MRI focused ultrasound thalamotomy reduces essential tremor symptoms
1. Patients undergoing MRI focused ultrasound thalamotomy had their essential tremor symptoms significantly reduced by 3-months post-procedure and maintained at 12-month follow-up.
2. Major adverse outcomes of the ultrasound thalamotomy procedure included gait disturbances and paresthesias (or numbness), though quality of life for the treated group was significantly better.
Evidence Rating: 1 (Excellent)
Study Rundown: Essential tremor is a movement disorder that can have a marked impact on patients’ quality of life. Medications serve as first line treatment for the condition, but medication resistance or side effects can develop. For these patients, procedures aimed at disrupting the nucleus ventralis intermedius of the thalamus have been developed. Because lesioning of this region is permanent, image guided procedures are desired. In this study a trial was conducted comparing symptomatic outcomes for patients undergoing MRI focused unilateral ultrasound thalamotomy versus a sham procedure.
Patients who had moderate to severe medication resistance essential tremor were included in this study. Trial groups included a treatment group and a sham group undergoing the same procedure without delivery of lesioning ultrasound waves. At 3-months post-procedure the Clinical Rating Scale for Tremor (CRST) showed a significantly higher improvement in the treatment group compared to the shame group. Adverse events occurred in higher prevalence in the treated group compared to the sham group, with the major events for the treated group being parenthesis or numbness and gait disturbance. On a Quality of Life in Essential Tremor Questionnaire (QUEST) there was a significantly higher reduction in score (improvement) in the treated group compared to the sham group.
Click to read the study, published today in NEJM
Relevant Reading: Treatment of patients with essential tremor
In-Depth [randomized control trial]: In this double-blind trial 76 patients were assessed at 8 international hospitals. Patients were divided 3:1 into treatment and sham groups (56 and 20, respectively), and at 3-months post-procedure patients in the sham group were allowed to cross over to receive the treatment. Patients were enrolled if they had a diagnosis of essential tremor classified as moderate to severe and disabling by CRST. The patient’s tremor must also have been refractory to 2 or more medical treatments. For the procedure, patients had MRI guided ultrasounds that ablated thalamic tissue, or in the sham group the same procedure without ultrasound delivery. Patient’s tremors were recorded on video and assessed by specialists blinded to a patient’s treatment group. Patient tremor was assessed at 1, 3, 6, and 12-months post-treatment for the treated group, and at 1 and 3 months for the sham group.
The primary outcome was change in tremor at 3 months as scored on the CRST. Secondary outcomes were measurement of disability on CRST, quality of life at 3 months assessed with QUEST, and reduction in hand tremor at 12 months. At 3 months CRST scores were 18.1±4.8 to 9.6±5.1 for the treatment group and 16.0±4.4 to 15.8±4.9 for the sham group (p < 0.001). Disability scores showed a higher reduction in the treatment group compared to the sham group (16.5±4.6 to 6.2±5.6 vs. 16.0±4.3 to 15.6±4.6, p < 0.001). Quality of life scores were also significantly improved for the treatment group versus the sham group (2.6±18.3 to 23.1±16.9 versus 2.8±19.5 to 41.4±19.4, p < 0.001). At 12 months the treatment group maintained significant reduction in hand tremor (18.1±4.8 to 10.9±4.5, p < 0.001). Treated patients experienced paresthesia or numbness (38%) and gain disturbance (36%) as their main adverse events. At 12 months the treatment group showed a 40% CRST improvement. This study shows improvement in all tremor and quality of life related metrics compared to a sham group, though understanding how this procedure compares to other lesioning procedures (radiosurgery, deep-brain stimulation) would likely be a better comparison.
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