Do cannabinoids reduce multiple sclerosis-related spasticity?

Background: The plant Cannabis sativa contains numerous cannabinoids, which are aromatic hydrocarbons that have central nervous system effects mediated through specific cannabinoid receptors. Some patients with multiple sclerosis (MS) report symptomatic relief from spasticity, pain, and other symptoms when using smoked cannabis, and small trials have suggested some symptomatic benefit. Objective: Do cannabinoids improve spasticity in patients with MS? Methods: We addressed the question through the development of a structured, critically appraised topic. Participants included consultant and resident neurologists, clinical epidemiologists, medical librarian, and clinical content experts in the field of MS. Participants started with a clinical scenario and a structured question, devised search strategies, located and compiled the best evidence, performed a critical appraisal, synthesized the results, summarized the evidence, provided commentary, and declared bottom-line conclusions. Results: The largest randomized, placebo-controlled trial of oral cannabinoid therapy detected no improvement for MS-related spasticity as measured by the Ashworth scale. However, subjective participant reports indicated improvement in spasticity (P = 0.01), spasms (P = 0.038), sleep quality (P = 0.025), and pain (P = 0.002) without detriment to depression, fatigue, irritability, or walk time. A second randomized controlled trial, which used subjective participant report as the primary outcome, revealed the same discrepancy between subjective and objective spasticity outcome measures. Conclusion: Randomized controlled trials have failed to confirm objective evidence for a beneficial effect of cannabinoids on MS-related spasticity. However, improvement in subjective assessments of spasticity and other related symptoms have been consistently noted, raising questions about the sensitivity and validity of current objective outcome instruments. Further research is warranted with regards to both outcome instrument development and the effects of cannabinoids on MS-related spasticity.