Other potential anti-spasmodics which have been tested in the SCI population include L-threonine, diazepam and dantrolene and a recent investigation noted an anti-spastic effect for naxolone. L-threonine is an α-amino acid with a putative mechanism of anti-spastic action through increasing spinal glycine levels (Paisley et al. 2002). No current studies (1980 to date) were found that investigated the specific use of diazepam (valium) or dantrolene in the treatment of SCI spasticity, although both of these remain in use today. Notably, diazepam has earlier evidence of effectiveness based on RCTs conducted in persons with SCI (Wilson et al. 1966; Corbett et al. 1972). Although Levetiracetam has been trialed in a recent RCT, it has shown no effect on neuropathic pain, evoked pain or spasms (Finnerup et al. 2009).
Other potential anti-spasmodics used in SCI include L-threonine, diazepam and dantrolene. A randomized, controlled study of L-threonine (Lee & Patterson 1993; N=33) only showed minimal effects on spasticity. Nance et al. 1989 in a study of clonidine for SCI spasticity showed that effects of diazepam and placebo were not different from pre-treatment values. However, an earlier cross-over study (Corbett et al. 1972, N=19) showed that Valium was more effective than amytal and placebo in reducing spasticity (p<0.02-0.05).
An inadvertent side effect discovered during an investigation of neuroendocrine function in SCI using naloxone is the profound increase in spasticity after naloxone treatment in all 3 SCI subjects compared to no such activity in the 3 able-bodied study volunteers (Brackett et al. 2007). This interesting finding indicates a relationship between opioid receptors and spasticity that has previously been suggested in patients where morphine is found to be effective when ITB tolerance is an issue.
Very little recent evidence supports current use of diazepam and dantrolene for reducing SCI-related spasticity. An RCT investigating L-threonine for the treatment of SCI spasticity showed only minimal effects on spasticity.
- The use of L-threonine in the treatment of SCI spasticity requires confirmation through additional well-designed studies.
- Continued use of diazepam and dantrolene would benefit from controlled comparison studies.