Double-blind, sham-controlled, trial of rhythmic 10 Hz median nerve stimulation for the reduction of tics in Tourette syndrome: Analyses of 3-month follow-up data for those receiving active stimulation.

Tourette syndrome [TS] is a neurological disorder of childhood onset characterised by the occurrence of tics: repetitive, purposeless movements or vocalisations. Effective treatment for tic disorders is an area of considerable unmet clinical need. A pre-registered UK-wide parallel double-blind sham-controlled trial, consisting of 4-weeks of daily home-administered rhythmic 10 Hz median nerve stimulation [rMNS], demonstrated that 10 Hz rMNS reduced tic frequency during stimulation, relative to a sham-stimulation control group and produced a significant reduction in tic severity at the end of a 4-week period of daily 10-min periods of stimulation (again relative to a sham-stimulation control group). The purpose of this paper is twofold. First, in the interests of clarity, to report the effects of 4-weeks of daily rMNS on secondary measures of neuropsychiatric conditions that commonly co-occur with TS, specifically obsessive-compulsive disorder [OCD] and anxiety disorder, that were not reported in the previous paper. Second, for completeness, to report the effects of rMNS on primary and secondary clinical measures at the point of a 3-month follow-up for the group who received active stimulation. The results demonstrate that, after 4 weeks of daily stimulation, motor and vocal tic severity scores, premonitory urge experiences and OCD symptoms were substantially reduced relative to baseline levels. Importantly, this reduction in motor and vocal tic severity scores, premonitory urge experiences and OCD symptoms persisted at the 3-month follow-up point, indicating that clinical benefits can outlast the immediate period of stimulation.