Sleep-related faciomandibular myoclonus: A sleep-related movement disorder different from bruxism

We describe a 33-year-old man who presented with lip and tongue nibbling and bleeding during sleep. Videopolysomnography revealed myoclonic jerks involving the masticatory and facial muscles recurring mainly during NREM sleep. There was no tonic EMG masticatory activity typical of bruxism. EMG analysis demonstrated the recruitment of V- to VII innervated muscles and, in half of the episodes, also the sternocleidomastoideus. Our patient had sleep-related faciomandibular myoclonus (SFMM) with spontaneous jerks of oromasticatory and cervical muscles, occurring only during sleep. Tooth grinding, temporomandibular joint pain, abnormal tooth mobility, tooth wear, and other dental problems were clinically absent. We propose that, on the basis of the clinical and EMG features, SFMM may be considered a distinct disorder and different from sleep bruxism.