Functional MRI-navigated Repetitive Transcranial Magnetic Stimulation over Supplementary Motor Area in Chronic Tic Disorders

Background: Open label studies have shown repetitive transcranial magnetic stimulation to be effective in reducing tics.

Objectives: To determine whether 8 sessions of continuous theta burst stimulation (cTBS) over supplementary motor area (SMA) given over 2 days may reduce tics and motor cortical network activity in Tourette syndrome/chronic tic disorders.

Methods: This was a randomized (1:1), double-blind, sham-controlled trial of functional MRI (fMRI)-navigated, 30 Hz cTBS at 90% of resting motor threshold (RMT) over SMA in 12 patients ages 10-22 years. Comorbid ADHD (n = 8), OCD (n = 8), and stable concurrent medications (n = 9) were permitted. Neuro-navigation utilized each individual's event-related fMRI signal. Primary clinical and cortical outcomes were: 1) Yale Global Tic Severity Scale (YGTSS) at one week; 2) fMRI event-related signal in SMA and primary motor cortex (M1) during a finger-tapping motor task.

Result: Baseline characteristics were not statistically different between groups (age, current tic/OCD/ADHD severities, tic-years, number of prior medication trials, RMT). Mean YGTSS scores decreased in both active (27.5 ± 7.4 to 23.2 ± 9.8) and sham (26.8 ± 4.8 to 21.7 ± 7.7) groups. However, no significant difference in video-based tic severity rating was detected between the two groups. Two-day post-treatment fMRI activation during finger tapping decreased significantly in active vs. sham groups for SMA (P = 0.02), left M1 (P = 0.0004), and right M1 (P < 0.0001). No serious adverse events occurred.

Conclusion: Active, fMRI-navigated cTBS administered in 8 sessions over 2 days to the SMA induced significant inhibition in the motor network (SMA, bilateral M1). However, both groups on average experienced tic reduction at 7 days. Larger sample size and protocol modifications may be needed to produce clinically significant tic reduction beyond placebo effect.