A retrospective analysis of the efficacy of treatment of neuropathic peripheral pain

Abstract

Introduction: Neuropathic pain is defined as pain arising from a direct consequence of lesion or disease affecting the somatosensory system. Although there are several guidelines for neuropathic pain managent and various effective drugs are accessible, neuropathic pain remains untreated or undertreated. The goal of this study was to evaluate retrospectively efficacy of combining topic capsaicin 8% with oral neuropathic pain therapy in peripheral neuropathic pain/localized neuropathic pain, by measuring pain intensity and pain treatment area reduction. Methods: This retrospective study was conducted at the Chronic Pain Unit in the Hospitalar Center Tondela-Viseu, Portugal. Forty-three patients with either post-herpetic neuralgia or post-traumatic/post-surgical neuropathic pain with localized allodynia and submitted to a combined therapy with oral neuropathic pain medication (opioids, anticonvulsants, antidepressants) and topical capsaicin 8% were enrolled. Therapeutic efficacy was evaluated considering pain intensity and treatment area variables. Pain intensity was assessed at baseline and 7-14 days after each treatment, using the numerical pain rating scale (NPRS). Treatment pain area was assessed at baseline and after each treatment. Results: The median percentage reduction in NPRS score was -40.0, [-50.0,-33.3] (95% CI, bootstrap) and the median percentage reduction in treatment pain area was -35.1 [- 50.9, 3.4] (95% CI, bootstrap). There was no significant difference in efficacy between postherpetic and post-traumatic/postsurgical neuropathic pain. No differences were detected in pain intensity and pain treatment area reduction regardless the use of different concomitant oral pain medication. Conclusion: This study evaluates clinical efficacy of combined topical capsaicin and oral neuropathic pain therapy in PNP/localized neuropathic pain by combining NPRS scores and treatment area assessment. This study newly demonstrates that combined medication significantly reduces both peripheral neuropathic pain and treatment pain area in localized neuropathic pain.