title: Chronic Lateral Epicondylalgia Does Not Exhibit Mechanical Pain Modulation in Response to Noxious Conditioning Heat Stimulus.
abstract: OBJECTIVE
  The impaired attenuation of pain by the application of a noxious conditioning stimulus at a segmentally distinct site, known as conditioned pain modulation (CPM), has been implicated in clinical pain states. Chronic lateral epicondylalgia (LE), which is characterized by lower pressure pain thresholds (PPTs) at sites remote to the affected elbow and spinal cord hyperexcitability, is a clinical pain state that might plausibly involve less efficacious CPM. This study aimed to determine whether LE exhibits a less efficacious CPM compared with that in pain-free controls.
  
  
  RESULTS
  Results: Twenty participants with LE, aged 50.7 years (SD=7.05) and who had their condition for 10.2 months (range: 2 to 80 mo), were matched by age and sex to 22 pain-free participants. All participants indicated their PPT over the lateral epicondyle(s) before and during a conditioning noxious heat stimulus that was applied over the calf. A CPM score was calculated as the difference between the PPT before and during the heat pain-conditioning stimulus expressed as a percentage of PPT before the heat pain-conditioning stimulus. The condition (LE vs. control) by side (affected vs. unaffected) analysis of variance revealed a significant condition effect (P=0.001), but not side effect (P=0.192) or side-by-condition interaction effect (P=0.951). Follow-up tests for the effect of condition revealed a mean deficit in CPM of -24.5% (95% confidence interval, -38.0 to -11.0) in LE compared with that in pain-free participants.
  
  
  CONCLUSIONS
  The results that suggest an impaired ability to modulate pain might be associated with the previously observed spinal cord hyperexcitability and the mechanical hyperalgesia that characterizes LE.
authors.affiliation: *Centre of Clinical Research Excellence in Spine, Division of Physiotherapy, School of Health and Rehabilitation Sciences, the University of Queensland, St Lucia ‡Centre for National Research on Disability and Rehabilitation (CONROD), NHMRC Centre of Research Excellence in Road Traffic Injury, Menzies Health Institute Queensland, Griffith University, Parklands Drive, QLD, Australia †Department of Physiotherapy, Singapore General Hospital, Singapore, Singapore.
authors.forename: Edwin Choon Wyn
authors.initials: ECW
authors.lastname: Lim
authors.forename: Michele
authors.initials: M
authors.lastname: Sterling
authors.forename: Bill
authors.initials: B
authors.lastname: Vicenzino
mesh_terms: D000704:Analysis of Variance; D059350:Chronic Pain / Q000503:physiopathology*; D005260:Female; D007839:Functional Laterality; D006358:Hot Temperature; D006801:Humans; D007866:Leg / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D059226:Nociceptive Pain / Q000503:physiopathology*; D017288:Pain Threshold / Q000502:physiology; D013716:Tennis Elbow / Q000503:physiopathology*; D014110:Touch