Short-term effects of repetitive transcranial magnetic stimulation on sleep bruxism – a pilot study

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. A therapeutic technique based on electromagnetic pulses may provide relief from pain caused by grinding teeth during sleep. Sleep bruxism is a condition in which sufferers grind their teeth continuously at night, causing significant discomfort and jaw pain. In a pilot study, Jing-Lu Zhang at Nanjing Medical University, China, and co-workers investigated the effects of a non-invasive technique called repetitive transcranial magnetic stimulation (rTMS) on sleep bruxism in 12 patients. The team used electromagnetic coils to send 20 min of targeted magnetic pulses to the primary motor cortex of each patient every day for 5 days. The patients rated their levels of pain before, during and after rTMS treatment, and reported a significant drop in soreness levels. Further trials will verify if rTMS therapy is beneficial for those suffering from sleep bruxism.