Risperidone-induced Pisa syndrome in MS: resolution with lurasidone and recurrence with Chlorpromazine

To report a case of risperidone-induced Pisa syndrome in a patient with multiple sclerosis (MS) that resolved with lurasidone, recurred with chlorpromazine, and was complicated by possible drug-drug interactions.

A 31-year-old white male with MS developed Pisa syndrome after years of treatment with risperidone at varying doses for behavioral symptoms associated with pervasive developmental disorder. The patient experienced improvement in symptoms after treatment was switched to lurasidone; however, due to psychiatric decompensation, a switch to chlorpromazine was made and Pisa syndrome recurred. To maintain control of the patient's behavioral symptoms, chlorpromazine was not discontinued.

Pisa syndrome is a rare adverse drug reaction induced most often by neuroleptic medications. The reaction is characterized by dystonia affecting cervical and lumbar musculature, resulting in flexion of the head and body to one side with axial rotation of the trunk. The etiology is believed to involve a dopaminergic-cholinergic imbalance. Most practitioners are not familiar with this syndrome, and it has not been reported previously in a patient with MS. Definitive diagnostic criteria and treatment have not been established. We identified 15 case reports involving risperidone, paliperidone, chlorpromazine, clomipramine, or valproic acid. The time to development of Pisa syndrome, patient demographics, dosing and titration of causative medications, approach to treatment, and resolution of Pisa syndrome varied widely in these reports. Dystonia in MS often presents differently than Pisa syndrome. The Naranjo probability scale indicated a probable relationship between either risperidone or chlorpromazine in each instance of Pisa syndrome in our patient.

Pisa syndrome is a rare adverse drug reaction associated with neuroleptic medications. Our report highlights the importance of identifying this uncommon type of dystonia in order to consider modification of the medication regimen when appropriate.