Phase I study of transcranial MR-guided focused ultrasound thalamotomy sees reduced tremor


Research findings offered on 29 April 2013 at the 81st American Association of Neurological Surgeons (AANS) Annual Scientific Meeting (27 April–1 May 2013, New Orleans, USA) showed that the use of transcranial MR-guided focused ultrasound for producing a thalamotomy can have significant positive effects on subjects suffering from essential tremor.

A preliminary clinical trial suggested that acoustic energy could be delivered precisely to generate a focal stereotactic ablation deep within the brain. In a Food and Drug Adminstration (FDA)-approved clinical trial, 15 patients with medication-refractory essential tremor underwent transcranial MR-guided focused ultrasound thalamotomy targeting the Vim nucleus.

Adverse events were recorded throughout the study, according to a press release, with comprehensive neurologic assessments for sensation, gait, strength and balance. A 160-point validated rating scale of tremor was used to assess the procedure’s efficacy in the patients, and a quality-of-life-in-essential-tremor questionnaire was obtained at pre, three-months and twelve-months post treatment. In addition, MR assessments were made of the lesions at one day, one week, one month and three months. The results of this study, “The one year results of a phase I study of transcranial MR guided focused ultrasound thalamotomy for the treatment of medication refractory essential tremor”, were presented by William Jeffrey Elias, University of Virginia School of Medicine, Charlottesville, USA.

According to Elias, results showed a 67% reduction in contralateral hand tremor at one year. This unilateral reduction of tremor in the dominant hand resulted in substantial improvements in daily disabilities (83%) and quality of life as assessed by clinicians and the subjects. Adverse events from the therapy were minimal and consisted mostly of mild paresthesia of the face or hand, but it is important to note that this preliminary feasibility study was not powered to determine the true safety and efficacy of the treatment. The researchers concluded that this initial investigation of transcranial MR-guided focused ultrasound thalamotomy seems feasible and safe enough to proceed with more comprehensive clinical trials. Elias noted that the investigators “plan to follow these patients annually just as we do in our clinic with other movement-disorder procedures. We also are planning a long-term follow-up for our next multi-center and international clinical trial, which is scheduled to begin this summer.”

Elias added that “it is important to realise from these results and those of other tremor procedures that tremor suppression in the dominant hand, even if it is 75% on a rating scale, translates to very significant improvement in functional abilities. Our patients experienced almost no residual disabilities in day-to-day activities with this degree of tremor suppression.” He also noted that the researchers were “extremely surprised” by the amount of interest the tremor community had in this clinical trial. “We have been contacted by more than 2,000 people with tremor, which I think reflects their desire for more treatment options than we currently offer.”

Disclosure: William Jeffrey Elias disclosed that the Focused Ultrasound Surgery Foundation provided grant/research support and an honorarium.