Topical Capsaicin in Severe Neuropathic Pain

ABSTRACT

A case of severe neuropathic pain in a middle-aged Swiss patient that did not respond well to several routine approaches is described. A topical 8% capsaicin patch was effective. The use, limitations, efficacy, and mechanism of action for this pharmacotherapy are discussed. Perspectives on this case are provided by consultants from the United Kingdom and Sweden are provided.

This feature is adapted from paineurope 2011; Issue 4, ©Haymarket Medical Publications Ltd., and is presented with permission. paineurope is provided as a service to pain management by Mundipharma International, Ltd., and is distributed free of charge to health care professionals in Europe. Archival issues can be accessed via the Web site: http://www.paineurope.com, at which European health professionals can register online to receive copies of the quarterly publication.

KEYWORDS :

• capsaicin
• neuropathic
• pain
• topical

COMMENTARY FROM THE UNITED KINGDOM

Neuropathic pain disorder is a difficult condition to treat. Capsaicin cream has been used successfully, but is cumbersome and demanding for patients, affecting compliance. The 8% cutaneous patch is more effective in achieving desensitization and a single application can last for months. The application is more difficult because it needs to be carried out as a day case. Remifentanil infusion appears to be a good way of controlling pain during application, but it can produce rebound increase in analgesic need when discontinued, and also requires the presence of a person appropriately trained in respiratory function.

Current randomized controlled trials (RCTs) of the capsaicin 8% patch have been carried out in human immunodeficiency virus (HIV) neuropathy and postherpetic neuralgia. The patch may also be useful in treating peripheral neuropathic pains such as postthoracotomy and postmastectomy pain and others. Further studies are needed to determine the effectiveness of the patch in these other neuropathic pain conditions.

The high concentration of capsaicin in this formulation results in reversible desensitization of transient receptor potential vanilloid 1–expressing cutaneous sensory nerve endings and reduction in nerve fiber density in the epidermis (1). The resulting pain relief is long lasting: up to 12 weeks following a single application (2,3).

COMMENTARY FROM SWEDEN

This case history describes a situation that is not uncommon in the pain clinic. It is known that up to 46% cases of chronic pain begin with some form of medical procedure (1).

Postsurgical pain syndromes are still very common, with incidences of 30–50% after amputations, 20–30% after breast surgery, 30–40% post thoracotomy, 10% after inguinal hernia repair, 30–50% after coronary artery bypass graft, and 10% after cesarean section (2).

Moreover, neuropathic pain can commonly occur after laparotomy. For example, after nephrectomy, the patient may present with a typical, radiating neuropathic pain around the abdominal scar. This is most often due to damage to the ipsilateral iliohypogastric nerve. Damage to the ilioinguinal and genitofemoral nerves is also very common after hernia repair surgery.

These pain syndromes are always severe and create a challenge for the pain clinician: namely managing the pain in the abdominal/groin/genital region, the not uncommon secondary sexual dysfunction, and disappointment from the patient and their family.

Pharmacological therapy also can create situations with unpleasant side effects such as incomplete pain relief, cognitive impairment, and further sexual side effects. Drug treatment tends to relieve—at most—50% of the pain for about half of the patients.

Therefore, this local treatment, which appears to have few systemic side effects, seems very attractive (3,4). Patients with a similar degree of successful response are re-treated once each third, fourth, or six month. The long-term efficacy and safety profile of this treatment is as yet unknown. But so far, the ability to help some patients successfully for some time using this therapy is good enough, although there are many we cannot help.

Declaration of Interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.