Pisa syndrome induced by discontinuation of low dose sulpiride: a case report

Abstract Background Pisa syndrome is a type of dystonia characterized by lateral flexion of the trunk, often induced by cholinesterase inhibitors and antipsychotics. Seemingly opposite hypotheses of the underlying mechanism have been proposed: cholinergic-dopaminergic imbalance toward cholinergic dominance and dopamine hypersensitivity associated with long-term antipsychotic administration. Case presentation: We herein report a case of a 64-year-old woman presenting with Pisa syndrome immediately after discontinuation of low dose sulpiride. To the best of our knowledge, this is the first case of Pisa syndrome induced by withdrawal of sulpiride, an antipsychotic that preferentially binds to presynaptic dopaminergic receptors at low doses, presumably resulting in increased dopaminergic action. Conclusions Our case not only supports the cholinergic-dopaminergic imbalance hypothesis as the mechanism underlying Pisa syndrome, but also suggests the paradoxical dopaminergic effects of sulpiride.