The results of a pilot study, published in the New England Journal of Medicine, show that delivery of high-intensity focused ultrasound through the intact human cranium with magnetic resonance imaging (MRI) guidance reduced tremor by creating a small ablation deep in the brain.
Tremor is usually treated through deep brain stimulation involving the implantation of electrodes in the brain. Focused ultrasound requires no surgery or invasive procedure by using a convergence of ultrasound beams to reach and destroy targeted tissue without harming surrounding areas. It is performed with the patient awake and does not involve anaesthesia, incisions in the skull or a lengthy hospital stay.
This preliminary study from the University of Virginia Health System, Charlottesville, USA, investigated the use of transcranial MRI-guided focused ultrasound thalamotomy for the treatment of essential tremor. The results showed that all 15 study participants saw “significant improvement” in their dominant hand tremor. All participants reported substantial improvement in their quality of life with essentially no residual disabilities from their tremor at one year after treatment.
In the study, scores for hand tremor improved from 20.4 at baseline to 5.2 at 12 months (p=0.001). Total tremor scores improved from 54.9 to 24.3 (p=0.001). Disability scores improved from 18.2 to 2.8 (p=0.001). Quality-of-life scores improved from 37% to 11% (p=0.001).
The most common side-effects reported in the trial were unsteadiness or tingling in face or fingers, but these resolved or were mild. The most serious adverse effect was a persistent uncomfortable sensation in a single participant’s dominant index finger.
“Large, randomised, controlled trials will be required to assess the procedure’s efficacy and safety in 15 patients with severe, medication-refractory essential tremor,” the authors, W Jeffrey Elias, associate professor of Neurosurgery and Neurology, University of Virginia, USA, and colleagues, wrote.
Based on their successful findings, University of Virginia Health System researchers have partnered with InSightec, the maker of the focused ultrasound device, to design a multicentre, international study that is FDA-approved to further assess the safety and long-term effectiveness of focused ultrasound in treating essential tremor.