Role of the Cortico-Subthalamic Hyperdirect Pathway in Deep Brain Stimulation for the Treatment of Parkinson Disease: A Diffusion Tensor Imaging Study.

Abstract

To evaluate the clinical effect of the position of stimulation contacts relative to the hyperdirect pathway (HDP) on the alleviation of motor symptoms in patients with Parkinson disease (PD). A group of 11 patients diagnosed with idiopathic PD were included in this study, and all selected targets were in the subthalamic nucleus (STN). In 1 patient, a single side electrode was implanted because of unilateral symptoms; in all other patients, bilateral electrodes each containing 4 discrete contacts were implanted. Nine contacts were excluded due to adverse reactions caused by stimulation, and thus a total of 75 active contacts were evaluated using the same stimulus parameters. Fiber tractography results were individually processed using StealthViz software before all data were subjected to statistical analysis. Under the same stimulus parameters, the shortest distance of each contact to the HDP was smaller in group I (n= 45; >50% improvement rate) compared with group II (n= 30; ≤50% improvement rate) (mean, 1.18 ± 0.86 mm vs. 2.14 ± 1.20 mm; t= 3.78; P < 0.05), and the shortest distance had a negative correlation with the improvement of motor symptoms (r=-0.48; P < 0.05). Stimulation of the HDP coincided with the improvement of motor symptoms in patients with PD. We propose an improvement of the direct visualization method based on diffusion tensor imaging fiber tractography of the HDP to select the motor part of the STN. Further rigorous clinical trials are needed to verify the value of this method for achieving precise target location and individualized treatment.