Tardive oculogyric crisis during treatment with clozapine: report of three cases.

Tardive oculogyric crisis (OGC) is a dystonic syndrome that starts after long-term use of dopamine receptor antagonists. Atypical antipsychotics have reduced liability for inducing tardive dystonia and show antidystonic properties in patients with pre-existing tardive dystonia. Clozapine is an atypical antipsychotic drug, and there have been case reports that clozapine may be an effective treatment for tardive dystonia. Surprisingly, we found that three patients appeared to develop tardive OGC while taking clozapine. The relationship between tardive OGC and clozapine is still unknown. However, it is possible that the previous antipsychotic exposure could have created a sensitising or priming effect on the striatum. Also, there are some suggestions of an underlying susceptibility and possibly a genetic predisposition, at least in some patients.