Dolor neuropático localizado / Localized neuropathic pain

Resumen El dolor neuropático localizado (DNL) es de origen periférico y se caracteriza por áreas circunscritas de dolor con sensibilidad anormal de la piel o síntomas espontáneos característicos de dolor neuropático, por ejemplo, dolor urente. Se debe resaltar que el DNL está confinado a un área específica no mayor a una hoja de papel tamaño carta. El DNL representa 60 % de las condiciones de dolor neuropático. No existe una única etiología. El abordaje diagnóstico es similar al de otros síndromes dolorosos neuropáticos. Se utilizan herramientas diagnósticas generales para evaluar las características clínicas. En la actualidad no existen guías específicas de manejo del DNL, por lo que se utilizan las guías para dolor neuropático en general. En las guías de la Sociedad Canadiense de Dolor se incluyen los tratamientos tópicos como parte de las estrategias de segunda línea. Pese a la falta de guías, los parches de lidocaína a 5 % y los parches de capsaicina a 8 % han demostrado ser efectivos en modelos de DNL.

Abstract Localized neuropathic pain (LNP) is of peripheral origin and is characterized by circumscribed areas of pain with abnormal skin sensitivity or spontaneous symptoms that are characteristic of neuropathic pain, e.g. burning pain. It should be noted that LNP is confined to a specific area no larger than a letter size sheet of paper. LNP accounts for 60 % of neuropathic pain conditions. There is no single etiology of LNP. The diagnostic approach is similar to that for other neuropathic pain syndromes. General diagnostic tools are used to assess clinical features. So far, there are no specific guidelines for the management of LNP; for this reason, guidelines for general neuropathic pain are used. Topical treatments are included as part of second-line strategies in the Canadian Pain Society guidelines. Despite the lack of guidelines, 5 % lidocaine patches and 8 % capsaicin patches have been proven effective in LNP models.

Efficacy of Piroxicam Patch Compared to Lidocaine Patch for the Treatment of Postherpetic Neuralgia

BACKGROUND: The lidocaine patch has been effectively used as a first-line therapy to treat neuropathic pain such as postherpetic neuralgia (PHN). OBJECTIVE: To evaluate the safety and efficacy of the topical piroxicam patch as a treatment option for the treatment of PHN. METHODS: Eighteen patients completed a 3-session study, applying three different patches (lidocaine, piroxicam and control) in random order. A maximum of three patches were applied to the most painful area for three consecutive days (12 hours on followed by 12 hours off). Each session was conducted at least seven days apart. The changes in visual analog scale (VAS) scores based pain intensity, quality of sleep and adverse effects were recorded. RESULTS: When compared to the control, both the lidocaine and piroxicam patches significantly reduced the mean VAS scores of pain intensity of all different types. However, the lidocaine patch was better at reducing allodynia, whereas the piroxicam patch was more effective for dull pain. The lidocaine patch worked faster than the piroxicam patch for the response to overall pain relief. CONCLUSION: The results of this study suggest the use of the piroxicam patch for dull pain and in patients where the lidocaine patch is contraindicated.

An Open-Label Trial of the 5% Lidocaine Patches for the Treatment of Chronic Pain

BACKGROUND: There have been limited reports on the effectiveness of 5% lidocaine patches (L5Ps) for treating a few types of chronic pain. We utilized L5Ps for chronic pain patients with various diagnoses and who had incompletely responded to their current treatment regimen. This study aimed at describing the results of a retrospective review of an open-label L5P trial to assess L5Ps' effectiveness and safety for treating various chronic pain patients. METHODS: The chronic pain patients with pain lasting longer than 6-month duration were offered a 2-week L5P treatment trial. The patients were maintained on their other analgesic regimens. The treatment effect was measured according to the change from the baseline visual analog scale (VAS) to the week 2 VAS. After a 2-week trial, the patients were asked if they perceived pain improvement with L5Ps by using a four-item Pain Relief Scale (1 = a lot of relief, 2 = slight relief, 3 = no change, 4 = worse pain). RESULTS: In the combined patient population (n = 177), 2-week treatment with the L5Ps significantly improved the week 2 VAS (P = 0.000). Significant improvement in the VAS was reported by the chronic pain patients with postherpetic neuralgia, intercostal neuralgia, degenerative osteoarthritis at knee joint, and other maladies. A higher proportion of the chronic pain patients reported improving their pain by the L5Ps. Seven patients experienced mild or moderate patch-related adverse events. CONCLUSIONS: The L5P provided clinically meaningful pain relief in some refractory chronic pain patients without any severe adverse events.

A Study on the Effect of Topical 5% Lidocaine Patches on Postherpetic Neuralgia

BACKGROUND: Postherpetic neuralgia (PHN) is the most common and serious complication of herpes zoster and its incidence is increasing in the aging population. Despite the many approaches thath have been proposed to treat postherpetic neuralgia, none of the therapies are satisfactory in their efficacy and safety. OBJECTIVE: Assessment of the effectiveness and safety of the 5% lidocaine patch, a targeted peripheral analgesic, for the treatment of postherpetic neuralgia. METHOD: Fifteen patients with established PHN completed a three-session, random-order, double-blind, vehicle-controlled study. A maximum of three patches were applied to the most painful area for 12 hours, twice in two consecutive days (i.e., 12 hours on followed by 12 hours off). Two sessions were done with the 5% lidocaine patches and one session with a placebo patch. The sessions were conducted at least 7 days apart. RESULTS: The 5% lidocaine patch significantly reduced the mean VAS scores (pain intensity) at the time points from hours 12 to 72 compared with baseline (individual time points p<0.001 to p=0.033) and from hours 12 to 72 compared with the vehicle patch (individual time points p<0.001 to p=0.015). The lidocaine patch also provided significantly greater pain relief on the 6-item scale compared with the vehicle patch (individual time points p<0.001 to p=0.04). The patches were well tolerated by all patients. Neither systemic side effects nor significant skin irritation were noted. CONCLUSION: This study demonstrates that use of the 5% lidocaine patch resulted in statistically significant pain relief. Patients suffering from PHN will find the patches easy to use and there is minimal risk of systemic toxicity