Efficacy of Gabapentin for Treatment of Adults with Phantom Limb Pain

OBJECTIVE: To evaluate the effectiveness of gabapentin in adults with phantom limb pain. DATA SOURCES: A PubMed search (1966-September 2012) was conducted using the key words phantom limb pain and gabapentin. Search limits were English language, humans, adult, clinical trials, and randomized controlled trial. STUDY SELECTION AND DATA EXTRACTION: Randomized controlled trials that studied the effectiveness of gabapentin in adults with phantom limb pain were identified and selected. Primary outcomes were associated with pain. Pediatric population studies were excluded. DATA SYNTHESIS: Three studies, with a total of 89 patients, were reviewed. All studies employed a pain rating scale to determine the primary outcome. Results varied. One crossover study reported a significant difference in pain intensity at 6 weeks compared with baseline (p < 0.01) and compared with placebo (p = 0.03). Another crossover study did not find a significant difference for the primary outcome of pain intensity, but did report a significant decrease in a secondary outcome measure related to pain. The third study displayed a decreased use of rescue pain medications by patients in the gabapentin treatment group. Heterogeneity of the study designs precludes a direct comparison of the results. Several confounding factors that may affect the interpretation of these results include the use of rescue pain medication, small sample size, short-term treatment, and different pain scales. CONCLUSIONS: Given the results of these trials, oral gabapentin in patients aged 18 years or older may decrease phantom limb pain. A strong recommendation for the effectiveness of gabapentin in phantom limb pain cannot be ascertained until more methodologically sound studies are executed in this population.