Bell's Palsy

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1.12 Bell's Palsy (Idiopathic Facial Paralysis)

Presentation

This condition creates a very frightening facial disfigurement. An adult complains of sudden onset of "numbness," a feeling of fullness or swelling, pain or some other change in sensation on one side of the face; a crooked smile, mouth "drawing" or some other asymmetrical weakness of facial muscles; an irritated, dry or tearing eye; drooling out of the corner of the mouth; or changes in hearing or taste. Often there will have been a viral illness one to three weeks before. Upon initial observation of the patient, it is immediately apparent that he is alert and oriented, with a unilateral facial paralysis that includes one side of the forehead.

What to do:

Perform a thorough neurological examination of cranial and upper cervical nerves, and limb strength, noting which are involved, and whether unilaterally or bilaterally. Ask the patient to wrinkle the forehead, close the eyes forcefully, smile, puff the cheeks and whistle, observing closely for facial assymetry. Central or cerebral lesions result in relative sparing of the forehead. Check tearing, ability to close the eye and protect the cornea, corneal dessication, hearing, and, when practical, taste. Examine the ear canals for herpetic vesicles and the tympanic membrane for signs of otitis media or cholesteatoma. Patients presenting with facial paralysis accompanied by acute otitis media, chronic suppurative middle ear disease, otorrhea or otitis externa require otolaryngologic consultation.
If the cornea is dry or injured from the patient's inability to make tears and blink, protect it by patching. If patching is not necessary, then recommend wearing eyeglasses and applying methylcellulose artificial tears regularly during the day and using a protective bland ointment at night.
If there is a history of head trauma, obtain a CT scan of the head (including the skull base) to rule out a temporal bone fracture.
If the diagnosis is clearly an early idiopathic cranial nerve palsy not caused or complicated by trauma, infection, or diabetes, try to ameliorate symptons with a short course of corticosteroids (e.g., prednisone 60mg qd, tapering after 5 days.)
Send a serum specimen for acute phase Lyme disease titers, if available, because this is another treatable disorder which can present as a facial neuropathy. In areas where Lyme disease is endemic, a 10 day course of tetracycline or doxycycline may be indicated.
If the etiology appears to be zoster-varicella (e.g., grouped vesicles on the tongue) prescribe acyclovir or famcyclovir as for shingles.
Reassure the patient that 70-80% of cases of Bell's palsy recover completely in a few weeks, but provide for definite followup and reevaluation.
Provide appropriate specialty referral when there is a mass in the head or neck or a history of any malignancy.

What not to do:

Do not forget alternate causes of facial palsy which require different treatment, such as cerebrovascular accidents and cerebellopontine angle tumors (which usually produce weakness in limbs or defects of adjacent cranial nerves), multiple sclerosis (which is usually not painful, spares taste, and often produces intranuclear ophthalmoplegia), Ramsay Hunt syndrome (or herpes zoster of the geniculate ganglion, which causes decreased hearing, pain, and vesicles in the ear canal), and polio (which presents as fever, headache, neck stiffness, and palsies).
Do not order a CT unless there is a history of trauma or the symptoms are atypical and include such findings as vertigo. central neurological signs, or severe headache.
Do not make the diagnosis of Bell's palsy in patients who report gradual onset of facial paralysis over several weeks or facial paralysis that has persisted 3 months or more. These patients need further evaluation by a neurologist or otolaryngologist.

Discussion

Idiopathic nerve paralysis is a common malady. It affects 20 per 100,000 people a year. Although Bell's palsy was described classically as a pure facial nerve lesion, and physicians have tried to identify the exact level at which the nerve is compressed, the most common presenting complaints are related to trigeminal nerve involvement. The mechanism is probably a spotty demyelination of several nerves at several sites, caused by a viral infection. Diabetics and pregnant women have increased incidence of Bell's palsy.

References:

Austin JR, Peskind SP, Austin SG, et al: Idiopathic facial nerve paralysis: a randomized double blind controlled study of placebo versus prednisone. Laryngoscope 1993;103:1326-1333.
Stankiewicz JA: A review of the published data on steroids and idiopathic facial paralysis. Otolaryngol Head Neck Surg 1987;97:481-486.

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