Wrist Neuromodulation Device Curbs Essential Tremor

Megan Brooks

May 13, 2020

Noninvasive peripheral nerve stimulation applied repeatedly at home over a 3-month period reduced hand tremors in patients with essential tremor (ET), new research shows.

In a large prospective study, more than half of patients with ET experienced at least a 50% improvement in hand tremors using the wrist-worn Cala trio (Cala Health) neuromodulation device.

These findings "continue to build on the body of data supporting noninvasive nerve stimulation relieves symptoms in patients with ET," Rajesh Pahwa, MD, chief, Parkinson and Movement Disorders Division, Department of Neurology, University of Kansas Medical Center, Kansas City, told Medscape Medical News.

The new findings, said Pahwa, "confirm that noninvasive neuromodulation therapy is safe for patients and that it offers minimal side effects while treating symptomatic ET."

The research is being presented on AAN.com as part of the American Academy of Neurology (AAN) 2020 Science Highlights. Owing to the COVID-19 pandemic, the AAN had to cancel the 2020 annual meeting that was scheduled for April 25 to May 1 in Toronto, Canada.

Common, Troubling Condition

ET affects an estimated 10 million Americans. It causes involuntary shaking, most often of the hands, making it hard to perform daily activities, such as writing, typing, eating, and drinking.

The Cala trio neuromodulation device was approved by the US Food and Drug Administration in April 2018 for the transient relief of hand tremors in adults with ET.

Pahwa and colleagues tested the device in an open-label, single-arm study involving 263 patients with ET from 26 sites. Patients were instructed to use the device for 40-minute sessions twice daily for 3 months. The device was calibrated to each patient's tremor frequency and delivered patterned electrical stimulation to nerves through the skin. A total of 205 patients completed the study.

The two co-primary endpoints ― improvement in scores on the clinician-rated Tremor Research Group Essential Tremor Rating Assessment Scale (TETRAS) and the patient-rated Bain and Findley Activities of Daily Living (ADL) dominant hand rating ― were met (P < .0001).

The data show that 62% of patients experienced improvements in tremor severity from severe/moderate to mild/slight according to the TETRAS and that 68% of patients experienced improvement in tremor severity from severe/moderate to mild/slight according to the Bain and Findley ADL (baseline vs 3 months).

Wrist-worn accelerometer recordings before and after 21,806 therapy sessions showed that 54% of patients experienced ≥50% improvement in tremor power. This finding, said Pahwa, "validates patients can improve the power of their tremors while in the comfort of their own home."

Clinical and patient global impression of improvement showed that 68% of clinicians and 60% of patients indicated improvement at 3 months. Significant improvement was also reflected in Quality of Life in Essential Tremor Questionnaire (QUEST) scores.

Device-related adverse events, such as wrist discomfort, skin irritation, and pain, occurred in 18% of patients. There were no device-related serious adverse events.

"Excellent" Addition to Treatment Toolbox

The new findings support an earlier study by Pahwa and colleagues that was presented at the AAN 2018 annual meeting, as reported by Medscape Medical News.

Reached for comment, Okeanis Vaou, MD, director, Movement Disorders and Deep Brain Stimulation Center, St. Elizabeth's Medical Center, Brighton, Massachusetts, noted that ET is the most common movement disorder and that patients have "only a few treatment options."

"Although medication and deep brain stimulation (DBS) can be successful in treating ET, the individualized noninvasive treatment (Cala trio) is an excellent addition to the armamentarium of ET treatment options," Vaou told Medscape Medical News.

"Patients who don't respond well to medication, can't tolerate them, or do not wish to have invasive treatment with DBS therapy would be appropriate candidates for Cala trio. Cala trio used as adjunctive therapy should also be considered," said Vaou.

The study was supported by Cala Health. Pahwa has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Cala Health and other pharmaceutical companies. Vaou has disclosed no relevant financial relationships.

American Academy of Neurology (AAN) 2020 Science Highlights. Abstract S55.006.

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