Topical lidocaine (a local anaesthetic) for the treatment of postherpetic neuralgia (nerve pain)

Khaliq W, Alam S, Puri NK

Published Online:

October 8, 2008

Topical lidocaine may benefit some patients on an individual basis though there is stronger evidence for the use of other drugs. Postherpetic neuralgia is a long-lasting pain disorder that causes pain from stimuli that are not normally painful. Local anaesthetics (such as lidocaine) can reduce the sensation of pain that is transmitted through nerves, and allow pain relief in patients with postherpetic neuralgia. This review found three small studies involving 182 topical lidocaine treated participants and 132 control participants using lidocaine for patients with postherpetic neuralgia. Two studies provided data on pain relief amongst patients with postherpetic neuralgia, and they showed some improvement in pain when topical lidocaine was compared to a placebo. No comparison was made with other medications that are in current use for the treatment of postherpetic neuralgia. The side effects of topical lidocaine are very minimal, but include skin problems (such as irritation and redness). We are unable to recommend the use of topical lidocaine as a first-line treatment for postherpetic neuralgia at this stage. Further studies are needed to compare topical lidocaine to other medications in the treatment of postherpetic neuralgia.

Abstract (click to read)

Background:

This is an update of the original Cochrane review published in Issue 2, 2007. The cause of postherpetic neuralgia is damage to peripheral neurons, dorsal root ganglia, and the dorsal horn of the spinal cord, secondary to herpes zoster infection (shingles). In postherpetic neuralgia, peripheral neurons discharge spontaneously and have lowered activation thresholds, and exhibit an exaggerated response to stimuli. Topical lidocaine dampens peripheral nociceptor sensitisation and central nervous system hyperexcitability, and may benefit patients with postherpetic neuralgia.

Objectives:

To examine efficacy and safety of topical lidocaine in the treatment of postherpetic neuralgia.

Search strategy:

We searched the Cochrane Pain, Palliative and Supportive Care Group Trials Register, CENTRAL, MEDLINE, EMBASE, LILACS, SIGLE, Citation Index, the reference lists of all eligible trials, key textbooks, and previous systematic reviews. Last search conducted July 2008.

Selection criteria:

Randomised or quasi-randomised trials comparing topical applications of lidocaine in patients of all ages with postherpetic neuralgia (pain persisting at the site of shingles at least one month after the onset of the acute rash).

Data collection and analysis:

Two review authors extracted data, and a third checked them.

Main results:

In the original review three trials involving 182 topical lidocaine treated participants and 132 control participants were included. Two trials gave data on pain relief, and the remaining study provided data on secondary outcome measures. The largest trial published as an abstract compared topical lidocaine patch to a placebo patch and accounted for 150 of the 314 patients (48%).

A meta-analysis combining two studies identified a significant difference between topical lidocaine and control groups for the primary outcome measure: a mean improvement in pain relief according to a pain relief scale. Topical lidocaine relieved pain better than placebo (P = 0.003).

There was a statistical difference between the groups for the secondary outcome measure of mean VAS score reduction (P = 0.03), but this was only for a single small trial. There were a similar number of adverse skin reactions in both treatment and placebo groups.

The highest recorded blood lidocaine concentration varied between 59 ng/ml and 431 ng/ml between trials. The latter figure is high and the authors of the study suggest that the sample had been contaminated during the assay procedure.

Authors' conclusions:

Since the last version of this review in Issue 2, 2007 no new studies have been found and the results therefore remain the same. There is still insufficient evidence to recommend topical lidocaine as a first-line agent in the treatment of postherpetic neuralgia with allodynia. Further research should be undertaken on the efficacy of topical lidocaine for other chronic neuropathic pain disorders, and also to compare different classes of drugs (e.g. topical anaesthetic applications versus anti-epileptic drugs).

This record should be cited as:

Khaliq W, Alam S, Puri NK. Topical lidocaine for the treatment of postherpetic neuralgia. Cochrane Database of Systematic Reviews 2007, Issue 2. Art. No.: CD004846. DOI: 10.1002/14651858.CD004846.pub2

Assessed as up to date:

July 2, 2008

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Primary Review Group:

Pain, Palliative and Supportive Care Group

Health topics:

Anaesthesia & pain control > Chronic non-cancer pain management > Pharmacological therapies

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Topical lidocaine (a local anaesthetic) for the treatment of postherpetic neuralgia (nerve pain)

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