Facial palsy
Facial palsy is weakness of the muscles innervated by the facial nerve (cranial nerve VII); most cases are idiopathic (Bell palsy), producing unilateral weakness of both upper and lower facial muscles, distinguishing it from the upper-face-sparing pattern of a central (stroke) lesion. Classic Bell palsy needs no imaging and is treated with a 10-day course of oral prednisone started within 72 hours of onset.
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What this article covers
- Overview
Definition: facial palsy is weakness or paralysis of the muscles of facial expression resulting from dysfunction of the facial nerve (cranial nerve VII) or its central pathways.
- Epidemiology
Common condition: peripheral facial palsy, predominantly Bell palsy, is a frequently encountered cranial neuropathy in outpatient and emergency settings.
- Risk factors
Pregnancy: increased incidence in the third trimester and immediate postpartum period.
- Pathophysiology
Presumed viral/inflammatory mechanism in Bell palsy: the leading hypothesis is reactivation of latent herpes simplex virus within the geniculate ganglion, producing inflammation and edema of the…
- Clinical features
Diagnostic pattern for classic Bell palsy: acute (hours to 1-2 days) unilateral facial weakness involving both the upper face (impaired forehead wrinkling, incomplete eye closure) and lower face…
- Differential diagnosis
Central facial weakness (stroke or other upper motor neuron lesion): spares the forehead and eye closure from bilateral cortical innervation, and is often accompanied by contralateral limb weakness…
- Diagnosis
Bell palsy is a clinical diagnosis of exclusion: established by the acute, unilateral, whole-hemiface facial weakness pattern without historical or examination features suggesting a secondary cause…
- Management
First step for classic Bell palsy: start oral prednisone 60 mg PO once daily for 5 days, then tapered by 10 mg per day over the next 5 days, as a 10-day course, begun within 72 hours of symptom…
- Complications
Corneal exposure keratopathy: incomplete eyelid closure without adequate protection can progress to corneal abrasion, ulceration, and, rarely, vision loss.
- Prognosis
Favorable overall prognosis for Bell palsy: 70% to 90% of patients achieve full recovery within weeks, though early prednisone improves the rate and completeness of recovery.
- Prevention
No established primary prevention for idiopathic Bell palsy: the precise trigger is not fully defined, so there is no proven strategy to prevent a first episode.
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