Facial Weakness (Bell’s Palsy)

Abstract

Bell’s palsy is an idiopathic facial paralysis that results from acquired cranial nerve VII (facial nerve) dysfunction. It usually presents with a sudden onset unilateral inability to move facial muscles on the affected side, although it is mostly self-limiting. About 80–85 % of patients have spontaneous and complete recovery within 3 months, with a variable degree of residual deficits in the rest. Patients may complain about dry eyes due to incomplete eyelid closure, and they may drool due to inability to completely seal their lips. There may also be hyperacusis and a loss of taste sensation. The presence of these symptoms may be helpful in determining the degree of proximal extension of the facial nerve injury. Physical examination findings are consistent with a lower motor neuron-type facial nerve lesion without any other neurological deficits which would otherwise suggest a central cause. The clinical picture is typically unambiguous, and further investigations are often unnecessary. Where a central or a structural peripheral cause requires exclusion, brain imaging may be performed. Electrodiagnostic tests such as NCS/EMG including blink reflex testing can help to confirm the diagnosis and indicate severity but are usually not required.

Steroid usage is now a level A treatment recommendation. However, the additional benefit of acyclovir is uncertain. Particular vigilance should be observed in the management of dry eyes with the use of artificial eye drops and nightly eye patch application to avoid corneal ulceration.