Author Date

2022-12-14

Degree Name

BS

Department

Neuroscience

College

Life Sciences

Defense Date

2022-12-02

Publication Date

2023-02-07

First Faculty Advisor

Steven Charles

First Faculty Reader

Michael Brown

Honors Coordinator

Rebekka Matheson

Keywords

Essential Tremor, tremor suppression, sensory stimulation, electromyography, tremor frequency

Abstract

Electrical stimulation of peripheral muscles below motor neuron threshold (sensory stimulation) has shown potential as an effective, low-cost, and minimally invasive treatment for Essential Tremor (ET), one of the most common movement disorders. Past studies have shown that asynchronous sensory stimulation of antagonist muscles out of phase with tremor can suppress ET. Synchronous sensory stimulation, which stimulates antagonists simultaneously and is easier to implement, has yielded mixed results. To optimize available therapies and to understand tremor suppression mechanisms better, I investigated the effects of synchronous sensory stimulation with different stimulation frequencies on electromyographic tremor-band power and frequency in ET patients, expecting to see no significant stimulation effects on tremor signals at any stimulation frequency.

I studied the tremor effects of brief, synchronous sensory stimulation on the antagonistic flexor and extensor carpi radialis muscles by analyzing surface electromyograms (sEMG) that were recorded in an unpublished BYU study which tested 15 sensory stimulation frequencies from 10 to 150 Hertz on 21 ET patients. I extended this investigation by calculating sEMG-derived tremor-band power and frequency for pre- and poststimulation phases and comparing them across subjects using a mixed-model ANOVA.

Brief synchronous sensory stimulation did not result in tremor changes at any of the tested stimulation frequencies. There was no statistically significant interaction between phase and stimulation frequency for tremor-band power (p=0.45) nor frequency (p=0.81).

The lack of evidence for tremor suppression or tremor frequency changes is consistent with the hypothesis that brief sensory stimulation suppresses tremor via reciprocal inhibition reflexes, necessitating asynchronous stimulation instead of synchronous stimulation. I conclude that an asynchronous stimulation strategy or longer stimulation durations are necessary for future therapeutic applications of sensory stimulation for ET suppression.

Download

Share

COinS