Chronic tic disorders (CTD), including Tourette syndrome (TS), are associated with a substantially reduced quality of life (Evans et al 2016). Medication treatments are no more than 50-60% effective in randomized, controlled trials (RCTs), and are often discontinued due to unacceptable side effects (Thomas and Cavanna 2013). Behavioral therapies require ability to participate in therapy and a specially trained therapist (Scahill et al 2013), but weekly visits to psychologists are impractical for many Americans, especially in rural areas (Lin et al 2016). Patients strongly desire new treatment options (Cuenca et al 2015).
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 (Morera Maiquez et al 2020). 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 \[personal correspondence\]. 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.
Among the various questions still to be answered is the question of whether such a device would be practical for use in the real world. This study will supply participants with a commercially available transcutaneous electrical nerve stimulation (TENS) units to use for median nerve stimulation as described in the Nottingham study. Participants will be told to use the device as much or as little as desired to see how such stimulation might be utilized in the real world.
Here the investigators propose (a) to determine the real-world usage and apparent utility of stimulation in people with chronic tics, and (b) to determine momentary self-rated efficacy and side effects of stimulation. The investigators will also compare results from this study to those from the "Peripheral induction of inhibitory brain circuits to treat Tourette's: pilot" study, from which participants will be drawn, in order to compare laboratory and real-world efficacy.
Aim 1. Determine the real-world usage and apparent utility of stimulation in people with chronic tics. Participants will be allowed to choose when and for how long to use the stimulation, thus simulating how patients would use the stimulation in their daily lives.
Aim 2. Determine momentary self-rated efficacy and side effects of stimulation, using surveys taken at the beginning and end of stimulation periods, as well as twice daily when prompted.
Aim 3. Compare results of this trial with those from "Peripheral induction of inhibitory brain circuits to treat Tourette's: pilot." Participants in this study will have been drawn from completers of the "peripheral induction" blinded RCT, allowing for clear comparisons between the laboratory conditions of the first study and the real-world conditions of the second.
Completion of these Aims will provide practical information that can inform a future, controlled clinical trial of chronic MNS delivered by a portable device.
