5 Cédric Lamirel , Nancy J. Newman , and Valérie Biousse

Abstract Visual loss is a common symptom in neurologic emergencies. Although ocular causes of visual loss are usually identifi ed by eye care specialists, many patients appear in an emergency department or a neurologist’s offi ce when the ocular examination is normal or when it suggests a neurologic disorder. Indeed, many causes of monocular or binocular acute visual loss may reveal or precede a neurologic process. In this situation, a quick and simple clinical examination done at bedside in the emergency department allows the neurologist to localize the lesion and determine whether an urgent neurologic workup or further ophthalmologic consultation is necessary.

Keywords Central retinal artery occlusion • Funduscopic examination • • Retinal emboli • Visual fi eld • Visual loss

Acute vision changes typically precipitate emer- gency consultation. Although ocular causes are usually identifi ed by eye care specialists, many patients appear in an emergency department or a C. Lamirel , MD neurologist’s offi ce when the ocular examination Service d’ophtalmologie , Fondation Ophtalmologique is normal or when it suggests a neurologic disor- Adolphe Rothschild , Paris , France der. Indeed, many causes of monocular or binoc- e-mail: [email protected] ular acute visual loss may reveal or precede a N. J. Newman , MD • V. Biousse, MD () neurologic process. In this situation, a quick and Neuro- Unit , simple clinical examination done at bedside in Emory University School of Medicine , Atlanta , GA , USA the emergency department allows the neurologist e-mail: [email protected]; [email protected] to localize the lesion and determine whether an

K.L. Roos (ed.), Emergency Neurology, DOI 10.1007/978-0-387-88585-8_5, 95 © Springer Science+Business Media, LLC 2012 96 C. Lamirel et al. urgent neurologic workup or further ophthalmo- as “count fi ngers,” “hand motion,” “light percep- logic consultation is necessary [1, 2 ] . tion,” or “no light perception.”

The Neuro-Ophthalmologic Color Vision Examination in the Emergency Department Color vision testing is important to localize the lesion to the or to detect subtle visual Evaluation of visual function, examination of the changes when visual acuity is normal. Altered and extraocular movements, and ocular color vision can be the only early sign of an optic funduscopic examination are all part of the rou- neuropathy. A simple way to test it at bedside in tine neurologic examination. They are particularly patients complaining of unilateral vision loss is important when the patient has visual symptoms, to present a bright red object to each eye and to or when the neurologic disorder involves the ask the patient to estimate the amount of “redness” intracranial visual pathways or is classically asso- in each eye [1 ] . Unilateral optic neuropathies will ciated with neuro-ophthalmic manifestations or produce red desaturation (dimmer or darker red) complications. Often, a detailed neuro-ophthalmic in the affected eye. A more formal and quantita- examination provides helpful clues regarding the tive way to test color vision is with Ishihara or mechanism of neurologic symptoms and signs Hardy Rand Ritter pseudoisochromatic color and guides the neurologist when making acute plates. management decision in the patient with visual complaints. The only tools needed are a near visual acuity card (but a magazine from the wait- Visual Fields ing room can be suffi cient), a bright red object, a bright light for external and examinations, Visual fi elds are usually assessed in the emer- and a direct ophthalmoscope. gency department by confrontation methods, and can be of great value in helping localize the lesion. As for visual acuity, visual fi elds are tested Visual Acuity one eye at a time, with special attention directed to the horizontal and vertical axes of the visual Visual acuity is easily measured in cooperative fi eld. One eye is occluded and the patient is patients in the emergency department or in the instructed to count fi ngers presented within the neurologist’s offi ce. Each eye must be tested sep- central 30° by the physician while the patient arately and patients should wear their corrective looks at the examiner’s opposite eye or nose, and lenses (glasses or contact ) during the exami- maintains fi xation. The patient must perform the nation. A near card (or even your name tag or a task equally well in all four quadrants. An asym- magazine) is good enough to test visual acuity. metry along the horizontal axis in one eye is most Patients over the age of 50 must wear their read- suggestive of optic nerve disease, whereas an ing glasses (or a +3 lens must be used). If visual abrupt change across the vertical meridian sig- acuity is improved when the patient looks through nals visual loss of intracranial origin. For more small holes made on a piece of cardboard (so- peripheral visual fi eld testing, fi nger movements called pinhole), the problem is refractive or ocu- may be used because these parts of the visual lar, and not neurologic in origin. This pinhole is fi eld are more sensitive to motion than shape. If also useful to estimate distance visual acuity the visual fi eld defect is within the central 10° when patients do not have their glasses. If the and too small to be detected by confrontation vision loss is so profound that the patient cannot testing, the Amsler grid is useful to test the cen- see anything on the near card, vision is measured tral visual fi eld at bedside. 5 Acute Visual Loss 97

Formal visual fi eld testing, such as Goldmann suggestive of pituitary apoplexy with chiasmal or automated perimetry, provides a more stan- and cavernous sinus compression. dardized examination, will reveal more subtle abnormalities, and can quantify the defects in order to follow disease progression. These tests Eye Movements are easily performed in an ophthalmologist’s offi ce once the patient is stable and able to and ocular motility are discussed in cooperate. detail in Chap. 6. Some patients describe diplopia as “visual loss or blurriness” that resolves with covering either eye. True monocular or binocular Examination of the Pupils visual loss in association with abnormal eye movements should help localize the lesion (e.g., Pupillary examination in the dark and in the light to the orbital apex or to the sellar region). provides valuable information about the afferent and efferent visual pathways. Because both pupil- lary reactions to light and pupillary dilation in the Ocular Examination dark are examined, it is essential to turn the lights and Funduscopic Examination off to ensure that the level of light is low enough (which may be challenging in the emergency The ocular examination itself is usually the department or in an ICU). domain of the ophthalmologist, but careful pen- The search for a relative afferent pupillary light examination at bedside may reveal obvious defect (RAPD) is of great importance, particu- abnormalities of the anterior portion of the eye larly when visual loss is unilateral or asymmetric. (such as the or lens) that could be the Indeed, the presence of an RAPD in the setting of cause of decreased vision or that could obstruct a normal-appearing is diagnostic of a an adequate view of the fundus [3 ] . Abnormalities unilateral or asymmetric optic neuropathy. of the ocular media suffi cient to cause severe Exceptions include severe retinal diseases, such visual loss usually result in a poor view of the as retinal vascular occlusions, and large retinal ocular fundus: “If you can’t see in, the patient detachments, which are easily seen on fundu- can’t see out .” When media opacity is suspected, scopic examination. Corneal abnormalities, cata- the visual acuity should be tested without and racts, and macular disorders do not cause a with pinhole. Redness of the usually RAPD. indicates a problem involving the anterior seg- Unless the patient has a history of an ocular ment of the eye. Any ocular redness or pain asso- disorder (such as surgery or ), ciated with vision loss is usually an ophthalmic refl ects an efferent problem which may be either emergency and should prompt an immediate oph- a dilation problem (the smaller pupil does not thalmologic consultation. Corneal ulcerations, dilate well) or a constriction problem (the larger uveitis, and angle-closure present with pupil does not constrict well). Poor dilation acute painful visual loss (Fig. 5.1 ). refl ects a lesion involving the sympathetic path- Examination of the ocular fundus is essential ways, such as from Horner syndrome, whereas in all patients complaining of visual loss. poor constriction refl ects a lesion involving the Pharmacologic dilation of the pupils with parasympathetic pathways such as a third nerve short-acting drops, such as a parasympathetic palsy, tonic pupil, or pharmacologic . antagonist (tropicamide) and a sympathetic ago- Horner syndrome with acute visual loss points to nist (phenylephrine), allows the best and easiest the internal carotid artery, and may be the fi rst view of the optic nerve, macula, and blood ves- sign of a carotid dissection, whereas an acute sels. Phenylephrine should be avoided in patients third nerve palsy with visual loss is highly with severe systemic hypertension or malignant 98 C. Lamirel et al.

localize the lesion to the eye and often reveal ocular emergencies. More rarely, however, the ocular examination does not explain the visual loss and an optic neuropathy or an intracranial process is suspected; sometimes, the ophthalmol- ogist or emergency department physician identifi es a sign suggestive of a neurologic disor- der, such as optic nerve head edema, bitemporal or homonymous visual fi eld changes, an efferent pupillary disorder, or abnormal extraocular move- ments. A neurologic consultation should also be Fig. 5.1 Acute angle-closure glaucoma in the left eye with acute painful vision loss. The eye is red and the cor- requested when the patient is diagnosed with nea is cloudy. The pupil is dilated and not reactive to light. acute retinal ischemia (transient or permanent) or On palpation, the eye feels hard retinal emboli, which may precede a cerebral infarction and warrant urgent neurovascular hypertension. Pupillary dilation occurs within evaluation. 30 min and usually resolves within 6 h. Both pupils should be dilated at the same time, and time of instillation and agent used should be Ocular Causes of Acute Vision Loss: noted in the chart in the emergency department. What the Neurologist Should Know Identifi cation of optic nerve head edema, optic nerve head pallor, retinal whitening, retinal hem- Painful with Vision Loss orrhages, attenuation of the arteries, dilation of the veins, retinal emboli, or vitreous hemorrhages Acute vision loss with eye pain, , is extremely useful in neurologic emergencies tearing, and eye redness suggests an ocular dis- and allows the neurologist to manage these ease involving the anterior segment of the eye patients appropriately before even requesting an [ 3 ] . These disorders are mostly unilateral. ophthalmic consultation. Optic nerve pallor takes Trauma, corneal infections, anterior uveitis, and about 6 weeks to develop regardless of the mech- acute angle-closure glaucoma are classic causes anism of optic nerve injury; therefore, the fi nding of acute visual loss with pain, which should of optic nerve pallor in a patient complaining of always prompt an immediate examination by an acute visual loss suggests that the visual loss is ophthalmologist [4– 8 ] . related to an underlying long-standing process. Patients with corneal ulcerations or trauma are For example, a patient with a previously undiag- often unable to open their eye because of refl ex nosed pituitary mass may notice the visual loss blepharospasm. Angle-closure glaucoma is sus- only at the time of pituitary apoplexy, or some pected when the vision loss is preceded by severe patients with long-standing optic atrophy and eye pain and headaches and often associated with visual loss may erroneously blame the visual loss nausea. The eye becomes red rapidly and patients on a recent trauma. typically complain of seeing halos around lights in addition to blurry vision. The cornea is cloudy and the pupil is dilated, not reactive to light Where Is the Lesion? (Fig. 5.1 ). Palpation of both eyes allows the neu- rologist to realize that the affected eye feels In most cases, vision loss results from ocular dis- harder than the normal eye. Uveitis can only be orders, and an ophthalmologist should be con- diagnosed with slit lamp examination: most sulted fi rst in the emergency department when a patients complain of photophobia, fl oaters, and patient presents with acute visual changes. Ocular mild pain, and the eye may be moderately or redness, eye pain, or an abnormal fundus help very red. 5 Acute Visual Loss 99

Vision Loss with Abnormal Retina the cornea indicating the absence of the normal red refl ex. is common in A few neurologic emergencies may present with diabetic patients, and it may also occur in patients acute visual loss and retinal changes. Intravitreal with acute intracranial hypertension, particularly and preretinal hemorrhages cause acute visual resulting from subarachnoid hemorrhage (so- loss without pain. The anterior segment of the called Terson syndrome) (Fig. 5.2 ) [ 9 ] . eye looks normal, there is no RAPD, and the view Retinal diseases such as central retinal artery of the fundus is diffi cult; when looking at the eye occlusion (CRAO) (Fig. 5.3 ), and large retinal with an ophthalmoscope a few inches away, the detachments, can produce acute painless mon- examiner sees a dull or dark refl ex in the center of ocular visual loss with an RAPD. The RAPD is present because the retinal ganglion cells (whose axonal projections become the optic nerve) in the inner layers of the retina are affected by these processes. This is why a dilated funduscopic examination is necessary before localizing the lesion to the optic nerve in all patients with vision loss and an RAPD. CRAO produces acute, pain- less, severe, and permanent monocular visual loss resulting from acute inner retinal ischemia. The inner retina, which includes the ganglion cells, is infarcted and there is a dense RAPD. Funduscopic examination shows marked attenu- ation of the retinal arteries, sometimes occluded by emboli, and whitening of the ischemic inner retina with sparing of the outer retina in the foveal region supplied by the intact choroidal cir- culation, creating the classic “cherry-red spot” Fig. 5.2 Terson syndrome in the right eye of a patient with subarachnoid hemorrhage. There is a large preretinal (Fig. 5.3 ) [1– 10 ] . Acute CRAO is an emergency, hemorrhage as well as two small peripapillary hemorrhages should be considered a cerebral infarction of the

Fig. 5.3 Acute central retinal artery occlusion in the right compared with the left eye. The ischemic retina is edema- eye (shown on the left ). Note the attenuated central retinal tous and appears whitish compared to the left eye and artery with segmental narrowing in the right eye ( arrows ) there is a cherry-red spot (*) 100 C. Lamirel et al.

Optic Neuropathies

Optic neuropathies typically manifest with decreased visual acuity, altered color vision, and abnormal visual fi elds. An RAPD is always pres- ent when the optic neuropathy is unilateral or asymmetric. Acutely, the optic nerve may be nor- mal (posterior optic neuropathy), or may be swol- len (anterior optic neuropathy) (Fig. 5.5 ). The optic nerve becomes pale 4–6 weeks later regard- less of the mechanism. Optic neuropathies with acute or subacute vision loss are often evaluated in the emergency department. These optic neu- ropathies are best classifi ed by mechanism and Fig. 5.4 Acute central retinal vein occlusion in the left the clinical characteristics often allow a diagno- eye. There are numerous fl ame retinal hemorrhages, the veins are dilated (arrows ), and there are cotton wool spots sis (Table 5.1 ). Dedicated optic nerve imaging is ( arrow heads ) and optic nerve head edema often helpful, particularly to demonstrate optic nerve infl ammation, infi ltration, or compression anterior circulation, and should be evaluated (Fig. 5.5 ). However, it is important to emphasize similarly. In patients older than 50 years, giant that most brain scans (CT or MRI) do not allow cell arteritis must also be ruled out [11 ] . Acute proper evaluation of the optic nerves. A CT of the treatments for CRAO are limited, but there are orbits with contrast, thin cuts, and coronal recon- studies evaluating intravenous or intra-arterial structions is helpful when emergent MRI cannot thrombolysis in acute CRAO, and stroke neurol- be obtained, or in the setting of trauma. An MRI ogists are often consulted to determine whether of the orbits with contrast and fat suppression is thrombolysis may be considered in selected the most sensitive test to image the optic nerves CRAO patients presenting within a few hours of in the orbits, at the level of the orbital apex and visual loss. intracranially (see Fig. 5.5b ). It is particularly Numerous other retinal disorders involving important when an optic nerve sheath menin- the macula may produce central visual loss, but gioma or an orbital apex syndrome is suspected. are usually not associated with an RAPD. Central retinal vein occlusion (Fig. 5.4 ) is also a cause of painless monocular vision loss, which is usu- I n fl ammatory Optic Neuropathy ally not associated with neurologic disorders. () Age-related is a common cause of acute central visual loss in the elderly; Isolated optic neuritis is often the fi rst manifesta- these patients often also have a history of pro- tion of multiple sclerosis (MS) and is one of the gressive monocular or binocular visual loss with classic clinically isolated syndromes. However, metamorphopsia [12 ] . Acute worsening of infl ammation of the optic nerve may also occur in vision in one eye is usually related to bleeding association with numerous infectious and nonin- of a macular neovascular membrane. Central fectious infl ammatory disorders. serous is a cause of acute painless Patients with optic neuritis present with acute unilateral central vision loss with no RAPD and or subacute painful monocular visual loss. Central a normal-appearing optic nerve, most often vision typically deteriorates over hours or days. occurring in young men. Careful examination of In mild optic neuritis, color vision change can be the macula shows a “blister” in the macular the fi rst or the only visual complaint. Pain on region. eye movement is a frequent early complaint with 5 Acute Visual Loss 101

Fig. 5.5 Anterior optic neuritis in the left eye. (a ) Fundus contrast and fat suppression demonstrating enhancement photograph of both eyes showing mild optic nerve head of the left optic nerve (arrow ). (c ) Axial FLAIR MRI edema in the left eye (OS) compared with the right eye of the brain showing two periventricular ovoid lesions (OD). (b ) Axial T1-weighted MRI of the orbits with suggestive of demyelinating disease

Table 5.1 Most common causes of acute optic neuropathies Mechanism Optic neuropathies that often present with acute visual loss in the emergency department Infl ammatory (Optic neuritis) Clinically isolated syndrome or associated with multiple sclerosis Neuromyelitis optica Not associated with multiple sclerosis: Infectious diseases (syphilis, cat scratch) Systemic infl ammatory and autoimmune diseases (sarcoidosis) Vascular Ischemic optic neuropathy: Arteritic: Nonarteritic anterior ischemic optic neuropathy Compressive/infi ltrative Acute compression of the intracranial portion of the optic nerve or of the chiasm: Pituitary mass (pituitary apoplexy) Craniopharyngioma Internal carotid artery Any intracranial mass close to the anterior visual pathways Toxic/nutritional Methanol poisoning Hereditary Leber hereditary optic neuropathy Traumatic Direct or indirect mechanism Raised intracranial pressure Malignant hypertension Stage IV 102 C. Lamirel et al. the visual loss. On examination, there is but does not alter long-term visual outcome or decreased visual acuity, decreased color vision, the long-term risk of subsequent MS. The Optic and visual fi eld loss centrally [ 13 ] . An RAPD Neuritis Treatment Trial showed that 1 mg/kg/ will be present if the optic neuritis is unilateral or day of oral prednisone did not improve visual asymmetric. In isolated optic neuritis associated outcome and doubled the risk of recurrent optic with demyelinating disease, two-thirds of patients neuritis. Therefore, low-dose oral prednisone is have a normal optic nerve acutely and currently not recommended for patients with iso- one-third of patients have moderate optic nerve lated optic neuritis and intravenous steroids head swelling (so-called “anterior” optic neuritis should be discussed on a case-by-case basis. or papillitis) (see Fig. 5.5 ). Optic neuritis with A subgroup of patients with severe optic neu- normal-appearing optic nerve acutely is called ritis and poor recovery, or with bilateral or recur- “retrobulbar” or “posterior” optic neuritis. rent optic neuritis, are found to have positive In all cases, optic nerve head pallor develops neuromyelitis optica (NMO) antibodies, even in 4–6 weeks later. the absence of transverse myelitis [16 ] . Evaluation of the patient with optic neuritis Neuroretinitis characterizes patients with an varies based on the clinical presentation and the anterior optic neuritis associated with retinal exu- suspected diagnosis. A brain MRI is usually dates, usually in the shape of a star at the macula. obtained in patients with isolated optic neuritis to In most cases, neuroretinitis is due to an infection look for demyelinating disease (see Fig. 5.5 ). such as cat scratch disease or syphilis, or to a Blood tests and specifi c serologies may be noninfectious infl ammatory disorder, such as sar- obtained depending on the patient’s characteris- coidosis. Neuroretinitis is not associated with a tics. Syphilis, cat scratch disease, and sarcoidosis risk of MS [ 17 ] . Treatment of neuroretinitis or are common alternate causes of optic neuritis. infectious optic neuritis depends on the underly- A lumbar puncture may also be useful in this set- ing disease. ting. However, in most cases, optic neuritis remains idiopathic or is associated with multiple sclerosis. Ischemic Optic Neuropathy In patients with typical isolated optic neuritis, the risk of multiple sclerosis is best predicted by Ischemic optic neuropathies are classifi ed into a brain MRI: patients with a normal brain MRI anterior ischemic optic neuropathy (AION), in have a risk of multiple sclerosis estimated at 25% which case there is always optic nerve head at 15 years, whereas those with at least one typi- swelling acutely (Fig. 5.6 ), and posterior isch- cal demyelinating lesion on the MRI have a risk emic optic neuropathy (PION), in which the pos- close to 70% at 15 years (see Fig. 5.5 ) [14 ] . terior part of the optic nerve is ischemic with Among the patients with no lesions on the MRI, normal-appearing optic disk acutely [18 ] . AION any of the following features is associated with is much more common than PION, the latter virtually no risk of multiple sclerosis: male gen- remaining a diagnosis of exclusion. Ischemic der, absence of pain, severe optic nerve edema, optic neuropathies are also classifi ed as “nonar- peripapillary hemorrhages, or macular changes teritic” and “arteritic” (most often associated suggesting neuroretinitis. This emphasizes the with giant cell arteritis). Ischemic optic neuropa- importance of a funduscopic examination by an thies present with painless, acute or subacute ophthalmologist in all cases with presumed optic visual loss with visual fi eld defects and an RAPD; neuritis. 4–6 weeks later, the optic nerve becomes pale. The visual prognosis of isolated optic neuritis Nonarteritic AION (NAION) is the most com- is usually good even without treatment [ 15 ] . mon form of ischemic optic neuropathy, affecting High-dose intravenous methylprednisolone (1 g/ between 2 and 10 individuals per 100,000. The day for 3 days followed by oral prednisone 1 mg/ main risk factor is a small crowed optic disk with kg/day for 11 days) only accelerates visual recovery, no cup (so-called disk at risk) (see Fig. 5.6 ), but 5 Acute Visual Loss 103

arteritis may decrease the duration of treatment and the total dose of steroids used. However, the treatment remains mostly empirical with very few clinical trials available.

Traumatic Optic Neuropathy

Monocular visual loss after head trauma can result from a direct (when there is direct trauma to the optic nerve by penetrating orbital trauma or optic canal fracture) or indirect traumatic optic neuropathy [ 4 ] . These patients often have associ- ated brain and systemic injuries, and recognition Fig. 5.6 Anterior ischemic optic neuropathy in the right of vision loss is often delayed if there is no exter- eye. There is an optic nerve head edema, worse superiorly, nal sign of ocular injury. Identifi cation of an and a small peripapillary hemorrhage superiorly. The RAPD in a sedated or unconscious patient may patient had an inferior altitudinal visual fi eld defect be the only evidence of traumatic optic neurop- athy and should be looked for systematically in other disk anomalies such as optic nerve head all head trauma patients. Visual loss may be iso- drusen and papilledema can also predispose to lated, with a normal-appearing or swollen optic NAION [19 ] . Most patients with NAION are at nerve acutely. There may be associated signs least 50 years of age and have at least one cardio- suggesting ocular rupture, dislocation of the optic vascular risk factor. NAION is a small vessel nerve, or orbital trauma with proptosis, ophthal- disease involving the short posterior ciliary arter- moplegia, and elevated intraocular pressure. ies. It is not embolic and there is no increased risk Orbital imaging with a CT without contrast is of cerebrovascular disease in patients with essential to rule out an orbital fracture or an NAION. The pathophysiology involves local orbital hematoma, which may require immediate arteriolosclerosis involving small vessels, in treatment. An ophthalmologist must perform an addition to the “disk at risk.” Therefore, although immediate detailed examination when there is atheromatous vascular risk factors should be suspected ocular or orbital trauma. The treatment identifi ed and aggressively treated, search for a of direct traumatic optic neuropathies is usually carotid or cardiac source of emboli is usually not surgical, whereas indirect traumatic optic neu- necessary in patients with isolated NAION. There ropathies are usually observed. There is evidence is currently no proven treatment for ischemic that steroids are not only not useful in this sub- optic neuropathies, and the only emergency in group of patients, but also potentially harmful, evaluating a patient with AION or PION is to rule particularly in the setting of associated brain and out giant cell arteritis [ 19 ] . Indeed, giant cell systemic injuries [4 ] . arteritis should always be considered in all patients older than 50 years with AION or PION, and blood tests looking for a biologic infl amma- Compressive Optic Neuropathy tory syndrome need to be obtained emergently. High-dose steroids are initiated only in patients Patients with compressive optic neuropathies in whom there is high clinical suspicion of giant classically develop progressive uni- or bilateral cell arteritis, and a temporal artery biopsy should optic neuropathies. However, many of these be subsequently obtained in these patients [20 ] . patients are not aware of insidious visual loss and Administration of high doses of intravenous ste- present emergently when visual loss worsens, roids at the beginning of treatment for giant cell involves central vision, or keeps them from 104 C. Lamirel et al. reading or driving. These patients already have a pale optic nerve at presentation. More rarely, sud- den vision loss can result from compressive optic neuropathy. Most often, the lesion involves the orbital apex (metastases and fungal lesions are the most classic) or the intracranial optic nerve and chiasm (pituitary tumors, especially with apoplexy, ophthalmic artery , and craniopharyngiomas are the most common). Associated signs such as an orbital syndrome and ocular motor cranial nerve palsies help localize the lesion to the orbital apex or the intracranial portion of the optic nerve, respectively. Emergent evaluation with dedicated MRI of the brain and the orbits with contrast and fat suppression is indicated. MRA or CTA should be obtained when an aneurysm is suspected or when the MRI is normal.

Acute Bilateral Optic Neuropathies

Rarely, simultaneous bilateral optic neuropathies may occur with acute binocular visual loss. These patients are usually severely visually disabled Fig. 5.7 Acute binocular visual loss with bitemporal hemianopia from pituitary apoplexy. The patient also had and often present to the emergency department. headaches and diplopia with a left third nerve palsy. Because both optic nerves are affected, there may ( a) Humphrey visual fi elds showing a bitemporal hemi- not be an RAPD on examination. When the optic anopia. ( b ) Coronal T2-weighted MRI demonstrating a nerves appear normal acutely (such as from bilat- large pituitary mass (arrowhead ) with chiasmal compres- sion and cavernous sinus compression eral posterior optic neuropathies), the diagnosis may be diffi cult and relies on pupil examination (which are sluggish in response to light) and bilateral optic neuropathies (Fig. 5.7 ). Most visual fi eld testing. patients also have headaches, sometimes with Bilateral infl ammatory optic neuritis, with or abnormal extraocular movements and altered without disk edema, should suggest an infectious mental status. or infl ammatory disorder and should prompt a more Hypertensive retinopathy with bilateral optic extensive evaluation than isolated unilateral optic nerve head edema can also produce acute or sub- neuritis. A lumbar puncture is usually performed, acute bilateral visual loss (Fig. 5.8 ). looking for a meningeal process; sarcoidosis and In most cases, raised intracranial pressure neuromyelitis optica are classic causes. with bilateral papilledema produces slowly pro- Bilateral simultaneous ischemic optic neurop- gressive visual loss with secondary optic atro- athies in patients older than 50 are highly sugges- phy, rather than acute or subacute visual loss. tive of giant cell arteritis, and erythrocyte However, fulminant idiopathic intracranial sedimentation rate and C-reactive protein should hypertension or acute causes of raised intracra- be systematically obtained in the emergency nial pressure such as cerebral venous thrombosis department [18 ] . can cause severe bilateral papilledema and rap- Pituitary apoplexy with sudden chiasmal and idly progressive bilateral visual loss (Fig. 5.9 ) optic nerve compression is also a classic cause of [ 21, 22 ] . 5 Acute Visual Loss 105

Fig. 5.8 Hypertensive retinopathy with bilateral optic nerve edema and retinal hemorrhages. The retinal arteries are attenuated. Blood pressure was 210/130 mmHg. This is consistent with stage IV hypertensive retinopathy

Fig. 5.9 Bilateral severe optic nerve edema consistent ( arrows), and severe dilation of the veins. The patient had with papilledema (from raised intracranial pressure). The thrombosis of the superior sagittal sinus with elevated optic nerves are elevated with numerous cotton wool spots CSF opening pressure

Leber hereditary optic neuropathy may pres- Mitochondrial DNA mutations are routinely ent with acute bilateral optic neuropathies and tested on a blood sample. profound visual loss [ 23 ] . The visual loss is iso- Nutritional and toxic optic neuropathies are lated and there is no pain. Brain and MRIs typically bilateral and slowly progressive. Acute are typically normal without optic nerve enhance- visual loss can occur after ingestion of methanol ment. The diagnosis should be suspected in any (homemade alcohol or antifreeze). The optic patient with bilateral or rapidly sequential pain- nerves usually appear swollen acutely and less optic neuropathies, especially if the patient is patients often have associated neurologic signs a young man with a family history of visual loss on with confusion and altered mental status [ 24 ] . the maternal side, and absence of visual recovery. The visual prognosis is poor. 106 C. Lamirel et al.

Disk Edema

-Blood pressure -Ophthalmological evaluation: visual acuity, color vision, pupils, intra-ocular pressure, extraocular movements, dilated funduscopy, formal visual fields -Neurological evaluation: ? headache, nausea, diplopia, focal neurological symptoms and sings

Pseudo disk edema Optic neuropathy (anterior) Small, crowded optic nerve Optic neuritis Optic nerve drusen Anterior ischemicoptic neuropathy Congenital anomally Papilledema Compressive optic neuropathy Infiltrative optic neuropathy (raised intracranial pressure) Ocular hypotony Retinal fluorescein Ocular ultrasound Emergentneuro-imaing (Preferaby brain MRI with contrast)

Normal imaging, venous thrombosis Intracranial mass / hydrocephal us or meningeal enhancement

Lumbar puncture with opening pressure

Normal OP (<200 mm) Elevated OP (>250 mm) Elevated Op (>250 mm) Normal CSF contents Abnormal CSF contents Normal CSF contents

Pseudo disk edema Rule-out venous sinus thrombosis (Brain MRI / head and neck MRV)

Venous sinus thrombosis Idiopathic intracranial Chronic meningitis hypertension Elevated CSF protein (usually, occult spinal cord tumors)

Fig. 5.10 Diagram detailing the diagnosis of disk edema

Bilateral Optic Nerve Edema raised intracranial pressure should be suspected. All causes of raised intracranial pressure can Bilateral optic nerve edema may be the result of produce papilledema, which is associated with bilateral anterior optic neuropathies, raised progressive visual fi eld constriction, secondary intracranial pressure (i.e., papilledema), or optic atrophy, and irreversible visual loss if systemic hypertension (stage IV hypertensive intracranial hypertension is not timely treated. retinopathy). Indeed, visual loss is the main complication of Patients with bilateral anterior optic neuropa- idiopathic intracranial hypertension and is often thies have visual acuity loss, decreased color encountered in patients with cerebral venous vision, and abnormal visual fi elds. Classic causes thrombosis (see Fig. 5.9), intracranial mass include bilateral anterior optic neuritis and ante- lesions, or unrecognized hydrocephalus, empha- rior ischemic optic neuropathies. sizing the importance of systematically looking When there is bilateral disk edema and cen- at the fundus of all patients with chronic head- tral visual acuity is normal, papilledema from aches (Fig. 5.10 ). 5 Acute Visual Loss 107

Malignant systemic hypertension (or hyper- tensive crisis) is often associated with bilateral optic nerve head edema (see Fig. 5.8 ). There are usually also retinal and vascular changes suggestive of hypertensive retinopathy, such as attenuation of retinal arteries, retinal hemor- rhages, and retinal exudates (hypertensive retin- opathy stage IV).

Binocular Vision Loss from Chiasmal Lesions

Acute binocular visual loss may result from simultaneous damage to the intracranial portions of the optic nerves, often in association with chi- asmal compression. Pituitary tumors, sphenoid wing meningiomas, and craniopharyngiomas are the most common causes of the chiasmal syndrome. Pituitary apo- plexy is a classic cause of acute chiasmal syn- drome often associated with headaches, whereas other intracranial processes usually present with more insidious, progressive visual loss. The fi nd- ing of a bitemporal visual fi eld defect—the hall- Fig. 5.11 Left homonymous hemianopia secondary to a mark of the chiasmal syndrome—requires right occipital infarction. (a ) Humphrey visual fi elds immediate brain imaging in patients with acute showing a complete left homonymous hemianopia. ( b ) visual changes (see Fig. 5.7 ). Internal carotid Axial FLAIR MRI of the brain showed a right occipital infarction in the territory of the right posterior cerebral artery aneurysms can also produce compressive artery chiasmal syndromes.

A complete homonymous hemianopia (see Loss from Fig. 5.11 ) has no other specifi c localizing value Retrochiasmal Lesions than the contralateral retrochiasmal visual path- ways, but associated symptoms and signs are A lesion of the retrochiasmal visual pathways very helpful in localizing the lesion along the (optic tract, lateral geniculate body, visual radia- intracranial visual pathways. Optic tract lesions tions, or occipital cortex) classically produces a produce a contralateral RAPD, whereas parietal contralateral homonymous hemianopia (Fig. 5.11 ) lesions are associated with abnormal optokinetic [1, 25, 26 ] . Visual acuity should be normal in . Congruous incomplete homonymous each eye, unless there is superimposed damage to hemianopias (when the two abnormal fi elds are the anterior visual pathways. In cases of bilateral similar in both eyes) are most suggestive of an injury (most often bilateral occipital lobe lesions), occipital lesion, whereas incongruous homony- visual acuity may be decreased, but the amount mous hemianopias suggest a lesion along the of visual acuity loss is symmetric in both eyes. more anterior optic radiations. The most common Any central nervous system disorder involving cause of an isolated homonymous hemianopia is both occipital lobes may produce bilateral visual a stroke (most often a posterior cerebral artery loss from so-called cerebral blindness (Table 5.2 ). distribution infarction) (see Fig. 5.11 ) [ 27 ] . 108 C. Lamirel et al.

Table 5.2 Common neurologic causes of acute binocu- Table 5.3 Causes of transient visual loss lar visual loss (producing either a homonymous visual Monocular Binocular fi eld defect or binocular “cerebral” visual loss) Eye Bilateral anterior visual Cerebral causes of acute visual loss Ocular surface pathways • Vascular Anterior segment Ocular disorders affecting – Occipital infarction or hemorrhage Angle-closure glaucoma both eyes – Optic radiations or optic tract infarction or Hyperglycemia hemorrhage Bilateral optic neuropathies – Superior sagittal venous sinus thrombosis with Retina/ Intracranial visual pathways occipital venous infarction Ischemia Chiasmal compression – Arteriovenous malformation involving the visual Optic nerve Any transient process pathways Ischemia (giant cell affecting the occipital lobes or • Intracranial mass arteritis) the intracranial visual – Any mass involving the intracranial visual Compression pathways (most common are pathways Swelling, drusen, migrainous visual aura, • Occipital seizures crowding occipital seizures, and • Hypoglycemia occipital transient ischemic • Multiple sclerosis attacks) • Leukoencephalopathies • Posterior reversible encephalopathy syndrome (PRES) • Hypertensive encephalopathy • Trauma • Carbon monoxide intoxication

Transient Visual Loss

The most important step in evaluating a patient with transient visual loss is to establish whether the visual loss is monocular (a disorder of the eye or the optic nerve) or binocular (a disorder affect- ing the chiasm or retrochiasmal visual pathways) (Table 5.3 ). Deciding whether an episode of transient visual loss occurred in one eye or both is not always easy. Very few patients realize that bin- ocular hemifi eld (homonymous) visual fi eld loss Fig. 5.12 Branch retinal arterial embolus in a patient affects the fi elds of both eyes. They will usually with an episode of transient loss of vision in the right eye. localize it to the eye that lost its temporal fi eld. Fundus photograph of the right eye showing a retinal cho- The best clues to the fact that transient visual loss lesterol embolus (arrow head ) from a carotid artery ather- oma. There is a large intraretinal hemorrhage superiorly was actually binocular are reading impairment related to retinal ischemia (monocular visual loss does not impair reading unless the unaffected eye had prior vision impair- ment) and visual loss confi ned to a lateral hemi- abnormal pupil, retinal emboli (Fig. 5.12 ), retinal fi eld (i.e., to the right or left of midline with ischemia, optic nerve edema, or residual visual “respect” of the vertical meridian). Monocular fi eld defect. visual loss does not usually cause this pattern of visual loss. A detailed ocular examination is essential in Monocular Transient Visual Loss order to fi nd clues that may help understand the mechanism of visual loss, such as narrow ante- Neurologists are often called to evaluate patients rior chamber, elevated intraocular pressure, with transient monocular visual loss (TMVL). 5 Acute Visual Loss 109

Table 5.4 Differential diagnosis of transient monocular visual loss (TMVL) Vascular Orbital ischemia (ophthalmic artery) Retinal ischemia (central retinal artery and its branches, central retinal vein) Optic nerve ischemia (short posterior ciliary arteries/ophthalmic artery) Choroidal ischemia (posterior ciliary arteries) Ocular diseases Anterior segment disorders (dry eyes, , , spontaneously resolving attacks of angle-closure glaucoma, serous …) Optic nerve disorders Papilledema (transient visual obscurations) Optic disk drusen (transient visual obscurations) Congenitally anomalous optic disk (transient visual obscurations) Optic nerve compression (gaze-evoked TMVL) Uhthoff phenomenon (demyelination)

However, it is important to keep in mind that Orbital tumors may present as episodes of mon- numerous ocular conditions can also produce ocular TMVL precipitated by eye movements in TMVL and need to be ruled out by a detailed a specifi c gaze direction. ocular examination before assuming that the mechanism of TMVL is vascular (see Table 5.3 ). Mechanisms of Vascular Transient Monocular Visual Loss Ocular Causes of Monocular Vascular TMVL may result from a retinal tran- Transient Visual Loss sient ischemic attack (TIA) in the carotid circula- Most ocular disorders can produce fl uctuations in tion and should be managed emergently, similar vision and may be described as “TMVL” by to hemispheric TIAs, in order to reduce the risk patients. Ocular disorders usually produce tran- of permanent visual loss, stroke, or cardiovascu- sient blurry vision rather than complete blackout lar death (Table 5.4 ) [ 28, 29 ] . Vascular TMVL of vision as in vascular TMVL. Blurry vision may result from emboli in the ophthalmic artery worsened by reading (during which blinking is or in the central retinal artery, from ocular hypop- reduced) and improving with blinking or rubbing erfusion, or more rarely from central retinal artery the eye is highly suggestive of dry eyes and other spasm [28 ] . Vascular TMVL resulting from optic corneal surface disorders causing an abnormal nerve ischemia is rare and is highly suggestive of tear fi lm. Acute increase in intraocular pressure giant cell arteritis, in which case the optic nerve can produce transient visual changes, often is usually swollen. Rarely, TMVL may inaugu- described as halos around lights and associated rate a central retinal vein occlusion, with dilated with eye pain. Such episodes are suggestive of veins on funduscopic examination. spontaneously resolving angle-closure glaucoma The description of the visual loss, its duration, precipitated by dim light in hyperopic patients, or and the ocular examination (particularly of the pigmentary dispersion syndrome after exercise in ocular fundus) are helpful in understanding the young myopic patients. In patients with diabetes mechanism. Findings of retinal arterial emboli mellitus, acute hyperglycemia can cause blurry suggest a carotid, aortic arch, or cardiac source of vision lasting hours to days from transient refrac- emboli (see Fig. 5.12 ). Retinal hemorrhages and tive or macular changes. Anomalous optic disks dilation of the veins suggest chronic ocular such as papilledema, drusen, and tilted optic hypoperfusion and . disks can produce recurrent episodes of TMVL Optic disk edema suggests optic nerve ischemia lasting a few seconds (transient visual obscura- and should prompt immediate treatment and tions), often precipitated by changes in posture. workup for giant cell arteritis (see Fig. 5.6 ). 110 C. Lamirel et al.

Table 5.5 Characteristic s of the three most common causes of binocular transient visual loss Occipital transient Migrainous visual aura Occipital seizures ischemic attack Visual symptoms Positive Positive Negative (hemiano- Very rich, moving Simple visual phenomena pia or blindness) Often black and white, scintillat- (phosphenes, bubbles) ing, shimmering, jagged edges Colored Progression of Typical migrainous March, with Usually not progressive Sudden onset and symptoms progression of symptoms over time disappearance Duration of visual Typically 20–30 min. Less than an Usually brief (seconds) A few minutes symptoms hour Often repeated Associated symptoms Migrainous headache typically Often none Brow headache follows the aura May be associated with possible at the time Visual aura may be followed by other seizures of visual symptoms other migrainous aura (mostly Vertebrobasilar sensory) ischemia: Vertigo, dizziness Imbalance Diplopia Bilateral extremity weakness

Association of TMVL and ipsilateral painful Patients describe a scintillating expand- Horner syndrome points to internal carotid artery ing over several minutes into a visual fi eld, disease and is highly suggestive of internal carotid surrounded by jagged, luminous, shimmering artery dissection. Often, however, the ocular edges. The scotoma can lead to a complete hemi- examination is normal and the patient is evalu- anopia and disappears gradually. A migraine ated for all causes of retinal TIAs. All patients headache characteristically follows the scotoma over the age of 50 require emergent workup for but some patients experience the visual aura of giant cell arteritis. migraine without associated headache. The vision returns to normal within 20–30 min.

Binocular Transient Visual Loss Occipital Seizures Occipital seizures typically produce brief binocu- Binocular transient visual loss usually results lar positive visual phenomena often described as from intracranial processes involving the chias- fl ashing lights or bubbles. They typically last mal and retrochiasmal visual pathways. More only a few seconds, but they are usually repetitive rarely it can be related to bilateral ocular disor- and are relatively stereotyped in the same ders or to transient visual obscurations associated patient. with papilledema (see Table 5.3 ). Migrainous visual aura, occipital seizures, and occipital TIAs Occipital Transient Ischemic Attack are the most classic causes of binocular transient Episodes of transient, complete binocular visual visual loss, and are usually identifi ed based on loss may represent a TIA in the distribution of the the patient’s description (Table 5.5 ). basilar artery or the posterior cerebral arteries. A unilateral occipital TIA manifests as a transient Migrainous Visual Aura homonymous hemianopia whereas a bilateral Migrainous visual aura is the most common cause occipital TIA manifests as transient “cortical of transient binocular visual loss and is usually blindness.” As opposed to migraine, hemianopic easily diagnosed based on the patient’s description. events of ischemic origin are typically sudden in 5 Acute Visual Loss 111

Fig. 5.13 Posterior reversible encephalopathy syndrome involving both parieto-occipital lobes. (b ) Six weeks after ( PRES) secondary to hypertensive crisis. The patients pre- treatment of the hypertension, the MRI has normalized sented with headaches and binocular visual loss. (a ) Axial (and the vision has returned to normal) FLAIR MRI showing white matter hyperintense lesions

onset and last only a few minutes. There may be Conclusion associated headache, especially over the brow contralateral to the visual fi eld loss, but the pain Visual loss is a common symptom in neurologic is usually coincident with the visual loss, rather emergencies. Simple beside examination (includ- than following the visual loss as in migraine. ing ocular funduscopic examination) is crucial in Other symptoms of vertebrobasilar ischemia are localizing the lesion and identifying ocular often present, such as vertigo, dizziness, imbal- changes such as retinal emboli or optic nerve ance, diplopia, or bilateral extremity weakness. head edema that may require specifi c interven- Posterior Reversible tion and management. Encephalopathy Syndrome Posterior reversible encephalopathy syndrome References (PRES) classically produces acute bilateral visual loss lasting hours or days, usually associated with 1. Biousse V, Newman N. Neuro-ophthalmology illus- headaches and altered mental status. Malignant trated. NY, New York: Thieme; 2009. systemic hypertension, medications such as 2. Purvin V, Kawasaki A. Neuro-ophthalmic emergen- cyclosporine or tacrolimus, and various metabolic cies for the neurologist. Neurologist. 2005;11(4): disorders are classic causes of PRES. Brain MRI 195–233. 3. Robinett DA, Kahn JH. The physical examination of the shows T2 hyperintense lesions involving most eye. Emerg Med Clin North Am. 2008;26(1):1–16. v. often the white matter of both occipital lobes 4. Atkins EJ, Newman NJ, Biousse V. Post-traumatic (Fig. 5.13 ). Treatment of the underlying disorder visual loss. Rev Neurol Dis. 2008;5(2):73–81. usually results in dramatic improvement of visual 5. Bord SP, Linden J. Trauma to the and orbit. Emerg Med Clin North Am. 2008;26(1):97–123. vi-vii. function within days, followed by complete reso- 6. Dargin JM, Lowenstein RA. The painful eye. Emerg lution of the MRI changes within weeks [ 30 ] . Med Clin North Am. 2008;26(1):199–216. viii. 112 C. Lamirel et al.

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