Exploration of the Extent of Somato-Sensory Impairment in Patients with Unilateral Lateral Epicondylalgia

There is evidence suggesting an important role of nociceptive sensitization in lateral epicondylalgia (LE). Our aim was to explore somato-sensory changes in patients with unilateral LE to better understand this musculoskeletal condition. Twelve patients (6 female) with LE with a mean (SD) age 47 (10) years, and 16 controls (7 female), aged 41 (9) years were tested. The following somato-sensory parameters were assessed: pressure-pain threshold (PPT), heat- and cold-pain thresholds, thermal, cold- and vibration-detection thresholds. All these tests were bilaterally assessed over the lateral epicondyle (affected/unaffected in patients; dominant/nondominant in controls) and at the dorsal-lateral surface of the wrist in all patients and controls. The results showed that patients with unilateral LE not only exhibited substantial reductions in PPT on the affected side compared to the unaffected side (mean difference and 95% confidence intervals: 219 kPa [136.8 to 301.1 kPa] but also when compared to controls (581.1 kPa [340.5 to 821.7 kPa]), showing bilateral pressure-pain hyperalgesia. These differences represented an effect size (ie, standardized mean difference) of 1.23 and .94, respectively. In the same cohort, there were no such deficits in cold and heat pain, cold- and warm-detection thresholds, and vibration-detection thresholds, either between affected and unaffected sides in patients with LE or between patients and controls. Effect sizes for the sensory-detection tests were small, which were generally less than the pain tests. Our data imply that LE is largely characterized by peripheral and central mechanical pain hyperalgesia. Perspective: This article reveals the presence of bilateral pressure-pain hypersensitivity inpatients with unilateral LE. On the contrary, thermal and vibration tests were not significantly different from controls. (C) 2009 by the American Pain Society