The influence of pain intensity on somatosensory perception in patients suffering from subacute/chronic lateral epicondylalgia.

A confounding factor in the analysis of chronic pain patients is the finding of signs of somatosensory disturbances not only in neuropathic pain patients but also in a subgroup of patients with musculoskeletal pain. The purpose was to investigate if patients suffering from subacute/chronic lateral epicondylalgia demonstrated altered sensibility, and if this was affected by pain intensity. At the start of the experiment, quantitative sensory testing (QST) (thermal, pressure pain, touch) was performed in the local pain area and in the area of pain referral. QST was repeated following pain provocation (weight lifting). A local anaesthetic was then injected into the lateral epicondyle and QST was repeated in the area of pain referral. The contralateral arm was assessed, treated and injected in the same way. At the baseline assessment there was no difference in sensibility between sides, with the exception of a significantly lowered threshold to noxious heat (p<0.04) in the area of pain referral, present during the whole experiment. In the affected arm only, weight lifting resulted in significantly increased pain intensity in the local (p<0.01) and referred (p<0.01) pain areas, respectively. Repeated muscle contractions resulted in altered somatosensory functions in both the affected arm and the unaffected arm, consequently not dependent on ongoing pain in the assessed area. Tactile perception thresholds increased significantly following pain provocation in the area of pain referral (p<0.04) only and normalized following injection of local anaesthetic (p<0.02), indicating that the sensitivity to light touch was altered by the nociceptive input from the affected arm. Copyright 2000 European Federation of Chapters of the International Association for the Study of Pain.