Effect of dronabinol on central neuropathic pain after spinal cord injury: a pilot study.

OBJECTIVE: To test the efficacy and safety of a cannabinoid, dronabinol, compared with an active control, diphenhydramine, in relieving neuropathic pain in persons with spinal cord injury. DESIGN: A randomized, controlled, double-blind, crossover pilot study. RESULTS: Seven adults with spinal cord injury and neuropathic pain below the level of injury participated. Two participants withdrew while receiving dronabinol, their first medication. For the remaining five participants, change in pain on a scale of 0-10 from baseline to the end of the maintenance phase did not differ significantly between the two medications (mean change, dronabinol: 0.20 ± 0.837, range = -1.00 to 1.00; diphenhydramine: -1.80 ± 2.490, range = -6.00 to 0; Wilcoxon Z = 1.63, P = 0.102). Similar results were found when the average of the two ratings during the maintenance phase was used (dronabinol: -0.20 ± 0.671, range = -0.50 to 1.00; diphenhydramine: -1.40 ± 1.245, range = -3.50 to -0.50; Wilcoxon Z = 1.60, P = 0.109). The most common side effects were dry mouth, constipation, fatigue, and drowsiness for both medications. CONCLUSIONS: On average, dronabinol was no more effective than diphenhydramine for relieving chronic neuropathic pain below the level of injury.

Comparison of the effectiveness of amitriptyline and gabapentin on chronic neuropathic pain in persons with spinal cord injury.

OBJECTIVE: To test the hypotheses that both amitriptyline and gabapentin are more effective in relieving neuropathic pain than an active placebo, diphenhydramine. DESIGN: Randomized, controlled, double blind, triple crossover 8-week trial. SETTING: Veterans Affairs medical center. PARTICIPANTS: Community dwelling adults with spinal cord injury (N=38) were recruited by telephone, letters, and flyers. INTERVENTION: Eight-week trial each of amitriptyline, gabapentin, and diphenhydramine. MAIN OUTCOME MEASURES: Pain intensity measured with a 10-cm visual analog scale (VAS) and an 11-point (0-10) numeric rating scale (NRS) and depressive symptomatology measured with the Center for Epidemiologic Studies Depression Scale-Short Form (CESD-SF). RESULTS: Baseline VAS scores for participants with low (< 10) CESD-SF scores was 4.61 and for those with high scores (> or = 10) it was 7.41. At week 8, in participants with high baseline CESD-SF scores, amitriptyline (mean, 4.21) was more effective than diphenhydramine (mean, 6.67; P=.035), and there was a nonsignificant trend suggesting that amitriptyline may be more effective than gabapentin (mean, 6.68; P=.061). Gabapentin was no more effective than diphenhydramine (P=.97). There was no significant difference among the medications for those with lower CESD-SF scores. Results could not be attributed to dropout rates, order or dose of medications, amount of medication taken for breakthrough pain, or side effects. CONCLUSIONS: Amitriptyline is more efficacious in relieving neuropathic pain than diphenhydramine at or below the level of spinal cord injury in people who have considerable depressive symptomatology.

Prevalence and characteristics of chronic pain in veterans with spinal cord injury.

To assess prevalence and characteristics of individual chronic (>6 mo) pain components in the veteran spinal cord injury (SCI) population, we conducted a telephone survey with 348 (66%) of 530 veterans with SCI who received care from one regional Department of Veterans Affairs SCI center during a 3 yr period. The short-form McGill Pain Questionnaire was used to assess qualitative properties of the pain experience. Other questions were used to assess frequency, duration, intensity, exacerbating factors, and effects on daily activities. Of the participants, 75% reported at least one chronic pain component. The majority (83%) of the chronic pain components occurred daily (mean = 27.4 d/mo) and lasted most of the day (mean = 17.4 h/d). Mean pain intensity in the week before the interview averaged 6.7 (on a 0 to 10 scale), while worst pain intensity averaged 8.6. Two-thirds (67%) of the chronic pain components interfered with daily activities. The most commonly selected pain descriptors were "aching," "sharp," "hot-burning," and "tiring-exhausting." More research is needed to identify better ways to prevent, assess, and treat chronic pain in the veteran SCI population.