Seventh cranial neuropathy.

Facial neuropathy, or seventh cranial neuropathy, is the most common cranial neuropathy. The anatomy of the facial nerve is rather complex for a cranial nerve, with a long intracranial course, in which the nerve takes three bends (or genu). Electrodiagnosis can be helpful in prognosis, but not before several days. Imaging is rarely indicated in Bell's palsy, but is often abnormal nonetheless, and can be very useful in other causes of facial neuropathy. The clinical presentation is of unilateral facial weakness of upper and lower face, hyperacusis, dysgeusia, and disordered lacrimation and salivation. Many different disease processes can result in facial neuropathy, but 70% of cases are idiopathic, or as it is best known, Bell's palsy. Ramsay Hunt syndrome, defined as facial neuropathy with herpes zoster oticus, is another common cause. Steroids given acutely are beneficial in improving outcome in Bell's palsy, and antiviral therapy seems helpful in more severe cases. Antiviral therapy is definitely helpful in Ramsay Hunt disease when given within 3 days of onset. Antibiotics are helpful in Lyme facial neuropathy, which has a very good prognosis.