Subthalamic stimulation for Parkinson disease: determination of electrode location necessary for clinical efficacy

Abstract

<jats:sec> <jats:title>Object</jats:title> <jats:p>Deep brain stimulation (DBS) of the subthalamic nucleus (STN) performed using intraoperative microelectrode recording (MER) to adjust electrode placement has become a widely used treatment for patients with advanced Parkinson disease (PD). Few studies have been conducted to examine the location of implanted electrodes relative to the intended target, and even fewer have been undertaken to investigate the degree to which variations in the location of these electrodes impacts their clinical efficacy. This study was performed to examine these issues.</jats:p></jats:sec> <jats:sec> <jats:title>Methods</jats:title> <jats:p>The authors located 52 bilaterally implanted DBS electrode tips on postoperative magnetic resonance (MR) images obtained in 26 consecutive patients. Postoperative and preoperative planning MR images were merged to determine the DBS electrode tip coordinates relative to the midcommissural point. Surgical records listed the intended target coordinates for each DBS electrode tip. Clinical outcome assessment included the Unified PD Rating Scale (UPDRS) motor score at 1 year, standardized questionnaires, and routine follow-up visits.</jats:p> <jats:p>The mean difference between electrode tip location and intended target for all 52 electrodes was less than 2 mm in all axes. Only one electrode was farther than 3 mm from the intended target, and this was the only electrode that had to be replaced due to lack of clinical efficacy (lack of tremor suppression); its reimplantation 4 mm more medially provided excellent tremor control. High correlation coefficients indicate that the MR imaging analysis accurately determined the anatomical location of the electrode tips. Blinded videotape reviews of UPDRS motor scores comparing effects of stimulation in patients who were “on” and “off” medication identified subgroups in whom there was minimal and maximal stimulation response. Patients in these subgroups had no differences between the MR imaging–determined actual electrode tip location and its intended location. Similarly, improvements of dyskinesias and severity of symptoms encountered during the wearing-off period for the drug did not correlate with variations of electrode tip location.</jats:p></jats:sec> <jats:sec> <jats:title>Conclusions</jats:title> <jats:p>The findings in this study lead the authors to suggest that a DBS electrode placed anywhere within a 6-mm-diameter cylinder centered at the presumed middle of the STN (based on stereotactic atlas coordinates) provides similar clinical efficacy. Future studies may be warranted to evaluate prospectively the degree to which MER modification of the anatomically and/or image-determined target improves clinical efficacy of DBS electrodes.</jats:p></jats:sec>

Estimation of Electrode Position with Fused Images of Preoperative MRI and Postoperative CT Using the Mutual Information Technique After STN DBS in Patients with Advanced Parkinson's Disease

“…However, the improvement of Parkinsonian symptoms, LEDD, neuropsychological changes other than speech, and stimulation side effects did not vary with the variation of electrode location found in this series of patients. This study thus supports the idea proposed by McClelland et al (2005) that there is a significant target volume in the region of the STN that provides equivalent clinical efficacy. Fig.…”

“…Postoperative confirmation of the electrode location was not carried out. McClelland et al (2005) calculated the electrode tip coordinates in x, y, and z planes relative to the midcommissural point from fused MRI scans of postoperative and preoperative planning images in 26 consecutive patients and compared electrode tip location with clinical outcome. Yokoyama et al (2006) compared the clinical improvement of Parkinsonian symptoms after monopolar stimulation using four electrode contacts, the locations of which were determined using intraoperative x-rays obtained after placing the DBS electrode in the STN.…”

Deep Brain Stimulation to Reward Circuitry Alleviates Anhedonia in Refractory Major Depression

“…This technique is deep brain stimulation (DBS), and refers to the stereotaxic placement of unilateral or bilateral electrodes in target brain regions connected to a permanently implanted neurostimulator, which electrically stimulates that brain region (Schlaepfer and Lieb, 2005). Today, DBS is widely used as a treatment for symptoms of Parkinson's disease (Ghika et al, 1998;Greenberg and Rezai, 2003;McClelland et al, 2005). In these patients, electrodes are placed in the subthalamic nucleus or the globus pallidus internus, and provide immediate recovery to otherwise debilitating motor symptoms.…”

Parkinson’s disease outcomes after intraoperative CT-guided “asleep” deep brain stimulation in the globus pallidus internus

“…Studies of these methods with postoperative imaging to assess final lead location in the STN 3,11,15,20,23,26,33 or GPi 5,14,28,30 revealed important correlations between the precise anatomical lead position and clinical outcome. These data coupled with improved MRI resolution led the way for "direct" targeting, wherein the targeted structure is directly visualized on MRI.…”