MR-guided focused ultrasound (MRgFUS) therapy can produce dramatic and lasting improvements in patients with moderate to severe essential tremor, according to a multicenter clinical trial published in the August 25 issue of the New England Journal of Medicine.
In the study, InSightec's Exablate Neuro device yielded a 47% improvement in a composite tremor score at three months after treatment. These benefits largely persisted a year later, according to the research team led by Dr. W. Jeffrey Elias of the University of Virginia.
The findings were used as key data that resulted in U.S. Food and Drug Administration (FDA) approval for Exablate Neuro. The focused ultrasound device was the first to be approved by the FDA for treating essential tremor.
The randomized, double-blind study included 76 patients with moderate to severe essential tremor; 56 were randomly assigned to receive Exablate and 20 were given a sham procedure. The 20 study participants who received a sham procedure were later given the opportunity to have an Exablate Neuro treatment. The researchers assessed the performance of Exablate Neuro by combining the Clinical Rating Scale for Tremor (CRST) parts A and B, an eight-element measure of tremor and hand function (NEJM, August 25, 2016, Vol. 375:8, pp. 730-739).
Patients treated with Exablate Neuro had a mean composite tremor score of 9.6 ± 5.1 three months after treatment, a 47% improvement from the mean score of 18.1 ± 4.8 at baseline. The group of patients who received the sham procedure had no change in their mean score. The difference between the two groups of patients was statistically significant (p < 0.001). At 12 months following treatment, the patients in the treatment group still had a 40% lower mean score than at baseline.
In other findings, patients in the treatment group had a 63.4% reduction in tremor amplitude, an improvement that was maintained one year after the procedure. In addition, treated patients had a 68% improvement in total disability score and gave a 51% better assessment of their quality of life at 12 months following treatment.
"The degree of tremor control was very good overall in the study, but the most important aspects were the significant gains in disabilities and quality of life -- that's what patients really care about," Elias said.
The most commonly reported side effects were gait disturbances and numbness in the hand or face. Most of the side effects were temporary, although some were permanent, according to the group.
Other institutions participating in the study were Stanford University Medical Center, the University of Maryland, Brigham and Women's Hospital, Swedish Medical Center in Seattle, Yonsei University Medical Center in South Korea, Sunnybrook Health Sciences Centre in Canada, and Tokyo Women's Medical University in Japan.
The study was funded by the Focused Ultrasound Foundation, US-Israel Binational Industry R&D (BIRD), and InSightec.
