A meta-analysis of outcomes and complications of magnetic resonance-guided focused ultrasound in the treatment of essential tremor.

OBJECTIVE Magnetic resonance-guided focused ultrasound (MRgFUS) is a novel technique that uses high-intensity focused ultrasound to achieve target ablation. Like a lens focusing the sun's rays, the ultrasound waves are focused to generate heat. This therapy combines the noninvasiveness of Gamma Knife thalamotomy and the real-time ablation of deep brain stimulation with acceptable complication rates. The aim of this study was to analyze the overall outcomes and complications of MRgFUS in the treatment of essential tremor (ET). METHODS A meta-analysis in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines was made by searching PubMed, Cochrane library database, Web of Science, and Cumulative Index to Nursing and Allied Health Literature (CINAHL). Patients with the diagnosis of ET who were treated with MRgFUS were included in the study. The change in the Clinical Rating Scale for Tremor (CRST) score after treatment was analyzed. The improvement in disability was assessed with the Quality of Life in Essential Tremor Questionnaire (QUEST) score. The pooled data were analyzed by the DerSimonian-Laird random-effects model. Tests for bias and heterogeneity were performed. RESULTS Nine studies with 160 patients who had ET were included in the meta-analysis. The ventral intermediate nucleus was the target in 8 of the studies. The cerebellothalamic tract was targeted in 1 study. There was 1 randomized controlled trial, 6 studies were retrospective, and 2 were prospective. The mean number of sonications given in various studies ranged from 11 ± 3.2 to 22.5 ± 7.5 (mean ± SD). The maximum delivered energy ranged from 10,320 ± 4537 to 14,497 ± 6695 Joules. The mean of peak temperature reached ranged from 53°C ± 2.3°C to 62.0°C ± 2.5°C. On meta-analysis with the random-effects model, the pooled percentage improvements in the CRST Total, CRST Part A, CRST Part C, and QUEST scores were 62.2%, 62.4%, 69.1%, and 46.5%, respectively. Dizziness was the most common in-procedure complication, occurring in 45.5%, followed by nausea and vomiting in 26.85% (pooled percentage). At 3 months, ataxia was the most common complication, occurring in 32.8%, followed by paresthesias in 25.1% of the patients. At 12 months posttreatment, the ataxia had significantly recovered and paresthesias became the most common persisting complication, at 15.3%. CONCLUSIONS The MRgFUS therapy for ET significantly improves the CRST scores and improves the quality of life in patients with ET, with an acceptable complication rate. Therapy with MRgFUS is a promising frontier in functional neurosurgery.

Effects on cognition and quality of life with unilateral magnetic resonance-guided focused ultrasound thalamotomy for essential tremor.

OBJECTIVE Although neurosurgical procedures are effective treatments for controlling involuntary tremor in patients with essential tremor (ET), they can cause cognitive decline, which can affect quality of life (QOL). The purpose of this study is to assess the changes in the neuropsychological profile and QOL of patients following MR-guided focused ultrasound (MRgFUS) thalamotomy for ET. METHODS The authors prospectively analyzed 20 patients with ET who underwent unilateral MRgFUS thalamotomy at their institute in the period from March 2012 to September 2014. Patients were regularly evaluated with the Clinical Rating Scale for Tremor (CRST), neuroimaging, and cognition and QOL measures. The Seoul Neuropsychological Screening Battery was used to assess cognitive function, and the Quality of Life in Essential Tremor Questionnaire (QUEST) was used to evaluate the postoperative change in QOL. RESULTS The total CRST score improved by 67.3% (from 44.75 ± 9.57 to 14.65 ± 9.19, p < 0.001) at 1 year following MRgFUS thalamotomy. Mean tremor scores improved by 68% in the hand contralateral to the thalamotomy, but there was no significant improvement in the ipsilateral hand. Although minimal cognitive decline was observed without statistical significance, memory function was much improved (p = 0.031). The total QUEST score also showed the same trend of improving (64.16 ± 17.75 vs 27.38 ± 13.96, p < 0.001). CONCLUSIONS The authors report that MRgFUS thalamotomy had beneficial effects in terms of not only tremor control but also safety for cognitive function and QOL. Acceptable postoperative changes in cognition and much-improved QOL positively support the clinical significance of MRgFUS thalamotomy as a new, favorable surgical treatment in patients with ET.

Magnetic resonance-guided focused ultrasound thalamotomy for essential tremor: a 5-year single-center experience.

OBJECTIVE: The authors report their experience in treating patients suffering from medication-resistant essential tremor (ET) with MR-guided focused ultrasound (MRgFUS) thalamotomy over a 5-year period. METHODS: Forty-four ET patients treated with unilateral MRgFUS ventral intermediate nucleus (VIM) thalamotomy were assessed using the Clinical Rating Scale for Tremor (CRST) score and the Quality of Life in Essential Tremor Questionnaire (QUEST) over a 5-year span. RESULTS: Tremor was significantly improved immediately following MRgFUS in all patients and ceased completely in 24 patients. CRST scores in the treated hand at baseline (median 19; range 7-32, 44 patients) improved by a median of 16 at 1 month (44 patients; p < 0.0001), 17 at 6 months (31 patients; p < 0.0001), 15 at 1 year (24 patients; p < 0.0001), 18 at 2 years (15 patients; p < 0.0001), 19 at 3 years, (10 patients; p < 0.0001), 21 at 4 years (6 patients; p < 0.01), and 23 at 5 years (2 patients, significance not tested). Return of tremor that impacted activities of daily living was reported in 5 patients (11%). QUEST scores showed significant improvement, with median change of 35 points (p < 0.0001; 44 patients) at 1 month, 33 (p < 0.0001; 31 patients) at 6 months, 27 (p < 0.0001; 24 patients) at 1 year, 26 (p < 0.001; 15 patients) at 2 years, 25 (p < 0.001; 10 patients) at 3 years, 33 (p < 0.001; 6 patients) at 4 years, and 28 (significance not tested, 2 patients) at 5 years. Adverse events after the procedure were reversible in all but 5 patients (11%). CONCLUSIONS: MRgFUS thalamotomy for ET is an effective and safe procedure that provides long-term tremor relief and improvement in quality of life even in patients with medication-resistant disabling tremor. Additional studies with a larger group of patients is needed to substantiate these favorable results.