Indian J. Psychiat, 1997, 39(2), 176-177

RABBIT SYNDROME :AN UNCOMMON SIDE EFFECT OF NEUROLEPTICS MANILAL GADA

ABSTRACT The rabbit syndrome, a neuroleptic induced extrapyramidal side effect with Vafe onset, consists of rapid fine rhythmic movements of the lips that mimic the chewing movements of a rabbit. This syndrome was first described by Villeneuve in 1972. Unlike the buccolingual movements of the tardive dyskinesia, the rabbit syndrome improves with antiparkinsonian medication. The condition is reported to be rare. To the best knowledge of the author, no case has been described or reported from India. A case of rabbit syndrome is described with review of the literature. Key words: Rabbit syndrome, neuroleptics, antiparkinsonian medications

Rabbit syndrome is a perioral involuntary, To the best of author's knowledge no such extrapyramidal movement distrubance associ­ case is reported or published from India. A case ated with prolong use of neuroleptics of rabbit syndrome is described. (Villeneure, 1972; Berger and Roxroth, 1980). The distrubance involves the oral and CASE REPORT masticatory musculature except for the tongue; it is similar in appearance to the movements of Ms A, 46 years old medical graduate, rabbit's mouth. Quickly alternating, regular had undergone treatment for psychosis from movements along a vertical axis occur at psychiatrists. She was hospitalised several frequency of approximately 5 Hz. There is an times. Results of physical examination associated popping like sound produced as the and CT scan were normal. She was lips rapidly separate. Differential diagnosis diagnosed to be suffering from chronic between tardive dyskinesia and rabbit syndrome schizophrenia with acute exacerbations off and is often confused; tardive dyskinesis also can on. She was on oral flupenthixol for last one invlove orofacial musculature but is manifested year without any antiparkinsonian medication. by chewing like movements that include Earlier she was given other neuroleptics like writhing or thrusting tongue motion. Differen­ , trifluoperazine etc. tiation between the two conditions is made She was noticed to have rapid clinically. Abnormal movements in tardive involuntary orofacial movements without lingual dyskinesia are significantly slower and less involvement. Her jaw moved alternately up and regular than in rabbit syndrome. Although both down. The movements decreased in severity disorders are sequelae of long-term neurolep­ with voluntary activity including talking. No other tic treatment (Jus etal., 1979), rabbit syndrome extrapyramidal signs were present. A responds to antiparkinsonian medication, while diagnosis of rabbit syndrome was made. Oral tardive dyskinesia is often exacerbated by such flupenthixol was stopped and trihexyphendyl therapy. HCI2 mg three times a day was started. Within Rabbit syndrome was first described by 4 days, she responded to the treatment and in Villeneuve in 1972. The condition is reported a fortnight, all the movements stopped. to be rare (Todd et al., 1S83). Flupenthixol was reintroduced later along

176 RABBIT SYNDROME : A CASE REPORT with trihexyphenydil HCI.No abnormal rabbit syndrome and concern over aggravating movements were noticed later. tardive dyskinesia may lead to withholding higly effective treatment with agents DISCUSSION or unecessarily reducing the dose of required neuroleptic. The rabbit syndrome has been reported primarily in middle-aged and elderly patients REFERRENCES (Jus et al., 1979). It occurs with a variety of neuroleptics. Following neuroleptics have been Berger, P. & Rexroth, K. (1980) Tardive reported to produce rabbit syndrome-haloperi- dyskinesia.In: Haloperidol Update 1958-1980, dol, , perphenezine, trifluopera­ (Ed.) Ayd, F.J.,- Baltimore: Ayd Medical zine, thioproperazine and mesoridazine (Sovner Communication. and Mascio, 1977; Todd et al., 1983; Yassa and Gerlach, J., Reisby, N. & Randrup, A. Lai, 1986). (1974) Dopaminergic hypersensivity and Anticholinergic agents in general cholinergic hypofunction in the pathophysiology of aggravate or uncover tardive dyskinesia, tardive dyskinesia. Psychopharmacologia, 36, although in some cases no effect or 21-35. occasionally amelioration occurs (Gerlach et al., Jus, A., Jus, K. & Fontaine, P. (1979) Long- 1974). In contrast, consistently term treatment of tardive dyskinesia. Journal of improve the rabbit syndrome, as was noted in Clinical Psychiatry, 40, 72-77. the present case. Sovner, R. & Dimascio, A. (1977) The The rabbit syndrome is uncommon in effect of benztropine mesylate in the rabbit syn­ patients chronically treated with neuroleptics. drome and tardive dyskinesia. American Journal of Yassa and Lai (1986) reported the incidence to Psychiatry, 134, 1301-1302. be 2.3%. The reasons for the apparent Todd, R., Lipmann, S. & Manshadi, M. infrequency of rabbit syndrome may be related (1983) Recognition and treatment of rabbit to the following factors: (1) many patients syndrome; an uncommon complication of receive concomitant antiparkinsonian medica­ neuroleptic therapies. American Journal of tion; (2) it is not a well-known side effect and Psychiatry, 140, 1519-1520. may be mistaken for tardive dyskinesia; (3) in Villeneuve, A. (1972) The rabbit syndrome: some patients the syndrome is mild and only a peculiar extrapyramidal reaction. Canadian elicited by a distracting task and (4) most scales Psychiatric Association Journal, 17 (Suppl 2), used to evaluate do 69-72. not include an item for the rabbit syndrome (an Yassa, R. & Lai, R. (1986) Prevalence of exception is the Simpson Rating Scale for Tar­ the rabbit syndrome. American Journal of dive Dyskinesia). Failure to recognise the Psychiatry, 143, 656-657.

MANILAL GADA, Head & Hon. Prof, Dept. of Psychiatry, D. Y. Patil Medical College (affiliated to University of Bombay). Residence: Manosmruti Polyclinic, Prabhukrupa, LBS. Marg, Ghatkopar (W), Mumbai 400 086.

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