Isolated mandibular sleep-related rhythmic movement disorder: A case report.

Background: Rhythmic masticatory muscle activity (RMMA) in sleep is usually not considered pathological unless associated with bruxism. On the other hand, so-called sleep-related rhythmic movement disorders (SRRMD) are a recognized category of sleep disorders, which involve prolonged rhythmic activity of large muscle groups, such as the whole body, the head, or a limb, but typically not the masticatory muscles.Clinical Presentation: A polysomnographic description of a patient with symptomatic RMMA without bruxism, fulfilling the diagnostic criteria of an SRRMD, is presented. The symptoms were initially misdiagnosed as bruxism and then as sleep-related epilepsy, which delayed an adequate treatment. Therapy of the comorbid obstructive sleep apnea with a positive airway pressure device (APAP) led to a self-reported improvement.Conclusion: The differential diagnosis of jaw movement in sleep is vast; a correct diagnosis is of the essence for adequate treatment. The prevalence of isolated RMMA resulting in perturbation of sleep warrants further exploration.