Hypomania as an adverse effect of subthalamic nucleus stimulation: report of two cases

Mania following subthalamic nucleus (STN) deep brain stimulation (DBS) is well described and obvious to both the patient and their physician. The authors describe two patients who developed hypomania following STN-DBS but were unaware of their mood disturbance. Two Parkinson's patients with no previous mood disorders received bilateral STN electrodes. Both experienced dramatic improvement in their motor function and neither complained of any side effects. Their families reported detrimental hypomanic behaviour. Readjusting the stimulation parameters resolved the hypomania with continued motor benefits. The authors draw attention to potential adverse effects of STN-DBS that might be neglected by patients.