Is methylphenidate-induced chorea responsive to chlorpromazine?

Case Report A 6-year-old girl was seen for acute involuntary movements. She had psychomotor developmental delay without a definite diagnosis after an extensive unrevealing investigation. As her parents were firstdegree relatives, a genetic basis for her disease was suspected. Clinically, besides late psychological and motor acquisitions, she had discrete macrocephalus, congenital mild ataxia, and hyperactivity. Otherwise healthy, she was not medicated and had no familial history of neurological disease. She had the first 18 mg extended-release methylphenidate pill that morning and went to school, where she was unusually agitated and could not stay quiet, persistently moving the neck, arms, and legs as if she was dancing. Upon examination, she had persistent choreoathetoid movements of orofacial muscles, arms, and legs, with transient dystonic postures of the right arm. There was no clinical improvement when she was treated with biperiden, Chlorpromazine, 6 mg t.i.d. (0.25 mg/kg/day), was attempted at the eighth hour after symptom onset, with immediate decrease of the involuntary movements, which further faded over the next hours leaving the child in the previous neurological state.