A Case Report of Stuttering Induced by Risperidone and Chlorpromazine.

Stuttering, a disturbance in the normal fluency and time patterning of speech is usually developmental. In some cases, it is acquired, and causes include stroke, brain tumor, and trauma. Implicated in the causation of stuttering are overactive presynaptic dopamine systems in the region of the brain that modulate verbalization. It is a rare side effect of antipsychotic medications and has been reported with phenothiazines, clozapine, and risperidone. This is a report of a patient who developed stuttering when treated first with chlorpromazine and later with risperidone. Patient had a diagnosis of schizoaffective disorder and had been treated with antipsychotic medications including haloperidol, olanzapine, and paliperidone. He developed stuttering for the first time upon receiving intramuscular injections of chlorpromazine for treatment of agitation. The stutter improved and eventually resolved. He subsequently presented with a severe stutter when he was treated with risperidone. The stutter improved after risperidone was discontinued. It is speculated that drug-induced stuttering may be a manifestation of akathisia leading to noradrenergic and serotonergic mechanisms being implicated. It could be that either the cholinergic, dopaminergic or serotonergic systems are involved or that there is an imbalance of these systems that may be relevant.