Tramadol for neuropathic pain

BACKGROUND: Peripheral neuropathic pains often include symptoms such as burning or shooting sensations, abnormal sensitivity to normally painless stimuli, or an increased sensitivity to normally painful stimuli. Neuropathic pain is a common symptom in many diseases of the peripheral nervous system. 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 (June 2005), MEDLINE (January 1966 to June 2005), EMBASE (January 1980 to June 2005), and LILACS (January 1982 to June 2005) 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 authors extracted data and scored trial quality. We calculated relative risks and numbers needed to treat for effectiveness and adverse effects. MAIN RESULTS: We identified six eligible trials, four comparing tramadol with placebo, one comparing tramadol with clomipramine, and one comparing tramadol with morphine. All four trials comparing tramadol with placebo showed a significant reduction in neuropathic pain with tramadol. Three of the trials which compared tramadol to placebo (total 269 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 3.8 (95% confidence interval 2.8 to 6.3). 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. Three trials provided these data, and the combined number needed to harm was 8.3 (95% confidence interval 5.6 to 17). AUTHORS' CONCLUSIONS: Tramadol is an effective treatment for neuropathic pain.