The facial nerve is the motor nerve to all muscles of facial expression and the nerve most commonly subjected to peripheral palsy from Bell palsy, parotid tumours, temporal bone fractures, and middle ear infections. Its long course through the facial canal in the temporal bone is its most vulnerable segment. The assessment of facial nerve function using the House-Brackmann scale guides management decisions in facial palsy.
| Origin | Facial nucleus in the caudal pons, with special visceral afferent from the nucleus solitarius |
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Bell palsy is idiopathic acute peripheral facial nerve palsy (presumed viral, possibly herpes simplex reactivation) producing complete unilateral facial paralysis including the forehead — distinguishing it from central facial palsy where the forehead is spared. Early treatment with oral corticosteroids within 72 hours of onset significantly improves recovery. The facial nerve is at risk during parotidectomy from its course through the parotid gland, and meticulous nerve identification using the tympanomastoid fissure as the landmark is essential.
Idiopathic peripheral facial nerve palsy producing complete unilateral facial weakness including forehead, managed with early corticosteroids and eye protection, with recovery in 70 to 80 percent of cases.
Iatrogenic facial branch injury during superficial parotidectomy producing partial or complete facial muscle weakness, managed with immediate nerve repair if identified and reinnervation procedures for delayed discovery.
