Medical Cannabis Improved Self-Reported Spasticity Rating in Patients with Chronic Spinal Cord Injury: a Placebo-Controlled, Double-Blind, Crossover Pilot Clinical Trial

Background: Previous studies demonstrated that cannabinoids may reduce spasticity in patients with spinal cord injury (SCI); however, the effect of naturally extracted THC:CBD oil, the most commonly used naturally extracted cannabinoids, has yet to be elucidated. Objectives: To assess the effect of a 1:1 THC:CBD oil on reducing spasticity in chronic SCI patients Design: A single-center, placebo-controlled, double-blind crossover clinical trial. Methods: Sixteen chronic SCI patients with intractable spasticity were randomly assigned to either the intervention (1:1 THC:CBD oil) or control (placebo) phase for 1 month, then crossed over. The primary outcome (combined Ashworth Scale [AS] of all involved muscle groups) and the secondary outcomes, including patient-rated visual analog scale (VAS) of spasticity, were assessed before and after both phases and analyzed using a multilevel mixed-effects model. Results: All participants completed the study. The average (SD) dose of THC:CBD oil was 11.6 (1.3) mg. No significant difference in the total AS score for all involved muscle groups was found between the pre- and post-treatment phases, or between the experimental and control phases (all p > 0.05). A significant reduction was observed in the patient rating VAS (effect size = −13.9 [95% CI: −25.5 to −2.3; p = 0.010). Conclusion: In people with chronic SCI who had intractable spasticity, there was no statistically significant effect of 1:1 THC:CBD oil on spasticity-related outcomes, except for patient rating VAS reduction. Further studies are needed to evaluate the efficacy of higher doses of THC (>12 mg/day) and to use patient-reported spasticity scores as the primary outcome measure. Trial registration: The study was registered with the Thai Clinical Trials Registry (TCTR identification number: TCTR20220329001).