<unk>  is a rare form of extrapyramidal side effect of antipsychotic drugs in which perioral tremors occur at a rate of approximately 5 Hz.<unk>  is characterized by involuntary, fine, rhythmic motions of the mouth along a vertical plane, without involvement of the tongue, and resembling the chewing movements of a<unk> . It is usually seen after years of pharmacotherapy, and is more prominent with high potency drugs like haloperidol, fluphenazine, and pimozide. There is also a low incidence with thioridazine, clozapine, olanzapine, aripiprazole, and low doses of risperidone.<unk>  can be treated with anticholinergic drugs. It generally disappears within a few days of treatment but may re-emerge after anticholinergic treatment is stopped. Another treatment strategy is to switch the patient to an atypical antipsychotic with high anti-cholinergic properties.
Rabbit syndrome
Morvan's syndrome
Michels Caskey syndrome
Wellens' syndrome
Nevo syndrome
Corneal-cerebellar syndrome
Woodhouse–Sakati syndrome
Todd's paresis