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an involuntary muscular contraction; a form of hyperkinesia. A tic may be related to the effect of encephalitis on parts of the brain; it may be a congenital pathological condition, frequently associated with a neuropathic personality; it may appear with attacks of trigeminal neuralgia (tic douloureux); or it may result from neuritis of the facial nerve. A distinction is made between generalized tics, involving all the muscles, and local tics, which are more common. The muscles usually affected are those of the face and neck. The twitching resembles such voluntary movements as winking, frowning, lip-smacking, or lip-licking. Tics generally disappear during sleep and become more severe under emotional stress. Treatment consists of the administration of sedatives, tranquilizers, and anticonvulsants.