Subthalamic Nucleus Deep Brain Stimulation in Advanced Parkinson's Disease: Analysis of Anatomical Location versus Intended Target and Clinical Outcome
Shearwood McClelland III BA1, Blair Ford MD, FRCPC2, Patrick B Senatus MD, PhD1, Linda M Winfield RN, MPH2, Seth L Pullman MD, FRCPC2, Qiping Yu PhD2, Guy M McKhann II MD1, Robert R Goodman MD, PhD1
Departments of 1Neurological Surgery and 2Neurology, Columbia University, College of Physicians and Surgeons, New York, NY
OBJECT: Deep brain stimulation (DBS) of the subthalamic nucleus (STN) for medically refractory Parkinson's disease (PD) patients is gaining acceptance. Little is known regarding correlation of electrode location with the intended target or clinical outcome. This study was performed to address these issues.
METHODS: 26 consecutive patients underwent bilateral STN implantation, aided by stereotactic MRI, microelectrode recording (MER), and intraoperative macro-stimulation. Electrode tip stereotactic coordinates were independently obtained by three observers by fusion of post-operative and immediate pre-operative MRIs. Coordinates were compared to the intended target coordinates. Nearly all patients reported significant improvement of "on" versus "off" time. One year postoperatively, patients were video analyzed for hand tremor (with stimulation "off" and "on") and other PD symptoms/signs.
RESULTS: The mean distance of the tip from the idealized target was less than 2 mm in any single dimension (X, Y, Z). There was excellent interobserver agreement. Tremor was effectively suppressed by 12 of 16 implants. Focusing on the "X" dimension, the mean tip position was 10.2 mm lateral to midline; 10 of 12 "effective" electrodes were within 1 mm, while all 4 "ineffective" electrodes were more than 1 mm from the overall mean (p=0.008). One "ineffective" electrode (the most laterally placed of all 52) was reimplanted, with excellent tremor/symptom control.
CONCLUSIONS: MRI accurately detects DBS electrode location. The laterality from the desired target may be the most important determinant of clinical benefit for tremor. In further studies we are addressing the relation of electrode location to other components of clinical efficacy.