Ischemic Ulcer Pain Is Both Nociceptive and Neuropathic Pain Based on a Discriminant Function Analysis Using the...

The McGill Pain Questionnaire (MPQ) is composed of 78 words reflecting the mechanisms underlying chronic pain conditions. Ischemic ulcer pain is generally regarded as a nociceptive and inflammatory pain condition. However, it is sometimes refractory to nonsteroidal anti-inflammatory drug (NSAID) and opioid treatment. We categorized ischemic pain into nociceptive/inflammatory pain (NocP) or neuropathic pain (NeP), on the basis of patients' descriptions of their pain using the MPQ. We investigated pain characteristics of 365 patients with NeP and 124 with NocP using the 78 words of the MPQ. We thereby developed a discriminant function, which efficiently discriminates descriptions of NocP from those of NeP. We applied this function to 18 ischemic pain patients (before and after peripheral revascularization) and categorized their pain as either NocP or NeP. The discriminant probability of the function was 72.8% (P <.05), suggesting relatively accurate discrimination of NocP from NeP. Among the 78 words, only "annoying" was not utilized for the function. On the basis of this function, 9 of the 18 ischemic pain patients' complaints were classified as NeP. Ten patients received revascularization and after revascularization, 7 of 10 patients' complaints were still NeP. Our results suggest that ischemic ulcer pain should be regarded as a mixed pain condition composed of both NocP and NeP and that it might be treated with medications for NeP (e.g., pregabalin, duloxetine) in combination with NSAIDs and opioids.