Gabapentin in postamputation phantom limb pain: a randomized, double-blind, placebo-controlled, cross-over study.
OBJECTIVE
Severe phantom limb pain after surgical amputation affects 50% to 67% of patients and is difficult to treat. Gabapentin is effective in several syndromes of neuropathic pain. Therefore, we evaluated its analgesic efficacy in phantom limb pain.


METHODS
Patients attending a multidisciplinary pain clinic with phantom limb pain were enrolled into this randomized, double-blind, placebo-controlled, cross-over study. Other anticonvulsant therapy was discontinued. Each treatment was 6 weeks separated by a 1-week washout period. Codeine/paracetamol was allowed as rescue analgesia. The daily dose of gabapentin was titrated in increments of 300 mg to 2400 mg or the maximum tolerated dose. Patients were assessed at weekly intervals. The primary outcome measure was visual analog scale (VAS) pain intensity difference (PID) compared with baseline at the end of each treatment. Secondary measures were indices of sleep interference, depression (Hospital Anxiety and Depression [HAD] scale), and activities of daily living (Bartel Index).


RESULTS
Nineteen eligible patients (mean age, 56 years; range, 24 to 68 years; 16 men) were randomized, of whom 14 completed both arms of the study. Both placebo and gabapentin treatments resulted in reduced VAS scores compared with baseline. PID was significantly greater than placebo for gabapentin therapy at the end of the treatment (3.2 +/- 2.1 v 1.6 +/- 0.7, P =.03). There were no significant differences between placebo and gabapentin therapy in terms of the number of tablets of rescue medication required, sleep interference, HAD scale, or Bartel Index. The medication was well tolerated with few reports of adverse effects.


CONCLUSIONS
After 6 weeks, gabapentin monotherapy was better than placebo in relieving postamputation phantom limb pain. There were no significant differences in mood, sleep interference, or activities of daily living, but a type II error cannot be excluded for these variables.
Bone
Margaret
M
Departments of Anaesthesia and Pain Management, University Hospitals of Leicester NHS Trust, Leicester General Hosptial, Leicester, UK.
Critchley
Peter
P
Buggy
Donal J
DJ
D000085:Acetates / Q000009:adverse effects / Q000627:therapeutic use*; D000203:Activities of Daily Living / Q000523:psychology; D000328:Adult; D000368:Aged; D000588:Amines; D000671:Amputation, Surgical / Q000009:adverse effects* / Q000523:psychology; D018592:Cross-Over Studies; D003509:Cyclohexanecarboxylic Acids; D003866:Depressive Disorder / Q000453:epidemiology / Q000209:etiology; D004311:Double-Blind Method; D018691:Excitatory Amino Acid Antagonists / Q000009:adverse effects / Q000627:therapeutic use*; D005260:Female; D000077206:Gabapentin; D006801:Humans; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement; D010591:Phantom Limb / Q000188:drug therapy* / Q000523:psychology; D011183:Postoperative Complications / Q000453:epidemiology / Q000209:etiology; D012893:Sleep Wake Disorders / Q000453:epidemiology / Q000209:etiology; D013997:Time Factors; D016896:Treatment Outcome; D005680:gamma-Aminobutyric Acid
D000085:Acetates; D000588:Amines; D003509:Cyclohexanecarboxylic Acids; D018691:Excitatory Amino Acid Antagonists; D005680:gamma-Aminobutyric Acid; D000077206:Gabapentin