Abstract
Objective This study was aimed at identifying the potential outcome predictors, comparing the efficacy in patients with different tremor characteristics, and summarizing the adverse effect rates (AERs) of deep brain stimulation on the ventral intermediate nucleus (VIM-DBS) for essential tremor (ET). Methods An extensive search of articles published to date in 2019 was conducted, and two main aspects were analyzed. Improvement was calculated as a percentage of change in any objective tremor rating scale (TRS) and analyzed by subgroup analyses of patients' tremor characteristics, laterality, and stimulation parameters. Furthermore, the AERs were analyzed as follows: the adverse effects (AEs) were classified as stimulation-related, surgical-related, or device-related effects. A simple regression analysis was used to identify the potential prognostic factors, and a two-sample mean-comparison test was used to verify the statistical significance of the subgroup analyses. Results Forty-six articles involving 1714 patients were included in the meta-analysis. The pooled improvement in any objective TRS score was 61.3% (95% CI: 0.564-0.660) at the mean follow-up visit (20.0 ± 17.3 months). The midline and extremity symptoms showed consistent improvement (P = 0.440), and the results of the comparison of postural and kinetic tremor were the same (P = 0.219). In addition, the improvement in rest tremor was similar to that in action tremor (OR = 2.759, P = 0.120). In the simple regression analysis, the preoperative Fahn-Tolosa-Marin Tremor Rating Scale (FTM-TRS) scores and follow-up time were negatively correlated with the percentage change in any objective TRS score (P < 0.05). The most common adverse event was dysarthria (10.5%), which is a stimulation-related AE (23.6%), while the rates of the surgical-related and device-related AEs were 6.4% and 11.5%, respectively. Conclusion VIM-DBS is an efficient and safe surgical method in ET, and the efficacy was not affected by the body distribution of tremor, age at surgery, and disease duration. Lower preoperative FTM-TRS scores likely indicate greater improvement, and the effect of VIM-DBS declines over time.
Highlights
Essential tremor (ET), known as primary tremor, is defined as an isolated tremor syndrome consisting of a bilateral upper extremity action tremor for at least 3 years with or without tremor in other locations and without other neurological signs [1]
After we identified that the follow-up time is a predictive factor, the data from Barbe et al [22] were excluded because the patients underwent the operation at least 3 months before their trials to optimize the efficacy of Deep brain stimulation adverse effects (AEs) (DBS), causing strong heterogeneity based on the sensitivity analysis, and we could not identify the detailed follow-up time after the first surgery
The 26 studies shown in Table 1 were included to identify the efficacy of VIM-DBS; 7 of these studies and the 20 additional studies shown in Table 4 were used to summarize the AEs
Summary
Essential tremor (ET), known as primary tremor, is defined as an isolated tremor syndrome consisting of a bilateral upper extremity action tremor for at least 3 years with or without tremor in other locations and without other neurological signs [1]. The management of this disorder focuses on controlling the symptoms, and pharmacotherapy is the primary therapy. Drug therapy is only effective in 50% of ET patients [2]. Surgical options include stereotactic radiofrequency thalamotomy, gamma knife thalamotomy, and deep brain stimulation [3,4,5] Among these options, deep brain stimulation in the ventral intermediate nucleus (VIM-DBS) is more reversed than thalamotomy and can effectively suppress tremors while avoiding the common complications of thalamotomies [6, 7]. The posterior subthalamic area/caudal zona incerta and subthalamic nucleus, except for the VIM, are targets of DBS; far, studies are still limited with a short follow-up period compared to that in studies investigating VIM [8]. 1050 additional records identified through Embase and the Cochrane Library
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