Segmented Leads for Deep Brain Stimulation in Patients with Parkinsonís Disease

Special Issue – Clinical Neurophysiology

Austin Neurol & Neurosci. 2017; 2(1): 1018.

Segmented Leads for Deep Brain Stimulation in Patients with Parkinson’s Disease

Bour LJ*

Department of Neurology/Clinical Neurophysiology, Academic Medical Center, University of Amsterdam, Netherlands

*Corresponding author: Lo J. Bour, Department of Neurology/Clinical Neurophysiology, Academic Medical Center, University of Amsterdam, Netherlands

Received: April 04, 2017; Accepted: May 15, 2017; Published: May 22, 2017

Limitations of Conventional DBS Leads

Deep Brain Stimulation (DBS) of the Sub-Thalamic Nucleus (STN) is an effective treatment for Parkinson Disease (PD) [1]. The efficacy of DBS may be limited by current spread into adjacent structures, inducing side effects such as muscle contractions, dysarthria, and cognitive or behavioral disturbances [2]. The goal is to have the largest Therapeutic Window (TW) as possible, i.e. the largest difference between the lowest threshold for therapeutic effect and the highest threshold for adverse effects. The most effective position for obtaining the best therapeutic effect in PD has been demonstrated to be the dorsolateral area of the STN. This means that this area in fact is considerably smaller than the size of the STN itself (about 40%) and, therefore, for STN-DBS precise targeting within an accuracy of 1-2 mm is required. Conventional DBS leads (CC) have not been changed in the past decennia and harbor 4 ring-shaped contacts. Adjacent contacts from center to center are separated by 2 mm. In total the distance from the center of the most dorsal contact point #3 to the center of the most ventral contact point #0 subtends six millimeter in depth (Figure 1).

Imaging in the past decennia has improved considerably by high precision 3D MRI and its ultimate accuracy is about 1-2 mm [3]. Other inaccuracies in the surgical procedure including the final placement of the lead may add up to the total inaccuracy of the procedure [4]. This means statistically that in some of the patients the deviation of the optimum target position will be larger than 1-2 mm. CC leads do not have sufficient degrees of freedom to correct sufficiently for too large positional error. Particularly when the target is located 2-3 mm too lateral or too medial the current has to be increased considerably such that adjacent structures are stimulated, leading to unwanted adverse effects (Figure 2) and a decrease of the TW.