Approach to Facial Weakness.

Facial palsy is a common neurologic concern and is the most common cranial neuropathy. The facial nerve contains motor, parasympathetic, and special sensory functions. The most common form of facial palsy is idiopathic (Bell's palsy). A classic presentation requires no further diagnostic measures, and generally improves with a course of corticosteroid and antiviral therapy. If the presentation is atypical, or concerning features are present, additional studies such as brain imaging and cerebrospinal fluid analysis may be indicated. Many conditions may present with facial weakness, either in isolation or with other neurologic signs (e.g., multiple cranial neuropathies). The most important ones to recognize include infections (Ramsay-Hunt syndrome associated with herpes zoster oticus, Lyme neuroborreliosis, and complications of otitis media and mastoiditis), inflammatory (demyelination, sarcoidosis, Miller-Fisher variant of Guillain-Barré syndrome), and neoplastic. No matter the cause, individuals may be at risk for corneal injury, and, if so, should have appropriate eye protection. Synkinesis may be a bothersome residual phenomenon in some individuals, but it has a variety of treatment options including neuromuscular re-education and rehabilitation, botulinum toxin chemodenervation, and surgical intervention.