EP 15. Choreatic side effects of deep brain stimulation of the subthalamic nucleus for treatment resistant OCD: A case history

Abstract

Introduction Patients with severe treatment resistant obsessive-compulsive disorder (OCD) are potential candidates for deep brain stimulation (DBS). The anteromedial limbic part of the subthalamic nucleus (STN) and the ventral capsule/ventral striatum (VC/VS) are among the most commonly used targets. Objective To report a side effect of anteromedial STN-DBS in an OCD patient that has not been described before. Method Case report. Results A 49-year old female patient with a 30-year history of treatment-resistant obsessive-compulsive disorder was indicated for anteromedial STN-DBS. Correct target identification was done using electrophysiological recordings preoperatively and confirmed with CT scanning post-operatively. Already after the first days of STN stimulation, there was a clear mood-enhancing effect. However, the patient developed compulsive behavior towards the operation wounds (scratching and itching), which may have been the cause of a subsequent hardware infection. The infection resolved after surgery and antibiotic therapy. In the outpatient period, the programming was limited by the fact that STN-DBS caused motor symptoms at voltages above circa 2.5 V. These consisted of bilateral hyperkinesia and dyskinesias, as well as sudden large amplitude choreatic movements of the arms and legs. With lower stimulation amplitude (and 90 ms and 130 Hz) there was no effect on compulsions. Due to this programming limitation, we decided to re-operate and target the VC/VS, with the deepest electrode contact point in the area of the nucleus accumbens. After programming, the patient now experiences a substantial reduction (50%) of the key symptoms and obtained an acceptable quality of life. Conclusion In this 49-year old patient with OCD, anteromedial STN-DBS induced hyperkinetic movements in the lower extremities that limited the programming possibilities. Choreatic movements and (contralateral) hemiballismus have since long been associated with damage to the subthalamic nucleus ( Hawley and Weiner, 2012) , and have been described as a side-effect of STN-DBS in Parkinson’s disease ( Baizabal-Carvalla and Jankovic, 2016) . However, the emergence of such motor symptoms as a side-effect of STN-DBS in OCD has to our knowledge not been described before. Reimplantation to the VC/VS successfully overcame this limitation and resulted in adequate therapeutic response.