Muscle Pain Sensitivity and Prevalence of Temporomandibular Disorders in Patients with Narcolepsy with Cataplexy: A Controlled Cohort Study

Disturbed nocturnal sleep contributes to the central sensitization of pain, thus predisposing to orofacial pain. Central disorders of hypersomnolence are characterized by excessive daytime sleepiness (EDS) not linked to impairment of nocturnal sleep or misaligned circadian rhythms. The main disorder of this group is narcolepsy type 1 (NT1), which seems to be related to alterations in pain perception mediation, supposedly caused by low orexin levels. The aim of this study was to evaluate the pain sensitivity and the prevalence of temporomandibular disorders (TMDs) in patients with NT1. After a 3-day hospital evaluation with laboratory polysomnography, 39 consecutive adult patients diagnosed with NT1 and 39 matched heathy controls were evaluated by means of Axis I and Axis II of the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) protocol. Furthermore, pain sensitivity was investigated by measuring the pressure pain thresholds (PPTs) on the head-neck muscles by means of a Fischer algometer. No significant differences were found between the PPTs of the two groups for all the muscles evaluated, nor in the prevalence of TMD diagnoses, but the NT1 group reported significantly higher values in the Patient Health Questionnaire (PHQ-9), corresponding to a depressive state. The present study presents an important investigation into NT1 patients, showing no alterations in pain perception and no differences in the prevalence of TMD diagnosis compared to the controls.