Background: Neuropathic pain syndrome consists of a group of symptoms, including burning or shooting sensations, abnormal sensitivity to normally painless stimuli, or a greatly raised sensitivity to painful stimuli. A wide range of disorders can cause neuropathic pain, nerve damage being the only common factor.
Objectives: We aimed to review systematically the evidence from randomised controlled trials for the efficacy of tramadol in treating neuropathic pain.
Search strategy: We searched the Cochrane Neuromuscular Disease Group trials register (July 2002), MEDLINE (January 1966 to July 2002), EMBASE (January 1980 to July 2002), and LILACS (January 1982 to July 2002) for randomised and quasi-randomised controlled trials. We also searched bibliographies of published trials.
Selection criteria: We included randomised and quasi-randomised controlled trials comparing tramadol with placebo, other pain relieving treatment, or no treatment in people of both sexes and all ages with neuropathic pain of all degrees of severity.
Data collection and analysis: Two reviewers extracted data and scored trial quality. We calculated relative risks and numbers needed to treat for effectiveness and adverse effects.
Main results: We identified five eligible trials, three comparing tramadol with placebo, one comparing tramadol with clomipramine, and one comparing tramadol with morphine. All three trials comparing tramadol with placebo showed a significant reduction in neuropathic pain with tramadol. Two of the trials that compared tramadol to placebo (total 161 participants) were combined in a meta-analysis. The number needed to treat with tramadol compared to placebo to reach at least 50% pain relief was 3.5 (95% confidence interval 2.4 to 5.9). There were insufficient data to draw conclusions about the effectiveness of tramadol compared to either clomipramine or morphine. Only one trial considered subcategories of neuropathic pain. It found a significant therapeutic effect of tramadol on paraesthesiae, allodynia, and touch-evoked pain. Numbers needed to harm were calculated for side effects resulting in withdrawal from the placebo-controlled trials. Two trials provided these data, and the combined number needed to harm was 7.7 (95% confidence interval 4.6 to 20).
Reviewers' conclusions: Tramadol is an effective treatment for neuropathic pain.