E. Lee Murray, MD
CHAPTER CONTENTS
OVERVIEW
The most common primary cranial nerve deficits to come to the attention of the hospital neurologist are listed below. Not discussed here are other medical disorders which produce cranial nerve deficits as part of their clinical presentation including vascular disease (Chapter 16), demyelinating disease (Chapter 22), infectious diseases (Chapter 17) and tumors (Chapter 25). The disorders with primary cranial nerve manifestations include:
•Hemifacial spasm (Chapter 23)
•Vestibulopathies (Chapter 32)
•Trigeminal neuralgia (Chapter 20)
•Multiple cranial nerve palsies
Some of these are discussed in the chapters indicated. The remainder are discussed in this chapter.
BELL PALSY AND RAMSAY-HUNT SYNDROME
Bell palsy is the most common cause of unilateral facial weakness. The most common causes are herpes simplex virus (HSV) and varicella zoster virus (VZV); less likely are autoimmune and other infections. Ramsay-Hunt syndrome is peripheral facial palsy with herpes zoster oticus.
PRESENTATION is with subacute onset of unilateral facial palsy, typically involving upper and lower face (peripheral palsy), although early in the course or with milder symptoms the upper face involvement may be difficult to determine and the lesion might be thought to be central. Pain in or around the ipsilateral ear may be present before, contemporaneous with, or after the onset of the weakness. Bilateral involvement is uncommon and when present suggests diagnoses other than idiopathic facial palsy.
DIAGNOSIS is considered in all patients with unilateral facial weakness. Classic clinical features can make the diagnosis with sufficient accuracy to avoid extensive evaluation. With atypical presentation or other associated symptoms, additional study may be needed. The main differential diagnoses are stroke and demyelinating disease, although diabetes, cerebellopontine angle (CPA) tumor, Lyme disease, and infectious or neoplastic meningitis are considered. Magnetic resonance imaging (MRI) of the brain with special attention to the facial nerve can show inflammatory change but is of most value in ruling out other lesion such as tumor, stroke, or demyelinating plaque.
MANAGEMENT includes protection of the eye from exposure if eye closure and blinking are incomplete. Corticosteroids and antiviral agents are considered.1
•Corticosteroids can hasten recovery and reduce residual damage. These are usually used unless contraindicated by comorbid condition (e.g., uncontrolled diabetes).
•Antivirals have been used but their benefit is unproved. They may be considered especially for patients with severe deficit.
DIABETIC OPHTHALMOPLEGIA
Diabetic ophthalmoplegia is a common cause for hospital neurology consultation because of concerns over stroke syndrome or aneurysm. Etiology is likely ischemia affecting the central portion of the nerve, sparing the peripheral fibers innervating the pupil.
PRESENTATION is most commonly with pupil-sparing CN 3 palsy producing diplopia but without anisocoria unless there is another reason for that. Ptosis can occur. Pain can occur in a peri-orbital distribution. CN 6 or 4 palsies can occur but with lower incidence.
DIAGNOSIS is suspected in a diabetic with pupil-sparing CN 3 palsy. However, imaging with MRI and MR angiography (MRA) is almost always needed to look for aneurysm, cavernous sinus lesion, or other lesion. Brainstem ischemia or demyelination would be unlikely to produce an isolated cranial nerve palsy.
MANAGEMENT is supportive. The key is to rule out more concerning lesions. Most patients improve.
ABDUCENS NERVE PALSY
Abducens palsy in adults is usually due to ischemic neuropathy. Typical vascular risk factors predispose to this.
PRESENTATION is with horizontal diplopia, worse with lateral gaze to the affected side. With complete lesions, the eye does not abduct beyond the midline. If the abducens palsy is vascular, no other deficit is expected. If the lesion is in the cavernous sinus, CSF, or elsewhere in the brain, then additional deficits would be expected.
DIAGNOSIS is suspected by horizontal diplopia in the absence of other findings.
•MRI of the brain is appropriate to look for vascular disease, structural abnormality, or demyelinating disease.
•MRA or computed tomography angiography (CTA) can be performed to look for aneurysm.
•CSF is obtained if no other cause identified and microvascular etiology is not suspected (e.g., young patient, no risk factors).
•Lab may include myasthenia panel, but monocular abduction deficit in with myasthenia gravis (MG) would be uncommon in the absence of other ocular motor deficits. Labs to be considered may include studies for diabetes, syphilis, or vasculitis.
MANAGEMENT is usually supportive; most cases improve spontaneously within weeks to months.
•Patching of the eyes alternately is needed by some patients to allow for functional vision.
•Ocular prisms are used mainly for patients who have not recovered well after several months of follow-up.
•If symptoms of giant cell arteritis are seen with abducens palsy, then corticosteroids are started urgently while the evaluation is completed.
HORNER SYNDROME
Horner syndrome is dysfunction of sympathetic innervation to the eye. Anisocoria is an occasional trigger for neurologic consultation in the hospital. There are multiple potential central and peripheral causes. A few of the causes include:
◦Carotid artery damage (e.g., trauma, surgery, occlusion)
◦Tumor anywhere in the pathway
PRESENTATION is with ptosis and miosis on the affected side, often with anhydrosis. Other associated findings can be clues to localization and diagnosis (e.g., other cranial nerve deficits or ataxia with a brainstem lesion, or limb weakness and corticospinal tract signs with myelopathy).
DIAGNOSIS is clinical. Further study is guided by localization: is this cerebral, spinal, or peripheral? If there is no known inciting factor such as neck trauma, then vascular imaging for carotid lesion should be considered.
MANAGEMENT depends on etiology. For most patients, the task for the hospital neurologist is making the etiologic diagnosis.
HERPES ZOSTER OPHTHALMICUS
Herpes zoster ophthalmicus is reactivation of VZV with involvement of the upper division of the trigeminal nerve (V1 of CN 5). This is most commonly seen in older patients and in those with immune deficiency such as lymphoma.
PRESENTATION usually begins with dysesthesias on the forehead. This is followed by a vesicular rash in a V1 distribution. Periorbital edema with an inflammatory appearance may develop, including corneal edema. Late features may be corneal scarring, retinitis, episcleritis, and ultimately postherpetic neuralgia.
DIAGNOSIS is suspected by the clinical presentation of the prodromal sensory symptoms followed by the rash. This usually makes the diagnosis. Additional studies are usually not needed unless there are atypical features.
MANAGEMENT includes antiviral agents—usually acyclovir, famciclovir, or valacyclovir. Topical corticosteroids are used for uveitis or keratitis. Oral corticosteroids are often used but of unproved benefit.
GLOSSOPHARYNGEAL NEURALGIA
Glossopharyngeal neuralgia is neuropathic pain affecting CN 9. It is usually idiopathic but occasionally due to local tumor. Some patients have symptoms due to cardiodepressant effects in a portion of the vagus.
PRESENTATION is with brief episodes of severe pain in the throat. The pain is activity-dependent, often triggered by chewing, talking, or yawning. The cardiodepressant effects can produce bradycardia and syncope.
DIAGNOSIS is made by clinical presentation. However, because of the possibility of a structural abnormality, imaging if often necessary with MRI or CT studying the throat and lower cranial nerves.
MANAGEMENT of the pain begins with medical therapy but may require surgery.
•Medical management is with anticonvulsants (especially oxcarbazepine, carbamazepine, and gabapentin) or baclofen, sometimes in combination.
•Surgery may be needed and includes decompression of the glossopharyngeal nerve or section of the glossopharyngeal nerve and upper aspect of the vagus nerve.
MULTIPLE CRANIAL NERVE PALSIES
A wide variety of disorders can be associated with clinical presentation of multiple cranial nerve palsies:
•Herpes zoster: CN 5 or CN 7 can both be affected. Also possible is CN 8, 9, or 10. Associated with ear pain and then peripheral facial palsy.
•Sarcoidosis: Multiple cranial nerve palsies are possible with aseptic meningitis with lymphocytic predominance.
•Wegener granulomatosis: Multiple cranial nerve palsies; can develop mononeuritis multiplex and/or polyneuropathy.
•Intracranial aneurysm: Unruptured aneurysm can produce multiple cranial nerve palsies by compression of adjacent cranial nerves. Ruptured aneurysm, with subarachnoid hemorrhage can produce more distant cranial nerve palsies.
•Neoplastic meningitis: Confusion is the most common symptom but also can produce multiple cranial neuropathies and radiculopathies.
•Lyme disease: Suggested by bilateral facial palsies. Can also develop disparate multiple cranial neuropathies. Meningitis may present with multiple cranial nerve palsies and polyradiculopathies.
•CPA tumors: Involvement and/or compression can affect CN 8, CB 5, CN 7 especially. With brainstem compression, lower cranial nerves can be affected.
•Neurofibromas: NF2 is especially likely to not only have bilateral acoustic neuromas but also to have involvement of other cranial nerves from local compression.
•Nasopharyngeal carcinoma: Cranial nerve palsies can develop, with CN 5 being most commonly affected, CN 6 next most common; it can also affect CN 3 and CN 4 in the cavernous sinus. Can also affect other cranial nerves by extension and invasion into the skull base.
•Chiari malformation: Hydrocephalus is the most common serious neurologic consequence. Lower cranial nerve palsies can develop.
•Chronic meningitis: Multiple cranial nerve palsies can develop, but presentations differ depending on etiology. Hearing loss, facial weakness, and ocular motor deficits are most common at presentation.
•Cavernous sinus thrombosis: Involves CN 3 most commonly, but CN 6 and/or CN 4 also may be affected. Headache is the most common and earliest symptom.
•Tolosa-Hunt syndrome: CN 5 (especially V1), CN 3, CN 6 are most commonly affected.
•Stroke: Multiple stroke syndromes produce cranial nerve palsies, but these are combined with signs of other neurologic dysfunction (e.g., cerebellar or corticospinal).
