Effects of repetitive transcranial magnetic stimulation on sleep bruxism

Summary

Abstract The purpose of this study was to investigate the effects of repetitive transcranial magnetic stimulation (rTMS) on patients with sleep bruxism (SB). Twelve patients with SB were included in an open, single-intervention pilot study. rTMS at 1 Hz and an intensity of 80% of the active motor threshold was applied to the ‘hot spot' of the masseter muscle representation at the primary motor cortex bilaterally for 20 min per side each day for 5 consecutive days. The jaw-closing muscle electromyographic (EMG) activity during sleep was recorded with a portable EMG recorder at baseline, during rTMS treatment and at follow-up for 5 days. In addition, patients scored their jaw-closing muscle soreness on a 0–10 numerical rating scale (NRS). Data were analysed with analysis of variance. The intensity of the EMG activity was suppressed during and after rTMS compared to the baseline (P = 0.04; P = 0.02, respectively). The NRS score of soreness decreased significantly during and after rTMS compared with baseline (P < 0.01). These findings indicated a significant inhibition of jaw-closing muscle activity during sleep along with a decrease of muscle soreness. This pilot study raises the possibility of therapeutic benefits from rTMS in patients with bruxism and calls for further and more controlled studies. Keywords: behavioural science, brain function, electromyography, orofacial pain, repetitive transcranial magnetic stimulation, sleep bruxismIntroduction Sleep bruxism (SB) is defined as a repetitive jaw-closing muscle activity characterised by clenching or grinding the teeth and/or by bracing or thrusting the mandible during sleep.1 SB is thought to be potentially harmful to the stomatognathic system because it causes, for example, excessive tooth wear, masseter hypertrophy, temporomandibular disorders (TMD) and headaches.2,3,4 The aetiology of SB is complex but most likely includes arousal responses and autonomic dysregulation, genetic, psycho-emotional and pharmacological...