Assessment of Pressure-Pain Thresholds and Central Sensitization of Pain in Lateral Epicondylalgia

Objective. To assess pain sensitivity and spreading hyperalgesia in lateral epicondylalgia (LE). Subjects. Twenty-two women with LE, and 38 controls were included. Outcome Measures. Computerized cuff pressure algometry was used for assessment of pressure-pain threshold and tolerance. The stimulus was applied using a single (stimulation-area: 241cm2) or double-chambered (stimulation-area: 482cm2) tourniquet on the arm and leg. Spatial summation was expressed as the ratio between pressure-pain thresholds to single and double cuff-chamber stimulation. During 10-minute constant pressure stimulation at intensity relative to the individual pain threshold, the pain intensity was continuously recorded using an electronic visual analogue scale (VAS), and from this the degree of temporal summation was estimated. For LE, a Doppler ultrasound examination of the elbow was made to identify inflammation. Results. In LE compared with controls the pressure-pain threshold and tolerance were on average reduced by respectively 31% (nonsignificant) and 18% (nonsignificant) on the lower arm and by 32% (P<0.05) and 22% (P<0.05) on the lower leg (spreading sensitization). Within the LE group, pressure-pain thresholds were on average reduced by 20% (P<0.05) and pain tolerance by 10% (nonsignificant) on the painful compared with the asymptomatic side. Spatial summation (P<0.01) and temporal summation (P<0.05) was facilitated in LE compared with controls. In LE patients without signs of peripheral inflammation assessed by Doppler ultrasound, temporal summation was significantly stronger than in patients with ongoing inflammation (P<0.01). Conclusion. Patients with LE may be subgrouped based on pain hypersensitivity and Doppler ultrasound into clinically meaningful subgroups with varying duration of symptoms and different degrees of central sensitization. These groups may require different pain management strategies.