Journal of Vestibular Research 19 (2009) 1–13 1 DOI 10.3233/VES-2009-0343 IOS Press

Classification of vestibular symptoms: Towards an international classification of vestibular disorders First consensus document of the Committee for the Classification of Vestibular Disorders of the B ar« any« Society

Alexandre Bisdorffa,∗, Michael Von Brevernb, Thomas Lempertc and David E. Newman-Tokerd aDepartment of Neurology, Centre Hospitalier Emile Mayrisch, L-4005 Esch-sur-Alzette, Luxembourg bVestibular Research Group Berlin, Department of Neurology, Park-Klinik Weissensee, Berlin, Germany cVestibular Research Group Berlin, Department of Neurology, Schlosspark-Klinik, Berlin, Germany dDepartment of Neurology, The Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA

On behalf of the Committee for the Classification of Vestibular Disorders of the Bar« any« Society: Pierre Bertholon, Alexandre Bisdorff, Adolfo Bronstein, Herman Kingma, Thomas Lempert, Jose Antonio Lopez Escamez, Måns Magnusson, Lloyd B. Minor, David E. Newman-Toker, Nicolas« Perez,« Philippe Perrin, Mamoru Suzuki, Michael von Brevern, John Waterston and Toshiaki Yagi

Received 4 February 2009 Accepted 1 September 2009

1. Introduction such as psychiatry and headache, where often there is no histopathologic, radiographic, physiologic, or other The Committee for Classification of Vestibular Dis- independent diagnostic standard available. However, orders of the Bar´ any´ Society was inaugurated at the diagnostic standards and classification are also crucial meeting of the Bar´ any´ Society in Uppsala 2006. Its in areas of medicine such as epilepsy and rheumatolo- charge is to promote development of an implementable gy, where, although confirmatory tests do exist, there classification of vestibular disorders. is substantial overlap in clinical features or biomarkers Symptom and disease definitions are a fundamen- across syndromes. tal prerequisite for professional communication both in Interestingly, not only scientific and therapeutic clinical and research settings. However, the perceived progress but also public awareness of psychiatric and need for a formalized classification system, uniform headache disorders has vastly increased after the in- definitions, or explicit diagnostic criteria varies some- troduction of the Diagnostic and Statistical Manual what by discipline. Having structured criteria for di- of Mental Disorders (DSM) by the American Acade- agnosis is obviously mandatory for disciplines which my of Psychiatry and the International Classification rely heavily on symptom-driven syndromic diagnosis, of Headache Disorders (ICHD) by the International Headache Society (IHS). In contrast, vestibular nomen- ∗ clature remains in its infancy. Other than the definition Corresponding author: Alexandre Bisdorff, Department of Neu- rology, Centre Hospitalier Emile Mayrisch, L-4005 Esch-sur-Alzette, of Meniere` disease by the American Academy of Oto- Luxembourg. E-mail: [email protected]. laryngology – Head and Neck Surgery (AAOHNS) [3]

ISSN 0957-4271/09/$17.00  2009 – IOS Press and the authors. All rights reserved 2 A. Bisdorff et al. / Classification of vestibular symptoms: Towards an international classification of vestibular disorders and the Classification of Peripheral Vestibular Dis- A small working group of clinicians formed a Classifi- orders by the Spanish Society of Otorhinolaryngolo- cation Committee and began to draft the concept of the gy [4], we are unaware of other systematic efforts to approach, analysing what existed in this area and what create widely accepted classification criteria. prior models to follow. The International Headache Although numerous advances in vestibular research Society’s International Classification of Headache Dis- have been made over the past several decades, there orders [7] provided the most inspiration. is now mounting evidence that the field may be ham- Since there is no consensus on the use of terms to pered moving forward by the lack of explicit and describe vestibular symptoms, the Committee decided uniform criteria for various clinical disorders. For to initiate the classification process by first defining and example, witness the ongoing controversy surround- building consensus around formalized definitions of ing the distinction between “vestibular migraine” and key vestibular symptoms. This document would then, “vestibular Meniere` disease” [2] or the varied use of the in turn, serve as a basis for a subsequent classification terms “vestibular neuritis,” “cochleovestibular neuri- of specific vestibular disorders. It was agreed upon tis,” “labyrinthitis,” “cochleolabyrinthitis,” and “acute that the definitions should cover all principal symptoms peripheral vestibulopathy” in the medical literature. thought to arise from disturbances of the vestibular Worse yet, problems of terminology have now been system, with this system defined broadly as the sensory demonstrated at the level of describing core vestibular inputs, central processing and motor outputs that relate symptoms such as dizziness and vertigo. Even when to balance. studied in a single, English-speaking country, the term The discussion gradually involved members and “vertigo” has been shown to have diverse meanings for opinion leaders worldwide, mainly through electronic patients [5], generalist physicians [6] and even otolo- communications as well as several in-person meetings gists [6]. and phone conferences. The task was to make the best We believe the time is right to pursue development of compromise between traditional use of terms, modern the first International Classification of Vestibular Disor- developments, and practicability in the research and ders (ICVD-I). Initially, we expect its predominant use clinical settings. A first draft was presented at the XXV would be to guide investigators conducting clinically- Bar´ any´ Society Meeting in Kyoto in April 2008 [8,9] oriented vestibular research. It is our belief that, over with the opportunity for the delegates to discuss and time, well-honed research criteria will gradually spread cast votes on controversial issues from the Committee’s to use in the clinical domain. We envision a staged discussions. and iterative development process that involves interna- The input from the Kyoto Meeting was very help- tional experts from both neurology and otolaryngology ful for the Classification Committee to see what defi- backgrounds. It is our hope that the Bar´ any´ Society will nitions were easily accepted and which were rejected partner with the AAOHNS and other neuro-otological or required further clarification. The draft was then associations who are willing to promote this project, discussed at the annual meeting in May 2008 in Lau- including funding agencies whose priorities are to sup- sanne, Switzerland of the French speaking Societ´ e´ In- port vestibular research. To initiate this process, the ternationale d’Otoneurologie. Members of the latter Committee sought first to define key vestibular symp- society as well as members of the Spanish Comision´ toms as a basis for a subsequent classification of spe- de Otoneurolog´ıa de la Sociedad Espanola˜ de Otorrino- cific vestibular disorders and then to build consensus laringolog´ıa and the American Academy of Otolaryn- around these formalized definitions. gology – Head and Neck Surgery (AAOHNS) joined the Bar´ any´ Society’s Classification Committee to final- ize the present classification. 2. Methods

The Bar´ any´ Society is an international society com- 3. Results prised of vestibular experts with a wide range of back- grounds from basic science, bioengineering, and space In the attached document (Appendix 1), we present flight to clinical medicine and physiotherapy. At the the first iteration of a consensus classification of XXIV Bar´ any´ Society Meeting 2006 in Uppsala, Swe- vestibular symptoms (ICVD-I: Classification of Symp- den, the General Assembly decided to launch an initia- toms v 1.0) produced by the committee. The commit- tive to elaborate a classification of vestibular disorders. tee also developed an algorithm to facilitate coding of A. Bisdorff et al. / Classification of vestibular symptoms: Towards an international classification of vestibular disorders 3 symptoms observed in a particular patient (Appendix the head to a new position, rather than the attainment 2). Several broad principles were agreed upon as part and maintenance of that new head position. The com- of the consensus building process: mittee’s consensus, however, was that this differenti- ation was impractical given the relatively obtuse na- 1) Symptoms chosen for definition should be broad ture of the distinction and well-established status of the enough to cover the spectrum of clinical symp- symptom positional vertigo. toms typically resulting from vestibular disorders The introduction of a separate category on vestibulo- yet specific enough to enable effective research. visual symptoms was unanimously considered impor- 2) No “vestibular” symptom has a totally specific tant, but the specific symptom definitions generated meaning in terms of topology or nosology and its much discussion. The fact that vestibular dysfunction pathogenesis is likely to be incompletely under- can result in a range of visual disturbances is not always stood. well understood outside the vestibular community. De- 3) Symptom definitions should be as purely phe- veloping a category devoted to these symptoms was, in nomenological as possible without reference to a part, an explicit attempt to promote awareness around theory on pathophysiologyor a particular disease. this issue. The principal controversy surrounded how 4) Definitions for symptoms are clearest if they are to define the visual sense of motion that typically ac- non-overlapping and non-hierarchical but allow companies the balance or “bodily” sense of vestibular one or more symptoms to coexist in a particular motion in patients who experience spinning vertigo. patient. Because these two sensations can sometimes be disso- 5) Consideration should be given in choice of termi- ciated clinically (e.g., in a patient who sees the world nology to ease of translation to languages beyond spinning or rotating from jerk nystagmus but feels no English, given current word usage patterns. spinning with eyes closed), the committee agreed that Some areas were relatively uncontroversial, while the visual sense of motion should not simply be incor- others sparked disagreement and even heated debate. porated into the definition of vertigo. Some wished to Although typical American usage identifies dizziness call this sense of visual flux “oscillopsia” as has been as an umbrella term that includes vertigo as a subset [5], done in some prior studies [10]. However, the majori- the decision to make terms non-hierarchical suggested ty preferred that oscillopsia be used only to describe a that dizziness and vertigo should be defined separate- bidirectional, to-and-fro visual motion that incorporat- ly, as is more often done in Europe. This choice was ed complaints such as “jumping” or “bouncing” vision. also felt to be more compatible with certain linguistic The term “objective vertigo” was rejected as it was issues in anticipation of future translations. The def- considered confusing to label a symptom “objective” inition of vertigo was controversial, as some wished when all sensory symptoms are, by definition, subjec- to restrict its usage to only a false sense of spinning, tive experiences. “Visual vertigo” was not a consid- while others felt it should refer to any false sense of eration, since this term is now often used to refer to motion, a controversy that has been described previous- the experience of vertigo incited by the movement of ly [1]. If non-spinning sensations were to be consid- objects within a patient’s field of vision. The proposal ered “not vertigo,” alternatives would have been to in- to introduce the neologism “vertigopsia,” preferred by troduce one or more new terms or to include these sen- some, was eventually dropped in favour of the new term sations within the framework of dizziness, making that “external vertigo.” definition less clear. The compromise was the addition The definitions for postural balance symptoms that of a specification to note whether vertigo is spinning or often accompany vestibular disorders required little dis- non-spinning. cussion to achieve consensus. The committee was com- Because vertigo and dizziness are often triggered fortable using unsteadiness as the preferred descriptive symptoms and many vestibular disorders are identified term for postural instability (when sitting, standing, or by the presence (or absence) of particular triggers, it walking), rather than the often-used but more linguis- was considered crucial to elaborate symptom defini- tically ambiguous terms disequilibrium or imbalance. tions for several common types of triggered vertigo and The term drop attack (sudden fall without loss of con- dizziness. As others have previously, some members sciousness) was considered ambiguous, since neuro- initially advocated for use of the term “positioning” otologists sometimes restrict the term to those with vertigo as opposed to “positional” vertigo to indicate vestibular causes for the fall but neurologists, cardiolo- patients whose symptoms are tied to the act of moving gists, and generalists typically do not (Meissner, 1986; 4 A. Bisdorff et al. / Classification of vestibular symptoms: Towards an international classification of vestibular disorders

Table 1 Planned stages for developing the ICVD-I Stage Name Description I Classification Create ICVD-I IA Symptoms Develop definitions for vestibular symptoms IB Nosology Establish rubric for classifying vestibular disorders IC Disorders Define diagnostic criteria for vestibular diseases or syndromes ID Harmonization Unify diagnostic criteria into cohesive compendium (ICVD-I) II Dissemination Promulgate use of these criteria for research purposes (e.g., publication, endorsement of relevant professional societies) III Renewal Establish a mechanism for knowledge maintenance and periodic updates to the criteria with evolving scientific knowledge.

Parry, 2005). Drop attacks of apparent vestibular cause the classification “vanguard.” As a consequence, some were instead parsed into the categories balance-related modules may be disseminated in published form while falls and balance-related near falls. others remain merely topic placeholders. Interrogating A decision was made in this first iteration not to op- the process of developing these “vanguard” modules erationally define all symptoms that might be linked will then inform development of subsequent modules. to dizziness or vertigo if they were less specifically Throughout the process we plan to solicit period- linked to vestibular disorders (e.g., syncope, diplopia, ic feedback from the vestibular community and begin dysarthria, dysmetria). Similarly, no specific defini- validating and testing definitions or criteria that have tions are offered in this iteration for neurovegetative reached a more advanced stage. For example, we hope (e.g., nausea, vomiting, fatigue, malaise, weakness) to recruit investigators willing to validate criteria for or neuropsychiatric (e.g., anxiety, depression, phobia) those disorders where strong reference standard diag- symptoms that might accompany vestibular disorders. nostic tests exist (e.g., benign paroxysmal positional However, we do offer limited definitions (in commen- vertigo) and establish reliability of coding rules where tary) for some such symptoms where necessary to clar- no firm diagnostics are available (e.g., vestibular mi- ify an important distinction from a defined vestibular graine). symptom (motion sickness, presyncope, mental confu- We anticipate that these subsequent stages of devel- sion, depersonalization/derealisation). opment will prove more challenging than this symptom classification and will require more resources. Even with an ambitious timeline for development, adequate 4. Discussion finances, and political support from relevant stakehold- ers, completing just the first stage (developing a com- This work on vestibular symptom classification rep- plete, published ICVD-I) will take at least several years. resents an initial step towards the first International We look forward to partnering with societies and fund- Classification of Vestibular Disorders (ICVD-I). We en- ing agencies to advance the science of vestibular disor- vision three successive stages to implement this pro- ders research through consensus criteria for classifica- gram (Table 1). Although these stages are listed in tion and diagnosis. order, implying a linear progression, the actual pro- cess is likely to be dynamic and iterative. This will be Appendix 1 particularly so during the genesis of ICVD-I (Stage I), where subsequent work (e.g., defining diagnostic crite- International Classification of Vestibular Disorders ria) may lead to substantial revision of prior work (e.g., I (ICVD-I) establishing a classification schema). Authored and approved by the Committee for the To successfully navigate this complex process, we Classification of Vestibular Disorders of the Bar´ any´ expect to take a modular approach. For example, a few Society. parallel working groups will be tasked with defining diagnostic criteria for a small subset of related vestibu- ICVD-I: Classification of Symptoms v1.0 (January, lar diseases (e.g., “positional vertigo syndromes” or 2009) “acute peripheral vestibulopathies”). These first mod- Contents ules will be chosen based on priority for the vestibular community, and will likely develop at a greater pace as 1. Vertigo A. Bisdorff et al. / Classification of vestibular symptoms: Towards an international classification of vestibular disorders 5

Ð Spontaneous vertigo sification, no distinction is made between a false sense Ð Triggered vertigo of rotational motion and a false sense of linear motion (often referred to as “translation”) or static tilt with re- ∗ Positional vertigo spect to gravity (often referred to as “tilt”); all three ∗ Head-motion vertigo are considered vertigo when experienced by a patient ∗ Visually-induced vertigo as a symptom of false motion. If a sensation of sway is ∗ Sound-induced vertigo ∗ felt only when standing or walking then this should be Valsalva-induced vertigo unsteadiness ∗ termed and labelled under postural symp- Orthostatic vertigo toms (see 4 below) rather than vertigo. If the internal ∗ Other triggered vertigo sensation of vertigo is accompanied by a false sense of 2. Dizziness external visual motion (external vertigo oroscillopsia), this should be labelled as an additional vestibulo-visual Ð Spontaneous dizziness symptom (e.g., “combined internal and external spin- Ð Triggered dizziness ning vertigo” or “non-spinning vertigo with oscillop- ∗ Positional dizziness sia”). A false sense of visual motion that occurs in iso- ∗ Head-motion dizziness lation (without false internal sensation of self-motion) ∗ Visually-induced dizziness should only be labelled as external vertigo or oscillop- ∗ Sound-induced dizziness sia. Vertigo should always be further categorized as ∗ Valsalva-induced dizziness spinning, non-spinning, or both (see Symptom Coding ∗ Orthostatic dizziness Algorithm). ∗ Other triggered dizziness Terms not used in this nomenclature: true vertigo, false vertigo, objective vertigo, subjective vertigo, ro- 3. Vestibulo-visual symptoms tatory/rotational vertigo, linear/translational vertigo. Ð External vertigo Ð Oscillopsia Several contexts where vertigo occurs are distin- Ð Visual lag guished: Ð Visual tilt 1.1. Spontaneous vertigo Ð Movement-induced blur Definition: Spontaneous vertigo is vertigo that oc- 4. Postural symptoms curs without an obvious trigger. Ð Unsteadiness Comment: Spontaneous vertigo may be exacerbated Ð Directional pulsion by movements (especially head movements). When Ð Balance-related near fall spontaneous vertigo is aggravated by such movements, Ð Balance-related fall a second symptom (head-motion vertigo 1.2.2) should be added.

1. Vertigo 1.2. Triggered vertigo

Definition:(Internal) vertigo is the sensation of Definition: Triggered vertigo is vertigo that occurs self-motion when no self-motion is occurring or the with an obvious trigger. sensation of distorted self-motion during an otherwise Comment: The presence of an “obvious” trig- normal head movement. This “internal” vestibular sen- ger requires a temporally-appropriate relationship be- sation is distinguished from the “external” visual sense tween trigger stimulus and vertigo. Under most cir- of motion referred to in this classification as either ex- cumstances, a reproducible, repetitive relationship be- ternal vertigo or oscillopsia (see 3. Vestibulo-visual tween trigger stimulus and vertigo spell should also symptoms). For simplicity, the unmodified term “verti- be present. Note that while chemical triggers (e.g., go” will mean, by default, “internal vertigo.” The term food, hormonal states, medications) may contribute to encompasses false spinning sensations (spinning verti- the cause of apparently-spontaneous vertigo spells in go) and also other false sensations like swaying, tilting, patients with certain vestibular disorders (e.g., vestibu- bobbing, bouncing, or sliding (non-spinning vertigo). lar migraine or Meniere` disease), these should only be Comment: An appropriate sensation of motion (i.e., considered triggered vertigo if the relationship between matching an actual motion) is not vertigo. In this clas- the trigger and vertigo episode is clear. 6 A. Bisdorff et al. / Classification of vestibular symptoms: Towards an international classification of vestibular disorders

1.2.1. Positional vertigo Terms not used in this nomenclature: space and mo- Definition: Positional vertigo is vertigo triggered by tion discomfort, space and motion sensitivity, visual and occurring after a change of head position in space vertigo. relative to gravity. 1.2.4. Sound-induced vertigo Comment: This is distinguished from head-motion Definition: Sound-induced vertigo is vertigo trig- vertigo, which occurs during a head movement (see gered by an auditory stimulus. 1.2.2). A note should be made whether symptoms are Comment: Sound-induced vertigo should not be
persistent ( 1 minute) when the head reaches and used to describe vertigo triggered by Valsalva, pres- < maintains the new position, or merely transient ( 1 sure changes across the tympanic membrane (e.g., as minute). If transient, the duration should be noted. with pneumo-otoscopy), or vibration, which should ei- Positional vertigo should also be distinguished from ther be classified as Valsalva-induced vertigo or other orthostatic vertigo (see 1.2.6). triggered vertigo (see 1.2.5 and 1.2.7). Terms not used in this nomenclature: positioning Terms not used in this nomenclature: Tullio phe- vertigo. nomenon 1.2.2. Head-motion vertigo 1.2.5. Valsalva-induced vertigo Definition: Head-motion vertigo is vertigo occur- Definition: Valsalva-induced vertigo is vertigo trig- ring only during head motion (i.e., that is time-locked gered by any bodily maneuver that tends to increase to the head movement). intracranial or middle ear pressure. Comment: Such vertigo may be triggered by the Comment: Typical behavioral stimuli that tend to de- head movement (from a baseline state without vertigo), crease venous return from the intracranial space by rais- or spontaneous vertigo may be exacerbated by the head ing intrathoracic pressure against a closed glottis (glot- movement. Head-motion vertigo is conceptualized as tic Valsalva) include coughing, sneezing, straining, lift- a distorted sensation of self-motion during actual self- ing heavy objects etc. By contrast, nose-pinched Val- motion. This state is differentiated from positional ver- salva forces air directly into the middle ear cavity with- tigo, which occurs after head motion, upon adoption out a significant change in intrathoracic pressure. A of a new resting head position in space. Head-motion note should be made whether symptoms are triggered vertigo should also be distinguished from motion sick- by glottic Valsalva, nose-pinched Valsalva, or both. ness, in which the predominant symptom is a lasting, Pneumatic otoscopy/insufflation and other “extrinsic” visceral feeling of nausea. pressure changes should be classified as other triggered Terms not used in this nomenclature: space and mo- vertigo (see 1.2.7 below). tion discomfort, space and motion sensitivity. 1.2.6. Orthostatic vertigo 1.2.3. Visually-induced vertigo Definition: Orthostatic vertigo is vertigo triggered Definition: Visually-induced vertigo is vertigo trig- by and occurring on arising (i.e. a change of body pos- gered by a complex, distorted, large field or moving ture from lying to sitting or sitting to standing). visual stimulus, including the relative motion of the Comment: Orthostatic vertigo (present on arising) positional visual surround associated with body movement. should be distinguished from vertigo (trig- gered by a change in head position relative to gravity) Comment: The symptom includes the visually- and head-motion vertigo, since positional symptoms induced illusion of circular or linear self-motion (often may be triggered by the head motion that occurs dur- referred to as “vection”). If the sensation is one of ing arising (see 1.2.1 and 1.2.2 above). See orthostatic non-vertiginous dizziness triggered by a visual stimu- dizziness (2.2.6 below) for additional comment. lus, it should be classified under 2.2.3 (visually-induced Termsnot used in this nomenclature: postural vertigo dizziness). If the disturbing visual input originates from a primary ocular motility disorder (e.g. ocular 1.2.7. Other triggered vertigo muscle myokymia or non-vestibular nystagmus) and Definition: Other triggered vertigo is vertigo trig- induces vertigo, the symptom should be classified here. gered by any other stimulus than those listed above. Visually-induced vertigo should also be distinguished Comment: Other triggers include those related to de- from motion sickness, in which the predominant symp- hydration, drugs, environmental pressure shifts (such tom is a lasting, visceral feeling of nausea. as those during deep-sea diving, height, hyperbaric A. Bisdorff et al. / Classification of vestibular symptoms: Towards an international classification of vestibular disorders 7 oxygenation, pneumatic insufflation during pneumo- Comment: The presence of an “obvious” trigger re- otoscopy), exercise/exertion (including upper extrem- quires a temporally-appropriate relationship between ity exercise), after prolonged exposure to passive mo- trigger stimulus and dizziness. See 1.2 above for addi- tion (as occurs following sea voyages), hormones, hy- tional comment. perventilation, phobic situations, tight neck collars, vi- 2.2.1. Positional dizziness bration and idiosyncratic, atypical triggers unique to a particular patient. Definition: Positional dizziness is dizziness trig- gered by and occurring after a change of head position 2. Dizziness in space relative to gravity. Comment: This is distinguished from head-motion Definition:(Non-vertiginous) dizziness is the sen- dizziness which occurs during a head movement (see sation of disturbed or impaired spatial orientation with- 1.2.2). A note should be made whether symptoms are out a false or distorted sense of motion. persistent (
1 minute) when the head reaches and Comment: Dizziness as defined here does not in- maintains the new position, or merely transient (< 1 clude vertiginous sensations. Often the term is used in minute). If transient, the duration should be noted. a broad sense encompassing sensation of false move- Positional dizziness should also be distinguished from ment but here the terms vertigo and dizziness are clearly orthostatic dizziness (see 2.2.6). distinguished. In the description of the symptoms of a Terms not used in this nomenclature: positioning patient several symptoms may coexist or occur sequen- dizziness. tially, e.g. vertigo and dizziness. For this classifica- tion, one symptom does not pre-empt the other (specif- 2.2.2. Head-motion dizziness ically, the presence of vertigo does not, a priori, pre- Definition: Head-motion dizziness is dizziness oc- clude labelling the patient as having [non-vertiginous] curring only during head motion (i.e. that is time-locked dizziness if both symptoms are present). to the head movement). The term should not be applied when there is a pure Comment: Such dizziness may be triggered by the sensation of impending faint (presyncope), disordered head movement (from a baseline state without dizzi- thinking (mental confusion), or detachment from reali- ness), or spontaneous dizziness may be exacerbated by ty (depersonalization or derealization) when such sen- the head movement. Head-motion dizziness is concep- sation is unaccompanied by a sense of spatial disorien- tualized as a distorted sensation of spatial orientation tation. Likewise, dizziness should not be applied when during actual self-motion. This state is differentiat- a patient’s complaint is one of generalized or focal mo- ed from positional dizziness, which occurs after head tor weakness or a non-specific sense of malaise,fatigue, motion, upon adoption of a new resting head position or ill-health (sometimes referred to as “the weak and in space. Head-motion-induced dizziness should also dizzy patient”). be distinguished from motion sickness, in which the Terms not used in this nomenclature: lightheaded- predominant symptom is a lasting, visceral feeling of ness, non-specific dizziness nausea. Several contexts where dizziness occurs are distin- Terms not used in this nomenclature: space and mo- guished: tion discomfort, space and motion sensitivity 2.1. Spontaneous dizziness 2.2.3. Visually-induced dizziness Definition: Visually-induced dizziness is dizziness Definition: Spontaneous dizziness is dizziness that triggered by a complex, distorted, large field or moving occurs without an obvious trigger. visual stimulus, including the relative motion of the Comment: Spontaneous dizziness may be exacer- visual surround associated with body movement. bated by movements (especially head movements). Comment: If the visual input induces clear circu- When spontaneous dizziness is aggravated by such lar or linear vection then the symptoms should be la- movements, a second symptom (head-motion dizziness belled under 1.2.3 (visually-induced vertigo). If the 2.2.2) should be added. disturbing visual input originates from a primary ocular 2.2. Triggered dizziness motility disorder (e.g. ocular muscle myokymia or non- vestibular nystagmus) and induces dizziness, the symp- Definition: Triggered dizziness is dizziness that oc- tom should be classified here. Visually-induced dizzi- curs with an obvious trigger. ness should also be distinguished from motion sick- 8 A. Bisdorff et al. / Classification of vestibular symptoms: Towards an international classification of vestibular disorders ness, in which the predominant symptom is a lasting, it is not the only possible cause; it is not the intent of visceral feeling of nausea. this nomenclature to consider the two as synonymous. Terms not used in this nomenclature: space and mo- Orthostatic dizziness is a symptom, while orthostatic tion discomfort, space and motion sensitivity, visual hypotension a disorder or etiology. dizziness. Terms not used in this nomenclature: postural dizzi- ness 2.2.4. Sound-induced dizziness Definition: Sound-induced dizziness is dizziness 2.2.7. Other triggered dizziness triggered by an auditory stimulus. Definition: Other triggered dizziness is dizziness Comment: Sound induced dizziness should not be triggered by any other stimulus than those listed above. used to describe dizziness triggered by Valsalva, pres- Comment: Other triggers include those related to de- sure changes across the tympanic membrane (e.g., as hydration, drugs, environmental pressure shifts (such with pneumo-otoscopy), or vibration, which should ei- as those during deep-sea diving, height, hyperbaric ther be classified as Valsalva-induceddizziness or other oxygenation, pneumatic insufflation during pneumo- triggered dizziness (see 2.2.5 and 2.2.7). otoscopy), exercise/exertion (including upper extrem- Terms not used in this nomenclature: Tullio phe- ity exercise), after prolonged exposure to passive mo- nomenon tion (as occurs following sea voyages), hormones, hy- perventilation, phobic situations, tight neck collars, vi- 2.2.5. Valsalva-induced dizziness bration and idiosyncratic, atypical triggers unique to a Definition: Valsalva-induced dizziness is dizziness particular patient. triggered by any bodily maneuver that tends to increase intracranial or middle ear pressure. 3. Vestibulo-visual symptoms Comment: Typical behavioral stimuli that tend to de- crease venous return from the intracranial space by rais- Definition: Vestibulo-visual symptoms are visual ing intrathoracic pressure against a closed glottis (glot- symptoms that usually result from vestibular pathology or the interplay between visual and vestibular systems. tic Valsalva) include coughing, sneezing, straining, lift- These include false sensations of motion or tilting of ing heavy objects etc. By contrast, nose-pinched Val- the visual surround and visual distortion (blur) linked salva forces air directly into the middle ear cavity with- to vestibular (rather than optical) failure. out a significant change in intrathoracic pressure. A Comment: Visual illusions or hallucinations that in- note should be made whether symptoms are triggered volve movement of objects within the visual surround, by glottic Valsalva, nose-pinched Valsalva, or both. but in which the visual surround itself remains stat- Pneumatic otoscopy/insufflation and other “extrinsic” ic, should not be considered vestibulo-visual symp- pressure changes should be classified as other triggered toms. Examples would include seeing mobile visual dizziness (see 2.2.7 below). “floaters,” migrating scintillations of migraine visual 2.2.6. Orthostatic dizziness aura, etc. Definition: Orthostatic dizziness is dizziness trig- 3.1. External Vertigo gered by and occurring on arising (i.e.,a change of body posture from lying to sitting or sitting to standing). Definition: External vertigo is the false sensation Comment: Orthostatic dizziness (present on arising) that the visual surround is spinning or flowing. should be distinguished from positional dizziness (trig- Comment: The symptom external vertigo encom- gered by a change in head position relative to gravi- passes the false sensation of continuous or jerky visual ty) and head-motion-induced dizziness, since position- flow in any spatial plane (e.g., horizontal [yaw]). It is al symptoms may be triggered by the head motion that distinguished from oscillopsia (see 3.2 below) by the occurs during arising (see 2.2.1 and 2.2.2 above). The absence of bidirectional (oscillatory) motion. External distinction between positional and orthostatic dizziness vertigo (visual motion) often accompanies a sense of can be accomplished by asking the patient with dizzi- internal vertigo (bodily motion) (see 1 above for de- ness on arising whether the symptoms also occur on re- tails). However, jerk nystagmus alone may provoke a clining or while recumbent (e.g., when rolling in bed); sense of continuous visual flow even without a false if so, the symptoms are likely positional rather than sensation of self-motion ([internal] vertigo). In this orthostatic. Although the most common cause of or- classification visual and bodily symptoms are differ- thostatic dizziness is probably orthostatic hypotension, entiated and may (or may not) co-exist in the same A. Bisdorff et al. / Classification of vestibular symptoms: Towards an international classification of vestibular disorders 9 patient. Therefore, the false sensation of visual flow (with an approximate angle specified) is preferred in (e.g., world spinning) should be coded separately from this nomenclature. If the sense of visual tilt is in mo- vertigo (e.g., “combined internal and external spinning tion (i.e., angle changing) rather than fixed (i.e., angle vertigo”) (see Symptom Coding Algorithm). fixed), then it should be referred to as external vertigo Term not used in this nomenclature: true vertigo, (for the visual sensation) or (internal) vertigo (for the false vertigo, objective vertigo, subjective vertigo, ro- bodily sensation) rather than visual tilt. tatory/rotational vertigo, linear/translational vertigo. Terms Not Used in This Nomenclature: room tilt illusion, room inverted illusion, upside down vision. 3.2. Oscillopsia 3.5. Movement-induced blur Definition: Oscillopsia is the false sensation that the visual surround is oscillating. Definition: Movement-induced blur is reduced vi- Comment: The term oscillopsia, as a hybrid from sual acuity during or momentarily after a head move- Latin and Greek means swinging and vision. This ment. back-and-forth movement can occur in any direction Comment: The vestibular system contributes to the and will often be reported as an experience of “bounc- stabilization of the retinal image during head motion. A ing,” “bobbing,” or “jerking” of the visual world. As disturbance of this function can lead to retinal slip and, with external vertigo, the visual symptom of oscillop- consequently, to reduced visual acuity during or im- sia is distinguished and recorded separately from any mediately after head motion. This sense of visual blur associated bodily sense of motion (i.e., vertigo or dizzi- may be continuous during a continuous head movement ness). It should be specified if the symptom is head- (e.g., during walking) or be momentary (e.g., in associ- movement-dependent or occurs even when the head is ation with head-motion vertigo or dizziness (see 1.2.2 completely still (as in oculomotor disorders like pen- and 2.2.2 above)). Some people experience oscillopsia dular nystagmus) (see Symptom Coding Algorithm). or visual lag rather than visual blur in these situations 3.3. Visual lag (see 3.2 and 3.3 above). Definition: Visual lag is the false sensation that the 4. Postural symptoms visual surround follows behind a head movement with Definition: Postural symptoms are balance symp- a delay or makes a brief drift after the head movement is completed. toms related to maintenance of postural stability, occur- Comment: This sense of visual lag is momentary, ring only while upright (seated, standing, or walking). lasting generally less than 1–2 seconds. It may occur Comment: The term “postural” in this nomenclature in association with head-motion vertigo or dizziness refers to balance symptoms while upright (e.g., stand- (see 1.2.2 and 2.2.2 above). This brief movement of ing) rather than the set of symptoms linked to changing the visual surround should not be classified as external body posture with respect to gravity (e.g., standing up). vertigo, since it lacks the sense of continuous motion These latter symptoms are referred to as “orthostatic” or flow. in this nomenclature. 3.4. Visual tilt 4.1. Unsteadiness Definition: Visual tilt is the false perception of the Definition: Unsteadiness is the feeling of being un- visual surround as oriented off the true vertical. stable while seated, standing, or walking without a par- Comment: Symptomatic static visual tilt with the ticular directional preference. head upright is typically episodic and brief (lasting Comment: Regardless of upright position (seated, seconds to minutes) and is not synonymous with the standing, or walking), added stability (as in holding on- asymptomatic, static alteration in perception of the sub- to a stable surface, such as a wall) should clearly reduce jective visual vertical (SVV tilt) seen under controlled or eliminate any unsteadiness present; if it does not, viewing conditions among patients with central or pe- consideration should be given to whether the symp- ripheral vestibular disorders. The so-called “room tilt tom is, instead, vertigo or dizziness. Unsteadiness is illusion” (or “room inverted illusion”) is often used a symptom which can occur in many other conditions to refer to a special form of visual tilt with tilt an- beyond those of the vestibular system. If unsteadiness gles of either 90◦ or 180◦, although the term visual tilt is present without any other vestibular symptom (see 1, 10 A. Bisdorff et al. / Classification of vestibular symptoms: Towards an international classification of vestibular disorders

2, 3 above), a vestibular disorder is unlikely although to as “otolithic crises” or “drop attacks” (particularly not excluded. if sometimes associated with completed falls). In this Terms Not Used in This Nomenclature: disequilibri- nomenclature, these near falls are referred to simply as um, imbalance. balance-related near falls. Similar near falls unlinked to other vestibular symptoms (also sometimes referred 4.2. Directional pulsion to as “drop attacks”) may be seen in various condi- tions (e.g., carotid sinus syndrome, cardiac arrhythmia, Definition: Directional pulsion is the feeling of be- epilepsy) and should not be classified as balance-related ing unstable with a tendency to veer or fall in a partic- in the absence of corroborative vestibular symptoms. ular direction while seated, standing, or walking. The Terms Not Used in This Nomenclature: drop attack, direction should be specified as latero-, retro or an- otolithic crisis, Tumarkin’s crisis. teropulsion. If lateropulsion, the direction (right or left) should be specified. 4.4. Balance-related fall Comment: Regardless of upright position (seated, standing, or walking), added stability (as in holding Definition:Abalance-related fall is a completed onto a stable surface, such as a wall) should clearly fall related to strong unsteadiness, directional pulsion, reduce or eliminate any directional pulsion present; if or other vestibular symptom (e.g., vertigo). it does not, consideration should be given to whether Comment: Falls which are “caught” (e.g., by an out- the symptom is, instead, vertigo or dizziness. stretched arm reaching a wall) should be classified as Terms Not Used in This Nomenclature: disequilibri- near falls (see 4.3 above). Although it is not always um, imbalance. possible to identify balance-related falls with perfect certainty, falls clearly due to environmental obstacles 4.3. Balance-related near fall (e.g., “slip-trip”), weakness (e.g., acute motor stroke), or loss of consciousness (e.g., syncope, seizure, or co- Definition:Abalance-related near fall is a sensa- ma) should not be classified as balance-related. Falls tion of imminent fall (without a completed fall) relat- sometimes result from a sudden alteration in the per- ed to strong unsteadiness, directional pulsion, or other ception of verticality (as with visual tilt), a feeling of vestibular symptom (e.g., vertigo). being pushed over or pulled to the ground, or unantic- Comment: Falls which are “caught” (e.g., by an ipated loss of lower extremity or postural tone linked outstretched arm reaching a wall) should be classi- temporally to other vestibular symptoms. In neuro- fied as near falls. Although it is not always possible otologic parlance, such spells are often referred to as to identify balance-related near falls with perfect cer- “otolithic crises” or “drop attacks.” In this nomencla- tainty, near falls clearly due to environmental obsta- ture, these falls are referred to simply as balance-related cles (e.g., “stumble”), weakness (e.g., leg buckling un- falls. Similar falls unlinked to other vestibular symp- der strain), or near loss of consciousness (e.g., presyn- toms (also sometimes referred to as “drop attacks”) cope) should not be classified as balance-related. Near may be seen in various conditions (e.g., carotid sinus falls sometimes result from a sudden alteration in the syndrome, cardiac arrhythmia, epilepsy) and should perception of verticality (as with visual tilt), a feel- not be classified as balance-related in the absence of ing of being pushed over or pulled to the ground, or corroborative vestibular symptoms. unanticipated loss of lower extremity or postural tone Terms Not Used in This Nomenclature: drop attack, linked temporally to other vestibular symptoms. In otolithic crisis, Tumarkin’s crisis. neuro-otologic parlance, such spells are often referred A. Bisdorff et al. / Classification of vestibular symptoms: Towards an international classification of vestibular disorders 11

Appendix 2. Symptom Coding Algorithm

1. Spinning 1.1.1 1. (internal) 1. spontaneous vertigo vertigo 2. Non-spinning (rocking, swaying, etc.) 1.1.2

1. Spinning 1.2.1.1.1 1. transient 2. triggered 1. positional 2. Non- 1.2.1.1.2 vertigo vertigo spinning

2. persistent 1. Spinning 1.2.1.2.1

2. Non- 1.2.1.2.2 spinning

2. head-motion 1. Spinning 1.2.2.1 vertigo 2. Non- 1.2.2.2 spinning

3. visually-induced 1. Spinning 1.2.3.1 vertigo 2. Non- 1.2.3.2 spinning

4. sound-induced 1. Spinning 1.2.4.1 vertigo 2. Non- 1.2.4.2 spinning

1. Spinning 1.2.5.1.1 1.glottic 5. Valsalva- 2. Non- 1.2.5.1.2 induced spinning vertigo 2. nose 1. Spinning 1.2.5.2.1 pinch 2. Non- 1.2.5.2.2 spinning

6. orthostatic 1. Spinning 1.2.6.1 vertigo 2. Non- 1.2.6.2 spinning

1. Spinning 1.2.7.1 7. other triggered vertigo 2. Non- 1.2.7.2 spinning 12 A. Bisdorff et al. / Classification of vestibular symptoms: Towards an international classification of vestibular disorders

2. dizziness 1. spontaneous dizziness 2.1

1. transient 2.2.1.1 2. triggered 1. positional dizziness dizziness

2. persistent 2.2.1.2

2. head-motion 2.2.2 dizziness

3. visually- 2.2.3 induced dizziness

4. sound-induced 2.2.4 dizziness

1. glottic 2.2.5.1 5. Valsalva- induced dizziness 2. nose pinch 2.2.5.2

6. orthostatic 2.2.6 dizziness

7. other triggered 2.2.7 dizziness

3. vestibulo-visual

symptoms 1. external vertigo 3.1

1. head-movement 3.2.1 2. oscillopsia dependent

2. occurs without 3.2.2 head movements

3. visual lag 3.3

4. visual tilt 3.4

5. movement- 3.5 induced blur A. Bisdorff et al. / Classification of vestibular symptoms: Towards an international classification of vestibular disorders 13

4. postural symptoms

1. unsteadiness 4.1

right 4.2.1.1 2. directional pulsion 1. latero left 4.2.1.2

2. antero 4.2.2

3. retro 4.2.3

3. balance-associated near fall 4.3

4. balance-associated fall 4.4

References [7] Headache Classification Committee. The International Clas- sification of Headache Disorders, Cephalagia 24(Suppl.1) [1] B.W. Blakley and J. Goebel, The meaning of the word “verti- (2004), 9–160. go”, Otolaryngol Head Neck Surg 125(3) 2001, 147–150. [8] A. Bisdorff, A. Bronstein A, H. Kingma, T. Lempert, H. [2] K.P. Boyev, Meniere’s disease or migraine? The clinical sig- Neuhauser, D.E. Newman-Toker, A. Radtke and M. von nificance of fluctuating hearing loss with vertigo, Arch Oto- Brevern, Building worldwide expert consensus around a glos- laryngol Head Neck Surg 131(5) (May 2005), 457–459. sary of vestibular symptoms – the first step towards a struc- [3] E.M. Monsell, T.A. Balkany, G.A. Gates, R.A. Goldenberg, tured international classification of vestibular disorders. Ab- W. Meyerhoff and J.W. House, Committee on Hearing and stracts of the Bar´ any´ Society XXV International Congress. Equilibrium guidelines for the diagnosis and evaluation of Kyoto, Japan, March 31–April 3, 2008. therapy in Meniere’s disease, Otolaryngol Head Neck Surg [9] T. Lempert, M. von Brevern, D.E. Newman-Toker, A. Bron- 113 (1995), 181–185. stein, H. Neuhauser, H. Kingma, A. Radtke and A. Bisdorff, [4] C. Morera, H. Perez,´ N. Perez´ and A. Soto, Peripheral Vertigo Controversies in the classification of dizziness and vertigo. Classification. Consensus Document. Otoneurology Commit- Abstracts of the Bar´ any´ Society XXV International Congress. tee of the Spanish Otorhinolaryngology Society (2003-2006), Kyoto, Japan, March 31–April 3, 2008. Acta Otorrinolaringol Esp 59(2) (2008), 76–79. [10] H.K. Neuhauser, M. von Brevern, A. Radtke, F. Lezius, M. [5] D.E. Newman-Toker, L.M. Cannon, M.E. Stofferahn, R.E. Feldmann, T. Ziese and T. Lempert, Epidemiology of vestibu- Rothman, Y.H. Hsieh and D.S. Zee, Imprecision in patient lar vertigo: a neurotologic survey of the general population, reports of dizziness symptom quality: a cross-sectional study Neurology 65(6) (27 Sep 2005), 898–904. Erratum in: Neu- conducted in an acute-care setting, Mayo Clin Proc 82(11) rology 67(8) (24 Oct 2006), 1528. (Nov 2007), 1329–1340. [11] I. Meissner, D.O. Wiebers, J.W. Swanson and W.M. O’Fallon, [6] V.A. Stanton, Y.H. Hsieh, C.A. Camargo Jr., J.A. Edlow, P. The natural history of drop attacks, Neurology 36 (1986), Lovett, J.N. Goldstein, S. Abbuhl, M. Lin, A. Chanmugam, 1029–1034. R.E. Rothman and D.E. Newman-Toker, Overreliance on [12] S.W. Parry and R.A. Kenny, Drop attacks in older adults: sys- symptom quality in diagnosing dizziness: results of a multi- tematic assessment has a high diagnostic yield, J Am Geriatr center survey of emergency physicians, Mayo Clin Proc 82(11) Soc 53 (2005), 74–78. (Nov 2007), 1319–1328.