Deep brain stimulation in the subthalamic area is more effective than nucleus ventralis intermedius stimulation for bilateral intention tremor

Abstract

SummaryBackground. The ventro-lateral thalamus is the stereotactic target of choice for severe intention tremor. Nevertheless, the optimal target area has remained controversial, and targeting of the subthalamic area has been suggested to be superior.Patients and methods. Eleven patients with disabling intention tremor of different etiology (essential tremor (n ¼ 8), multiple sclerosis (n ¼ 2) and one with, spinocerebellar ataxia) were implanted bilaterally with DBS electrodes targeted to the ventro-lateral thalamus using micro-recording and micro-stimulation. Among five tracks explored in parallel optimal tracks were chosen for permanent electrode implantation. Postoperative tremor suppression elicited by individual electrode contacts was quantified using a lateralised tremor rating scale at least 3 months (in most patients >1 year) after implantation. The position of electrode contacts was determined retrospectively from stereotactic X-ray exams and by correlation of pre-and postoperative MRI.Results. In all patients, DBS suppressed intention tremor markedly. On average, tremor on the left and right side of the body was improved by 68% (AE19; standard deviation) and 73% (AE21), respectively. In most patients, distal electrode contacts located in the subthalamic area proved to be more effective than proximal contacts in the ventro-lateral thalamus. In stereotactic coordinates, the optimal site was located 12.7 mm (AE1.4; mean AE standard deviation) lateral, 7.0 (AE 1.6) mm posterior, and 1.5 (AE 2.0) mm ventral to the mid-commissural point. In general, the best contacts could be selected for permanent stimulation. Nevertheless, in some instances, more proximal contacts had to be chosen because of adverse effects (paraesthesiae, dysarthria, gait ataxia) which were more pronounced with bilateral stimulation resulting in slightly less tremor suppression on the left and right side of body (63 AE 18 and 68 AE 19%, respectively).Conclusion. Direct comparison of different stimulation sites in individual patients revealed that DBS in the subthalamic area is more effective in suppressing pharmacoresistant intention tremor than the ventro-lateral thalamus proper. Anatomical structures possibly involved in tremor suppression include cerebello-thalamic projections, the prelemniscal radiation, and the zona incerta.

Deep Brain Stimulation of the Caudal Zona Incerta: Tremor Control in Relation to the Location of Stimulation Fields

“…The posterior subthalamic area (PSA) is situated immediately inferior to the VIM and posteromedial to the subthalamic nucleus (STN). Cerebellothalamic axons are particularly dense within the PSA before dispersing into the VIM, and promising results have been reported regarding DBS in this area [5,6,7,8,9]. One plausible explanation for the effectiveness of PSA DBS is that stimulation of axons instead of nuclei actually affects more neurons and therefore also alters tremor oscillations more efficiently [3,4,10].…”

Multitarget, dual-electrode deep brain stimulation of the thalamus and subthalamic area for treatment of Holmes' tremor

“…The overall activity was reduced in the SA, usually beginning within 1 mm from the intercommissural level. 13 After confirmation of neural activity, we performed macrostimulation by using the outer cannula of the microelectrode, with a contact point length of 1 mm, from 2-4 mm below the target to 2-4 mm above the target at 1-to 2-mm intervals to confirm the effects of stimulation on the tremor. We were concerned about brain shift due to leakage of CSF during surgery.…”

“…Only one report comparing the effects of thalamic and SA stimulation on tremor has been published, and this study indicated that SA stimulation is more effective than VIM nucleus stimulation at treating intentional tremor. 13 Since the underlying pathology involves a structural lesion, a variable combination of neural elements is damaged, giving rise to a rich variety of tremor phenomenology in HT. 8 Further studies are thus needed to clarify the optimal stimulation sites for exerting effects on each tremor component of HT.…”

Role of DaTSCAN and clinical diagnosis in Parkinson disease

“…Then, as recent evidence suggests, the subthalamic nucleus could be considered a better target for neurosurgical treatment of ET than the VIM. 7,8 Copyright © 2012 by AAN Enterprises, Inc.…”