Efectos de la administración precoz de gabapentina en el dolor de miembro fantasma postamputación.

Abstract

INTRODUCTION More than 70% of patients with limb amputation develop a neuropathic pain known as phantom pain. The treatment of this kind of pain uses to be complicated, with frequently failures after surgery. It would be interesting trying to prevent this pain when surgery is scheduled. Gabapentin has demonstrated to be effective in several neuropathic pain including phantom pain. In this study we evaluate the analgesic efficacy of gabapentin in postoperative phantom pain when is administrated before surgery. METHODS A retrospective-prospective cohort study was designed, comparing amputated patients through 2002 with amputated patients through 2003 when gabapentin was included into de analgesic protocol after amputation. Gabapentin was administrated before surgery until 900mg and pain level was assessed at first week, one month and three months. Doses were incremented until 2400mg if necessary. The primary outcome measure was Visual Analog Scale (VAS) and Lattinen test. For comparisons a p<0.05 was considered significant. RESULTS 28 patients were included into the control group and 30 into the intervention group. 5 patients (16.6%) didnt finish the study. Spontaneous pain was present at first week in 92.9% of patients. At 3 month, 14.3% in control group and 56% in study patients were free of pain (p:0.01). Incidence of phantom limb pain at 3 month was 75% in the control group and 40% in the study group (p:0.010).Differences in VAS and Lattinen between groups were significant since the postoperative period and first month respectively. Considering as main outcome a decrease of 30% of initial VAS, both groups were significant different at the 3 months, with a NNT of 2.63 patients. When main outcome was considered to achieve a VAS less than 30mm, which would be considered tolerate pain, again differences were significant at 3 months, with a NNT of 2.04 patients. Finally in a Cox multivariate analyzes, only pertinence to intervention group was significant to get a VAS less than 30mm. CONCLUSIONS: Our results at three months together with tolerance suggest that gabapentin administrated before surgery could be an alternative for treatment of phantom limb pain. Anyway a randomized controlled trial would be necessary to confirm these results.