title: Pain profiling of patients with temporomandibular joint arthralgia and osteoarthritis diagnosed with different imaging techniques.
abstract: BACKGROUND
  Clinical differentiation between pain mechanisms of temporomandibular joint (TMJ) arthralgia and osteoarthritis (OA) is challenging. The aims were to compare somatosensory function at the TMJs and conditioned pain modulation (CPM) effects between TMJ arthralgia and OA patients diagnosed clinically and based on different imaging techniques and age- and gender-matched healthy controls (n = 41).
  
  
  METHODS
  Patients (n = 58) underwent standard clinical examination and three different TMJ imaging modalities. After each examination, they were classified into arthralgia or OA based on the findings. TMJ region somatosensory testing was performed in all participants. Z-scores were calculated for patients based on healthy reference data. CPM was tested by comparing pressure pain thresholds (PPTs) at TMJ and thenar (control) before, during and after the application of painful and nonpainful cold stimuli. Data were analyzed using analyses of variance.
  
  
  RESULTS
  Somatosensory abnormalities were commonly detected in both patient groups. Assessment of somatosensory function at the TMJ revealed that arthralgia patients were less sensitive to warmth, cold and tactile stimuli than OA patients (P < 0.048). OA patients showed pressure hyperalgesia compared with arthralgia patients (P = 0.025). There was a significant CPM effect at both test sites during painful cold application in all groups (P < 0.001). There was no significant difference in the relative CPM effect between groups except for clinically diagnosed arthralgia patients showing reduced CPM effect compared with controls (P = 0.047).
  
  
  CONCLUSIONS
  Pain profiles including somatosensory function differed between TMJ arthralgia and OA patients although CPM effects were similar in patients and controls. Thus, different TMJ pain conditions may share common pain mechanisms but the present study for the first time also indicated that differential pain mechanisms could be involved.
authors.affiliation: Section of Orofacial Pain and Jaw Function, Institute of Odontology and Oral Health, Aarhus University, Vennelyst Boulevard 9, DK-8000, Aarhus C, Denmark. simple.futarmal@odont.au.dk.|Scandinavian Center for Orofacial Neurosciences (SCON), Aarhus University Hospital, Aarhus, Denmark. simple.futarmal@odont.au.dk.
authors.forename: Simple Futarmal
authors.initials: SF
authors.lastname: Kothari
authors.affiliation: Section of Orofacial Pain and Jaw Function, Institute of Odontology and Oral Health, Aarhus University, Vennelyst Boulevard 9, DK-8000, Aarhus C, Denmark.|Scandinavian Center for Orofacial Neurosciences (SCON), Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Lene
authors.initials: L
authors.lastname: Baad-Hansen
authors.affiliation: Department of Radiology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Lars Bolvig
authors.initials: LB
authors.lastname: Hansen
authors.affiliation: Department of Radiology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Niels
authors.initials: N
authors.lastname: Bang
authors.affiliation: Department of Neuroradiology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Leif Hovgaard
authors.initials: LH
authors.lastname: Sørensen
authors.affiliation: Department of Neuroradiology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Helle Wulf
authors.initials: HW
authors.lastname: Eskildsen
authors.affiliation: Section of Orofacial Pain and Jaw Function, Institute of Odontology and Oral Health, Aarhus University, Vennelyst Boulevard 9, DK-8000, Aarhus C, Denmark.|Scandinavian Center for Orofacial Neurosciences (SCON), Aarhus University Hospital, Aarhus, Denmark.|Department of Dental Medicine, Karolinska Institutet, Huddinge, Sweden.
authors.forename: Peter
authors.initials: P
authors.lastname: Svensson
mesh_terms: D000328:Adult; D000368:Aged; D018771:Arthralgia / Q000000981:diagnostic imaging* / Q000503:physiopathology; D054893:Cone-Beam Computed Tomography; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010003:Osteoarthritis / Q000000981:diagnostic imaging* / Q000503:physiopathology; D010146:Pain / Q000000981:diagnostic imaging / Q000503:physiopathology; D010147:Pain Measurement / Q000379:methods*; D017288:Pain Threshold / Q000502:physiology; D020886:Somatosensory Disorders / Q000000981:diagnostic imaging / Q000503:physiopathology; D013705:Temporomandibular Joint Disorders / Q000000981:diagnostic imaging* / Q000503:physiopathology; D014463:Ultrasonography; D055815:Young Adult
keywords: Conditioned pain modulation; Cone-beam computed tomography; Magnetic resonance imaging; Quantitative sensory testing; Somatosensory function; Temporomandibular joint arthralgia; Temporomandibular joint osteoarthritis; Ultrasonography