Using Diffusion Tensor Imaging to Find Optimal Stimulation Targets in Obsessive‐Compulsive Disorder Treatment

Abstract

Obsessive‐compulsive disorder (OCD) is a common psychiatric condition that can be severe and treatment‐resistant in some patients. Treatment‐resistant OCD (tr‐OCD) can now be managed with deep brain stimulation (DBS), an invasive neuromodulation therapy. However, due to the small population of tr‐OCD patients being treated with DBS, there is little consensus on the best target for stimulation. Past research targeted the anterior limb of the internal capsule (ALIC), the subthalamic nucleus, and the nucleus accumbens (NAc). The purpose of this study is to use diffusion tensor imaging (DTI) to refine the optimal target for DBS in tr‐OCD patients, when targeting the ALIC, specifically studying the NAc (COMIRB #14‐0554). We performed tractography analysis on fiber tracts going through the volume of tissue activation (VTA), using each patient’s DTI. We then related the change in OCD symptom severity on the Yale‐Brown Obsessive‐Compulsive scale (Y‐BOCS) from pre‐surgery, up to one‐year post‐surgery. Preliminary results (n=1) show there was a 6.45% increase in OCD symptom severity, and that was correlated with putatively activated tracts within the VTA, or area of stimulation. Comparing two time points we found that there was change in the diffusion coefficients of 1.16% for FA and 2.62% for MD on the left, and 28.96% for FA and 3.07% for MD on the right. Changes in these DTI coefficients between the two‐time points suggest that modification in stimulation parameters that led to clinical benefit was associated with activation of putatively distinct fiber populations and thus different neural pathways.