Unilateral Lateral Epicondylalgia Shows a Pro-nociceptive Pain Profile: A Case-control Observational Study

Objective:Lateral epicondylalgia (LE, tennis elbow) is characterized 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.Materials and Methods:This case-control observational study included 25 participants with LE of at least 6 weeks' duration and 15 age-matched (5y) 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, cold pain threshold, conditioned pain modulation (CPM), and temporal summation (TS).Results:The LE group exhibited significantly lower pain-free grip and pressure pain threshold bilaterally compared with the control group. Cold pain threshold was significantly reduced on the affected side compared with the matched control side. There was no significant difference between groups for CPM; however, the LE group exhibited significantly increased facilitation as measured by TS (between-group difference in change score of 9.6mm on a 0 to 100mm pain visual analogue scale; 95% confidence intervals, 3.4-15.8mm). There was no significant correlation between pain modulation and clinical measures of pain and disability.Discussion:LE is characterized by locally increased facilitation of pain, as measured by TS, but this is not associated with severity of pain or disability.