Median Nerve Stimulation Pilot

Overview

Results from the University of Nottingham suggested that rhythmic median nerve stimulation (MNS) improves tic symptoms in Tourette syndrome (TS). The investigators will (1) provide a first replication of their study, (2) test the hypothesized electrophysiological mechanism and rule out a placebo effect as cause for the symptomatic benefit, and (3) gather information on the duration of effect after the end of stimulation and on individual characteristics that predict improvement with simulation. Completion of these Aims will give a clear go/no-go signal for a future clinical trial of chronic MNS delivered by a yet-to-be-developed wristwatch-style device. NOTE: This study is not intended to evaluate a specific device for future use. Rather it is a study to determine the action of pulsed electrical stimulation on tic symptoms and to gain early evidence of effectiveness. This is a non-significant risk device study.

Chronic tic disorders (CTD), including Tourette syndrome (TS), are associated with a substantially reduced quality of life. Medication treatments are no more than 50-60% effective in randomized controlled trials, and are often discontinued due to unacceptable side effects. Behavioral therapies require ability to participate in therapy and a specially trained therapist, but weekly visits to psychologists are impractical for many Americans, especially in rural areas. Patients strongly desire new treatment options. In June, 2020, Stephen Jackson's group at the University of Nottingham published a fascinating report in Current Biology on a potential novel treatment for tics. The radical new idea arose from observations associating movement inhibition with 8-14 Hz activity in motor cortex. They first showed that rhythmic 12 Hz peripheral stimulation of the median nerve evoked synchronous contralateral EEG activity over primary sensorimotor cortex, whereas arrhythmic stimulation at the same mean rate did not. As hypothesized, median nerve stimulation (MNS) at 12 Hz created small but statistically significant effects on initiation of voluntary movements. Importantly, they also demonstrated that this stimulation did not meaningfully impair concentration, suggesting that the effect did not operate through simple distraction. They went on to test 10 Hz MNS in 19 TS patients, and demonstrated using blinded video ratings a significant reduction in tic number and severity during 1-minute stimulation epochs vs 1-minute no-stimulation epochs. They noted that in some participants, benefit lasted beyond the end of the stimulation epoch. Videos accompanying the publication showed dramatic benefit during MNS in some subjects. Although the authors appropriately noted the steps needed to generalize these results to clinical practice, news reports already have led a number of TS patients to contact them asking for treatment. The Nottingham group has referred such inquiries from the U.S. to me as leader of our Wash.U. Tourette Association of America (TAA) Center of Excellence. The hypotheses of this project are that the tic benefits reported by the Nottingham investigators are replicable, that they are specific to rhythmic stimulation, which alone entrained cortical activity, rather than to a placebo effect, and that they endure past the end of stimulation. This project (a) will replicate the Nottingham findings using identical methods, and (b) will test rhythmic MNS against a placebo treatment (arrhythmic MNS at the same mean frequency). It also will gather additional preliminary data needed for a future R01 application, including response and tolerability with longer (5-minute) stimulation blocks, and the duration of benefit after the end of a stimulation block.