Bell's palsy

	Bell's palsy Microchapters
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Editor-in-Chief: Gilbert Abou Dagher, M.D.

Overview

The House-Brackmann grading system was devised both as a clinical indicator of severity and also an objective record of progress.
Clinically incomplete lesions tend to recover.
The natural history without treatment was described in a study of 1011 patients in 1982:

67% had incomplete paralysis, with 94% rate of return to normal function
33% had complete paralysis, with 60% rate of return to normal function
By 3 weeks, 71% had complete recovery, 13% had slight sequelae , and 16% had residual weakness

Herpes zoster is associated with more severe paresis and worse prognosis compared with "idiopathic" Bell's palsy.
There is a favorable prognosis if some recovery is seen within the first 21 days of onset.
In severe lesions that recover, the outgrowth of new axons from the injury site may be disorganized and misdirected.
On blinking there is twitching of the angle of the mouth, and on smiling the eye may close or wink.
With misdirected autonomic fibers, a salivary stimulus may result in excess lacrimation, the syndrome of "crocodile tears."
Recurrent attacks of on either the ipsilateral or contralateral side have been observed in 7 to 15% of patients.

Sullivan FM, Swan IRC, Donnan PT, et al. Early treatment with prednisolone or acyclovir in Bell's palsy. N Engl J Med 2007;357:1598-1607.
"The Merck Manual"
New England Journal of Medicine, Sept. 2004
Lambert, Michael. (2007-03-05) "Bell's Palsy." (Website.) Emedicine. Retrieved on 2007-09-27.