Overview of Neuro-ophthalmologic and Cranial Nerve Disorders: Neuro-ophthalmologic and Cranial Nerve Disorders: Merck Manual Professional

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Neuro-ophthalmologic and Cranial Nerve Disorders

Overview of Neuro-ophthalmologic and Cranial Nerve Disorders

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Overview of Neuro-ophthalmologic and Cranial Nerve Disorders

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Dysfunction of certain cranial nerves may affect the eye, pupil, optic nerve, or extraocular muscles and their nerves; thus, they can be considered cranial nerve disorders, neuro-ophthalmologic disorders, or both. Neuro-ophthalmologic disorders may also involve dysfunction of the central pathways that control and integrate ocular movement and vision. Cranial nerve disorders can also involve dysfunction of smell, vision, chewing, facial sensation or expression, taste, hearing, balance, swallowing, phonation, head turning and shoulder elevation, or tongue movements (see Table 1: Neuro-ophthalmologic and Cranial Nerve Disorders: Cranial Nerves). One or more cranial nerves may be affected.

Table 1

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Cranial Nerves
Nerve	Function	Possible Findings	Possible Causes^*
Olfactory (1st)	Provides sensory input for smell	Anosmia	Head trauma Nasal disorders (eg, allergic rhinitis) Neurodegenerative disorders (eg, Alzheimer disease, Parkinson disease) Paranasal sinusitis Tumors of the cranial fossa, nasal cavity, and paranasal sinuses
Optic (2nd)	Provides sensory input for vision	Amaurosis fugax (transient monocular blindness)	Embolism of retinal arteries Ipsilateral internal carotid disease
		Anterior ischemic optic neuropathy	Complications after cataract extraction Connective tissue disease that causes arteritis (eg, temporal arteritis, antiphospholipid antibody syndrome) Diabetes Hypotension or hypovolemia if severe Ipsilateral internal carotid artery obstruction Migraine Phosphodiesterase type 5 (PDE5) inhibitors (eg, sildenafilSome Trade Names VIAGRA Click for Drug Monograph , tadalafilSome Trade Names CIALIS Click for Drug Monograph , vardenafilSome Trade Names LEVITRA Click for Drug Monograph ) Retinal artery embolism
		Optic neuritis (papillitis and retrobulbar)	Acute demyelinating disease (eg, multiple sclerosis, neuromyelitis optica) Bacterial infections (eg, TB, syphilis, Lyme disease) Postinfectious or disseminated encephalomyelitis Uveitis Viral infections (eg, HIV, herpes simplex, hepatitis B, cytomegalovirus)
		Toxic-nutritional optic neuropathy (toxic amblyopia)	Drugs (chloramphenicolSome Trade Names CHLOROMYCETIN Click for Drug Monograph , ethambutolSome Trade Names MYAMBUTOL Click for Drug Monograph , isoniazidSome Trade Names INH NYDRAZID Click for Drug Monograph , streptomycinSome Trade Names No US trade name Click for Drug Monograph , sulfonamides, digitalis, chlorpropamideSome Trade Names DIABINESE Click for Drug Monograph , ergot, disulfiramSome Trade Names ANTABUSE Click for Drug Monograph ) Methanol ingestion Nutritional deprivation if severe Organic mercury Vitamin B₁₂ deficiency
		Bitemporal hemianopia	Craniopharyngioma Meningioma of tuberculum sellae Saccular aneurysm in the cavernous sinus Suprasellar extension of pituitary adenoma
Oculomotor (3rd)	Raises eyelids Moves eyes up, down, and medially Adjusts amount of light entering eyes Focuses lenses	Palsies	Aneurysm of posterior communicating artery Ischemia of the 3rd cranial nerve (often due to small-vessel disease as occurs in diabetes) or of the midbrain Transtentorial herniation due to intracranial mass (eg, subdural hematoma, tumor, abscess)
Trochlear (4th)	Moves eye in and down via the superior oblique muscle	Palsies	Often idiopathic Head trauma Infarction often due to small-vessel disease (eg, in diabetes) Tentorial meningioma Pinealoma
Trigeminal (5th)
Ophthalmic division	Provides sensory input from the eye surface, tear glands, scalp, forehead, and upper eyelids	Neuralgia	Vascular loop compressing the nerve root, occasionally multiple sclerosis Lesions of cavernous sinus or superior orbital fissure
Maxillary and mandibular divisions	Provides sensory input from the teeth, gums, lip, lining of palate, and skin of the face	Neuralgia	Lesions of cavernous sinus or superior orbital fissure Multiple sclerosis (occasionally) Vascular loop compressing the nerve root
Maxillary and mandibular divisions	Moves masticatory muscles (chewing, grinding the teeth)	Neuropathy	Carcinomatous or lymphomatous meningitis Connective tissue disorders Meningiomas, schwannomas, or metastatic tumors at the skull base
Abducens (6th)	Moves the eye outward (abduction) via the lateral rectus muscle	Palsies	Often idiopathic Head trauma Increased intracranial pressure Infarction (may be mononeuritis multiplex) Infections or tumors affecting the meninges Multiple sclerosis Nasopharyngeal carcinoma Pontine or cerebellar tumors Pontine infarction Wernicke encephalopathy
Facial (7th)	Moves muscles of facial expression Proximal branches: Innervate tear glands and salivary glands and provide sensory input for taste on the anterior two thirds of the tongue	Palsies	Vestibular schwannoma Basilar skull fracture Bell palsy Guillain-Barré syndrome Infarcts and tumors of the pons Lyme disease Melkersson-Rosenthal syndrome Ramsay Hunt syndrome Sarcoidosis Tumors that invade the temporal bone Uveoparotid fever (Heerfordt syndrome)
Facial (7th)		Hemifacial spasm	Artery loop compressing the nerve root
Vestibulocochlear (8th)	Provides sensory input for equilibrium and hearing	Tinnitus, vertigo, sense of fullness in the ear, and hearing loss	Meniere disease
		Benign positional vertigo	Ear surgery Labyrinthine concussion Occlusion of the anterior vestibular artery Otitis media Otolithic aggregation in semicircular canal related to aging
		Vestibular neuronitis	Viral infection
		Hearing loss or disturbance	Acoustic neuromas Aging Barotrauma Cerebellopontine angle tumors Congenital rubella infection Exposure to loud noises Hereditary disorders Meningitis Viral infection (possibly)
Glossopharyngeal (9th)	Provides sensory input from the pharynx, tonsils, posterior tongue, and carotid arteries	Glossopharyngeal neuralgia	Ectatic artery or tumor (less common) compressing the nerve
Glossopharyngeal (9th)	Moves muscles of swallowing and salivary glands Helps regulate BP	Glossopharyngeal neuropathy	Tumor or aneurysm in the posterior fossa or jugular foramen
Vagus (10th)	Moves vocal cords and muscles for swallowing Transmits impulses to the heart and smooth muscles of visceral organs	Hoarseness, dysphonia, and dysphagia Vasovagal syncope	Entrapment of recurrent laryngeal nerve by mediastinal tumor Herpes zoster Infectious or carcinomatous meningitis Medullary tumors or ischemia (eg, lateral medullary syndrome)
Accessory (11th)	Turns the head Shrugs the shoulders	Partial or complete paralysis of the sternocleidomastoid and trapezius	Iatrogenic (eg, due to lymph node biopsy in posterior triangle of the neck) Idiopathic Trauma Tumors at the skull base or near the meninges
Hypoglossal (12th)	Moves the tongue	Atrophy and fasciculation of tongue	Intramedullary lesions (eg, motor neuron disease, tumors) Lesions of the basal meninges or occipital bones (eg, platybasia, Paget disease of skull base) Surgical trauma (eg, due to endarterectomy) Motor neuron disease (eg, amyotrophic lateral sclerosis)
^*Systemic disorders (eg, myasthenia gravis, botulism, variant Guillain-Barré syndrome, poliomyelitis with bulbar involvement, progressive supranuclear palsy) can cause diffuse cranial nerve dysfunction. Amyotrophic lateral sclerosis may cause prominent tongue fasciculations.

Cranial Nerves

Nerve

Function

Possible Findings

Possible Causes^*

Olfactory (1st)	Provides sensory input for smell	Anosmia	Head trauma Nasal disorders (eg, allergic rhinitis) Neurodegenerative disorders (eg, Alzheimer disease, Parkinson disease) Paranasal sinusitis Tumors of the cranial fossa, nasal cavity, and paranasal sinuses
Optic (2nd)	Provides sensory input for vision	Amaurosis fugax (transient monocular blindness)	Embolism of retinal arteries Ipsilateral internal carotid disease
		Anterior ischemic optic neuropathy	Complications after cataract extraction Connective tissue disease that causes arteritis (eg, temporal arteritis, antiphospholipid antibody syndrome) Diabetes Hypotension or hypovolemia if severe Ipsilateral internal carotid artery obstruction Migraine Phosphodiesterase type 5 (PDE5) inhibitors (eg, sildenafilSome Trade Names VIAGRA Click for Drug Monograph , tadalafilSome Trade Names CIALIS Click for Drug Monograph , vardenafilSome Trade Names LEVITRA Click for Drug Monograph ) Retinal artery embolism
		Optic neuritis (papillitis and retrobulbar)	Acute demyelinating disease (eg, multiple sclerosis, neuromyelitis optica) Bacterial infections (eg, TB, syphilis, Lyme disease) Postinfectious or disseminated encephalomyelitis Uveitis Viral infections (eg, HIV, herpes simplex, hepatitis B, cytomegalovirus)
		Toxic-nutritional optic neuropathy (toxic amblyopia)	Drugs (chloramphenicolSome Trade Names CHLOROMYCETIN Click for Drug Monograph , ethambutolSome Trade Names MYAMBUTOL Click for Drug Monograph , isoniazidSome Trade Names INH NYDRAZID Click for Drug Monograph , streptomycinSome Trade Names No US trade name Click for Drug Monograph , sulfonamides, digitalis, chlorpropamideSome Trade Names DIABINESE Click for Drug Monograph , ergot, disulfiramSome Trade Names ANTABUSE Click for Drug Monograph ) Methanol ingestion Nutritional deprivation if severe Organic mercury Vitamin B₁₂ deficiency
		Bitemporal hemianopia	Craniopharyngioma Meningioma of tuberculum sellae Saccular aneurysm in the cavernous sinus Suprasellar extension of pituitary adenoma
Oculomotor (3rd)	Raises eyelids Moves eyes up, down, and medially Adjusts amount of light entering eyes Focuses lenses	Palsies	Aneurysm of posterior communicating artery Ischemia of the 3rd cranial nerve (often due to small-vessel disease as occurs in diabetes) or of the midbrain Transtentorial herniation due to intracranial mass (eg, subdural hematoma, tumor, abscess)
Trochlear (4th)	Moves eye in and down via the superior oblique muscle	Palsies	Often idiopathic Head trauma Infarction often due to small-vessel disease (eg, in diabetes) Tentorial meningioma Pinealoma
Trigeminal (5th)
Ophthalmic division	Provides sensory input from the eye surface, tear glands, scalp, forehead, and upper eyelids	Neuralgia	Vascular loop compressing the nerve root, occasionally multiple sclerosis Lesions of cavernous sinus or superior orbital fissure
Maxillary and mandibular divisions	Provides sensory input from the teeth, gums, lip, lining of palate, and skin of the face	Neuralgia	Lesions of cavernous sinus or superior orbital fissure Multiple sclerosis (occasionally) Vascular loop compressing the nerve root
Maxillary and mandibular divisions	Moves masticatory muscles (chewing, grinding the teeth)	Neuropathy	Carcinomatous or lymphomatous meningitis Connective tissue disorders Meningiomas, schwannomas, or metastatic tumors at the skull base
Abducens (6th)	Moves the eye outward (abduction) via the lateral rectus muscle	Palsies	Often idiopathic Head trauma Increased intracranial pressure Infarction (may be mononeuritis multiplex) Infections or tumors affecting the meninges Multiple sclerosis Nasopharyngeal carcinoma Pontine or cerebellar tumors Pontine infarction Wernicke encephalopathy
Facial (7th)	Moves muscles of facial expression Proximal branches: Innervate tear glands and salivary glands and provide sensory input for taste on the anterior two thirds of the tongue	Palsies	Vestibular schwannoma Basilar skull fracture Bell palsy Guillain-Barré syndrome Infarcts and tumors of the pons Lyme disease Melkersson-Rosenthal syndrome Ramsay Hunt syndrome Sarcoidosis Tumors that invade the temporal bone Uveoparotid fever (Heerfordt syndrome)
Facial (7th)		Hemifacial spasm	Artery loop compressing the nerve root
Vestibulocochlear (8th)	Provides sensory input for equilibrium and hearing	Tinnitus, vertigo, sense of fullness in the ear, and hearing loss	Meniere disease
		Benign positional vertigo	Ear surgery Labyrinthine concussion Occlusion of the anterior vestibular artery Otitis media Otolithic aggregation in semicircular canal related to aging
		Vestibular neuronitis	Viral infection
		Hearing loss or disturbance	Acoustic neuromas Aging Barotrauma Cerebellopontine angle tumors Congenital rubella infection Exposure to loud noises Hereditary disorders Meningitis Viral infection (possibly)
Glossopharyngeal (9th)	Provides sensory input from the pharynx, tonsils, posterior tongue, and carotid arteries	Glossopharyngeal neuralgia	Ectatic artery or tumor (less common) compressing the nerve
Glossopharyngeal (9th)	Moves muscles of swallowing and salivary glands Helps regulate BP	Glossopharyngeal neuropathy	Tumor or aneurysm in the posterior fossa or jugular foramen
Vagus (10th)	Moves vocal cords and muscles for swallowing Transmits impulses to the heart and smooth muscles of visceral organs	Hoarseness, dysphonia, and dysphagia Vasovagal syncope	Entrapment of recurrent laryngeal nerve by mediastinal tumor Herpes zoster Infectious or carcinomatous meningitis Medullary tumors or ischemia (eg, lateral medullary syndrome)
Accessory (11th)	Turns the head Shrugs the shoulders	Partial or complete paralysis of the sternocleidomastoid and trapezius	Iatrogenic (eg, due to lymph node biopsy in posterior triangle of the neck) Idiopathic Trauma Tumors at the skull base or near the meninges
Hypoglossal (12th)	Moves the tongue	Atrophy and fasciculation of tongue	Intramedullary lesions (eg, motor neuron disease, tumors) Lesions of the basal meninges or occipital bones (eg, platybasia, Paget disease of skull base) Surgical trauma (eg, due to endarterectomy) Motor neuron disease (eg, amyotrophic lateral sclerosis)
^*Systemic disorders (eg, myasthenia gravis, botulism, variant Guillain-Barré syndrome, poliomyelitis with bulbar involvement, progressive supranuclear palsy) can cause diffuse cranial nerve dysfunction. Amyotrophic lateral sclerosis may cause prominent tongue fasciculations.

Causes and symptoms of neuro-ophthalmologic and cranial nerve disorders overlap. Both types of disorders can result from tumors, inflammation, trauma, systemic disorders, and degenerative or other processes, causing such symptoms as vision loss, diplopia, ptosis, pupillary abnormalities, periocular pain, facial pain, or headache.

Diagnosis

Evaluation includes the following:

Detailed questioning about symptoms
Examination of the visual system (see also Symptoms of Ophthalmologic Disorders)
Tests to detect nystagmus (see Sidebar 1: Approach to the Patient With Ear Problems: Nystagmus)
Examination of the cranial nerves (see Approach to the Neurologic Patient: Cranial nerves)

Visual system examination includes ophthalmoscopy and testing of visual acuity, visual fields (see Table: Approach to the Ophthalmologic Patient: Visual field testing), pupils (see Table 2: Neuro-ophthalmologic and Cranial Nerve Disorders: Common Pupillary Abnormalities), and eye movements (ocular motility—see Table 3: Neuro-ophthalmologic and Cranial Nerve Disorders: Common Disturbances of Ocular Motility). As part of this testing, the 2nd, 3rd, 4th, and 6th cranial nerves are examined (see also Approach to the Neurologic Patient: Cranial nerves). Neuroimaging with CT or MRI is also usually required.

The following parts of the visual examination are of particular interest in diagnosing neuro-ophthalmologic and cranial nerve disorders.

Pupils are inspected for size, equality, and regularity. Normally, the pupils constrict promptly (within 1 sec) and equally during accommodation and during exposure to direct light and to light directed at the other pupil (consensual light reflex). Testing pupillary response to consensual light via a swinging flashlight test can determine whether a defect is present. Normally, the degree of pupillary constriction does not change as the flashlight is swung from eye to eye.

If a relative afferent defect (deafferented pupil, afferent pupillary defect, or Marcus Gunn pupil) is present, the pupil paradoxically dilates when the flashlight swings to the side of the defect. A deafferented pupil constricts in response to consensual but not to direct light.
If an efferent defect is present, the pupil responds sluggishly or does not respond to both direct and consensual light.

Table 2

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Common Pupillary Abnormalities
Finding	Explanation
Asymmetry of 1–2 mm between pupils, preserved light responses, and no symptoms	Normal variant (physiologic anisocoria)
Asymmetry, impaired light responses, and preserved response to accommodation (light-near dissociation or Argyll Robertson pupil)	Neurosyphilis (possibly)
Bilateral constriction	Opioids Miotic eye drops for glaucoma (most common; causing unilateral constriction if single eye is dosed) Pontine hemorrhage Organophosphate or cholinergic toxins
Bilateral dilation with preserved light reflexes	Hyperadrenergic states (eg, withdrawal syndromes, drugs such as sympathomimetics or cocaine, thyrotoxicosis)
Bilateral dilation with impaired light response	Mydriatic eye drops such as sympathomimetics (eg, phenylephrineSome Trade Names NEO-SYNEPHRINE Click for Drug Monograph ) and cycloplegics (eg, cyclopentolateSome Trade Names AK-PENTOLATE CYCLOGYL CYLATE Click for Drug Monograph , tropicamideSome Trade Names MYDRAL MYDRIACYL TROPICACYL Click for Drug Monograph , homatropineSome Trade Names ISOPTO Click for Drug Monograph , atropineSome Trade Names ATROPEN ATROPINE-CARE SAL-TROPINE Click for Drug Monograph ) Brain herniation Hypoxic or ischemic encephalopathy
Unilateral dilation with afferent pupillary defect	Lesions of the eye, retina, or 2nd cranial (optic) nerve
Unilateral dilation with efferent pupillary defect	Third cranial (oculomotor) nerve palsies, often due to compression (eg, due to aneurysm of the posterior communicating artery or to transtentorial herniation) Iris trauma (also irregular pupil) Mydriatic eye drops^*
Unilateral dilation with minimal or slow direct and consensual light reflexes and pupil constriction in response to accommodation	Tonic (Adie) pupil^†
^*Transtentorial herniation and use of mydriatic eye drops can often be distinguished by instilling a drop of pilocarpineSome Trade Names ISOPTO CARPINE PILOPINE HS SALAGEN Click for Drug Monograph ocular solution into the dilated pupil; no constriction in response suggests mydriatic eye drops.
^†Tonic pupil is permanent but nonprogressive abnormal dilation of the pupil due to damage of the ciliary ganglion. It typically occurs in women aged 20 to 40. Onset is usually sudden. The only findings are slight blurring of vision, impaired dark adaptation, and sometimes absent deep tendon reflexes.

Eye movements are checked by having the patient hold the head steady while tracking the examiner's finger as it moves to the far right, left, upward, downward, diagonally to either side, and inward toward the patient's nose (to assess accommodation). However, such examination may miss mild paresis of ocular movement sufficient to cause diplopia.

Diplopia may indicate a defect in bilateral coordination of eye movements (eg, in neural pathways) or in the 3rd (oculomotor), 4th (trochlear), or 6th (abducens) cranial nerve. If diplopia persists when one eye is closed (monocular diplopia), the cause is probably a nonneurologic eye disorder (see Symptoms of Ophthalmologic Disorders: Diplopia). If diplopia disappears when either eye is closed (binocular diplopia), the cause is probably a disorder of ocular motility. The 2 images are furthest apart when the patient looks in the direction served by the paretic eye muscle (eg, to the left when the left lateral rectus muscle is paretic). The eye that, when closed, eliminates the more peripheral image is paretic. Placing a red glass over one eye can help identify the paretic eye. When the red glass covers the paretic eye, the more peripheral image is red (see also Symptoms of Ophthalmologic Disorders: Physical examination).

Table 3

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Common Disturbances of Ocular Motility
Clinical Finding	Syndrome	Common Causes
Pareses
Paresis of horizontal gaze in one direction	Conjugate horizontal gaze palsy	Lesion in the ipsilateral pontine horizontal gaze center or in the contralateral frontal cortex
Paresis of horizontal gaze in both directions	Complete (bilateral) horizontal gaze palsy	Wernicke encephalopathy Large bilateral pontine lesion affecting both horizontal gaze centers
Bilateral paresis of all horizontal eye movements except for abduction of the eye contralateral to the lesion; convergence unaffected	One-and-a-half syndrome	Lesion in the medial longitudinal fasciculus and ipsilateral pontine horizontal gaze center
Unilateral or bilateral paresis of eye adduction in horizontal lateral gaze but not in convergence	Internuclear ophthalmoplegia	Lesion in the medial longitudinal fasciculus
Bilateral paresis of upward eye movement with dilated pupils, loss of the pupillary light response despite preservation of pupillary accommodation and constriction with convergence, downward gaze preference, and downbeating nystagmus	Parinaud syndrome (a type of conjugate vertical gaze palsy)	Pineal tumor Midbrain infarct
Bilateral paresis of downward eye movements	Conjugate downward gaze palsy	Progressive supranuclear palsy
Unilateral eye deviation (resting position is down and out); unilateral paresis of eye adduction, elevation, and depression; ptosis; and often a dilated pupil	3rd cranial nerve palsy	Aneurysms Oculomotor nerve or midbrain ischemia Trauma Transtentorial herniation
Unilateral paresis of downward and inward (nasal) eye movement, which may be subtle, causing symptoms (difficulty looking down and inward) Head tilt sign (patient tilts the head to the side opposite the affected eye)	4th cranial nerve palsy	Idiopathic Head trauma Ischemia Congenital
Unilateral paresis of eye abduction	6th cranial nerve palsy	Idiopathic Infarct Vasculitis Increased intracranial pressure Wernicke encephalopathy Multiple sclerosis
Skew deviation (vertical misalignment of the eyes)	Partial and unequal involvement of 3rd cranial nerve nuclei, vertical gaze center, or median longitudinal fasciculus	Brain stem lesion anywhere from midbrain to medulla
Weakness or restriction of all extraocular muscles	External ophthalmoplegia	Dysfunction of eye muscles or of neuromuscular junction Usually caused by the following: Myasthenia gravis Graves disease Botulism Mitochondrial myopathies (eg, Kearn-Sayre syndrome) Oculopharyngeal dystrophy Myotonic dystrophy Orbital pseudotumor
Involuntary or abnormal movements
Rhythmic involuntary movements, usually bilateral	Nystagmus	see Sidebar 1: Approach to the Patient With Ear Problems: Nystagmus
Fast downward jerk and slow upward return to midposition	Ocular bobbing	Extensive pontine destruction or dysfunction
Gaze overshoot followed by several oscillations	Ocular dysmetria	Cerebellar pathway disorders
Burst of rapid horizontal oscillations about a point of fixation	Ocular flutter	Many causes: Postanoxic encephalopathy Occult neuroblastoma Paraneoplastic effects Ataxia-telangiectasia Viral encephalitis Toxic effects of drugs
Rapid, conjugate, multidirectional, chaotic movements, often with widespread myoclonus	Opsoclonus	Many causes (same as for ocular flutter, above)

Common Disturbances of Ocular Motility

Clinical Finding

Syndrome

Common Causes

Pareses
Paresis of horizontal gaze in one direction	Conjugate horizontal gaze palsy	Lesion in the ipsilateral pontine horizontal gaze center or in the contralateral frontal cortex
Paresis of horizontal gaze in both directions	Complete (bilateral) horizontal gaze palsy	Wernicke encephalopathy Large bilateral pontine lesion affecting both horizontal gaze centers
Bilateral paresis of all horizontal eye movements except for abduction of the eye contralateral to the lesion; convergence unaffected	One-and-a-half syndrome	Lesion in the medial longitudinal fasciculus and ipsilateral pontine horizontal gaze center
Unilateral or bilateral paresis of eye adduction in horizontal lateral gaze but not in convergence	Internuclear ophthalmoplegia	Lesion in the medial longitudinal fasciculus
Bilateral paresis of upward eye movement with dilated pupils, loss of the pupillary light response despite preservation of pupillary accommodation and constriction with convergence, downward gaze preference, and downbeating nystagmus	Parinaud syndrome (a type of conjugate vertical gaze palsy)	Pineal tumor Midbrain infarct
Bilateral paresis of downward eye movements	Conjugate downward gaze palsy	Progressive supranuclear palsy
Unilateral eye deviation (resting position is down and out); unilateral paresis of eye adduction, elevation, and depression; ptosis; and often a dilated pupil	3rd cranial nerve palsy	Aneurysms Oculomotor nerve or midbrain ischemia Trauma Transtentorial herniation
Unilateral paresis of downward and inward (nasal) eye movement, which may be subtle, causing symptoms (difficulty looking down and inward) Head tilt sign (patient tilts the head to the side opposite the affected eye)	4th cranial nerve palsy	Idiopathic Head trauma Ischemia Congenital
Unilateral paresis of eye abduction	6th cranial nerve palsy	Idiopathic Infarct Vasculitis Increased intracranial pressure Wernicke encephalopathy Multiple sclerosis
Skew deviation (vertical misalignment of the eyes)	Partial and unequal involvement of 3rd cranial nerve nuclei, vertical gaze center, or median longitudinal fasciculus	Brain stem lesion anywhere from midbrain to medulla
Weakness or restriction of all extraocular muscles	External ophthalmoplegia	Dysfunction of eye muscles or of neuromuscular junction Usually caused by the following: Myasthenia gravis Graves disease Botulism Mitochondrial myopathies (eg, Kearn-Sayre syndrome) Oculopharyngeal dystrophy Myotonic dystrophy Orbital pseudotumor
Involuntary or abnormal movements
Rhythmic involuntary movements, usually bilateral	Nystagmus	see Sidebar 1: Approach to the Patient With Ear Problems: Nystagmus
Fast downward jerk and slow upward return to midposition	Ocular bobbing	Extensive pontine destruction or dysfunction
Gaze overshoot followed by several oscillations	Ocular dysmetria	Cerebellar pathway disorders
Burst of rapid horizontal oscillations about a point of fixation	Ocular flutter	Many causes: Postanoxic encephalopathy Occult neuroblastoma Paraneoplastic effects Ataxia-telangiectasia Viral encephalitis Toxic effects of drugs
Rapid, conjugate, multidirectional, chaotic movements, often with widespread myoclonus	Opsoclonus	Many causes (same as for ocular flutter, above)

Treatment

Treatment of neuro-ophthalmologic and cranial disorders depends on the cause.

Last full review/revision July 2012 by Michael Rubin, MDCM

Content last modified November 2012

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