Characteristics of chronic ischemic pain in patients with peripheral arterial disease.

Chronic ischemic pain is a leading cause of pain in the lower extremities. A neuropathic component in ischemic pain has been shown. Neuropathic pain questionnaires are established as a common tool in pain research. The aim of this study was to analyze the clinical nature and the character of chronic ischemic pain in peripheral arterial disease (PAD). One hundred and two patients suffering from symptomatic PAD (Fontaine stages II-IV) were surveyed using validated pain questionnaires (VAS, NPSI, S-LANSS, PDI, SF-MPQ). Pain related disability was 22.7+/-1.7 (mean+/-SEM) in patients with intermittent claudication (CI) and 34.0+/-2.3 in patients with critical limb ischemia (CLI). Neuropathic pain questionnaires revealed distinctly higher scores for CLI than for CI: The S-LANSS indicated pain of predominantly neuropathic origin in patients with CLI (17.2+/-0.8) compared to CI (6.7+/-0.8; p<0.001). Global NPSI scores were 34.1+/-3.1 for CLI and 6.6+/-1.1 for CI (p<0.001). S-LANSS and NPSI correlated well (Spearman's rho=0.779; p<0.001). The SF-MPQ revealed that patients with CLI scored significantly higher for pain descriptors stabbing, hot-burning, tender and cruel-punishing compared to those with CI. The results suggest that the character of ischemic pain changes from nociceptive pain in patients with CI to predominantly neuropathic pain in patients with CLI. A neuropathic pain component seems to be a serious aspect in CLI, while it is not in CI. Questionnaires might be a helpful tool to investigate and diagnose ischemic pain.