Unilateral lateral epicondylalgia demonstrates a pro-nociceptive pain profile: a case control observational study

Lateral epicondylalgia (LE, tennis elbow) is characterised by both local tissue pathology and features indicative of secondary hyperalgesia. The aim of this study was to evaluate endogenous pain modulation characteristics in people with chronic LE, and to investigate the relationship between endogenous pain modulation and clinical characteristics.This case control observational study included 25 participants with LE of at least 6 weeks' duration and 15 age-matched (±5▒y) healthy control participants, who were each evaluated in a single session. Pain and disability were assessed using the Patient-Rated Tennis Elbow Evaluation and pain-free grip strength. Endogenous pain modulation was assessed using pressure pain threshold (PPT), cold pain threshold (CPT), conditioned pain modulation (CPM) and temporal summation.The LE group exhibited significantly lower PFG and PPT bilaterally compared to the control group. CPT was significantly reduced on the affected side compared to the matched control side. There was no significant difference between groups for CPM, however the LE group exhibited significantly increased facilitation as measured by temporal summation (between-group difference in change score of 9.6▒mm on a 0-100▒mm pain visual analogue scale, 95% confidence intervals 3.4 to 15.8▒mm). There was no significant correlation between pain modulation and clinical measures of pain and disability.LE is characterised by locally increased facilitation of pain, as measured by temporal summation, but this is not associated with severity of pain or disability