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Overview of Neuro-ophthalmologic and Cranial Nerve Disorders

by Michael Rubin, MDCM

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: Cranial Nerves). One or more cranial nerves may be affected.

Cranial nerves.

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), unilateral loss of superior or inferior visual field

Embolism of the ophthalmic artery

Ipsilateral internal carotid disease

Embolism of retinal arteries

Anterior ischemic optic neuropathy

Crowded optic disk morphology (called disk at risk)

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

Phosphodiesterase type 5 (PDE5) inhibitors (eg, sildenafil, tadalafil, vardenafil)

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 (chloramphenicol, ethambutol, isoniazid, streptomycin, sulfonamides, digitalis, chlorpropamide, ergot, disulfiram)

Methanol ingestion

Nutritional deprivation if severe

Organic mercury

Vitamin B 12 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 its fascicle in 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

Myokymia of the superior oblique muscle (typically with brief episodic ocular movements that cause subjective visual shimmering, ocular trembling, and/or tilted vision)

Entrapment of the trochlear nerve by a vascular loop (similar to the pathophysiology of trigeminal neuralgia)

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

Multiple sclerosis (occasionally)

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

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)

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

Barotrauma

Benign paroxysmal positional vertigo

Otolithic aggregation in the posterior or horizontal semicircular canal, related to aging and/or trauma

Infection (occasionally)

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

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)

*Disorders that cause diffuse motor paralysis (eg, myasthenia gravis, botulism, variant Guillain-Barré syndrome, poliomyelitis with bulbar involvement) often affect cranial nerves. 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.

Resources In This Article

Drugs Mentioned In This Article

  • Drug Name
    Select Trade
  • CIALIS
  • DIABINESE
  • VIAGRA
  • LANIAZID
  • No US brand name
  • ANTABUSE
  • LEVITRA
  • MYAMBUTOL
  • ATROPEN
  • MYDRIACYL, TROPICACYL
  • TUSSIGON
  • ISOPTO CARPINE, PILOPINE HS, SALAGEN
  • AKPENTOLATE, CYCLOGYL

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