Noninvasive Ultrasound Technique Reduces Essential Tremor

Pauline Anderson

October 07, 2011

October 7, 2011 (Washington, DC) — A painless, noninvasive magnetic resonance imaging (MRI)-guided focused ultrasound safely and effectively controls symptoms in patients with essential tremor (ET), preliminary results of a pilot study suggest

Results from the first 10 patients show that the experimental treatment is about as effective in controlling tremor as invasive treatments such as deep brain stimulation and stereotactic thalamotomy, said lead study investigator W. Jeffrey Elias, MD, associate professor, Department of Neurosurgery and Neurology, University of Virginia, Charlottesville.

Investigators report a 78% improvement in contralateral tremor scores in the hand and a 92% improvement in functional activities, as measured by the Clinical Rating Scale for Tremor.

These improvements have been life changing, said Dr. Elias. Patients can now use their dominant hand to write legibly, drink and eat without spilling, and button clothes — tasks they were unable to perform before the treatment, he said.

The preliminary results from the single-group, nonrandomized, phase 1, US Food and Drug Administraction–approved clinical trial were presented here at the Congress of Neurological Surgeons 2011 Annual Meeting.

One of the benefits of the new technology is that it avoids invasive surgery, said Dr. Elias. "Patients have a lot of anxiety and fear about the current treatments for [ET] or Parkinson's disease that involve an 'awake' surgery."

Precise, High Resolution

The study includes adult patients with ET who have failed at least 2 medications. These patients lie on a specially designed table in an MR machine equipped with ultrasound transducers that deliver focused ultrasound waves with frequencies of 650 kHz (well beyond what the human ear can hear) through the patient's skull.

The MRI allows precise targeting of nerve cells in the thalamus that are linked to ET and produces "very precise and high-resolution images of brain," said Dr. Elias.

Treatments are monitored with MR thermography. "What's different about this approach is that we use part of the MRI (thermal imaging) that's usually used only for research purposes, so we can use sequences from the MRI that detect temperature," said Dr. Elisa.

As the ultrasound heats up the tissue, researchers can actually see it on the MRI. "It's a unique thing to be able to watch the treatment as it's being delivered; we don't usually do that with our treatments," said Dr. Elias.

Patients receive no anesthesia and remain awake throughout procedure. Under the study protocol, only 1 side of the brain is treated.

The treatment takes 3 to 4 hours, but researchers expect that in future it will take much less time, said Dr. Elias.

Ready for Prime Time

Researchers assessed tremor and potential adverse events at baseline, 1 day, 1 week, 1 month, and 3 months. Seven of the 10 patients are have now been followed up for more than 3 months, said Dr. Elias

Phase 1 of the study was approved for the treatment of 15 patients. "We think it's very favorable, and we're hopeful to go to the next step, which will be to design a larger, more definitive clinical trial," possibly a randomized one, said Dr. Elias.

A lot of preclinical work has gone into getting the device ready for use in human clinical trials. "This has been in development for decades, and now it's ready for prime time," said Dr. Elias.

The research team hopes to study the technique in patients with Parkinson's disease, and perhaps eventually in those with other brain diseases. Focused ultrasound therapy may also eventually be possible for other organs such as the breast, liver, and pancreas.

According to background information included in a press release, MR-guided focused ultrasound is a US Food and Drug Administraction–approved therapy for uterine fibroids and is approved in Europe and elsewhere for the treatment of uterine fibroids and pain associated with bone metastasis. Clinical trials are under way around the world to test the therapy in prostate, breast, bone, and uterine tumors.

Novel and Exciting

Approached for a comment, Theresa A. Zesiewicz, MD, professor of neurology and director, Parkinson's Disease and Movement Disorders Clinic, James A. Haley Veterans' Administration, Tampa, Florida, and a member of the American Academy of Neurology, said MR-guided focused ultrasound represents "a potentially novel and exciting" method of treating ET, which is a debilitating disorder.

About 30% to 50% of patients with ET do not respond well to tremor medications, and many patients with ET who do respond eventually discontinue medications because of adverse effects or advancing tremor, Dr. Zesiewicz told Medscape Medical News. She noted that in this study, the procedure was performed in patients who no longer responded well to medical management.

The longevity and adverse effects of MR-guided focused ultrasound need to be studied in a larger population of patients under controlled conditions, said Dr. Zesiewicz.

Dr. Elias has disclosed no relevant financial relationships.

Congress of Neurological Surgeons 2011 Annual Meeting: Abstract 966 Presented October 3, 2011.

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