MINNEAPOLIS -- Researchers have devised a way to shoot focused beams of ultrasound through the skull to calm essential tremor, potentially the first non-invasive approach for hard-to-treat forms of the involuntary-shaking disorder.
As many as 10 million people in the United States have essential tremor, which is four times more common than its close cousin Parkinson's disease. The condition often begins in young adults, worsening over time. While drugs help, deep-brain stimulation and surgery are used for those with disabling symptoms.
A study of 15 patients published recently in the New England Journal of Medicine shows technological advances in the past decade allow doctors to deliver the laser-beam therapy into the brain without removing a portion of the skull. Word of the small clinical trial spread among patients, creating waiting lists with dozens of people who want to participate in the next wave of research, doctors said.
"This was the first trial to treat a movement disorder, a neurologic disease, in which we suppressed essential tremor," Jeffrey Elias, the lead researcher and an associate professor of neurosurgery at the University of Virginia Health Sciences Center in Charlottesville, said in a telephone interview. "It's one of the first to use ultrasound to treat something in the brain, not just provide images."
The technology was developed by InSightec Ltd., a closely held Israeli company owned by General Electric, Elbit Medical Technologies, MediTech Advisors and its employees. The system, called ExAblate Neuro, is approved in Europe for essential tremor, Parkinson's disease and neuropathic pain. A similar product is approved in the U.S. for treating uterine fibroids and cancer that has spread to the bone.
The device uses a helmet-like transducer that shoots more than 1,000 ultrasound beams. The procedure is guided by MRI to ensure the beams hit the same one-millimeter spot inside the thalamus where the tremors form. The energy caused a lesion at the location, stopping the aberrant electrical signals in the circuit from outside the skull.
Elias compared it to using a magnifying glass to focus the sun's rays onto a leaf.
"That's what's so incredible," Elias said. "We took 1,000 beams, sent them through the skull non-invasively, focused them all to one specific spot about the size of a grain of rice deep in the middle of the brain and stopped most of the tremors. It didn't appear to damage any of the intervening brain, just the point of convergence."
Essential tremor typically affects the hands and arms, though it can develop anywhere in the body.
-- Bloomberg News