Risperidone-induced rabbit syndrome: an unusual movement disorder caused by an atypical antipsychotic

Rabbit syndrome is a rare side effect of chronic neuroleptic administration characterized by rapid, fine, rhythmic movements of the mouth along a vert ical axis. It gains its name from an unusual resemblance to the chewing and puckering motions of the rabbit. It is generally thought to be an extra-py ramidal side effect, in part due to its rapid response to anti-cholinergic medication. This is the first case report of risperidone, an atypical antip sychotic, inducing the syndrome. The theoretical implications for the class ification of the syndrome along the spectrum of neuroleptic-induced movemen t disorders are discussed. (C) 1999 Elsevier Science B.V./ECNP. All rights reserved.