title: Nocturnal masseter muscle activity is related to symptoms and somatization in temporomandibular disorders.
abstract: OBJECTIVE
  Temporomandibular disorders (TMD) have often been related to sleep bruxism and elevated nocturnal masseter muscle activity (NMMA). However, previous studies have revealed controversial results, and the role of somatization, depression and anxiety has not been studied in this context. The aim of this study was to investigate the association between NMMA and pain intensity, TMD related symptoms, somatoform symptoms, depression, and anxiety in chronic TMD.
  
  
  METHODS
  Thirty-six subjects with chronic painful TMD, 34 subjects with pain free bruxism, and 36 healthy controls recorded their nocturnal masseter muscle activity during three consecutive nights with portable devices. In addition, participants completed pain diaries and questionnaires. Diagnoses were established using the research diagnostic criteria for TMD.
  
  
  RESULTS
  Subjects with chronic TMD reported a reduced general health state (p<.001), higher levels of somatoform symptoms (p<.001), depression (p<.05), and anxiety (p<.001) compared to control subjects with or without sleep bruxism. The amount of NMMA did not differ significantly between the groups. In subjects with TMD, pain intensity was not related to NMMA. However, higher NMMA was related to higher intensity of jaw related symptoms such as headache or tinnitus, and higher somatization in general.
  
  
  CONCLUSIONS
  Chronic TMD is associated with elevated levels of psychopathology. These findings suggest a common link between NMMA, somatization, and symptom intensity in chronic TMD.
authors.affiliation: Department of Clinical Psychology and Psychotherapy, Philipps University of Marburg, Germany. m.shedden@staff.uni-marburg.de
authors.forename: Meike
authors.initials: M
authors.lastname: Shedden Mora
authors.forename: Daniel
authors.initials: D
authors.lastname: Weber
authors.forename: Saskia
authors.initials: S
authors.lastname: Borkowski
authors.forename: Winfried
authors.initials: W
authors.lastname: Rief
mesh_terms: D000293:Adolescent; D000328:Adult; D001007:Anxiety / Q000503:physiopathology; D002012:Bruxism / Q000503:physiopathology; D059350:Chronic Pain / Q000503:physiopathology; D003863:Depression / Q000503:physiopathology; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D008406:Masseter Muscle / Q000503:physiopathology*; D012890:Sleep / Q000502:physiology*; D013001:Somatoform Disorders / Q000503:physiopathology*; D011795:Surveys and Questionnaires; D013705:Temporomandibular Joint Disorders / Q000503:physiopathology*