title: Nocturnal heart rate variability is lower in temporomandibular disorder patients than in healthy, pain-free individuals.
abstract: OBJECTIVE
  To determine whether patients with a painful myofascial temporomandibular disorder (TMD) have diminished nocturnal heart rate variability (HRV), a marker of autonomic nervous system (ANS) dysfunction, relative to healthy, pain-free controls.
  
  
  METHODS
  Participants with myofascial TMD and healthy, pain-free volunteers underwent nocturnal polysomnography studies during which HRV indices were measured. Multiple linear regression analyses were used to determine whether TMD status exerted unique effects on HRV.
  
  
  RESULTS
  Ninety-five participants (n = 37 TMD; n = 58 controls) were included in the analyses. The TMD group had a lower standard deviation of R-R intervals (89.81 ± 23.54 ms versus 107.93 ± 34.42 ms, P ⋜ .01), a lower root mean squared successive difference (RMSSD) of R-R intervals (54.78 ± 27.37 ms versus 81.88 ± 46.43 ms, P < .01), and a lower high frequency spectral power (2336.89 ± 1224.64 ms² versus 2861.78 ± 1319 ms², P = .05) than the control group. The ratio of the low-frequency (LF) to the high-frequency (HF) spectral power was higher in the TMD group (2.47 ± 2 versus 1.38 ± 0.65, P < .01). The differences in RMSSD (91.21 ms versus 112.03 ms, P = .05) and LF:HF ratio (0.71 versus 0.32, P < .01) remained significant after controlling for age and psychological distress.
  
  
  CONCLUSIONS
  Myofascial TMD patients revealed lower nocturnal HRV than healthy, pain-free controls. Further research should focus on processes that address this ANS imbalance, which may potentially lead to effective therapeutic interventions.
authors.affiliation: Center for Mind Body Research Department of Psychiatry and Behavioral Sceinces, Johns Hopkins University School of Medicine, Baltimore, Maryland 21224, USA.
authors.forename: Chete M
authors.initials: CM
authors.lastname: Eze-Nliam
authors.forename: Phillip J
authors.initials: PJ
authors.lastname: Quartana
authors.forename: Angela M
authors.initials: AM
authors.lastname: Quain
authors.forename: Michael T
authors.initials: MT
authors.lastname: Smith
mesh_terms: D000328:Adult; D018771:Arthralgia / Q000503:physiopathology; D001342:Autonomic Nervous System Diseases / Q000503:physiopathology*; D016022:Case-Control Studies; D002940:Circadian Rhythm; D004562:Electrocardiography; D005157:Facial Pain / Q000503:physiopathology; D005260:Female; D006339:Heart Rate; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D012893:Sleep Wake Disorders / Q000503:physiopathology*; D011795:Surveys and Questionnaires; D013706:Temporomandibular Joint Dysfunction Syndrome / Q000503:physiopathology*