning the head to with the Dix-Hallpike maneuver. Be- vertigo (the most the left results in robust left-beating cause this form of BPPV is typically common type), two horizontal nystagmus. Thus, direction- very short-lived, no treatment maneu- forms of positional nystagmus for changing positional nystagmus is re- vers have been established, although horizontal canal benign vealed, and it is considered geotropic maneuvers for posterior canal BPPV paroxysmal positional (toward the ground) because the are often employed. When identifying vertigo (geotropic and nystagmus beats toward the down- downbeat positional nystagmus in a apogeotropic), and one ward ear and toward the ground. The patient, it is important to remember form that is usually very geotropic form of horizontal canal that this may also be seen in central short lived for anterior BPPV is the most common, but a less nervous system (CNS) lesions near the canal benign paroxysmal common form in which the nystagmus cervicomedullary junction. Persisting positional vertigo. is apogeotropic (nystagmus beats and consistent downbeat positional Recognizing these away from the ground) may also occur. nystagmus should raise suspicion for forms of nystagmus The latter form of horizontal canal BPPV a brainstem or cerebellar process. will make it easier to has been considered suggestive of Differential diagnosis. Of course, recognize an outlier form of positional nystagmus cupulolithiasis, in which calcium ma- it is important to distinguish central that could be central in origin.

FIGURE 2-3 Supine head roll test (Pagnini-McClure maneuver) to determine the presence of horizontal canal benign paroxysmal positional vertigo. The patient’s head is turned rapidly from the straight-supine position (1) to the head right position (2) while observing for nystagmus. The patient is then taken back to the straight-supine position (1), and then from there, the head may be turned quickly to the left (3), again observing for nystagmus.

Reprinted with permission from Barrow Neurological Institute. B 2007, 2008 Barrow Neurological Institute, Phoenix, Arizona.

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KEY POINTS Prognosis. Therecurrencerateof h The canalith repositioning causes of vertigo from BPPV. Knowing maneuver is intended to and recognizing the patterns of nystag- BPPV after successful treatment at 4 years move, by the effect of mus characteristic of BPPV will aid in is about 30%, but most recurrences oc- gravity, the calcium recognizing when a type of positional cur within the first 6 months of symp- 12 carbonate material out of nystagmus ‘‘does not fit’’ with BPPV tom onset. Women are more prone the affected semicircular and, thus, may be of central origin. Cen- to developing BPPV and having recur- canal and back in the tral lesions may not necessarily be trig- rences, but some patients are likely main vestibule/utricle gered by positioning on one side only. more innately susceptible to BPPV and region from which The nystagmus may persist or be dis- prone to more recurrences.13 it originated. sociated (ie, both eyes are not moving h Two effective in the same way) or may be accompa- Vestibular Neuritis treatments exist for nied by slower, irregular eye move- Vestibular neuritis (also referred to as posterior canal benign ments. A general rule is that if the vestibular neuronitis, epidemic ver- paroxysmal positional nystagmus is typical of posterior canal tigo, vestibular paralysis, labyrinthitis, vertigo: the canalith BPPV and resolves with treatment, the and neurolabyrinthitis) is an acute pe- repositioning maneuver diagnosis is correct. If the nystagmus ripheral vestibular process most com- and the Semont monly due to reactivation of latent liberatory maneuver. is atypical of BPPV (eg, spontaneous, present with gaze testing, and if nys- herpes simplex virus in the vestibular These treatments are 14 safe and effective for tagmus fails to resolve with treatment ganglion. Degeneration of peripheral the most common of BPPV), then central causes should vestibular nerve fibers and of the (posterior canal) form of be considered. neuroepithelium of peripheral recep- benign paroxysmal Treatment. The canalith reposition- torshasbeenobservedonhistopatho- positional vertigo. ing maneuver is intended to move, by logic examination.15 h The recurrence rate of the effect of gravity, the calcium car- By one commonly used definition, benign paroxysmal bonate material out of the affected the term vestibular neuritis causes positional vertigo after semicircular canal and back in the only unilateral vestibular dysfunction successful treatment at main vestibule/utricle region from and does not affect hearing.16 On the 4 years is about 30%, which it originated. The canalith re- other hand, la byrinthitis refers to acute but most recurrences positioning maneuver (also referred unilateral loss of both hearing and occur within the to as the Epley maneuver) is the most vestibular function usually attributed first 6 months of commonly used (Figure 2-4), but a to a viral infection. symptom onset. second typeVthe Semont liberatory Vestibular neuritis most commonly h Vestibular neuritis is maneuver (Figure 2-5)Vis also highly affects the superior division of the most commonly due to effective.10,11 If properly done, these vestibular nerve, less commonly affects reactivation of latent treatment methods have nearly the both the superior and inferior divisions herpes simplex virus in same success rate of about 90% in together, and yet less often affects only the vestibular ganglion. eliminating symptoms and nystagmus the inferior division.14 The superior by the same or next day. Generally, anti- vestibular nerve division innervates the vertiginous medications such as mecli- anterior and horizontal semicircular zine are unnecessary unless the patient canals and the utricle and, if severely is exceptionally prone to motion sick- affected, results in caloric vestibular ness. Anxiolytic medications such as loss on the affected side. The inferior benzodiazepines do not detract from vestibular nerve division innervates the success of treatment and may have the saccule and the posterior semicir- a role when patients feel too anxious to cular canal,17 and isolated involvement proceed with treatment. Rarely, BPPV does not result in reduced caloric ves- can be refractory to repositioning ma- tibular responses on the affected side. neuvers and requires surgical occlusion The selective vulnerability of the supe- of the affected semicircular canal. rior vestibular nerve division may result

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Copyright © American Academy of Neurology. Unauthorized reproduction of this article is prohibited. FIGURE 2-4 A stepwise method of performing the canalith repositioning maneuver for right posterior canal benign paroxysmal positional vertigo. Step 1, The patient is positioned so he or she may be taken back en mass to avoid neck strain or forced hyperextension to the head-hanging position with the neck in slight extension. This is essentially the Dix-Hallpike maneuver. Step 2, Observe the eyes, holding them open if necessary. Wait for all the nystagmus to stop and then continue to wait about 15 additional seconds. Step 3, Keeping the head back with the neck slightly hyperextended, turn the head toward the opposite side and wait 20 seconds. Step 4, Roll the patient all the way in such a way to allow the head to be turned to face the ground and wait 20 seconds. Step 5, From this side-lying face-to-the-ground position, have the patient sit up. Hold the patient to stabilize him or her for 15 seconds or so. The procedure may be repeated once or twice.

Reprinted with permission from Barrow Neurological Institute. B 2007, 2008 Barrow Neurological Institute, Phoenix, Arizona. from its longer course in a more nar- The time course of vestibular neu- rowed pathway in the temporal bone ritis and labyrinthitis are similar to that makes it susceptible to the effects one another. Vertigo usually begins of swelling and entrapment. suddenly or may evolve over a period

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KEY POINT h Gaze-evoked nystagmus is nystagmus that changes direction with alterations in the direction of gaze and is a central nervous system finding. Direction-fixed nystagmus is nystagmus that beats in the same direction regardless of the direction of gaze and is more typical of peripheral vestibular loss, particularly if it intensifies with gaze in the direction of the fast phase of nystagmus (ie, it follows the FIGURE 2-5 Steps in performing the Semont liberatory maneuver to treat right posterior canal benign paroxysmal positional vertigo. Step 1, Start with the patient sitting Alexander law). on a table or flat surface with the head turned away from the affected side. Step 2, Quickly put the patient into the side-lying position toward the affected side, with the head turned up. Nystagmus will occur shortly after arriving at the side-lying position. Keep the patient here until at least 20 seconds after all nystagmus has ceased. Step 3, Rapidly move the patient back up and through the sitting position without stopping and continue moving the patient to the opposite side-lying position with the head facing down (head should not turn relative to the shoulders during the position change). Keep the patient in this position for about 30 seconds (some recommend up to 10 minutes). Step 4 (not depicted), From the position shown as Step 3, have the patient sit back up to the sitting position.

Reprinted with permission from Barrow Neurological Institute. B 2007, 2008 Barrow Neurological Institute, Phoenix, Arizona.

of 30 minutes to a few hours or, less direction of gaze. The nystagmus fast commonly, in a stuttering course over phase increases during gaze in the several weeks. Once patients have been direction of the fast phase and dimin- having vertigo for 20 to 30 minutes, ishes or abates entirely with gaze away most people experience nausea and from the fast phase of nystagmus. This vomiting, although this depends also is referred to as the Alexander law6 and on the severity of the vestibular asym- is characteristic of acute peripheral ves- metry. Vertigo is present in all head tibular loss, as mentioned in a previous positions but is aggravated by head section. The nystagmus of acute unilat- motion of any kind and even by seeing eral vestibular loss decreases within things in motion; it gradually abates in the first 12 to 36 hours in most cases, the days and weeks that follow. although in some patients this may last Examination can be very helpful and as long as 1 or 2 months. Generally, usually confirms the diagnosis and re- however, the spontaneous nystagmus veals the side affected. Acutely, and if subsides within 1 to 2 days after the significant vestibular asymmetry is pres- onset, and then the nystagmus can be ent, spontaneous horizontal nystag- seen only with gaze in the direction of mus may be seen that has a fast phase the fast phase. Eventually, the nystag- beating away from the affected ear. musisnolongervisibleorelicitableas Importantly, the direction of nystagmus the patient compensates. At this point, does not change with changing the the clinician needs to rely on caloric

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Copyright © American Academy of Neurology. Unauthorized reproduction of this article is prohibited. KEY POINT testing or the head impulse test to taken for vestibular neuritis, particu- h Acute unilateral confirm unilateral vestibular loss. Recall larly in the absence of unilateral loud peripheral vestibular loss that horizontal nystagmus in vestibular tinnitus or mention of hearing loss. associated with acute neuritis results from hypofunction of Attacks of Meńie`re disease, however, vestibular neuritis the horizontal semicircular canal. How- usually subside within 8 hours, where- usually results in ever, occasionally vestibular neuritis af- as residual symptoms usually continue nystagmus beating fects only the inferior vestibular nerve, for days to weeks in vestibular neuritis. away from the affected which does not innervate the horizontal If the patient reports a prior history of ear, which follows the canal; therefore, there may be dizziness a similar attack, Meńie`re disease might Alexander law, as well but no nystagmus. be more highly suspected since recur- as a head impulse test The differential diagnosis of acute rences of vestibular neuritis are low, at that is abnormal with quick head turns toward vestibular neuritis is limited but impor- about a 2% over a lifetime.20 the side affected. No tant. The most concerning issue is an Inmostcerebellarorbrainstem diplopia or limb isolated infarct of the posterior circula- strokes, other neurologic signs occur, incoordination occurs. tion.18 These syndromes are discussed such as unilateral dysmetria, slurred later in this article. speech, hemibody numbness, diplo- While small isolated cerebellar in- pia, or nystagmus that changes direc- farcts can mimic the history of vestib- tion when changing the direction of ular neuritis, the examination19 can gaze (gaze-evoked nystagmus). The separate these clinical entities fairly head impulse test is typically abnormal well, obviating the routine need for CT in peripheral causes and not abnormal angiography or magnetic resonance in most central disorders. Nystagmus of angiography (MRA) for clinicians who peripheral origin follows the Alexander learn how to carefully examine this law, as previously mentioned, and patient population. The first attack of remains unidirectional (Case 2-3). Meńie`re disease might easily be mis- Meanwhile, central nystagmus may

Case 2-3 A 76-year-old man presented to the emergency department because of acute vertigo that began 3 hours earlier. He had not been recently ill and recalled no similar vertigo in the past. On evaluation, the patient sat quietly on a gurney with an empty emesis basin by his side. He denied hearing loss, slurred speech, numbness, or double vision but reported feeling intense spinning and nausea. Examination revealed spontaneous right-beating nystagmus that appeared more intense when he looked to the right and that lessened in severity but continued to beat toward the right when he looked to the left. Head impulse testing appeared abnormal with quick turns to the left, but this testing made him feel more nauseated. Finger-nose coordination was normal, and his speech articulation was normal. No diplopia or evident ocular malalignment was seen on examination. He could walk a few steps but was cautious and had to hold on for balance; after reassuming his place on the gurney, he began to vomit. Comment. This case shows many of the characteristic features of acute left peripheral vestibular loss as would be seen with acute left vestibular neuritis. The nystagmus beats away from the hypofunctioning ear and remains fixed in terms of its direction, always beating to the right. Furthermore, the nystagmus follows the Alexander law, being more intense with gaze in the direction of the fast phase and less intense or gone with Continued on page 372

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Continued from page 371 gaze in the opposite direction. Head impulse testing is abnormal with quick turns to the left so that a catch-up saccade occurs. No diplopia is noted, and finger-nose coordination is symmetric and intact. Gait is affected, but with effort the patient can walk a bit, and movement aggravates the nausea. The main differential diagnosis would be a small cerebellar stroke; but in that case, the head impulse test would likely be normal, and if nystagmus was noted, it would change direction with changes in the direction of the gaze. In this case, the clinical and examination findings are highly supportive of peripheral vestibular loss. However, physicians may vary in their confidence of the examination and findings, particularly in someone with vascular risk factors. Consequently, the decision to obtain brain or vascular imaging remains a matter of clinical judgment by the evaluating physician.

change direction with changes in the Treatment of vestibular neuritis in direction of gaze or may be purely the first 1 or 2 days can be simply vertical or cyclotorsional. supportive and incorporate use of ves- Diagnostic vestibular testing using tibular suppressants as needed for videonystagmography with caloric nausea (Table 2-3). These medications testing can identify unilateral periph- should be discontinued within days to eral vestibular loss, which can be a clue a week as they may delay or limit CNS to the affected side long after vestibu- adaptation to the acute vestibular loss. lar loss has occurred. When more than Acute use of prednisone 60 mg/d for 24% asymmetry in caloric vestibular 1 week may help reduce the severity of nystagmus occurs, pathologic loss of vestibular neuritis if given in the first vestibular function may be present that few days, but insufficient evidence exists is related to the horizontal semicircular for greater functional improvement canal function. Videonystagmography based on currently published data. Herpes zoster oticus is due to re- need not be carried out in the first activation of latent varicella-zoster virus days of the vertigo, as unilateral ves- in the geniculate ganglion and may tibular loss remains detectable for cause hearing loss or ipsilateral pe- the rest of the patient’s life if perma- ripheral facial paresis. If varicella zos- nent vestibular loss is present. As men- ter is suspected, the patient should be tioned previously, the head impulse treated with corticosteroids and either test is another method for determin- acyclovir, famciclovir, or valacyclovir ing unilateral vestibular loss of the in high oral doses. With herpes zoster horizontal canal. oticus, the clinician should look care- Vestibular neuritis is not associated fully for painful vesicles on the posterior with slurred speech, diplopia, headache, auricle of the external ear or within the paresthesia, focal weakness, or limb back of the external ear canal. If the ataxia, so the presence of these symp- patient has significant localized ear pain toms should prompt further investiga- and the tympanic membrane appears tion. When vestibular neuritis is due normal, it is probably prudent to treat to herpes zoster oticus (Ramsay Hunt with one of the antiviral agents even in syndrome), pain in or around the af- the absence of visible vesicles. fected ear may occur, as described in Once nausea has subsided suffi- the following section. ciently to allow it, the patient should

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Copyright © American Academy of Neurology. Unauthorized reproduction of this article is prohibited. KEY POINT h TABLE 2-3 Motion Sickness and Vestibular Suppressant Medications For patients who are symptomatic for at least Most Common 1 week after vestibular Medication Dosage and Form Adverse Effects neuritis, vestibular rehabilitation improves Dimenhydrinate 50 mg orally 2 times a day Urinary retention, dry mouth functional outcome Meclizine 12.5Y50 mg orally 3 or 4 times Urinary retention, dry mouth compared to those a day that do not receive Promethazine 12.5Y50 mg orally or IM every Dose-dependent sedation, such therapy. 4Y6 hours; 50 mg rectal slightly lowered seizure suppository 4 times a day threshold Lorazepam 0.5Y2 mg 2 or 3 times a day Dose-dependent sedation Diazepam 2Y5 mg orally 3 to 4 times Dose-dependent sedation a day Clonazepam 0.25Y1 mg orally 2 or 3 times Dose-dependent sedation a day Scopolamine 1 (1.5 mg) patch every 3 days Urinary retention, dry mouth Metoclopramide 10Y20 mg orally every Extrapyramidal effects 4Y6 hours; 10Y20 mg IV every 6 hours Prochlorperazine 10Y20 mg orally every 4Y6 Extrapyramidal effects hours; 10 mg IV every 6 hours; 25 mg rectal suppository every 6 hours Ondansetron 4Y8 mg orally, sublingually, or Fatigue, diarrhea, potential IV every 4Y6 hours to prolong QT interval IM = intramuscular; IV = intravenous.

begin moving his or her head from side ous attacks of vertigo usually described to side, extending the activity each day as spinning, unilateral hearing loss, until the patient can undergo more ex- ear fullness, tinnitus. The prevalence of tensive vestibular exercises. Table 2-4 Me´nie`re disease is about 1 in 150,000 gives an example of some general exer- people, affecting men and women cises for patients to promote CNS adap- about equally. The peak incidence is tation, but it is probably better to have a between 40 and 60 years of age. therapist knowledgeable of techniques The role for the neurologist in this of vestibular rehabilitation to tailor an disorder is both to make the correct exercise program to the patient’s needs diagnosis and to exclude any neuro- based on a hands-on assessment. Ves- logic disorders that might account for tibular rehabilitation promotes CNS ad- the symptoms while also initiating aptation21,22 to the unilateral loss and treatment with a low-sodium diet and improves functional outcome in patients possibly the addition of a mild di- with unilateral vestibular loss.23,24 uretic. As long as patients are controlled acceptably, the patients can be fol- Me´ nie` re Disease lowed, but if recurrent attacks of vertigo Me´nie`re disease is an inner ear disorder continue, then referral to an otolaryn- characterized by recurrent, spontane- gologist is indicated.

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TABLE 2-4 Home Habituation Exercises for Patients for Recovery From Vestibular Loss

Exercise Description Fixation during Turn your head quickly from side to side and then up and down while focusing on head turning your thumb held out directly in front of you. As you move your head, move your thumb so that it is right in front of you so that you can keep your focus on it. As you move your head, your focus should be fixed on your thumb. Repeat these exercises for 30 to 60 seconds at least 5 times daily. This exercise helps to improve your ability to focus on objects while your head is moving from side to side. Head movement Practice slowly turning your head from side to side while seated and then later while habituation standing with your feet shoulder-width apart. Gradually increase the speed of the head movements. The head turning can include side-to-side and up-and-down movements rapidly and repetitively, with eyes open and in good lighting. When you can do this standing still, try to walk (eyes open) forward while turning the head side to side, gradually increasing the speed of head turns. This helps you become more used to rapid movements of the head, which are often a source of momentary imbalance. Rapid head Practice getting up from the lying-down position to standing as quickly (but carefully) movement as possible. This may be done on a sofa or bed. Practice getting up toward the left habituation side and toward the right side while being careful not to fall. Get up quickly 5 times to each side, gradually trying to increase the quickness, but without falling. This helps improve the coordination of quick movements of the head and body. Rapidly bend over and then straighten 5 consecutive times. Do this exercise twice. Time yourself and try to gradually increase your speed; eventually, try adding an about-face (180 degree) turn after each bend. Tightrope exercise Walk heel to toe, as if walking a tightrope. This can be done in a hallway or corridor where there is something to hold on to, if needed. Gradually try to achieve 10 steps (heel touching toe) without holding on or taking a side step. This improves the inner ear balance and cerebellar balance function. Standing balance test Stand with feet together (touching) and try to maintain the position for 15 seconds. After you accomplish that, try closing your eyes with someone nearby to keep you from falling. Work to eventually be able to stand with feet together and eyes closed for 8 seconds. This trains you to keep your balance using ankle sensation and inner ear signals. If you are able to do this for 8 seconds, practice standing on one leg (eyes open) or while standing on a foam pillow. Eventually, try to stand for 10 seconds on foam with eyes closed and to stand on one leg for 12 seconds. Walk and quick turns Walk 10 steps down in a corridor or hallway and then turn right and walk back to the starting point. Do this 5 times with turning to the right, then 5 times with turning toward the left. Time how long it takes you, and try to improve your speed, being careful to avoid falling. This helps balance with walking and turns.

The history of Meńie`re disease is one The criteria importantly add documen- in which at least one attack of vertigo tation of characteristic low-frequency has occurred, usually lasting 20 minutes hearing loss (Figure 2-6), even if it is up to 12 hours (Case 2-4). If the patient only transient and resolves on a subse- is aware of fluctuating hearing or recent quent audiogram. When patients expe- unilateral hearing loss and changes in rience an attack of Meńie`re disease, the pitch and loudness of tinnitus, the they may exhibit this low-frequency history is very suspicious for Meńie`re hearing loss for up to a few days af- disease. New diagnostic criteria were re- terward, and with repeated attacks, cently published for Meńie`re disease.25 eventual permanent hearing loss occurs

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Copyright © American Academy of Neurology. Unauthorized reproduction of this article is prohibited. KEY POINTS Case 2-4 h Although the classic triad of hearing loss, A 42-year-old woman presented for evaluation after experiencing five tinnitus, and vertigo is prolonged attacks of vertigo during the prior year. Each vertigo spell came on seen with Me´ nie` re randomly and consisted of severe spinning with nausea and vomiting that disease, it is important lasted 2 to 3 hours. During these spells, she could not get up, walk, or move, to know that it causes and she tried to remain as motionless as possible. Just prior to the onset of the characteristic unilateral spinning she felt fullness in the left ear and heard a roaring tinnitus in the left low-frequency hearing ear, and her hearing became muffled on the left side. The vertigo abated loss with tinnitus and gradually, but after each event she continued to feel a little off balance for attacks of vertigo, with the rest of the day. The first episode occurred 1 year ago, and she did not nausea and vomiting have another until about 6 months ago, but at the time of presentation they usually lasting hours. seemed to be occurring more often and were very disruptive to her life since she worked as an intensive care unit nurse. h Me´ nie` re disease is Her examination was normal, and her hearing had improved since her last idiopathic but appears attack. Her brain MRI was normal. An audiogram showed about 35 dB of to be associated sensorineural hearing loss on the left only at the low frequencies, and her with a process of hearing on the right was completely normal. endolymphatic hydrops. Comment. A patient’s hearing may fluctuate in Meńie`re disease, and unilateral fluctuation is characteristic of the diagnosis, as is unilateral low-frequency hearing loss. Early in the course of Meńie`re disease, vestibular function as determined by videonystagmography with caloric testing may be normal so that the audiogram is more helpful and sensitive. Initial treatment includes a sodium-restricted diet with the possible addition of a diuretic. in ensuing months and years that may attack of Meńie`re disease could mistak- affect all the frequencies. enly be diagnosed as vestibular neuritis, Infrequently, patients may experi- but if multiple vertigo attacks occur, the ence sudden unexpected falls without diagnosis of vestibular neuritis should loss of consciousness. These drop at- be abandoned. tacks are referred to as otolithic crises Meńie`re disease is idiopathic but of Tumarkin and may lead to serious appears to be associated with a process injury. They may occur presumably of endolymphatic hydrops. Endolymph from either mechanical deformation has the electrolyte composition similar or from sudden surges of nerve activity to intracellular fluid (high potassium, related to the utricle or saccule. This, in low sodium), and perilymph is similar turn, distorts the patient’s sense of in composition to extracellular fluid vertical, resulting in the reflexive loss (low potassium, high sodium). Each of tone and a fall. compartment is separated, and the elec- The main differential diagnosis is trolyte concentrations are maintained between Meńie`re disease and vestibu- by active transport. Endolymphatic lar migraine. The key distinction is a hydrops is a process whereby the greater likelihood of migraine in the perilymph enters the endolymph space personal history and the absence of by osmosis and thereby causes transient characteristic hearing loss in vestibular dysfunction of the peripheral vestibular migraine. Interestingly, Meńie`re dis- and hearing end organs as these re- ease and migraine occur together more gions of the membranous labyrinth than expected based on the epidemiol- swell. During periods of such swell- ogy of the two conditions. The first ing, acute asymmetry of vestibular

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FIGURE 2-6 Audiogram in a patient with Me´ nie` re disease on the right side demonstrating typical low frequency (250 Hz to 1000 Hz) sensorineural hearing loss. SDS = speech discrimination (the percentage of words correctly identified at an easily detectable sound intensity level).

function occurs, leading to vertigo, nau- dosed at 16 mg 2 times a day up to sea, vomiting, and acute asymmetry of 32 mg 3 times a day and can be obtained hearing, which causes louder tinnitus at compounding pharmacies through- (often described as roaring) and muf- out the United States. Betahistine is fled hearing in the affected ear. also available in most countries of the When endolymphatic hydrops is world. Betahistine is a potent hista- caused by a known cause such as syph- mine H3 receptor antagonist and ilitic otitis, the late effects of trauma, or weak histamine H1 receptor agonist, a viral infection or autoimmune mech- but the mechanism of betahistine in anisms, it is often referred to as Meńie`re Meńie`re disease is unknown. Some syndrome and delayed or secondary evidence suggests that this medication endolymphatic hydrops. affects histaminergic neurons of the Treatment during vertigo can con- tuberomammillary nucleus in the pos- sist of antivertiginous medications, as terior hypothalamus and also in the clinicians might consider for any cause vestibular nuclei.26 Other data sug- of acute vertigo (Table 2-3). Manage- gest a possible effect via H3 receptor ment of Meńie`re disease with a goal to antagonism and possible H1 receptor stop the recurrent vertigo and hearing modulation of the immune-regulatory symptoms should include a sodium- processes of the endolymphatic sac.27 restricted diet to about 1500 mg/d It should be noted that no modern and possibly the addition of a thiazide high-quality randomized clinical trials or another diuretic. Betahistine is not show that betahistine, sodium restric- approved for interstate transport in the tion, or diuretic use are beneficial United States but may have a role in in prevention of vertigo attacks in some cases of Meńie`re disease. It is Meńie`re disease.28

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Copyright © American Academy of Neurology. Unauthorized reproduction of this article is prohibited. For patients with disabling vertigo vestibular ablation procedure can result attacks from Meńie`re disease despite in bilateral vestibular loss. adhering to a sodium-restricted diet and using a diuretic, other approaches Bilateral Vestibular Loss should be considered by otolaryngol- Bilateral vestibular loss, sometimes re- ogists, including administration of ferred to as Dandy syndrome, denotes intratympanic corticosteroids or gen- bilateral peripheral vestibular loss.29 tamicin and endolymphatic mastoid Recognizing bilateral vestibular loss is shunt procedures. In cases not other- important to neurologists for three wise responsive, vestibular neurectomy reasons: (1) bilateral vestibular loss or labyrinthectomy are options, the can be very debilitating to the patient latter only if the patient is already deaf and is often but not always iatrogenic in the affected ear. Meńie`re disease (Case 2-5), (2) physicians must have may also become a bilateral process, some suspicion for the presence of but most commonly does so within the bilateral vestibular loss in order to first several years of symptom onset. even test for it and make the diag- Estimates on the incidence of bilateral nosis, and (3) bilateral vestibular loss Meńie`re disease vary widely, but are is partially remediable with proper generally between 15% and 20% when physical therapy.23 strict diagnostic criteria are used. When Bilateral vestibular loss may have present, bilateral involvement limits several causes, including ototoxic some of the destructive procedure medication exposure, bilateral Meńie`re options since treating both ears with a disease, neurosarcoidosis, bilateral ear

Case 2-5 A 53-year-old man with severe diabetes mellitus and diabetic neuropathy presented because of severe imbalance. He had developed pneumonia 7 weeks prior, and he had been admitted to the intensive care unit, was intubated, and received IV antibiotics for the subsequent 14 days. After he was extubated and started to move about, he noticed that he could not keep his balance well. Ever since he had been hospitalized, and despite outpatient physical therapy to regain his strength, he had been falling. His symptoms were especially severe in the dark such that he nearly always fell over. Sometimes, while watching television, he had noticed that the image oscillated with his own heartbeat, and sometimes he could not tell who was walking toward him unless he stopped walking himself and held still. Further history indicated that one of the antibiotics that had been administered for the treatment of his pneumonia was gentamicin. His examination showed a consistently positive Romberg sign and absent knee and ankle reflexes due to severe diabetic polyneuropathy (no worse than in the past). Head impulse testing was abnormal in both directions, and videonystagmography with caloric testing confirmed the absence of peripheral vestibular responses on both sides. Brain MRI was normal. Comment. This case illustrates one of the common causes of bilateral vestibular loss, which is due to exposure to an aminoglycoside. In this particular case, the patient had a preexisting severe diabetic polyneuropathy that is now compounded by the vestibular loss. In a sense, his vision is the only good sensory input he still has for maintaining balance.

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KEY POINTS h The most commonly surgery, some congenital disorders, and a positive Romberg sign, abnormal encountered cause of autoimmune inner ear disease. Among head impulse test responses related acquired bilateral these, the most commonly encoun- to both sides, and a dynamic visual vestibular loss is use tered cause of acquired bilateral vestib- acuity decline of three lines on a Snellen of a vestibulotoxic ular loss is use of a vestibulotoxic chart or Rosenbaum card during rapid medication, and medication, and gentamicin is the most side-to-side head shaking. Some mild gentamicin is the most common of these. Nevertheless, nearly nystagmus may be evident, but this is common of these. one-fourth of older patients with an generally not prominent if the vestib- h Bilateral peripheral imbalance of unknown origin have sig- ular loss is symmetric and chronic. vestibular loss should nificant bilateral vestibular loss, pre- Videonystagmography with caloric test- be considered in anyone sumably on a degenerative basis. ing shows bilaterally reduced nystag- with an unsteady gait, The symptoms may include some mus, and rotational chair testing would a positive Romberg sign, history of vertigo, but it is often minor, also be confirmatory of bilateral vestib- abnormal head impulse and the more vexing symptom for the ular loss if it shows reduced vestibulo- responses but an patient is unsteadiness that is worse ocular reflex gain responses during otherwise normal when walking, especially in darkness or chair rotations at all frequencies. examination, and a report of oscillopsia on uneven ground. However, if patients Treatment consists of stopping any (bouncy vision when make hand contact with a wall while offending cause or medication. The walking or moving). walking, their balance significantly im- next step in treatment is vestibular phys- proves as they gain sensory informa- ical therapy to promote adaptation and h The examination of the patient with bilateral tion about their body position through substitution, with the goal of improving vestibular loss often the upper limb, which can help in balance. Vestibular physical therapy includes a positive the absence of useful input from the can be helpful in achieving this in part Romberg sign, abnormal vestibular system. Oscillopsia, the per- by employing plastic properties of the head impulse test ception of bouncing vision, is a char- CNS and partly by using ‘‘substitution’’ responses related to both acteristic symptom of severe bilateral to better use vision and propriocep- sides, and a dynamic vestibular loss but is only notable in tive cues to stabilize gait and mobility. visual acuity decline of severe bilateral vestibular loss, so not Vestibular rehabilitation improves dy- three lines on a Snellen all patients have this symptom. Oscil- namic visual acuity, diminishes oscil- chart or Rosenbaum card lopsia occurs because each step or lopsia, and lessens asymmetry of during rapid side-to-side movement causes minor head oscilla- vestibuloocular function.23 head shaking. tions that are not countered well by the vestibuloocular reflex. Superior Canal In a patient with new unsteadiness Dehiscence Syndrome following a hospitalization and in whom Superior canal dehiscence syndrome no other cause is apparent, one should is an uncommon disorder caused by inquire whether the patient might have an abnormal opening (dehiscence) in received aminoglycoside antibiotics, the thin bony roof of the superior which could have caused bilateral ves- semicircular canal (Figure 2-7). The tibular loss. Unsteadiness may occur tendency for this may be related to within 1 to 3 weeks of administration of congenital thinning of the temporal an aminoglycoside. Some cases can be bone, which occurs in about 0.1% of due to overdosage of an aminoglycoside, the population. Once a bony opening but some individuals are particularly sus- has ‘‘eroded’’ through, this opening ceptible and may develop bilateral ves- renders the membranous labyrinth un- tibular loss even when the dosage is usually susceptible to changes in sound administered and monitored properly. and pressure. Patients commonly re- The examination of the patient with port autophony (hearing one’s own bilateral vestibular loss often includes voice and internal body sounds), ear

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Copyright © American Academy of Neurology. Unauthorized reproduction of this article is prohibited. KEY POINT h Superior canal dehiscence syndrome is caused by an abnormal opening in the bony roof of the superior semicircular canal probably due to congenitally thin bone in that region. It presents with various reports of dizziness, sensitivity to loud sounds, and autophony (ie, excessive hearing of one’s own voice, breathing, or body sounds). FIGURE 2-7 Depiction of superior canal dehiscence in which the roof of the superior canal is no longer enclosed in the temporal bone, resulting in intensification of sounds transmitted through the labyrinth and accounting for dizziness and autophony. Arrows show dehiscent region. A, Membranous labyrinth at rest; B, The arrow depicts reverberations through the dehiscence when exposed to sound.

Reprinted with permission from Barrow Neurological Institute. B 2007, 2008 Barrow Neurological Institute, Phoenix, Arizona. fullness or pressure, and various sen- difference), VEMP may serve as another sations of dizziness affected by certain way to ensure it is not a false-positive sounds, vibrations, or straining.30 A CT of the temporal bone. Tullio phenomenon (becoming dizzy This condition, when severe enough with exposure to some sounds) may to warrant it, is managed surgically and also be reported in some patients. Neu- should be referred to an otolaryngologist rologic examination is usually unreveal- for ongoing management. In order to ing in patients with this condition. The consider this disease as a diagnosis and audiogram may show mild conductive to make the proper referral, a certain hearing loss, but it is nonspecific. If awareness of this condition is important. the history prompts enough suspicion, the diagnosis is clarified by a thin-cut CENTRAL NERVOUS SYSTEM temporal bone CT and, if possible, cervi- CAUSES OF VERTIGO cal or ocular vestibular-evoked myogenic AND DIZZINESS potential (VEMP) testing may serve as a CNS causes of vertigo are, of course, physiologic confirmation. VEMP is an of great interest and concern to neurol- evoked potential related to saccule and ogists and other clinicians because of utricle function, but the waveform of a potentially more ominous progno- response in superior canal dehiscence sis if the cause is in the brainstem or syndrome is uniquely markedly increased cerebellum. The potential conditions and evoked with less stimulation.30 Since and lesions that may cause central ver- some temporal bone CT studies appear tigo are substantial, but fortunately, these to show an apparent dehiscence but causesarefarlesscommonthaninner actually are just very thin (and there is a ear causes. When due to structural

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causes, most lesions are located within tigo), vision (photophobia), and the the medulla, cerebellum, or pontine sense of smell (osmophobia).31 Both tegmentum and middle cerebellar pe- environmental and genetic factors par- duncle regions. Some central causes, ticipate in migraine-associated ver- such as anxiety, phobic dizziness, and tigo mechanisms. vestibular migraine, are not due to The dizziness of vestibular migraine structural lesions but are caused by varies both in duration and in descrip- more complicated mechanisms that tion from patient to patient and even are still poorly understood. sometimes in the same patient. Most otologic vestibular disorders have ste- Vestibular Migraine reotypic duration: episodes of BPPV last Migraine may be associated with vestib- 10 to 30 seconds, attacks of Me´nie`re ular symptoms such as episodic vertigo disease last hours, and vestibular neuri- and chronic motion sensitivity. Vertigo tis goes on for days to weeks. Migraine and motion sickness unaccompanied may behave quite variably in terms of by headache may also occur with spell duration. Most often, patients have migraine and together are referred to either recurrent random spells of dizzi- as migrainous vertigo, migraine- ness ranging from a few minutes to associated vertigo, or vestibular migraine. several weeks, and patients often have The pathophysiology of vestibular a general motion sensitivity and some- migraine is not known. Evidence times visual vertigo (Case 2-6). Visual suggests that certain brainstem nuclei vertigo, also called optokinetic motion may become hypersensitized, causing sickness, is a syndrome in which see- excessive sensitivity for pain recep- ing objects in motion (eg, moving ceil- tion (headache, allodynia), hearing ing fans, moving scenery, general visual (phonophobia), vestibular stimulation commotion, walking down grocery (vertigo, motion sickness, visual ver- store aisles) causes dizziness and

Case 2-6 A 38-year-old woman presented with a several-year history of recurrent spells of dizziness, which most commonly consisted of a rocking sensation that lasted for 30 minutes to half of the day and occasional sensations of spinning that lasted for 2 to 10 minutes. These symptoms were not provoked reliably by any particular circumstance, but rather seemed to occur randomly. Even between episodes of dizziness, she became motion sick easily when riding in a car or whenever exposed to motion or even when seeing things move around her. The patient experienced nausea that varied in severity along with the dizziness. She had migraine headaches, but most of the time they occurred at times separate from the dizziness. Her dizziness was worse when she felt fatigued or tired and when she was under more stress. She also noticed that drops in barometric pressure were associated with an increase in her dizziness. Her quality of life was severely impacted by these ongoing symptoms. Her examination was normal. Brain MRI and magnetic resonance angiography (MRA) of her head and neck had been recently performed and were normal. Videonystagmography testing and an audiogram were both normal. Comment. This patient had a typical presentation of vestibular migraine with mixed symptoms including rocking dizziness, spinning, and dizziness when exposed to motion and visual commotion. Because of the impact on the patient’s life, a migraine prophylactic should be considered.

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Copyright © American Academy of Neurology. Unauthorized reproduction of this article is prohibited. KEY POINTS sometimes nausea even if the individ- migraine prophylactic medications in h 32 Vestibular migraine ual is not in motion. Migraine head- the same way as migraine headaches. is a variant of migraine aches are also common in vestibular Although anecdotal, this author prefers in which vestibular migraine, although, in most cases, they platform treatment with either a tricyclic symptoms predominate. do not occur at the same moment as antidepressant, titrating from 50 mg/d Vestibular migraine the vertigo spell.33 to 75 mg/d at bedtime, or a seroto- should be considered in Recently published diagnostic cri- nin norepinephrine reuptake inhibitor a patient with multiple teria34 indicate that the diagnosis of (SNRI) such as venlafaxine, titrating to recurrent episodes of vestibular migraine is made by at least about 75 mg/d, especially when anxiety, vertigo or dizziness with five spells of dizziness, vertigo, and mo- panic attacks, or depression are prom- a prior history of tion sensitivity that last between 5 min- inent and nausea is less prominent. For migraine headaches and no hearing loss or utes and 72 hours and are associated those with lesser or no anxiety overlay other neurologic deficits with unilateral headache, photophobia and with more nausea or more head- on examination. or phonophobia, or a migraine visual aches, verapamil, titrating from 120 mg/d h aura that occurs in some of the dizzy to 240 mg/d, is a well-tolerated medi- Currently, no randomized controlled spells. The criteria are not perfect but at cation, dosed as once daily if in the trials exist to guide least are a good start. Diagnostic testing extended release form, and dosed at 3 treatment of vestibular is generally not helpful except to exclude times a day if in the regular formulation, migraine, so other causes. Hearing is unaffected, with seemingly good efficacy. Topira- management currently brain and vascular imaging is normal, mate dosed between 50 mg/d and consists of the same and videonystagmogram testing is often 200 mg/d (started as a dose every medications used normal or nonspecific, showing only night at bedtime, but which may be for migraine headache some minor degree of static positional splittotwicedailyifitisbetter prophylaxis. nystagmus in a minority of patients. tolerated as the daily dosage is in- Vestibular migraine is not life- creased) is often effective. Topiramate threatening nor does it shorten life is difficult for many patients because of span; however, it may have a dramatic its side effects, but it is reasonable to impact on quality of life and may, in offer the medication when outlining some cases, be disabling. Mild cases choices for patients to consider. Using a require no specific treatment and can combination treatment with two or even be managed with education, dietary three migraine prophylactic medica- and lifestyle changes where appropri- tions has been a helpful strategy in ate, and vestibular suppressant medi- many patients with severe vestibular cations (Table 2-3) if needed. migraine. In addition to the medica- When the symptoms are frequent tions listed above, other medications to or severe and interfere with quality of consider include zonisamide and oc- life, treatment with migraine prophylac- casionally acetazolamide. tic medication may be needed. These medications may include the daily use Chronic Subjective Dizziness of propranolol or similar $-adrenergic Chronic subjective dizziness refers to blockers (timolol, nadolol), tricyclic anti- a form of unexplained dizziness on- depressants (nortriptyline, imipramine, going for longer than 3 months. This amitriptyline), topiramate, divalproex name was aptly coined as it implies sodium, or verapamil. Unfortunately, chronicity and the subjective nature no randomized controlled trials have of the symptom; the name does not been performed to guide treatment or imply knowledge of its mechanism, compare medications to one another which is appropriate since the mech- for best effectiveness, and we do not anism is unknown.35 Recent ongoing know if vestibular migraine responds to efforts are underway to rename this

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condition or some variation of it as ‘‘per- is not worsened by head motion nearly sistent postural-perceptual dizziness.’’36 to the degree seen with most vestibular It is discussed here as a CNS cause of disorders. Symptoms are often wors- dizziness since it is highly likely to be a ened by sleep deprivation and stress complex syndrome related to behavior, (Case 2-7). Interestingly, some patients maladaptive adjustment to symptoms, have visual vertigo, and considerable but neurotransmitter function, and as yet not complete overlap exists with some unclear additional CNS mechanisms. presentations of vestibular migraine. As noted above, the syndrome of Cervical pain, migraine headaches, anx- chronic subjective dizziness is under- iety, and depression are common going a possible renaming to persistent comorbidities. Patients note aggrava- postural-perceptual dizziness.37 By tion of dizziness by complex stimula- whatever name, this condition affects tion including visual commotion, females about five to one over males flickering and sometimes fluorescent and is often described as a rocking or lights, scrolling on computer monitors, floating sensation without nausea and object motion in general, and not

Case 2-7 A 54-year-old woman presented with a 3-year history of dizziness that initially was intermittent but had become constant over the past year. She described a feeling of floating and lightheadedness and was mentally unable to focus. These symptoms were not provoked by anything but bothered her more when she was tired. She felt the sensation every day. She had no associated nausea, headache, prior motion sickness, or focal neurologic symptoms. She felt that she was at the end of her rope with the dizziness and had to stop working as a legal assistant 6 months ago, as she could not continue the stress of work, and she drove only very little. She periodically experienced panic attacks and felt that her life was spiraling out of control. She had sought medical advice extensively and had had a brain MRI, magnetic resonance angiography (MRA) of the head and neck, CT head and temporal bone, videonystagmography, audiogram, tilt table testing, extensive blood work, cervical spine MRI, and extensive cardiologic workup, all of which were normal. She had seen an endocrinologist, and she had tried lorazepam, which had helped slightly. In addition, she had been prescribed gabapentin, diuretics, meclizine, bupropion, and buspirone; had been advised to start a low-sodium diet; and went through 8 weeks of vestibular rehabilitation, all without clear benefit. She was desperate for relief. Her examination was completely normal, and she displayed a good ability to turn, to balance on one leg, and to walk quite normally. Comment. This case shows how some patients with chronic subjective dizziness have self-imposed restrictions on what they feel they can do, and how these restrictions seem to be out of proportion to the degree of expected impairment based on their examination and mobility. In this case, her extensive history indicated that she was very eager to find relief and demonstrated a willingness to try the recommendations of her physicians. In this kind of case, a selective serotonin reuptake inhibitor (SSRI) or serotonin norepinephrine reuptake inhibitor (SNRI), along with education about the nature of chronic subjective dizziness may be most helpful. Sometimes vestibular rehabilitation therapy can be helpful for restoring confidence and mobility.

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Copyright © American Academy of Neurology. Unauthorized reproduction of this article is prohibited. KEY POINTS infrequently by having too many sen- syndrome, and many other potential h Chronic subjective sory or cognitive inputs to juggle. causes. Many possibilities could under- dizziness (persistent Chronic subjective dizziness should be lie such symptoms at the outset, but postural perceptual suspected in a patient who feels severely the examination remains normal. The dizziness) is a disabled from chronic dizziness and yet presence of an anxious affect is not heterogenous group appears normal on examination and in itselfproofofcause,andTable 2-5 of conditions with a whom vestibular and cardiovascular describes differences between chronic common theme of evaluations have been unrevealing. subjective dizziness and vestibular nonvertiginous dizziness Chronic subjective dizziness may migraine, as these syndromes may look without nausea that develop de novo or may evolve after similar. Indeed, aside from nausea and may be chronic or some kind of emotionally impactful migraine headaches, considerable over- intermittent, may occur spontaneously or after event (eg, automobile accident, panic lap exists when the symptom is not a condition that causes attack), especially if associated with spinning vertigo but simply rocking or vertigo, and may dizziness or vertigo. Chronic subjective floating. Brain and cerebrovascular im- respond to some dizziness may linger following minor aging, vestibular testing, and audiometry selective serotonin head injury and become entwined with are all normal in this group of patients. reuptake inhibitors or some of the other symptoms of post- Because of the common co- serotonin norepinephrine concussive syndrome. occurrence of chronic subjective dizzi- reuptake inhibitors. The differential diagnosis of this com- ness and generalized anxiety, it is h Chronic subjective mon syndrome includes vestibular mi- tempting to consider this a cause and dizziness is a common graine, incompletely compensated effect phenomenon. This is possible but cause of chronic unilateral vestibular loss, superior canal not yet substantiated by the literature. nonvertiginous dizziness dehiscence syndrome, postural hypo- Treatment should first and foremost that may sometimes tension, postural orthostatic tachycardia consist of validation and education occur spontaneously but commonly develops after an emotionally impactful situation TABLE 2-5 Comparison of Clinical Features in Vestibular Migraine and Chronic Subjective Dizziness (eg, trauma, car accident, attack of Chronic vertigo, chronic stress Feature Subjective Dizziness Vestibular Migraine at work or home). Onset Abrupt (especially if Abrupt or gradual onset after an emotionally impactful event), less often gradual Description Rocking, swaying, Spinning, rocking, tilting, or floating floating, general motion intolerance, and motion sickness Migraine headaches Present in about Present in more than 80% 25% of cases of cases Anxiety Present in two-thirds Present in nearly one-half of cases of cases Effect of vestibular Modest improvement Minimal if any improvement rehabilitation therapy in some Examination Normal Normal, possibly cautious gait Nausea Uncommon Common Visual vertigo Common Common

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KEY POINT h Mal de de´barquement about the best understanding of this are still swaying or rocking. Usually, no syndrome refers to the perplexing condition. In many cases, associated nausea or motion sickness persistence of a rocking establishing rapport with the patient, occurs, and if they return to the motion sensation after a explaining the interplay between anxi- stimulus, such as getting back on the boating excursion or ety and dizziness, and treating any boat, the symptoms again abate. Its cruise and returning to remediable otogenic vestibular comor- cause is unknown but some have land. Symptoms may bidities goes a long way in allaying the speculated it to be a disorder of the last months to years, patient’s anxiety. In some cases, work- vestibular velocity storage mechanism and no treatment ing with a vestibular physical therapist with some limited ability to adapt. has been found to can help patients regain confidence, Table 2-639 lists proposed diagnostic be effective. hope, and improve anxiety.38 criteria for this disorder. Examination in Stress reduction, improved quality these patients is normal, and their gait of sleep, and possibly pharmaco- typically appears normal. No nystagmus therapy should be discussed if the is seen, and no abnormality on brain patient is severely troubled and wishes MRI or vestibular testing is present. to try treatment. Some patients improve The differential diagnosis for such well on selective serotonin reuptake dizziness includes vestibular migraine inhibitors (SSRIs), and some do not. and chronic subjective dizziness. Unlike This author prefers, based purely on vestibular migraine, no nausea occurs, anecdotal experience, the use of an and a history of migraine may not SNRI such as venlafaxine or duloxetine necessarily be present. Unlike chronic or possibly tricyclic antidepressants. subjective dizziness, the onset is typ- These medications usually require ically following disembarkment from about 4 to 5 weeks to assess effective- aboat. ness, so patients must be encouraged No established treatment is known, not to stop taking them too early to but a nonblinded nonrandomized trial reap the benefit. Vestibular suppres- suggests that inducement of readapta- sants seem to rarely be helpful, and tion of the vestibuloocular reflex may vestibular rehabilitation is helpful result in improvement.40 In this ap- mainly in those afflicted by avoidance proach, patients are exposed periodi- behavior and excessively cautious gait. cally to a rocking that mimics the pace Chronic subjective dizziness remains a and direction of their perceived sway common and challenging condition. while in a full-field optokinetic stimulus. Time will tell if this approach is truly Mal de De´ barquement effective in this group of patients. Syndrome Mal de de´barquement syndrome is an CENTRAL NERVOUS SYSTEM uncommon vestibular disorder charac- STRUCTURAL LESIONS terized by a persistent sense of rocking CAUSING DIZZINESS that continues after disembarking a Lesions that disrupt the vestibular path- boating excursion or cruise. Many in- ways of the CNS vestibular system can, dividuals experience transient ‘‘sea not surprisingly, lead to vertigo and legs’’ after returning to land after being imbalance. Any central (or peripheral) on a boat but, in a small percentage of process that leads to an acute vestibular people, the feeling persists sometimes asymmetry can lead to vertigo. The brain for weeks, months, or years. The syn- can adapt to this asymmetry over time, drome is most common in women and but imbalance may still occur if vestibu- has its onset soon after getting off a locerebellar pathways are impacted. For boat, at which time patients feel they example, a stroke may lead to sudden

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Copyright © American Academy of Neurology. Unauthorized reproduction of this article is prohibited. KEY POINTS h TABLE 2-6 Diagnostic Criteria of Persistent Mal de Structural, ischemic, De´ barquement Syndromea or degenerative central nervous system A. Onset of symptoms after exposure to passive motion,b such as following processes that affect travel by boat/cruise ship or airline the vestibular nuclei, flocculonodular lobe B. Main symptom is illusory rocking motion (vestibulocerebellum) of C. Symptoms improve with reexposure to passive travel, such as boat or car travel the cerebellum, the D. Nausea is not a prominent symptom cerebellar peduncles, and, very rarely, the c E. Minimum of 3-month duration of symptoms cerebral cortex (as may F. Not better accounted for by another International Classification of Headache occur with epileptic Disorders, Third Edition diagnosis or by another vestibular disorderd vertigo) may lead to a 39 central vertigo, Reprinted with permission from Saha K, Fife TD, Neurol Clin Pract. B 2015 American Academy of Neurology. cp.neurology.org/content/5/3/209.short. sometimes with b Exposure to passive motion must last at least several hours and more likely for days. accompanying c A diagnosis of mal de de´ barquement syndrome may still be made with symptoms lasting fewer than 3 months; however, for a diagnosis of persistent mal de de´ barquement syndrome, nystagmus. symptoms must have lasted more than 3 months. h Isolated vertigo d History and physical examination do not suggest another vestibular disorder, or another disorder was considered but excluded by appropriate measures, or another disorder is as a manifestation of present but as an independent condition that may be clearly differentiated. epilepsy is rare, but when it occurs, is usually in individuals with known seizure onset of vertigo, whereas an acoustic ical features suggest seizures such as disorders and is neuroma (vestibular schwannoma) automatisms, loss of awareness, and exceptionally rare as grows so slowly that adaptation to the convulsions that follow the aura of ver- the presenting asymmetry occurs gradually and imper- tigo. Of course, a brain MRI should be manifestation of ceptibly. The result is that an acoustic performed when this diagnosis is new-onset epilepsy. neuroma is much less likely to present strongly considered. EEG monitoring with vertigo than an acute event such as may be necessary to confirm an ictal a stroke. process when no structural lesion is A CNS lesion that is anatomically identified on brain imaging. Differential related to vestibulocerebellar pathways diagnostic considerations could include may lead to vertigo, dizziness, or transient ischemic attacks, migrainous imbalance. Too many possible lesions vertigo, and an episodic ataxia syn- can occur to enumerate here, but the drome such as episodic ataxia type 2. location is the key to properly ascrib- Treatment would include standard ing the lesion to the report of dizzi- antiepileptic medications as with any ness or vertigo. Examples are outlined other seizure disorder. in Table 2-7. Craniocervical Junction Epileptic Vertigo Syndromes Epileptic vertigo is an ictal condition in Within the region of the craniocervical which a seizure involving the vestibu- junction are the vestibulocerebellum lar cortex is the cause of dizziness or and posterior medulla, which carry vertigo. This is a rare condition even vestibular pathways. Lesions in this among patients known to have epi- region may lead to vertigo, dizziness, or lepsy,butitisevenrarerforisolated imbalance. The most prototypical of vertigotobethepresentingfeatureof such lesions is a Chiari malformation, epilepsy.41 In most cases, other clin- but other disorders affecting this area

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TABLE 2-7 Central Nervous System Regions That May Be Associated With Vertigo, Nystagmus, or Ataxia

Anatomic Location Structures Affected Signs or Symptoms Lesion Example Dorsolateral medulla Vestibular nuclei, root entry Nausea, nystagmus, Medulloblastoma, zone cranial nerve VIII vertigo, ataxia metastasis, multiple sclerosis, medullary infarction Floor of fourth Vestibular nuclei, especially Nausea, nystagmus, Medulloblastoma, cysts ventricle superior vestibular nucleus vertigo, ataxia Anterior cerebellar Cerebellar connections Ataxia Alcohol-related vermis cerebellar ataxia Dorsal cerebellar Flocculus, nodulus, uvula Nystagmus, ataxia, Cerebellar degeneration vermis connections; dorsal vermis; possibly vertigo, fastigial nucleus saccadic dysmetria Superior cerebellar Cerebellar efferents Positional vertigo Multiple sclerosis peduncle Middle Pontocerebellar fibers Ataxia, dysarthria, Pontine infarct, cerebellar peduncle ipsilateral limb clumsiness cavernous malformation Inferior cerebellar Vestibulocerebellar afferents Isolated vertigo, possible Cavernous malformation, peduncle ipsilateral limb clumsiness arteriovenous malformation Anterior cerebellum Flocculus, nodulus, uvula Vertigo, ataxia, Basilar meningitis gaze-evoked nystagmus Vestibular cortex Right temporal perisylvian Vertigo Partial epilepsy cortexa Dorsal midbrain Rostral interstitial nucleus of Disconjugate vertical/ Cavernous malformation, medial longitudinal fasciculus, torsional nystagmus, pinealoma, arteriovenous interstitial nucleus of Cajal vertical gaze disorders malformation a A discreet region of the vestibular cortex has not been conclusively identified in humans.

KEY POINT include atlantoaxial subluxation, and, this condition may lead to occipital h The incidental more rarely, basilar invagination. headaches, vertigo, nystagmus, and discovery of a Chiari A Chiari malformation occurs when ataxia in early childhood or later in life. malformation on the lower part of the cerebellum does Some Chiari malformations are found routine brain MRI occurs not fully migrate rostrally during fetal incidentally on brain MRI without ever frequently, and physicians should development, so that the cerebellar causing symptoms, whereas other cases consider the more tonsils remain below the foramen have a slowly progressive course. One common causes of magnum. This may lead to symptoms commonly used radiographic definition headache and dizziness early or later in life due to compression defines the presence of Chiari malfor- such as migraine or of the brainstem or spinal cord or by mation if the cerebellar tonsils are more inner ear causes before disrupting the normal flow of CSF with than 5 mm below the foramen magnum.42 attributing these the subsequent development of a Treatment is based on symptom se- symptoms to the cervical syrinx. The Chiari malforma- verity and consists of suboccipital de- Chiari malformation. tion may occur due to disorders of fetal compressive surgery. Because of the development of the brain or skull. The prevalence of Chiari malformations as compression of the cerebellum from incidental findings on routine brain MRIs,

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Copyright © American Academy of Neurology. Unauthorized reproduction of this article is prohibited. KEY POINT care should be taken before ascribing Transient ischemic attacks in the h Vascular narrowing dizziness or headaches necessarily to vertebrobasilar arterial system may of the vertebral arteries the Chiari malformation without con- produce vertigo, imbalance and ataxia, can lead to episodes sidering more common conditions such slurred speech, nystagmus, diplopia, of inadequate blood as migraine or inner ear conditions. drop attacks, and visual hallucinations flow to the brainstem Atlantoaxial subluxation is a serious or visual field defects. Vertigo may be and cerebellum medical condition that is usually due an isolated initial symptom of verte- (vertebrobasilar to erosion or malformation of the brobasilar insufficiency43 or may be insufficiency) and may ligaments holding C1 and C2 together. accompanied by other brainstem cause isolated vertigo or Possible causes include traumatic rup- symptoms.18 In most cases, treatment ataxia in episodes lasting ture of the ligaments, Down syndrome, of vertebrobasilar insufficiency consists several minutes. and rheumatoid arthritis. Patients with of controlling vascular risk factors and atlantoaxial subluxation may experi- using antiplatelet drugs. Table 2-8 de- ence severe headaches, neck pain, and lineates the clinical features of several vertigo and should additionally be eval- brainstem vascular syndromes that can uated with flexion and extension cer- be associated with vertigo. vical spine radiographs since routine Cerebellar strokes affecting the dis- CT spine or brain MRI do not neces- tribution of the vertebral artery, poste- sarily show laxity in these ligaments. rior inferior cerebellar artery, anterior inferior cerebellar artery, or superior VASCULAR CAUSES OF VERTIGO cerebellar artery can result in isolated AND DIZZINESS cerebellar infarction (Case 2-8).44 If the Vertebrobasilar insufficiency occurs infarction affects portions of the cere- when there is inadequate blood flow bellum that carry vestibular fibers, through the vertebral and basilar ar- vertigo and ataxia may occur. Small teries that supply the brainstem and cerebellar infarctions in the cerebellar cerebellum. Momentarily insufficient hemispheres are more likely to result blood flow may cause symptoms be- in vertigo or substantial ataxia than are midline or parasagittal lesions such as cause of ischemia of the brainstem or those of the flocculus or nodulus. cerebellar structures, resulting in dizzi- Spontaneous intraparenchymal cer- ness. A focal area of vascular narrowing ebellar hemorrhage may present with is the usual cause. vertigo, nausea, vomiting, headache, If stenosis of the right or left sub- the inability to stand or walk, and uni- clavian artery is just proximal to the lateral limb clumsiness. Involvement origin of the vertebral artery, it may of the cerebellum can often be distin- cause reversal of blood flow in the guished from peripheral vestibular ipsilateral vertebral artery. This rare vertigo because the former results in situation is referred to as subclavian dysmetria and limb clumsiness, nei- steal syndrome because the subcla- ther of which occurs with peripheral vian artery ‘‘steals’’ blood flow from vestibular lesions. Brain imaging by CT the vertebrobasilar system to supply or MRI accompanied by vascular im- the upper limb. In such cases, vertigo aging by CT angiography or MRA are and other symptoms of vertebrobasilar essential in documenting the status of insufficiency may be caused or exacer- the cerebral vasculature. bated by exercise of the arm on the Conditions that can produce focal affected side. Vascular imaging may and transient neurologic findings that localize the site of the narrowing and could cause or mimic a transient ischemic the reversal of blood flow. attack but that do not show occlusion

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TABLE 2-8 Selected Vascular Syndromes Associated With Vertigo and Ataxia

Vascular Syndrome Blood Supply Common Cause Features Vertebrobasilar transient Vertebral arteries, basilar Atherosclerosis Vertigo, clumsiness, ischemic attack artery, posterior inferior ataxia, dysarthria, diplopia, cerebellar artery or drop attacks anterior inferior cerebellar artery, rarely superior cerebellar artery Lateral medullary infarction Posterior inferior Atherosclerosis Vertigo, ipsilateral facial (Wallenberg syndrome) cerebellar artery or vertebral numbness, limb clumsiness, artery dissection Horner syndrome, diplopia, lateral pulsion of saccades, asymmetric-gaze nystagmus, slurred speech, falling to one side, contralateral loss of pain and temperature sensation Lateral pontine stroke Anterior inferior Atherosclerosis Vertigo, ipsilateral facial cerebellar artery numbness, facial paresis, unilateral hearing loss, limb dysmetria, Horner syndrome, diplopia, lateral pulsion of saccades, asymmetric-gaze nystagmus, slurred speech, falling to one side, contralateral loss of pain and temperature sensation

KEY POINT of the vessels include cardiogenic vestibular system; such lesions may also h Patients with thromboemboli (including paradoxi- result in nystagmus, ataxia, slurred multiple sclerosis are cal emboli), hyperviscosity syndromes, speech, and diplopia. Despite the in- certainly predisposed complicated migraine, and, rarely, mi- creased risk of CNS causes in patients to central nervous system causes of tochondrial cytopathies. with MS, non-MS causes such as BPPV vertigo, but peripheral Specifics of the diagnosis and man- and vestibular migraine may also occur, vestibular disorders are agement of patients with transient and the clinician should be careful also common in ischemic attacks and stroke are outside about assuming that dizziness or vertigo this population. of the scope of this discussion; for more are directly related to MS. However, information, refer to the February 2017 in patients with known or possible MS, Continuum issue, Cerebrovascular Dis- the presence of gaze-evoked nystag- ease.45 For patients with completed mus, spontaneous upbeat or downbeat infarction, the addition of physical ther- nystagmus, periodic alternating nystag- apy may speed and improve return of mus, ocular bobbing, seesaw nystag- vestibular function. mus, pendular nystagmus, dissociated nystagmus with internuclear ophthal- Multiple Sclerosis moplegia, or upgaze restriction with Multiple sclerosis (MS) may present with convergence-retraction nystagmus are dizziness, vertigo, or imbalance, partic- strong indicators of MS involvement, ularly as a result of lesions affecting the since none of these forms of nystagmus brainstem or cerebellum that affect the can be of peripheral vestibular origin.

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Copyright © American Academy of Neurology. Unauthorized reproduction of this article is prohibited. Case 2-8 A 75-year-old man with a history of hypertension, hyperlipidemia, and coronary artery disease presented for acute vertigo and clumsiness on the right side with falling to the right side. He had experienced about 6 weeks of intermittent vertigo and had a pending appointment with an otolaryngologist for suspected benign paroxysmal positional vertigo, although he had not actually been examined yet. The recent spells of vertigo were random and would last for 2 to 5 minutes or so, and he would feel spinning and a bit ‘‘drunk,’’ but then they would pass. He ordinarily took aspirin but had stopped it over the past few months because of gastrointestinal upset that he thought might be due to the aspirin. On the day of presentation, he awoke from bed in the morning severely off balance, felt some spinning, and fell to the floor before he was brought to the emergency department by paramedics. Examination showed that his speech was mildly slurred, he had horizontal gazeYevoked nystagmus that was most prominent when looking to his right, and a right Horner syndrome was present. He had marked right hemiataxia, poor balance, and some reduced sensation to pinprick on the left side of the body when compared to the right side. Brain MRI showed a large cerebellar infarction on diffusion-weighted imaging, with some additional involvement of the right lateral medulla (Figure 2-8).

FIGURE 2-8 Brain MRI from the patient in Case 2-8. Diffusion-weighted images at two different levels (A, B) and the fluid-attenuated inversion recovery (FLAIR) image (C) demonstrate infarction of the right inferior cerebellum and right lateral medulla in the distribution of the right posterior inferior cerebellar artery.

Comment. Transient ischemic attacks may present with isolated spells of dizziness lasting minutes. In such cases, the spells are not positionally provoked, and in between spells no examination findings are seen. This patient was likely having transient ischemic attacks in the form of spells of isolated dizziness, and eventually he had a posterior inferior cerebellar artery occlusion that led to a large cerebellar and lateral medullary stroke (Wallenberg syndrome).

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KEY POINT h Episodic ataxia For patients with MS with vertigo, a for this condition. The diagnosis should type 2 is a rare standard examination for neurologic be suspected in a patient with a long disorder but is signs related to dizziness should be history of recurrent bouts of unex- important to identify undertaken. This should include the plained vertigo associated with slurred since the random Dix-Hallpike maneuver and possibly speech and ataxic gait. Downbeat spon- attacks of vertigo, ataxic additional vestibular testing if no other taneous or positional nystagmus even gait, and sometimes new CNS signs or MRI-evident lesions betweenspellsisverysuggestiveofthe slurred speech lasting are present. diagnosis but is not present in all minutes to several days Specifics of the diagnosis and man- cases. Brain MRI may show midline often dramatically agement of patients with MS are out- cerebellar vermis atrophy in some but respond to side of the scope of this discussion; not all patients. acetazolamide. for more information, refer to the The differential diagnosis includes June 2016 Continuum issue, Multiple spinocerebellar ataxia type 6 and ves- Sclerosis and Other Demyelinating tibular migraine, but in the case of the Diseases.46 However, for patients with latter, downbeat nystagmus would not central vertigo and nystagmus due to be expected. The diagnosis is made by MS, medications such as gabapentin, history and response to acetazolamide. 4-aminopyridine, memantine, and occa- Transient ischemic attacks from verte- sionally baclofen can sometimes help brobasilar insufficiency are also a differ- diminish the nystagmus and, to a lesser ential consideration. degree, the dizziness, if any occurs. This condition is an important treat- able cause of vertigo because ataxia and Episodic Ataxia Syndromes vertigo attacks may subside with the Episodic ataxia type 2 is a rare sporadic use of acetazolamide in daily doses usu- or inherited ataxia disorder character- ally ranging from 375 mg/d to 1500 mg/d. ized by recurrent episodes of vertigo Responsiveness to acetazolamide is and ataxia. The onset of symptoms may further confirmation of the diagnosis occur in childhood or early adulthood of episodic ataxia type 2. and may continue undiagnosed well Episodic ataxia type 1 is a separate into late adulthood. This disorder is disorder related to disturbances in due to various mutations in the P/Q- potassium channels and differs clinically type voltage-sensitive calcium channel because the attacks of vertigo and ataxia (CACNA1A) in the case of episodic are shorter in duration and may be as- ataxia type 2. sociated with myokymia even between Episodic ataxia type 2 manifests with attacks. If the patient has dysarthric recurrent vertigo and ataxia often asso- speech during spells or interictal ciated with downbeat nystagmus, both myokymia, episodic ataxia type 1 during and even between attacks of should be considered. Treatment for vertigo and ataxia. Some patients ex- episodic ataxia type 1 and other sub- hibit no abnormalities between attacks, types is not well established. but often downbeat nystagmus is seen in the supine position even between HEMODYNAMIC CAUSES spells. During spells, patients report OF DIZZINESS dizziness, loss of balance, and some- Orthostatic hypotension is common in times slurred speech that may last from older people and may cause dizziness minutes to a day or two. The episodes without documented syncope based on may begin in childhood and continue transient reductions in global cerebral into adulthood. No specific diagnostic blood flow. Periodic hypotensive epi- gene tests are commercially available sodes may also occur even after the

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Copyright © American Academy of Neurology. Unauthorized reproduction of this article is prohibited. KEY POINT patient has been upright for a period of and the severity is self-reported, it is h Delayed orthostatic time or when orthostatic vital signs have more challenging for the physician, hypotension may occur been normal. Orthostatic hypotension patient, and employer to reach an 5 to 30 minutes after may occur 5 to 30 minutes after being agreement that the patient can work the patient has been asymptomatic in the upright position, some or not at all. upright and is thus not so it can be missed as a cause of per- When a patient is affected by diz- identified by routine iodic syncope or presyncopal dizzi- ziness that is lacking objective findings, orthostatic vital signs ness.47 For a discussion of syncope several questions should be consid- but can be a cause of and presyncope, refer to the article ‘‘Syn- ered (Table 2-9). Having a clear and recurrent transient cope’’ by William P. Cheshire Jr, MD, credible diagnosis that explains symp- dizziness (or syncope). FAAN,48 in this issue of Continuum. toms is important, although under- standably, in some cases, a clear Disability and Impairment diagnosis is what is lacking. from Dizziness or Vertigo In such cases, awareness of whether In ambulatory neurology, it is not un- or not the occupation in question has common for the treating neurologist components considered to be ‘‘safety tobeaskedtoaddressthework sensitive’’ may influence the ap- capabilities of a patient with vertigo proach. Safety sensitive refers to any or dizziness. When clear neurologic activity where impaired performance deficits exist, as may be seen in the could result in significant harm to aftermath of a brainstem or cerebellar self or others. For example, a com- stroke, the treating neurologist is well mercial airline pilot who appears equipped to judge the patient’s limi- normal but reports periodic blackouts tations. Communication of these lim- or spells of disorientation cannot be itations to the workplace, if requested clearedtoreturntohisoccupation by the patient, is usually straightforward fromasafetystandpoint.Otherjobs and sufficient to satisfy any questions of may have safety-sensitive compo- work capacity. However, in cases where nents that are not as obvious or are the symptoms are entirely subjective less subject to regulation. In those

TABLE 2-9 Questions to Consider in Determining Work Capability in Patients With Subjective Dizziness

b Is there a diagnosis that explains the symptoms, and is the diagnosis certain? b What is the nature of the patient’s occupation? b Are there objective findings that support the patient’s diagnosis, and are such findings expected? b Is there congruence between the severity and limitations reported and actual activity limitations? b Is there consistency between the severity and the examination findings and observations? b Is the patient’s report and symptom description credible? b Is there consistency between the expected response to treatment and the actual response? b Does the patient appear compliant and eager to improve and return to work?

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cases, clear communication between individual with little or no concern the treating physician and the employer regarding his or her condition (in the will be necessary for all parties to arrive absence of any neurologic basis for at correct decisions regarding work. indifference). In cases of dizziness not involving When dizziness is considered to be safety-sensitive issues, verification of significant by the treating neurologist, the presence and severity of disease may typical restrictions (advice from a phy- be the more immediate concern. In sician on what not to do) for patients these cases, any objective findings would be to avoid working at heights that support the diagnosis and the greater than 6 feet without safety patient’s reported limitation can be harnessing or a railing. Other restric- important, but some conditions by tions might include avoidance of their nature (eg, vestibular migraine) climbing ladders to rungs greater than do not exhibit examination or test ab- 6 feet above the ground. Driving re- normalities. Consistencies between strictions are sometimes necessary, but reported symptoms and observations most forms of dizziness occur with add to credibility, whereas embellish- enough forewarning that driving can ment or exaggeration by the patient can be accomplished, and if vertigo ensues, detract from it. The impact of symp- the patient has time to pull over. This is toms on nonwork-related activities is generally true for vestibular migraine also important to consider since being a and for Meńie`re disease. Patients with little uncomfortable but still functional BPPV rarely get dizzy while driving since will likely not meet a reasonable thresh- the provocative positioning is unlikely old for complete impairment from work. to occur when driving. Beyond that, in In some cases, accommodations or the case of BPPV, treatment is so highly advice to avoid specific kinds of activi- effective that if a patient continues ties may be more appropriate than to have dizziness, one should question simply not working at all. For example, whether the diagnosis is correct, and if limitations in the number of hours correct, consider whether the treatment worked per week or in a given time maneuver has been done correctly. span may make sense in particular cases. Meńie`re disease can sometimes cause Finally, assessment of how hard the work impairment because attacks of patient is trying to overcome reported vertigo last hours, occur at unpredic- impairments, such as compliance with table times, and may have lingering recommended treatment, may be help- nausea and dizziness for 1 to 2 days ful in the assessment of work capacity. even after the full vertigo attack sub- Ordinarily, when a person is significantly sides. When evaluating a patient with impaired with regard to personal com- Meńie`re disease, however, the physi- fort, function, or both, a physician would cian should determine if the diagnosis expect to see evidence of reasonable appears correct since it is often mis- interest in and effort toward improving. diagnosed or listed as a potential cause. The absence of such evidence may call Unilateral hearing loss is almost a sine into question the severity of the re- qua non of Meńie`re disease that is ported symptoms. In addition, re- severe enough to cause impairment, so sponses to treatment successes and if audiometry is normal, the physician failures can be weighed in terms of should question this as the basis for any whether or not they are consistent with work impairment. a significantly impaired person who is Vestibular migraine can sometimes attempting to improve, or more like an cause impairment, but this is uncommon.

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Copyright © American Academy of Neurology. Unauthorized reproduction of this article is prohibited. Most patients can improve substantially CONCLUSION with treatment using one or more mi- Dizziness and vertigo are very common graine prophylactic medication com- symptoms, and determining the cause bined with lifestyle adjustments. of dizziness and vertigo requires a com- Work restrictions and accommoda- bination of a careful history as well as tions should not be required for acute consideration of the quality of the symp- vertigo for more than a temporary toms, triggers, duration of symptoms, period of time because it is a self- and accompanying clinical features. limited problem. However, individuals Examination includes assessment of with chronic vertigo might require cerebellar and cranial nerve function, ongoing work restrictions or accommo- nystagmus, and, in some cases, the Dix- dations. Positional vertigo could require Hallpike maneuver and head impulse adaptation of work areas to assure the testing. Once this database of informa- individual is not forced to move the tion is acquired, it is a matter of pattern head at certain angles. Individuals may recognition and searching for over- need to avoid tasks requiring especially lapping patterns. Additional narrowing good balance or physical maneuvering, of the cause can be obtained by CT and such as working at heights or around MRI studies and quantitative vestibular moving machinery or driving. and audiometric testing. Overall, the assessment of work Many causes of dizziness exist, rang- capacity in patients with dizziness must ing from mechanical, infectious, inflam- be considered on an individual basis, matory, demyelinative, degenerative, with important factors including the and complex or unknown mecha- nature and severity of the underlying nisms. The challenge for all clinicians condition, response to treatment, and evaluating patients with dizziness and whether or not special circumstances vertigo is to develop their own ap- may be involved, such as safety-sensitive proach and algorithm suitable to their job duties. interest and background. REFERENCES TRENDS AND FUTURE DIRECTIONS 1. Kroenke K, Jackson JL. Outcome in New developments are refining our general medical patients presenting definitions and the conditions that can with common symptoms: a prospective study with a 2-week and a 3-month cause dizziness and vertigo. Random- follow-up. Fam Pract 1998;15(5):398Y403. ized controlled trials in the treatment of doi:10.1093/fampra/15.5.398. conditions such as vestibular migraine 2. Sloane PD, Coeytaux RR, Beck RS, Dallara J. and improved diagnostic criteria for Dizziness: state of the science. Ann Intern many vestibular disorders will improve Med 2001;134(9 pt 2):823Y832. doi:10.7326/ 0003-4819-134-9_Part_2-200105011-00005. the effectiveness of our treatments. Meanwhile, advances in vestibular 3. Newman-Toker DE, Cannon LM, Stofferahn ME, et al. Imprecision in patient testing appear to now provide the ability reports of dizziness symptom quality: to test the function of all parts of the a cross-sectional study conducted in an labyrinth, including the long elusive acute care setting. Mayo Clin Proc 2007;82(11):1329Y1340. doi:10.40.65/ utricle and saccule. Ultimately, the ability 82.11.1329. to diagnose causes of dizziness and 4. Kerber KA, Brown DL, Lisabeth LD, et al. vertigowilldependonthehistoryand Stroke among patients with dizziness, examination and recognition of the vertigo, and imbalance in the emergency department: a population-based study. patterns that help separate important Stroke 2006;37(10):2484Y2487. doi:10.1161/ causes of vastly differing origins. 01.STR.0000240329.48263.0d.

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