Bell’s Palsy

Synonyms

Idiopathic facial paralysis

Definition

Bell’s palsy is the acute onset of paralysis of the muscles innervated by the facial nerve, not due to obvious causes such as trauma, stroke, or local infection.

Current Knowledge

Anatomy

The facial nerve innervates the muscles that control the forehead and eyebrow, close the eyelids, and move the cheeks and lips. It also supplies taste to the anterior two thirds of the tongue and innervates the stapedius muscle (a small muscle in the middle ear, connecting the tympanic membrane to the stapes, that dampens excessive vibration in the tympanic membrane due to loud noises).

Clinical Presentation

The onset of paralysis may be preceded by pain behind the ear for 1 or 2 days. The paralysis is complete in 2 days in half the patients and by 5 days in almost all the patients. If the stapedius muscle is involved, there may be sensitivity to noise. Taste is impaired in almost all patients. Clinically, the forehead is unfurrowed, the eye cannot close...