Ultrasound May Ease Common Form of Hand Tremor
A treatment that delivers ultrasound waves to the brain may bring lasting relief to some people with debilitating hand tremors, a new study finds.
The study involved 76 patients with essential tremor -- a neurological condition that most often causes trembling in the hands during routine tasks like writing, eating and dressing. It can also affect the legs, head, trunk or voice.
Essential tremor is common -- affecting upwards of 7 million Americans, according to the American Academy of Neurology.
Yet many people have never heard of it, said Dr. Casey Halpern, the lead researcher on the new study and a neurosurgeon at Stanford University in California.
The cause of essential tremor is unknown, and there is no cure. However, there are treatments. Medications, including certain blood pressure and anti-seizure drugs, can help control the tremors.
When drugs fail, another option is deep brain stimulation, or DBS, where electrodes are placed in a specific brain region that helps control muscle activity. A pacemaker-like device, implanted under the collarbone, can then continuously send electrical pulses to the brain area -- blocking signals that cause the tremors.
More recently, doctors have been trying a less-invasive approach called focused ultrasound thalamotomy. The procedure uses ultrasound waves, guided by MRI, to heat and destroy tiny areas of brain tissue that are triggering the tremors.
The treatment was approved by the U.S. Food and Drug Administration in 2016, so there's been little known about its longer-term results.
Halpern's team found that when patients benefit from the procedure, there is a good chance the results will last.
The researchers used a standard scale to gauge patients' hand tremor and problems with daily function. Before the procedure, the study group scored an average of 20, out of a range of 0 to 32. Six months later, that had dropped (improved) to 8.6; at year three, it had risen slightly, to 9.5.
Overall, 58% of patients were showing at least a 50% improvement in their hand tremors and function at the three-year point, the findings showed.
"There can be some return of tremor, and patients should be aware of that," Halpern said.
But, on balance, he added, the benefits were durable. And there were no unexpected long-term side effects.
That's not to say there were no problems. The procedure can leave patients with some tingling and numbness, balance issues or muscle weakness -- side effects that may persist. Of patients in this study, 14% still had tingling and numbness at year three, while almost 7% had balance problems, and just under 3% had muscle weakness.
All said those issues were mild to moderate.
The study, published online Nov. 20 in Neurology, was partly funded by Insightec -- an Israel-based maker of focused ultrasound equipment.
According to Halpern, the ultrasound approach has some clear advantages over deep brain stimulation.
"There's no incision, no anesthesia, no devices implanted," he pointed out.
A disadvantage, though, is that the ultrasound therapy is currently performed on only one side of the brain. "That means you can only treat the dominant hand, not both," Halpern said.
Dr. Sean Nagel is a neurosurgeon at the Cleveland Clinic in Ohio -- one of the few medical centers in the United States performing focused ultrasound for essential tremor.
Nagel, who was not involved in the new study, called the results "encouraging."
"This is still a new therapy. But the early outcomes look good," he said.
"I think that for patients who've been reluctant to take the next step and try DBS, this is something worth talking to their neurologist about," Nagel said.
Nationally, only about a dozen hospitals offer the treatment, according to Halpern.
"But with more time," he said, "I expect it'll become more widely available."
To learn about essential tremor, visit the International Essential Tremor Foundation.
SOURCES: Casey H. Halpern, M.D., assistant professor, neurosurgery, Stanford University School of Medicine, Stanford, Calif.; Sean Nagel, M.D., neurosurgeon, Cleveland Clinic, Ohio; Nov. 20, 2019, Neurology, online
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