title: A systematic review of the comorbidity between Temporomandibular Disorders and Chronic Fatigue Syndrome.
abstract: The most common cause of chronic oro-facial pain is a group of disorders collectively termed temporomandibular disorders (TMDs). Chronic painful TMD is thought to be a 'central sensitivity syndrome' related to hypersensitivity of the nervous system, but the cause is unknown. A similar understanding is proposed for other unexplained conditions, including chronic fatigue syndrome (CFS). Exploring the comorbidity of the two conditions is a valuable first step in identifying potential common aetiological mechanisms or treatment targets.
  
  
  METHODS
  Systematic literature review. Studies were included if they recruited community or control samples and identified how many reported having both TMD and CFS, or if they recruited a sample of patients with either TMD or CFS and measured the presence of the other condition.
  
  
  RESULTS
  Six papers met inclusion criteria. In studies of patients with CFS (n = 3), 21-32% reported having TMD. In a sample of people with CFS and fibromyalgia, 50% reported having TMD. Studies in people with TMD (n = 3) reported 0-43% having CFS. Studies in samples recruited from oro-facial pain clinics (n = 2) reported a lower comorbidity with CFS (0-10%) than a study that recruited individuals from a TMD self-help organisation (43%).
  
  
  CONCLUSIONS
  The review highlights the limited standard of evidence addressing the comorbidity between oro-facial pain and CFS. There is a valuable signal that the potential overlap in these two conditions could be high; however, studies employing more rigorous methodology including standardised clinical assessments rather than self-report of prior diagnosis are needed.
authors.affiliation: Academic Psychiatry, Newcastle University, Newcastle upon Tyne, UK.|Northumberland Tyne and Wear NHS Foundation Trust, Newcastle upon Tyne, UK.
authors.forename: L J
authors.initials: LJ
authors.lastname: Robinson
authors.affiliation: Centre for Oral Health Research and Institute of Health & Society, Newcastle University, Newcastle upon Tyne, UK.
authors.forename: J
authors.initials: J
authors.lastname: Durham
authors.affiliation: Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, UK.|Newcastle Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK.
authors.forename: J L
authors.initials: JL
authors.lastname: Newton
mesh_terms: D000328:Adult; D015897:Comorbidity; D005157:Facial Pain / Q000150:complications* / Q000503:physiopathology / Q000523:psychology; D015673:Fatigue Syndrome, Chronic / Q000150:complications* / Q000503:physiopathology / Q000523:psychology; D006801:Humans; D008875:Middle Aged; D011788:Quality of Life; D011795:Surveys and Questionnaires; D013705:Temporomandibular Joint Disorders / Q000150:complications* / Q000503:physiopathology / Q000523:psychology
keywords: central sensitivity syndrome; chronic fatigue syndrome; diagnostic overlap; phenotyping; systematic review; temporo-mandibular disorder