Sleep bruxism and oromandibular myoclonus in rapid eye movement sleep behavior disorder: a preliminary report

ObjectiveWe aimed to compare rhythmic masticatory muscle activity typical of sleep bruxism and oromandibular myoclonus (OMM) during rapid eye movement (REM) sleep in patients with idiopathic REM sleep behavior disorder (iRBD) and in Parkinson disease (PD) patients with RBD (PD-RBD).MethodsSleep polygraphic data were collected from 9 age-matched controls and 28 patients (mean ± standard error of the mean, 66.0 ± 1.7 y) with a clinical and sleep laboratory diagnosis of RBD. Patients were divided into two groups: 13 patients with iRBD and 15 patients with PD-RBD. Rhythmic masticatory muscle activity, a marker of sleep bruxism, and OMM were scored blind to subject’s diagnosis from jaw electromyographic recordings during sleep.ResultsThe rhythmic masticatory muscle activity index was significantly higher during REM sleep in iRBD subjects compared to controls (P < .01) and was significantly higher during non-REM (NREM) sleep in both subject groups compared to controls (P ⩽ .03). A positive sleep laboratory diagnosis of sleep bruxism was made in 25% of all patients. In iRBD, patients had more OMM during REM sleep than controls (2.4 times higher; P = .01).ConclusionIn the presence of a high frequency of rhythmic masticatory muscle activity during REM sleep, RBD may be suspected and further neurologic assessment is recommended.