A wrist device that stimulates nerves in the arm may bring some relief to people with hand tremors, a preliminary study suggests.
The research involved more than 100 patients with essential tremor -- a neurological condition that causes trembling in the hands, legs, head or trunk. Researchers found that the wrist device, worn a couple times per day, reduced the severity of most patients' hand and arm tremors.
It also made routine daily tasks a little easier, the investigators added.
They stressed, however, that the study is preliminary, and it's not yet known whether the therapy can bring lasting benefits.
"This is a very early study, and there are still lots of questions," said lead researcher Dr. Rajesh Pahwa, of the University of Kansas Medical Center.
"I think the biggest concern long-term is that patients could develop a tolerance to the stimulation," he said.
Dr. Vicki Shanker is a neurologist at the Mount Sinai Icahn School of Medicine in New York City. She was not involved with the study but reviewed its findings.
She agreed that it's "unclear if patients will have sustained benefits from this therapy."
But, Shanker said, "the initial findings certainly warrant larger studies, and will likely be met with great enthusiasm by the essential tremor community."
Essential tremor affects upwards of 7 million Americans, according to the American Academy of Neurology. Its cause is unknown, and there is no cure.
Medications, including certain blood pressure and anti-seizure drugs, can help control the tremors. But their use is often limited by side effects, Shanker said.
When drugs fail, another option is deep brain stimulation (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 the signals that cause the tremors.
But while DBS can work, many patients want options that are less invasive, Shanker said.
Given that, the early results with the new wrist device are "exciting," she said.
The study involved two parts: In one, 77 patients with hand tremors had a single session with either the wrist device or a "sham" version.
The real device delivered pulses to the median and radial nerves in the wrist -- with a goal of blocking the nerve activity that generates the hand tremors. The sham device provided no stimulation, Pahwa said.
On average, patients who received the real therapy had a 65 percent reduction in their tremor severity soon afterward. In contrast, people in the sham group showed a 32 percent reduction.
In the second part of the study, 61 patients were randomly assigned to one of three groups: One used the wrist device at home -- at least twice a day for up to one month -- while a second used the sham device. The third group stuck with their usual therapy.
Sensors on the device measured patients' tremors before and after each therapy session -- which typically lasted about 40 minutes, Pahwa said.
Overall, the study found, patients using the real device showed an improvement in their tremors after almost 90 percent of the sessions. But even those using the sham device had a 62 percent reduction, the study found.
Side effects were mild, according to Pahwa: Three percent of the patients had skin redness or irritation that went away on its own.
The findings were to be presented next week at the American Academy of Neurology's annual meeting, in Los Angeles. Findings presented at meetings are generally considered preliminary until they are published in a peer-reviewed journal.
The study was funded by Cala Health Inc., the California-based company developing the wrist device. Right now, Pahwa said, the battery life does not allow for continuous use -- only short sessions.
It's possible that if the device were on 24 hours a day, the effects would be greater. On the other hand, it's possible that patients will develop a tolerance and no longer respond to the stimulation, Pahwa explained.
For now, he said, patients with essential tremor affecting the hands can have "hope" that a new therapy is on the horizon.
"But," Pahwa added, "I can't predict when it might become available."
The AAN has more on treatments for essential tremor.
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