Regional gray matter volumes are not predictive of axial symptom response to subthalamic deep brain stimulation in Parkinsonian patients

Introduction: In Parkinson's disease (PD), axial symptom response to deep brain stimulation of the subthalamic nucleus (STN-DBS) is heterogeneous. This single-center, retrospective study aimed to assess imaging biomarkers of routine magnetic resonance imaging (MRI) to predict axial symptom response to STN-DBS, specifically by using an index of volumes of mesencephalon, pons, middle, and superior peduncle ("MR PIGD index"). Methods: We investigated 94 PD patients pre- and three to six months postoperatively by using MDS-UPDRS III, Berg Balance Scale, Freezing of Gait Questionnaire (FOG-Q) and Ziegler Course, which were related to regional brain volumetry information using regression analysis and partial least squares correlation analysis. Results: STN-DBS led to significant, but heterogeneous improvement of axial PD symptoms. Neither the MR PIGD index nor other cortical brain volumes predicted the extent of the postoperative, axial symptom improvement. Conclusions: Response to STN-DBS in PD cannot be predicted by MRI regional gray matter volumes.