Quetiapine Induced Myoclonus

Miss D, a 19-year-old female presented to us with history suggestive of manic episode for the last 2 months. Her past history also revealed history of 2 GTCS around 6 years back for which no treatment was sought. Her family and personal history were non signiÞ cant. She was started on quetiapine gradually increased to 300 mg per day over a week and lorazepam 2 mg at night. She showed improvement in her symptoms over the next 2 weeks. After this, the dose was increased to 400 mg per day. After 2 days of this, she developed sudden abrupt jerks lasting for less than a second, especially involving the right upper extremity. These movements would at times be so frequent that she even dropped the things in her hand. An EEG revealed intermittent bilateral polyspike discharges. Her biochemical investigations and MRI brain were normal. The dose of quetiapine was decreased to 200 mg per day and after about 1 week the patient did not have these jerky movements. EEG after 10 days of this was normal. Quetiapine was then stopped and she was started on oxcarbamazepine and lorazepam and improved in 1 month.