ODs can manage neuro-ophthalmic disease with careful exam, diagnostic testing

Versions, ductions and cover test should be conducted on all patients with diplopia.

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The evaluation of patients with neuro-ophthalmic disease can be complex. Recognizing pertinent signs and symptoms will allow for timely diagnosis and management. While challenging, these conditions can be successfully managed either individually or in unison with other specialties.

This article reviews critical components of the exam, along with the appropriate ancillary testing required for proper diagnosis. The objective is to provide the reader with clinical pearls that may streamline diagnosis and management. Ultimately, these cases can be rewarding for both the patient and practitioner.

Detailed history critical

Taking a detailed history is critical in beginning the investigative process. From the moment the practitioner enters the exam room a physical review of the patients’ gait, posture and overall well-being can be assessed. This will allow for a systemic evaluation prior to assessing their ophthalmologic complaints. This is important, as many neuro-ophthalmic disorders present with systemic manifestations.

Next, a broad list of differential diagnoses can be considered, which will direct the exam toward narrowing that list to find the etiology. This approach helps keep clinical testing specific to the problem, instead of performing unnecessary tests. The following will address some of the more challenging cases encountered in clinical practice.

Diplopia

Diplopia can be characterized as either monocular or binocular. Monocular diplopia may be a result of uncorrected refractive error, corneal degeneration, lenticular opacification, maculopathy or, in rare instances, following cerebral damage.

In patients with true binocular diplopia, the patient will describe two images separated horizontally, vertically or a combination of the two, which is alleviated when one eye is closed. A complaint of acute constant horizontal diplopia should alert the physician to look for a lag of the lateral rectus or medial rectus, which is typically the result of sixth nerve palsy or internuclear ophthalmoplegia (INO), respectively. Those with complaints of vertical diplopia or a combination of the two can be harboring a third or fourth nerve palsy and rarely a skew deviation.

In cases where the diplopia is described as intermittent, it may be prudent to consider a decompensating phoria, breakdown of eye muscle fusion of a congenital cranial nerve paresis or pseudo INO secondary to myasthenia gravis (MG). While ocular motor disorders can be challenging, MRI has been of tremendous benefit in localizing ocular motor deficits. When considering dysfunction of the efferent system, there are four regions that should be scrutinized during interpretation of neuroimaging: ocular muscles, orbit, subarachnoid or cavernous sinus, and brainstem or posterior cranial fossa.

Ocular motility disorders: Third nerve palsy

Anatomically, the third nerve contains multiple subnuclei at the level of the superior colliculus of the midbrain. Its fascicles lie within brainstem parenchyma passing through the red nucleus and middle cerebral peduncles. The nerve travels through the subarachnoid space and between the posterior cerebral and superior cerebellar arteries, adjacent to the posterior communicating artery and pupillary fibers where it is susceptible to compression. It then passes through the superior orbital fissure, within the annulus of Zinn and innervates the inferior oblique, levator palpebrae superioris and the recti muscles with the exception of the lateral rectus and superior oblique. It is also responsible for providing motor neurons to the ciliary muscle and iris sphincter.

Third nerve palsies (TNPs) can be clinically differentiated as partial (i.e., divisional) vs. complete and pupil-sparing vs. pupil-involving and should be identified by the company they keep. In a profound TNP, the eye will adopt a down-and-out position because the only muscles working are the lateral rectus and superior oblique. The patient will also exhibit a significant ptosis on the affected side and may have an enlarged pupil. The degree of pupillary involvement provides important diagnostic clues to guide the investigation.

Because the two major functions of the third nerve are oculomotor and pupillomotor, either partial or complete TNP can be a manifestation of presumed ischemia in the setting of diabetes, hypertension, hyperlipidemia, giant cell arteritis and more serious pathologies. Common intracranial pathologies involving the oculomotor nerve include ischemic and hemorrhagic infarctions, primary and secondary neoplasms, aneurysm, cavernous malformation, infection and demyelinating disease. Knowing which cases require neuroimaging can be difficult, and there is much debate in the literature as to which cases need testing.

Although it is understood that acute painful TNP with complete external and internal dysfunction and those with divisional palsies undergo emergent neurovascular imaging, it is much more difficult to determine the fate of acute painful TNP with complete external dysfunction and normal pupil function. According to Trobe, aneurysms are likely to affect pupillomotor fibers in individuals with complete TNP but spare its function in superior division palsies. However, up to 20% of patients with microvascular TNP may have pupil involvement, with anisocoria of 1.5 mm or less, making the “rule of the pupil” a disconcerting rule to follow. Additionally, while acute orbital and head pain is a well-known symptom of aneurysmal TNP, it does not always suggest a more ominous cause, as pain has been reported in as few as 30% of patients with aneurysmal TNP and as many as 50% in those with a presumed microvascular cause. It is concerning that Lee and colleagues and Matthew and colleagues reported that the relative presence of aneurysm as a cause of isolated TNP ranged from 14% to 56%.

Fourth nerve palsy

 

The fourth nerve is located in the midbrain beneath the inferior colliculus and has the longest clinical course. It travels between the superior cerebellar artery and the posterior cerebellar artery, through the subarachnoid space and along the lateral wall of the cavernous sinus where it is highly susceptible to shearing forces from trauma. It enters the orbit through the superior orbital fissure (outside the annulus of Zinn) to innervate the superior oblique muscle, which is responsible for intorsion and depression of the eye. The most common causes of fourth nerve palsy (FNP) are congenital, traumatic and vasculopathic.

When evaluating patients with vertical diplopia, it is important to ask which position of gaze produces the greatest amount of diplopia. More often than not, this can localize the defect to the paretic muscle, because a down and in position will exclusively highlight the superior oblique as the paretic muscle. In subtle cases, the Bielschowsky three-step test as well as double Maddox rod testing is helpful in confirming the clinical suspicion. In patients with a FNP, the vertical diplopia is worse when the paretic eye is adducted. In addition, patients will often adapt a head tilt opposite to the affected eye, with the chin down.

Although truly isolated FNPs in older individuals are almost always vasculopathic in etiology, isolated palsies occur as manifestations of congenital paresis, trauma, midbrain hemorrhages, pituitary macroadenoma, posterior fossa tumors, dural fistulas, schwannomas and cavernomas of the fourth nerve. In patients older than 50, it is prudent to obtain an urgent erythrocyte sedimentation rate and C-reactive protein blood tests to discount occult giant cell arteritis as well. While it may be reasonable and cost-effective to observe truly isolated cases, an important lesion may be missed, especially if the patient were to develop additional neurologic symptoms during the observation period. Although controversial, obtaining contrast-enhanced MRI of the brain with attention to the cavernous sinus can be a prudent and reasonable approach, because there seems to be an increased prevalence of cavernous sinus disease as the cause in a small group of patients with isolated trochlear palsies.

One main differential diagnosis of FNP is skew deviation. It is important to discount skew deviation as the cause of the vertical deviation because its causes are much more ominous. Skew deviation is an acquired vertical paresis that may present as concomitant, non-concomitant, alternating or periodic. It is a cyclo-vertical misalignment that presents with additional neurologic signs and symptoms consistent with central or peripheral lesions.

Central lesions are more common and involve dysfunction of the brainstem or cerebellum. Peripheral lesions, secondary to vestibular dysfunction, occur as a result of abnormal input from the utricle and saccule of the inner ear. Both organs contain small calcium carbonate crystals and transmit information of linear motion and static head tilt to the vertically acting ocular motor neurons and interstitial nucleus of Cajal located within the midbrain.

Differentiating a skew deviation from a FNP can be difficult because some skew deviations can mimic fourth nerve disease during the three-step test. However, skew deviations typically present with hyperdeviations, which worsen toward the hypertropic. For example, a patient will exhibit a right hypertropia that is made worse on right gaze. When presented in a bilateral fashion, the patient will exhibit a right hypertropia worse in right gaze and a left hypertropia worse in left gaze.

Other clinical implications for differentiating skew deviation from FNP include double Maddox rod for cyclotorsion and ocular tilt reaction testing. Testing cyclotorsion with a double Maddox rod will induce excyclotorsion in the hyperdeviated eye in FNP and incyclotorsion of the hyperdeviated eye in skew deviation. Also, when evaluating the ocular tilt reaction, a skew deviation of the right eye will manifest a rotation of movement down toward the lower ear during left head tilt. Any patient who presents with signs and symptoms indicating skew deviation should undergo immediate neuroimaging of the brain with special attention to the posterior fossa.

Sixth nerve palsy

The abducens nucleus is located in the pons and passes through the pontine tegmentum. It ascends in the subarachnoid space along the clivus where it passes the anterior inferior cerebellar artery and enters the cavernous sinus. Here, it travels adjacent to the internal carotid artery, making it susceptible to compression and inflammation. It then passes through the superior orbital fissure, within the annulus of Zinn, and innervates the lateral rectus.

When evaluating patients with constant horizontal diplopia, it is important to ask whether the diplopia is worse at near or far. Paresis of the lateral rectus muscle can be elicited during versions when having the patient view a distance target. In extreme cases the affected eye will maintain an esotropic appearance in primary gaze. However, in subtle cases, standard extraocular motility testing will not be adequate to make the diagnosis. In these cases, cover testing in the cardinal positions will allow for small deviations to become manifest.

Saccadic testing can also help make the diagnosis in small deviations. During voluntary saccades, the paretic eye will show a decrease in both velocity and magnitude toward temporal fixation. In addition to the ocular motor portion of the exam, it is also important to test for the following signs: facial numbness, muscles of facial expression, pupil size, hearing loss and upper and lower extremity peripheral weakness.

Sixth nerve palsy (SNP) is the most common oculomotor nerve palsy. According to Richards and colleagues, the etiology of SNP is often attributed to ischemia, trauma, demyelinating disease, metastasis, aneurysm and intracranial hypertension. Because hypertension and diabetes cause SNP in up to 35% of patients, some authors argue that monthly follow-up is the best approach (Patel et al.). The main disadvantage of these studies is that brain MRI was not performed in all patients. Furthermore, Moster and colleagues described a lack of truly vasculopathic isolated SNP reported in the literature.

A literature search conducted by Miller and colleagues reported 199 patients with isolated SNP; 31 were traumatic, 42 were asculopathic, 43 were idiopathic, 50 were related to tumors and the remainder resulted from miscellaneous causes. Moreover, Volpe and Lessel reported spontaneous recovery of SNP in the presence of extramedullary compression caused by tumors located at the base of the brain.

Ultimately, it has been shown that there is not enough evidence to support observation alone, with the risk of delaying diagnosis of a potentially serious intracranial pathology. It is our recommendation to obtain an initial contrast-enhanced MRI of the brain in patients with acute isolated SNP, as previous studies have shown a lack of diagnostic benefit from computed tomography (CT).

Here is a clinical pearl: Multiple cranial neuropathies will typically present with additional neurologic dysfunction and must undergo immediate neuroimaging with attention to the brainstem, cavernous sinus and orbital apex.

Internuclear, supranuclear pathways

The ocular motor system is complex and involves neural connections from infranuclear, nuclear, internuclear and supranuclear pathways. The objective of the motor pathway is to coordinate the eyes in conjugate fashion to maintain foveal fixation. Highly ordered functions involving the cerebellum, cerebral cortex, vestibular structures and extraocular muscles are necessary to drive the neural impulse to the targeted system for normal function. The supranuclear system acts through the nuclei of cranial nerves III, IV and VI and directs the innervation of both versions and vergences, to allow for accurate binocular vision.

The clinical exam should include testing of fast eye movements (saccades), pursuit movements and optokinetic nystagmus, vestibulo-ocular reflex (VOR) and near convergence. Close attention to each of the motor components will allow for accurate anatomical location and supportive neuroimaging to confirm the etiology.

Internuclear disorders

The internuclear system plays a key role in transmitting information from the abducens nucleus to internuclear neurons located within the medial longitudinal fasciculus (MLF). The neural signal then travels to the subnucleus of the medial rectus muscle in the nuclear complex of the third cranial nerve to coordinate conjugate gaze.

For example, a patient who presents with a right adduction deficit and contralateral gaze-evoked dissociated nystagmus will harbor a lesion within the right MLF. In severe cases of INO, the affected eye may not be able to move past midline, but in subtle instances, saccadic testing will assist in eliciting a mild adduction deficit. In some cases of INO, testing pursuits may also reveal a vertical gaze paresis. Because some of the vertical eye movement pathways are located near the MLF, dysfunction to an adjacent region may affect vertical gaze.

Clinically, patients may exhibit impaired vertical gaze holding, abnormal optokinetic movements and pursuits, as well as decreased VOR gain, vertical gaze-evoked nystagmus, convergence retraction nystagmus and skew deviation. Unilateral INO may also present with an ocular tilt reaction and skew deviation with a lesion to the pontomesencephalic junction. However, in most cases, adduction will remain intact during convergence because the conjugate vergence system, responsible for the near reflex pathway, does not go below the level of the oculomotor complex. For example, lesions affecting the MLF at the level of the oculomotor complex will present with an adduction deficit during both versions and convergence.

In addition to damage of the MLF, a lesion may also affect the paramedian pontine reticular formation (PPRF) and/or adjacent abducens nerve nucleus. For example, a lesion involving the right MLF and PPRF (horizontal gaze center) will cause combined inhibition of adduction and abduction of the right eye and an adduction of the left eye. This is referred to as one-and-a-half syndrome and is characterized by a conjugate gaze palsy in one direction and an INO in the other. One-and-a-half syndrome is most often caused by multiple sclerosis (MS), brainstem stroke, brainstem tumors and arteriovenous malformations (AVM).

Management of INO will depend on the clinical findings. While acute unilateral INO is typically the result of infarction in the elderly and demyelinating disease in the young, extensive causes of INO include: vascular disorders of the brainstem and fourth ventricle, Arnold-Chiari malformation, brainstem encephalitis, hepatic and Wernicke encephalopathy, Fabry disease, medication toxicity (i.e., phenothiazines, tricyclic antidepressants, beta-blockers, lithium, d-penicillamine) and head trauma.

The prognoses of both infarction and demyelination are generally good. Initial management should include urgent MRI of the brain with and without contrast with attention to the ipsilateral MLF. However, because of the small anatomic location of the MLF, localizing a deficit can be challenging for the ordering physician as well as the neuro-radiologist. Widespread white matter disease most often indicates a diagnosis of multiple sclerosis. Elderly patients with INO, normal neuroimaging and absence of high-risk medication will usually have a diagnosis of presumptive infarction. Follow-up with their general physician is advised to manage their vascular risk factors and for antiplatelet therapy. Initial follow-up can occur in 2 weeks, and the clinical symptoms typically resolve over weeks to months.

Bilateral INO will clinically present as bilateral adduction deficits and are commonly caused by multiple sclerosis. In rare cases, patients may present with bilateral exotropia in primary position (wall-eyed) with bilateral adduction deficits and impaired convergence. This is referred to as a wall-eyed bilateral INO (WEBINO).

Supranuclear system, disorders

Supranuclear disorders can present in patients with complaints of blurred vision and/or diplopia. A comprehensive examination involving testing of pursuits, saccades, oculocephalic (doll’s head) maneuvers and convergence will help identify abnormal movements and their respective anatomic locations. Supranuclear palsies can be classified by the following: gaze palsies, tonic gaze deviation, saccadic disorders, smooth pursuit disorders, vergence disorders, nystagmus and ocular oscillations. In addition to the various categories of supranuclear palsies, specific clinical signs correlate with their respective anatomic site.

Saccades

The objective of maintaining binocular vision is to keep the object of interest on the fovea of each eye. This requires involvement of various eye movements and their respective pathways. The initial response during saccadic movement is simultaneous stimulation of the agonist muscle while inhibiting flow to its antagonist counterpart. The PPRF is responsible for horizontal saccades, and the rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF) generates vertical saccades. For example, the initiation of right saccades involves activation of the right PPRF and nucleus prepositus hypoglossi (NPH), which then sends a signal to the motor nuclei in order to generate a ballistic movement and provide stabilization.

Gaze-evoked nystagmus is a dysfunction of gaze holding. Because the NPH is responsible for maintaining horizontal gaze stabilization, a lesion within the brainstem can cause a horizontal refixation nystagmus, which causes both eyes to shift back to a midline position. As the speed of the horizontal saccade is increased, there will be a pronounced slowing of the movement back to the original fixation point. Clinically, it is important to recognize the difference between gaze-evoked nystagmus and physiologic end-point nystagmus. In gaze-evoked nystagmus, the defect can be caused by anti-seizure medication, tranquilizing medications or lesions of the brainstem and/or cerebellum.

Here is a clinical pearl: End-point nystagmus can be elicited in a normal functioning supranuclear system when gaze is taken past 35 degrees from fixation.

Examination of saccades

Testing of the saccadic system should be performed in both horizontal and vertical meridians. A 30-degree separation is adequate for testing horizontal saccades, and a 15-degree separation should be used for testing the vertical component. The patient is instructed to change fixation from one target to the next in rapid succession. It is important to monitor the patient’s response for both accuracy and velocity.

Saccadic disorders

Saccades that undershoot a target are more concerning than those that overshoot. When performing saccadic testing, it is important to look for accuracy. Brainstem disorders affecting the lateral medulla, known as Wallenberg syndrome, can cause dysmetria characterized by ipsilateral hypermetric saccades followed by hypometric saccades to the right, along with vertical saccades that veer to the affected side of the lesion.

Other disorders of the saccadic system include: saccadic palsy, slow saccades and ocular motor apraxia. Saccadic palsy is defined as an inability to generate saccades and is typically a result of a lesion of the contralateral eye field or ipsilateral PPRF. Saccadic testing that reveals a decrease in velocity in left or right gaze is typical of cerebellar degeneration, Huntington chorea, Wilson disease, lesions of the PPRF, paraneoplastic syndromes or medication toxicity. Lastly, children with slow or absent saccades and difficulty making purposeful horizontal eye movements often suffer from oculomotor apraxia. Clinically, this results in aberrant head movements toward the horizontal position of gaze. When evaluating these patients, MRI should be performed and may reveal developmental abnormalities within the corpus callosum, cerebellum and/or fourth ventricle.

Gaze palsies are limited conjugate eye movements that may occur in horizontal or vertical gaze and are a manifestation of cerebral disease. Depending on whether the abducens nucleus or PPRF is affected, a gaze palsy will have variable findings. For example, a lesion to the left abducens nucleus will affect the motor neuron of the ipsilateral lateral rectus as well as the ipsilateral MLF, resulting in an impaired medial rectus response and left conjugate paresis. A lesion within the left PPRF will cause either total loss of rapid eye movements to the ipsilateral side or reduced velocity of the saccadic response depending upon whether the lesion is complete or incomplete. It is important to keep in mind that lesions of the PPRF will have intact pursuits and VOR. In contrast to the above-mentioned pontine lesions, cerebral hemispheric lesions, such as infarction within the internal capsule, typically cause gaze paresis opposite to the side of the lesion.

The part of the supranuclear system that is responsible for vertical saccades is located adjacent to the Sylvian aqueduct. Associated anatomic structures involved in vertical gaze include: riMLF, nucleus of Cajal and decussating fibers within the posterior commissure. Innervation of vertical saccades involves initiation via the riMLF and stabilization through the nucleus of Cajal.

For example, in Parinaud’s syndrome, a lesion within the pineal gland will cause convergence retraction nystagmus on attempted upgaze with the fast component of the nystagmus in the upward direction. Other lesions near the pretectal midbrain can cause similar findings and are not exclusive to Parinaud’s syndrome.

Pursuits, optokinetic nystagmus

The smooth pursuit system is much slower than that of saccades. It is controlled by the cerebellum and other neural networks. When testing the pursuit system, the clinician should have the patient fixate in a slow steady fashion while observing the eyes in horizontal and vertical gaze. The movement should include a total of 20 degrees, 10 degrees to each side of midline for both horizontal and vertical movement. Additionally, testing should be done against a featureless background to avoid reflexive saccades. Caution should also be given with respect to the speed of the test. If done too quickly, the PPRF system will take over and initiate a saccadic response.

Clinically, it is important to note the speed and accuracy of the pursuit. A change in the speed of the eye movements or asymmetry between the two eyes should be considered abnormal. For example, a patient with a unilateral smooth pursuit deficit may harbor a lesion within the parietal-occipital junction or cerebellum. Those with bilateral smooth pursuit deficits should be evaluated for pathology within the cerebellum, cerebral hemispheres or brainstem.

Optokinetic nystagmus

Optokinetic nystagmus (OKN) is a measurement of motor activity testing the slow phase of movement and its fast counterpart during refixation. OKN can be tested using a drum with black and white alternating stripes or with a patterned ribbon held 20 inches away from the patient. The patient is then asked to fixate on the pattern of the band. The clinician will analyze the slow and fast phase of the movements. The slow phase should correspond to the speed at which the drum or band is being moved. Testing should be done using vertical and horizontal movements.

Generally, an abnormal pursuit or slow phase of the OKN response will be pathologic for horizontal deficits ipsilateral to the lesion. In these cases, it is important to consider structural damage to the parietal-occipital complex, brainstem or cerebellum; an exception would be a pontine lesion, which will cause a slow phase abnormality in the opposite direction of the lesion.

Vestibular, optokinetic systems

The VOR is a complex system that allows foveal fixation during head movements. The VOR arises from the labyrinthine canals of the inner ear. Its functions include stabilization and fixation during head movement. While the OKN system can maintain binocular foveal fixation during slow head turn, the VOR is responsible for maintaining fixation during rapid movements.

Testing the VOR can be achieved by having the patient read small characters while turning the head back and forth with increasing velocity. Determining whether the velocity is normal can be achieved by comparing the subjects’ response with that of the examiners because there is a threshold at which an object will remain illusory. This is referred to as oscillopsia. However, in order to confirm which side of the vestibular system is malfunctioning, an otolaryngologist must perform caloric lavage of the external auditory canal.

Vergence system

Vergences allow the eyes to form conjugate and disconjugate movements to keep an image on the fovea of both eyes. It involves neural connections of the internucleus of the medial and lateral rectus as well as occipital lobe and pontine tegmentum. Clinical findings will drive neuroimaging and appropriate anatomic location of pathology. For example, a patient with diplopia at near who manifests an inability to converge the eyes to a near focal point will exhibit convergence paresis. These patients should undergo neuroimaging with attention to the rostral midbrain as well as be evaluated for Parkinson’s disease or progressive supranuclear palsy.

Other forms of vergence disorders include convergence spasm, which presents with miotic pupils and episodic adduction. These patients may have signs and symptoms that mimic lateral rectus palsy; however, testing monocular eye movements will reveal normal ductions and fully functioning lateral rectus. The most important clinical findings to make a diagnosis of convergence spasm in the setting of episodic adduction are miotic pupils and full ductions.

Lastly, another imposter of lateral rectus paresis is divergence paralysis. The patients will exhibit esotropia at distance but normal lateral rectus function with both versions and ductions. It is important to keep in mind these imposters, as they can result in costly neuroimaging and extensive office visits.

Complete ophthalmoplegia

As its name implies, total ophthalmoplegia involves restriction of eye movements in all cardinal positions of gaze. It can be seen in progressive supranuclear palsy, systemic lupus erythematosus, Whipple’s disease, Wernicke encephalopathy, Miller Fisher syndrome and adverse reactions from phenytoin, carbamazepine, tricyclic antidepressants, lithium and baclofen.

Nystagmus, ocular oscillations

Nystagmus refers to rapid, involuntary eye movements. They are classified as jerk, pendular, rotary, dissociated or mixed forms. Jerk nystagmus encompasses the vast majority of cases and has numerous subcategories: horizontal, upbeat, downbeat, periodic, gaze-paretic, Bruns, rebound and central positional nystagmus.

Ocular oscillations are abnormal rapid, saccadic-like involuntary eye movements that are categorized as square wave jerks, ocular bobbing, ocular flutter and opsoclonus. Square wave jerks may be a physiologic or pathologic finding. They are characterized as small, conjugate saccades in which the eye moves away from the fixation position and then returns after a short period. They are typically made manifest during testing of the smooth pursuit. Evaluation for other cerebellar signs including ataxia is important, as pathologic causes include cerebellar degenerations, Parkinson’s disease, SNP and multiple system atrophy.

Macrosaccadic oscillations are horizontal saccadic movements that occur as rapid pulsed movements that crescendo up then down and are induced by a shift in gaze. Patients with these movements often describe symptoms consistent with oscillopsia. Neuroimaging is required with careful attention to the cerebellum and pons.

Ocular bobbing consists of spontaneous, rapid downward eye movements with a slow return to the mid-position. It is also associated with paralysis of spontaneous and reflex horizontal eye movements.

Lastly, ocular flutter and opsoclonus are often seen after eyelid closure or during gaze shifts between far and distant targets. The most common etiologies of these findings include: para-infectious brainstem encephalitis, multiple sclerosis, paraneoplastic syndromes, toxic metabolic states or, rarely, they are idiopathic. Clinical evaluation during a neurologic examination of systems will allow for differentiation between these disorders and will aid in providing anatomic detail for neuroimaging.

Take-home message

Neuro-ophthalmic eye movement disorders are complex. The initial presentation of a patient with diplopia should include a thorough neuro-ophthalmic history with special attention to versions, ductions and cover test. These will help solve the vast majority of ocular motor disorders. A practical neurologic exam can also provide clues to involvement of additional intracranial pathology including brainstem and cerebellar processes. Detailed attention to neuroimaging often identifies the affected anatomic local.

The infranuclear, nuclear, internuclear and supranuclear systems are much more complex and involve neural activity of the frontal eye fields, cerebral cortex, cerebellum, vestibular pathway and brainstem. Deliberate and precise evaluations of pursuits, saccades, oculocephalic response and convergence can help identify the anatomic origin of the problem. Differentiating nuclear from internuclear and supranuclear disease will allow for timely and accurate assessment through appropriate neuroimaging.

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• For more information:
• Michael DelGiodice, OD, FAAO, is a partner at Family Eye Health and Vision Center in Garfield, N.J., and also practices at LCA Vision in Paramus, N.J., and Riverdale Vision Care, Riverdale, N.J. He served a residency in primary care and ocular disease at East Orange/Lyons VA Hospital New Jersey Healthcare System. DelGiodice can be reached at mdelgiodice@yahoo.com.

Disclosure: DelGiodice reports no relevant financial disclosures.