The primary aim of this study is to assess whether continuous theta-burst stimulation (cTBS) can be helpful in reducing symptoms of idiopathic cervical dystonia. This will be a parallel-group, randomised, sham-controlled, double blind clinical trial. Patients and investigators measuring patient symptoms clinical scales will be blinded from allocation group, investigators delivering the intervention will not be blinded, as this is not feasible. Real cTBS will be compared to sham cTBS, with patients allocated to these two groups with a 1:1 recruitment ratio.
Bilateral cTBS will be delivered four times daily, over eight days, for a total of 32 bilateral cTBS sessions. The primary outcome is the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS). This will be administered at T1 (pre-cTBS), T2 (day 10, following days 2-9 where patients received the intervention), T3 (2 weeks post the final session of cTBS), and T4 (4-5 weeks post the final session of cTBS).
Secondary outcomes will be the TWSTRS subscales (severity, disability, pain), Quality of Life scale, Global dystonia severity rating scale (GDS), Fahn Tolosa Marin (FTM) modified (to include only questions relevant to head/neck tremor) tremor scale, kinematic data of patient's movement patterns, motor evoked potentials (MEPs), and resting-state fMRI data (fMRI).