E. Lee Murray, MD
CHAPTER CONTENTS
SINGLE CRANIAL NEUROPATHIES
Single cranial neuropathies are much more common than multiple cranial neuropathies but both are discussed here. The most common single cranial neuropathies are facial, abducens, oculomotor, and optic. Chapter 33 discuss ocular motor and other cranial nerve deficits in detail.
ETIOLOGY: Trauma, degenerative disease, chemicals, aging, some brain tumors (e.g., meningioma), malnutrition
FEATURES: Disturbance of vision due to prechiasmatic lesion
ETIOLOGY: Trauma; demyelination; orbital tumors; pituitary tumors; papilledema from any cause; ischemia including temporal arteritis, retinal artery ischemia; retinal vein thrombosis; infectious optic neuropathy (e.g., cat-scratch disease); optic glioma; toxic optic neuropathy (e.g., methanol, INH, and many others)
FEATURES: Diplopia, ptosis, mydriasis
ETIOLOGY: Oculomotor nerve ischemia from diabetes or other vascular risk factors, aneurysmal compression, brainstem ischemia in multiple locations, cavernous sinus lesions of any type, intraorbital mass or inflammation, increased intracranial pressure from any reason, pineal tumor
FEATURES: Vertical diplopia, greatest with downward gaze and gaze to the opposite side
ETIOLOGY: Congenital, brainstem tumors, hydrocephalus, demyelinating disease, aneurysm especially superior cerebellar artery, intracranial hypertension from any cause, orbital tumor or inflammatory lesions
FEATURES: Sensory loss in one or more of the trigeminal distributions: V1, V2, or V3
ETIOLOGY: Trigeminal neuralgia, tumor, trauma
FEATURES: Diplopia, lateral rectus paresis
ETIOLOGY: Nerve infarction, especially with diabetes; increased intracranial pressure
FEATURES: Lower motoneuron facial weakness
ETIOLOGY: Bell palsy, sarcoidosis, Lyme disease; often idiopathic
FEATURES: Hearing loss, tinnitus, and/or vertigo
ETIOLOGY: Acoustic neuroma, cerebellopontine angle tumors, chronic meningitis either infectious or neoplastic, infarction,
FEATURES: Dysphagia, dysarthria, loss of taste from the posterior tongue (likely unnoticed)
ETIOLOGY: Stroke, tumor, skull-based lesions
FEATURES: Dysphagia, dysarthria
ETIOLOGY: Stroke, tumors, meningitis
FEATURES: Trapezius weakness, scapular winging
ETIOLOGY: Trauma, intraoperative damage
FEATURES: Paralysis of the tongue, deviation to the side of the lesion with protrusion
Although we consider cranial neuropathies as isolated entities, there are many disorders that affect multiple cranial nerves.
MULTIPLE CRANIAL NEUROPATHIES
Multiple cranial neuropathies can develop for a variety of reasons, but among the most common are neoplastic meningitis, vasculitis, and diabetes. Intrinsic lesions of the brainstem can present with multiple cranial neuropathies, but there are usually other signs of parenchymal brainstem dysfunction, including gait ataxia, unilateral or bilateral limb weakness and/or incoordination, or mental status change. Cavernous sinus lesions can result in CN 3, 4, 6, and CN 5 V1 lesions, and, sometimes, Horner syndrome.
Mononeuropathy multiplex from any cause can produce multiple cranial neuropathies although peripheral nerves are commonly affected. Causes can be neoplastic, autoimmune, vasculitis, amyloid, infectious, multifocal tumor infiltration (e.g., lymphoma), or paraneoplastic.
Disorders with multiple cranial neuropathies include:
•Neoplastic meningitis: Multiple cranial neuropathies, often with multiple radiculopathies
•Infectious meningitis: Usually presents with headache, fever, mental status changes, but can have especially Abducens palsy with increased ICP. Hearing loss is common later in the course; other cranial neuropathies can occur also.
•Vasculitis: Multifocal cranial nerve deficits, often associated with peripheral nerve deficits
•Brainstem lesions: Gliomas and other infiltrating tumors; ischemia; hemorrhage, including subarachnoid hemorrhage
CRANIAL NERVE DEFICITS IN HOSPITAL PRACTICE
Facial palsy presenting to the hospital is more likely Bell palsy than vascular. Less likely is early acute inflammatory demyelinating polyneuropathy (AIDP).
Ocular motor palsy of a single nerve is most likely to be microvascular in patients with hypertension or diabetes.
Multiple ocular motor deficits such as ptosis with dysfunction of ocular muscles innervated by more than one nerve can be from cavernous sinus lesion, chronic meningeal disease, or brainstem lesion. A non–cranial nerve disorder, such as myasthenia gravis, is also possible.
Cranial nerve palsies without parenchymal brainstem involvement suggests infectious or neoplastic meningitis. Vasculitis is considered.
Cranial nerve palsies with brainstem deficits, such as descending motor or ascending sensory tract involvement, suggest a focal brainstem lesion such as ischemia, hemorrhage, tumor, or demyelination.
Some vascular brainstem syndromes with cranial nerve involvement include:
•PCA stroke produces hemianopia and, if bilateral, produces cortical blindness.
•Basilar thrombosis can produce deficit in lateral gaze with CN 6 palsies, relative preservation of vertical movements, and miosis, along with quadriplegia or coma.
•Posterior inferior cerebellar artery (PICA) occlusion can present with ipsilateral facial sensory loss, Horner syndrome, ataxia, dysphagia, and dysarthria. Contralateral sensory deficit below the brainstem is common.
•Anterior inferior cerebellar artery syndrome (AICA) occlusion can vertigo, nausea, vomiting, ipsilateral facial sensory deficit and contralaterai pain and temperature loss of the body and limbs. Horner syndrome, hearing loss, tinnitus, dysphagia, and dysarthria can be seen.
•Paramedian branch occlusion from the basilar can produce contralateral hemiparesis and cranial nerve deficits depending on the level of the lesion. Pons involvement affects especially CN 6 and CN 7 with ipsilateral lateral gaze and facial palsies. Midbrain involvement can produce CN 3 palsy with diplopia. Medullary involvement can produce a CN 12 deficit.
