Evolving Concepts in Posterior Subthalamic Area Deep Brain Stimulation for Treatment of Tremor: Surgical Neuroanatomy and Practical Considerations

Abstract

Background: Although thalamic deep brain stimulation (DBS) has been established as an effective therapy for refractory tremor in Parkinson's disease and essential tremor, reports investigating the efficacy of posterior subthalamic area (PSA) DBS for severe, debilitating tremors continue to emerge. However, questions regarding the optimal anatomical target, surgical approach, programming paradigms and effectiveness compared to other targets remain. Objectives: In this report, we aimed to review the current literature to assess different stereotactic techniques, anatomical considerations, adverse effects and stimulation settings in PSA DBS. Methods: A comprehensive literature review was performed searching for articles discussing tremors and PSA stimulation. We performed a quantitative analysis comparing different DBS tremor targets. Results: Tremor improvement is consistently documented in most reports with an average reduction in tremor of 79% depending on the specific tremor syndrome. Tremor benefit in patients with multiple sclerosis (MS) tremor was significantly higher than for other stimulation targets. Transient paresthesias, imbalance, dizziness and dysarthria are the most common side effects with PSA DBS. Conclusions: PSA DBS is an effective and safe treatment for tremor control and should be considered in patients with refractory tremors with associated cerebellar or dystonic features, proximal tremors and MS tremor.

Deep brain stimulation in the caudal zona incerta versus best medical treatment in patients with Parkinson’s disease: a randomised blinded evaluation

“…One review hinted at the need for blinded evaluations, 19 and the other review pointed to the need for quality-of-life assessments of patients. 20 It is interesting to note that open-label studies that focused specifically on patients with PD undergoing cZi DBS reported a very positive effect on other symptoms than tremor: Carillo-Ruiz et al 14 evaluated five patients and reported that the UPDRS-III was improved by 65%, with a 90% improvement in tremor, 94% in rigidity and 75% in bradykinesia. In a non-randomised open-label sequential study, Plaha et al 16 compared the effects of DBS in the STN (17 electrodes) and the cZi (27 electrodes) and reported that the best effect was achieved in the cZi with a reduction of contralateral UPDRS-III score by 76%, tremor 93%, rigidity 76% and bradykinesia 65%.…”

Interleaving Stimulation in Parkinson’s Disease, Tremor, and Dystonia

“…In 7 of these patients, the added dorsal contact was outside of the STN within the region of the rZI [15, 16]. The rZI is located superior to the STN, inferior to the thalamus, lateral to the red nucleus, and medial to the STN.…”

Advanced Imaging and Direct Targeting of the Motor Thalamus and Dentato-Rubro-Thalamic Tract for Tremor: A Systematic Review

“…Of note, although the DRTT passes through posterior subthalamic area (PSA) and caudal zona incerta (cZI), studies of those 2 white-matter targets using conventional imaging were excluded to preserve a focused topic review. The PSA and cZI targets have recently been thoroughly reviewed [49].…”