Risperidone induced acute dystonia: two case reports

Antipsychotic use in children is increasing. Neuroleptic-induced acute dystonia, or also known as acute dystonic reactions, are seen within days after starting or dose in crease of antipsychotics. Dystonic reactions are adverse extrapyramidal symptoms (EPS) and are common to antipsychotics. They are thought to have a significant impact on subjective tolerability and adherence with antipsychotic therapy in addition to impacting function. Unlike conventional antipsychotic medications, atypical antipsychotics have a significantly diminished risk of inducing acute EPS at recommended dose ranges. The purpose of the case reports was to provide guidance to clinicians on the clinical management EPS of second-generation antipsychotics.

Case 1. A 10-year-old boy was admitted to our polyclinic with irritability, aggressive behavior, loss of interest to lessons, and difficulty in adapting to the rules. Sub-scores of WISC-R were found as following: verbal score:118, performance score: 101, IQ: 112, general information: 15, arithmetic: 8, judgment: 16, block design: 8, sequence of numbers: 10, picture completion: 11, code: 9, picture completion: 15. Bender gestalt visual motor test score was found to be within 10% percentile. Low dose methylphenidate treatment was started and risperidone was added for behavioral problems. Methylphenidate and risperidone doses were increased to 36 mg/day and 2 mg/day, respectively during the clinical course. One month later, it was found out that risperidone was administered to the patient 4 mg/day instead of 2 mg/day, erroneously, by the family. Patient was admitted to emergency with acute dystonic reactions consisting of torticollis, tongue protrusion and respiratory distress that resolved with the intramuscular administration of biperiden 2.5 mg.

Case 2. A 5.5-year-old boy was the only child of the family. His neuromotor development was normal. He began to walk at 1 year-old and speak at 2 year-old. He wasn’t at school age. In particular of family history; his cousin was autistic. He was admitted to our polyclinic with complaints including: irritability, aggressive behavior, difficulty in establishing relationships and late bedtime. He didn’t know colors and shapes. His initial treatment was started with risperidone 0.25 mg/day. He was admitted to the emergency service with tongue protrusion, neck dystonia and inability to speak after the second dose. We diagnosed EPS and administered intravenous biperiden hydrochloride (1x1/8 bulbs in 100 cc %0,9 NaCl). Complaints were resolved with biperiden.

Acute dystonic reactions can occur within a few hours, days or weeks (4). Risk of EPS is increasing with high dose. However,single-dose or low-dose antipsychotics can induce dystonia. In this case report, we point at the importance of management of acute dystonia. Families should be informed about EPS.