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In a recent study, subthreshold 1 Hz repetitive transcranial magnetic stimulation (rTMS) over left motor or premotor cortex failed to improve tics in patients with Gilles de la Tourette syndrome (GTS) as determined by self assessment scores.1 However, video ratings of this study had not been analysed. Here, we present the results of blinded analysis of the video of GTS patients who participated in the previous study. We show that rTMS has a placebo effect and confirm that low intensity motor or premotor rTMS does not have a specific effect on tics in GTS.
In a placebo controlled cross-over study of 16 patients with GTS, subthreshold 1 Hz rTMS (2400 stimuli delivered on 2 consecutive days) were applied under three conditions in random order: left motor, left premotor, and left motor sham stimulation. Videotapes were recorded before and after each rTMS intervention in eight patients. One of the authors (AHS) who did not know the patients and was blinded to the treatment conditions, rated the video recordings. Data were analysed using two different rating scales, the Modified Rush Video Scale (MRVS)2 and an “Adapted Yale” Video Scale (AYVS) which was developed for this study. With the MRVS, the following five tic domains are rated from 0 to 4 according to severity: number of body areas involved with tics, motor tic severity, phonic tic severity, frequency of motor tics, and frequency of phonic tics. The sum of the five domain scores provides a total tic impairment score (0–20). As the MRVS does not consistently score the complexity, intensity, and interference of tics, we devised an additional scale using the categories of the Yale Global Tic Severity Scale (YGTSS).3 This new scale, the AYVS, rated the following five domains from 0 to 5 according to severity: number of different tics, frequency of tics, intensity of tics, complexity of tics, and interference of tics. Each domain was rated separately for motor and vocal tics. The sum of the five domains gave a total motor tic score and a total vocal tic score; these scores combined yielded the total tic impairment score (0–50).
Tics were partially, albeit non-significantly, suppressed following each of the three interventions (table 1 and fig 1, two factorial repeated measures ANOVA with the factors time and rTMS). However, the effect of active rTMS did not exceed the effect observed following sham stimulation. rTMS effects in this study were variable and tic scores showed a regression towards the mean, that is patients with high scores at baseline tended to have lower scores after the rTMS intervention, and vice versa (univariate ANOVA with the difference in video score before and after rTMS as dependent factor and baseline scores as covariant). In other words, the changes of tic severity that we observed most likely reflect the waxing and waning course of tics rather than an intrinsic rTMS effect.
The results of this video assessment are in keeping with patients’ self assessment based on the Motor tic, Obsessions and compulsions, Vocal tic Evaluation Survey (MOVES),4 a self rating scale that patients completed before and after rTMS.1 Neither motor and vocal tic subscales nor obsession and compulsion subscales were changed by rTMS, which indicates that rTMS as used in the present study is not an effective treatment for tics or obsessions/compulsions in GTS patients. However, because ADHD symptoms were not assessed, we cannot exclude the fact that rTMS as used in the present study might have an effect on ADHD.
There was good correlation between the MRVS and the AYVS (ρ = 0.69; p<0.01, Spearman’s correlation). The AYVS thus appears to be a valid and comprehensive tool to assess tic severity in GTS patients, but it needs to be evaluated further.
We conclude that left motor or premotor low intensity 1 Hz rTMS does not improve tics in GTS patient as assessed by blinded video scoring. Further studies, perhaps using higher intensity rTMS, longer rTMS trains, or bilateral stimulation, are needed to delineate the usefulness of rTMS in GTS patients. In these studies, blinded and independent video rating should be used.
The authors thank all patients who participated in this study.
A Münchau and M Orth were supported by the Tourette Syndrome Association (USA) and the Raymond Way Unit, Institute of Neurology, Queen Square, London, UK. AH Snijders was supported by the Hersenstichting Nederland
Competing interests: none declared
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