Hypomanic Symptoms After Deep Brain Stimulation for Obsessive-Compulsive Disorder

Introduction: Hypomanic symptoms are the most common adverse effect following deep brain stimulation (DBS) for obsessive-compulsive disorder (OCD), with a prevalence of approximately 20% in historical cohorts. As hypomania may limit therapeutic benefit of DBS, we explored the incidence of hypomania after DBS for OCD in a novel cohort of patients with surgical targeting using tractography.

Methods: All patients with DBS for OCD at one center from 2016 to 2023 were followed to their last clinical follow-up. Preoperative and postoperative OCD severity was documented by the Yale–Brown Obsessive–Compulsive Scale (Y–BOCS), and symptoms of mania-hypomania were documented.

Results: There were 18 patients included, with average preoperative Y–BOCS of 33.8 ± 3.8, decreased to an average of 19.2 ± 9.4 at a median follow-up of 13.4 months following DBS. For 17 patients, the surgical target was within the striatum (anterior limb of the internal capsule (ALIC) or ventral capsule/ventral striatum, while one patient with comorbid dystonia received subthalamic nucleus-DBS. Average stimulation amplitude was 5.7 ± 1.5mA. None of four patients with a history of mania/hypomania prior to DBS experienced worsening, including one patient with a remote history of bipolar 1 disorder. New postoperative hypomanic symptoms were noted in 2 patients (11.1%) with ALIC-DBS, including insomnia in both patients that required titration of therapeutic amplitude and medical treatment of insomnia.

Conclusion : New hypomanic symptoms, mainly insomnia, may complicate management with DBS for OCD. However, history of manic-hypomanic symptoms does not seem to predict postoperative exacerbation of hypomania-mania. When present, hypomanic symptoms can require titration in stimulation amplitude that may limit therapeutic benefit for OCD. We are actively exploring mechanisms of this adverse effect with tools including tractography and chronic electrophysiology.