A One year follow up study of persistent motor tic disorder treated with risperidone in a children’s hospital in Sri Lanka

Abstract

INTRODUCTION: Transient tics are common in children. In persistent motor tic disorders, single or multiple motor tics persist for more than a year. OBJECTIVE: To determine the one year outcome of persistent motor tic disorder treated with risperidone in a group of Sri Lankan children. METHOD: New patients presenting to the Child and Adolescent Mental Health Services of the Lady Ridgeway Hospital for Children in Colombo were screened for tics. Diagnosis was made by a consultant psychiatrist according to the Diagnostic and Statistical Manual of mental disorders 5th edition (DSM-5). The children were prospectively followed up for a period of one year with monthly assessments. Patients treated solely with oral risperidone from the beginning were analysed. In all children dose of risperidone ranged from 0.25-2 mg/day. Of all children with tics, only children with persistent motor tic disorder were included in the follow up. The symptom severity was measured using the Yale Global Tic Severity Scale (YGTSS). A reduction of the YGTSS score by 35% was considered as a satisfactory response to treatment. The presence of comorbid psychiatric disorders was assessed clinically as well as by using the Swanson, Nolan and Pelham teacher and parent rating scale 4th version and Yale Brown obsessive compulsive scale. Ethical approval was obtained from the ethical review committee of the Lady Ridgeway Hospital. RESULTS: Of the screened patients, 123 children were diagnosed with a persistent motor tic disorder at the beginning of the study. Of these, 17 were excluded because of irregular attendance at the monthly assessments and 3 were excluded as the diagnosis was changed to Tourette syndrome due to the detection of new symptoms. Eye blinking and shoulder shrugging were the commoner tic types in participants. Attention deficit hyperactivity disorder was the commonest comorbid psychiatric disorder. After 12 months follow up, 78.6% of participants responded to risperidone with a predefined 35% lessened tic severity score according to the YGTSS. The percentage of children with comorbid ADHD who had responded to risperidone at 35% YGTSS score reduction was significantly low compared to the children without ADHD (p<0.05). There was no statistically significant difference in the treatment response according to age, gender, complexity of tics or type of tics. CONCLUSIONS: After one year follow up, 79% of children with persistent motor tic disorder responded satisfactorily to risperidone. The percentage of children with comorbid ADHD who responded satisfactorily to risperidone was significantly low compared to the children without ADHD (p<0.05).