Comparison between deep brain stimulation and magnetic resonance-guided focused ultrasound in the treatment of essential tremor: a systematic review and pooled analysis of functional outcomes

Abstract

The current gold standard surgical treatment for medication-resistant essential tremor (ET) is deep brain stimulation (DBS). However, recent advances in technologies have led to the development of incisionless techniques, such as magnetic resonance-guided focused ultrasound (MRgFUS) thalamotomy. The authors perform a systematic review according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement to compare unilateral MRgFUS thalamotomy to unilateral and bilateral DBS in the treatment of ET in terms of tremor severity and quality of life improvement. PubMed, Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials and SCOPUS databases were searched. 45 eligible articles, published between 1990 and 2019, were retrieved. 1202 patients were treated with DBS and 477 were treated with MRgFUS thalamotomy. Postoperative tremor improvement was greater following DBS than MRgFUS thalamotomy (p<0.001). A subgroup analysis was carried out stratifying by treatment laterality: bilateral DBS was significantly superior to both MRgFUS and unilateral DBS (p<0.001), but no significant difference was recorded between MRgFUS and unilateral DBS (p<0.198). Postoperative quality of life improvement was significantly greater following MRgFUS thalamotomy than DBS (p<0.001). Complications were differently distributed among the two groups (p<0.001). Persistent complications were significantly more common in the MRgFUS group (p=0.042). While bilateral DBS proves superior to unilateral MRgFUS thalamotomy in the treatment of ET, a subgroup analysis suggests that treatment laterality is the most significant determinant of tremor improvement, thus highlighting the importance of future investigations on bilateral staged MRgFUS thalamotomy.

Deep-Brain Stimulation for Essential Tremor and Other Tremor Syndromes: A Narrative Review of Current Targets and Clinical Outcomes

“…Stimulation-related side-effects included speech disturbance (11.1%), gait disturbance (10.9%), paresthesias (8.8%), neuropsychiatric issues (5.1%) and other symptoms (8.3%). Across all complications, 76.6% were transient [85]. Overall, patient satisfaction with DBS for ET is very high [86], and outcomes appear to have been slightly improving over time (average of 0.4% improvement in tremor score per year in studies published between 1996 and 2019, Spearman's correlation coefficient = 0.357, p = 0.035), suggesting progress in the surgical techniques and hardware [85].…”

“…Tremor reduction was superior in patients receiving bilateral DBS (61.2% ± 5.2, SD, n = 69) versus unilateral DBS (56.4% ± 9.7, SD, n = 472, p < 0.001). Across studies, DBS for ET improved quality of life by 52.5% ± 16.2 (SD) at an average follow-up of 16.6 months [85]. Perioperative and hardware-related complications included lead problems (11.4%), local adverse symptoms (10.9%), infection (1.8%), intracranial hemorrhage (1.1%), seizures (0.5%) and death (0.1%).…”

“…When considering all targets together, a meta-analysis was recently performed and identified 37 studies (14 retrospective and 23 prospective) published between 1996 and 2019 and reporting the results of 1202 patients treated with DBS for medically refractory ET [85]. The average improvement in tremor score was 60.1% ± 9.7 (SD) at an average follow-up of 16.6 months.…”

Deep Brain Stimulation for Essential Tremor and Other Tremor Syndromes: A Narrative Review of Current Targets and Clinical Outcomes

“…DBS in ET is thought to act by inhibiting the pathological oscillations in the cerebello-thalamic pathways. [64]. Overall, patient satisfaction with DBS for ET is very high [65] and outcomes appear to have been slightly improving over time (average of 0.4% improvement in tremor score per year in studies published between 1996 and 2019, Spearman's correlation coefficient = 0.357, p = 0.035), suggesting progress in the surgical techniques and hardware [64].…”

“…While its efficacy in ET and PD are well established, the mechanisms underlying tremor suppression, stimulation habituation and side effect generation are still incompletely understood and will continue to be researched. Incremental improvement in surgical techniques have already been shown to have slowly improved outcomes over the last two decades [64]. require new study designs that focus less on the targets themselves and more on how to mitigate the loss of neurons within the circuit.…”