Identifying and modulating distinct tremor states through peripheral nerve stimulation in Parkinsonian rest tremor.
Beatriz S Arruda, Carolina Reis, James J Sermon and 3 others
PMID 34953492WHAT IT FOUND
In 10 people with Parkinsonian rest tremor, wrist stimulation could suppress tremor by 36% or amplify it by 117% on average when timed to the limb's movement.
No single timing worked across everyone, and tremor often shifted between patterns.
Key findings
01For the 10 analysed participants, stimulation at selected phases significantly amplified tremor by 117% and suppressed it by 36% on average.
02There was no systematically preferred suppressive or amplifying stimulation phase across study participants.
03In seven of 10 participants, tremor showed more than one distinct oscillation pattern during the recording.
STILL TO COME
How it was doneWhat they found
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What it does not show
Some recruited people were excluded because their diagnosis or tremor was not suitable for the hand test. Only 10 participants were analysed, and the paper states this small cohort cannot link tremor patterns to disease progression or phenotype. The stimulation effect was modest, with average suppression reported as 36%, and no single timing worked for everyone. The authors say the analysis windows may be too coarse to capture rapid shifts between tremor patterns. Stimulation may have affected nerves other than the median nerve, although it was kept below the level that caused a thumb twitch. EMG analysis was limited because stimulation artefacts contaminated muscle recordings during stimulation, and some EMG data were excluded for quality. Medication state varied, and some participants omitted the last dose before testing.
Declared interests
Funded by the Medical Research Council.
The easy way to misread this
Do not read this as evidence that wrist nerve stimulation is a ready treatment for Parkinsonian tremor. It was tested in 10 people, and the paper says the suppression achieved was modest and the effective timing differed between people and changed over time.