Twenty-eight studies were included in the review: 21 RCTs; one prospective controlled study; one observational study; three case series; and three before-and-after studies. PEDro scores ranged from 4 to 10. Nineteen RCTs were considered to be of excellent or good quality. Downs and Black scores ranged from 4 to 18.
Anticonvulsants: Pregabalin (two RCTs) and gabapentin (three RCTs, one case series, one before-and-after study) were found to improve neuropathic pain after spinal cord injury, although one RCT found no significant between group differences when gabapentin was compared with an active control. No statistically significant difference in pain was found for levetiracetam (one RCT), valproic acid (one RCT) and lamotrigine (one RCT), although a subgroup of patients with incomplete spinal cord injury reported a significant improvement in neuropathic pain.
Antidepressants: Compared with placebo, amitryptyline (a tricyclic antidepressant) was found to reduce post spinal cord injury pain in depressed persons (two RCTs). No significant difference in post spinal cord injury neuropathic pain was found between trazodone (a tricyclic antidepressant) and placebo (one RCT).
Analgesics: Intravenous lidocaine, intravenous ketamine and alfentanil, tramadol (one RCT) and intrathecal morphine and/or clonidine (one RCT, one prospective controlled study) were found to improve neuropathic pain. This association was largely of short-term benefits when associated with intravenous lidocaine. Intravenous morphine was found to improve dynamic mechanical allodynia pain after spinal cord injury (one RCT). A reduction in pain was reported following administration of topical lidocaine, capsaicin (one case study). No significant between-group difference in neuropathic pain was found when mexilitine was compared with placebo (one RCT).
Cannabinoids: Conflicting evidence was found for use of tetrahydrocannabinol in the reduction of spastic pain. A significant reduction was found in post spinal cord injury pain after 10mg oral tetrahydrocannabinol at day one compared with baseline measures (one before-and-after study). However, no significant improvement in pain was found compared with placebo on day eight and day 43 in a subset of these participants, as well as no difference in measures of mood or attention (one RCT).
Anti-spasticity medications: Intrathecal baclofen reduced musculoskeletal pain (one before-and-after study) associated with spasticity. There was conflicting evidence for neuropathic pain (one RCT, one before-and-after study). Botulinum toxin was found to reduce post spinal cord injury pain associated with spasticity (one case series).