Bell's palsy. Face of a 61 year old man with Bell's palsy, a unilateral facial paralysis. The condition is due to the inflammation of the facial nerve. It causes facial drooping, numbness, inability to close the eye and may also cause nervous tics. Onset may be overnight. The cause is not known although in some cases it may be due to infection with herpes virus. Treatment is with anti-inflammatory and antiviral drugs. The condition will resolve itself over time.