EFFECT OF MEXILETINE ON SPINAL-CORD INJURY DYSESTHETIC PAIN

Severe pain occurs in 5-30% of the spinal cord-injured (SCI) populatio n and is difficult to treat. Subarachnoid lidocaine has been used in s elected patients with some success. Mexiletine, an analog of lidocaine that acts at Na+/K+ channels in the peripheral nerve, has been found effective in persons with diabetic dysesthetic neuropathy. The effect of mexiletine in the treatment of spinal cord dysesthetic pain was exa mined in this study. Fifteen patients were enrolled, and 11 patients c ompleted the prospective, randomized, placebo-controlled, double-blind , crossover design trial. Inclusion/exclusion criteria were carefully defined. Al-wk washout period was followed by a 4-wk drug trial of eit her mexiletine (450 mg/day) or placebo, This was repeated for the seco nd medication in the second arm of the study. Patients were followed w eekly with McGill and visual analog pain scales. Baseline, midpoint, a nd endpoint Barthel function scores were recorded. The Wilcoxon's sign ed-rank test and paired t test were used for statistical analysis. Res ults showed no significant effect of mexiletine on SCI dysesthetic pai n scales or Barthel index. In conclusion, in this trial, mexiletine di d not appear to decrease spinal cord injury-related dysesthetic pain.