Bell's palsy ■ The most common form of facial paralysis is Bells palsy. Bell’s palsy is idiopathic palsy of facial nerve. Clinical Manifestations ■ The onset of Bell’s palsy is fairly abrupt, maximal weakness being attained by 48 h as a general rule. ■ Pain behind the ear may precede the paralysis for a day or two. ■ Taste sensation may be lost unilaterally, and hyperacusis may be present. ■ In some cases there is mild cerebrospinal fluid lymphocytosis. ■ MRI may reveal swelling and uniform enhancement of the geniculate ganglion and facial nerve, and, in some cases, entrapment of the swollen nerve in the temporal bone. ■ Approximately 80% of patients recover within a few weeks or months. ■ The presence of incomplete paralysis in the first week is the most favorable prognostic sign. Pathophysiology ■ Bell’s palsy is associated with the presence of herpes simplex virus type 1 DNA in endoneurial fluid and posterior auricular muscle, suggesting that a reactivation of this virus in the geniculate ganglion may be responsible. However, a causal role for herpes simplex virus in Bell’s palsy is unproven. Differential Diagnosis ■ Tumors that invade the temporal bone (carotid body, cholesteatoma, dermoid). ■ The Ramsay Hunt syndrome, presumably due to herpes zoster of the geniculate ganglion, consists of a severe facial palsy associated with a vesicular eruption in the pharynx, external auditory canal, and other parts of the cranial integument; often the eighth cranial nerve is affected as well. ■ Acoustic neuromas frequently involve the facial nerve by local compression. ■ Infarcts, demyelinating lesions of multiple sclerosis, and tumors are the common pontine lesions that interrupt the facial nerve fibers; other signs of brainstem involvement are usually present. ■ Bilateral facial paralysis (facial diplegia) occurs in Guillain-Barre' syndrome and also in a form of sarcoidosis known as uveoparotid fever (Heerfordt syndrome). ■ Lyme disease is a frequent cause of facial palsies in endemic areas. ■ The rare Melkersson-Rosenthal syndrome consists of a triad of recurrent facial paralysis, recurrent—and eventually permanent—facial (particularly labial) edema, and less constantly, plication of the tongue; ■ Leprosy frequently involves the facial nerve, and facial neuropathy may also occur in diabetes mellitus. ■ All these forms of nuclear or peripheral facial palsy must be distinguished from the supranuclear type. ■ In the latter, the frontalis and orbicularis oculi muscles are involved less than those of the lower part of the face, since the upper facial muscles are innervated by corticobulbar pathways from both motor cortices, whereas the lower facial muscles are innervated only by the opposite hemisphere. Treatment ■ Symptomatic measures include use of paper tape to depress the upper eyelid during sleep and prevent corneal drying, and Massage of the weakened muscles. ■ A course of glucocorticoids, given as prednisone 60 to 80 mg daily during the first 5 days and then tapered over the next 5 days, appears to shorten the recovery period and modestly improve the functional outcome. ■ In one double-blind study, patients treated within 3 days of onset with both prednisone and acyclovir (400 mg five times daily for 10 days) had a better outcome than patients treated with prednisone alone.