By Crystal Phend, Senior Staff Writer, MedPage Today
Published: May 14, 2012

Reviewed by Robert Jasmer, MD; Associate Clinical Professor of Medicine, University of California, San Francisco and Dorothy Caputo, MA, BSN, RN, Nurse Planner

This report is part of a 12-month Clinical Context series.

Smoking marijuana cuts spasticity and pain that’s resistant to conventional therapy in multiple sclerosis (MS), although with some cognitive effects, a small clinical trial affirmed.

Spasticity scores on the modified Ashworth scale dropped by an average 2.74-points more with smoked cannabis than with placebo (P<0.001), Jody Corey-Bloom, MD, PhD, of the University of California San Diego, and colleagues found.

A difference of 2 or more points is considered clinically meaningful on the 30-point Ashworth scale summing mobility of elbows, hips, and knees, they reported online in CMAJ.

The smoked cannabis findings support the largely anecdotal evidence from the many MS patients that say smoking it relieves spasticity, the researchers noted.

Trials, though, have focused on orally administered cannabinoids with mixed results.

“Any reductions in spasticity have generally only been seen on subjective ratings,” Corey-Bloom and colleagues noted.

Their trial included 30 patients with treatment-resistant spasticity randomized to double-blind use of a placebo cigarette or smoked cannabis, once daily for 3 days with crossover after an 11-day washout period.

Pain scores, although relatively low to begin with at an average 12 or 13 points on the 100-point Visual Analogue Scale, fell by an additional 5.28 points with medical marijuana compared with placebo (P=0.008).

Not surprisingly, smoking marijuana also reduced cognitive function acutely. Paced Auditory Serial Addition Test scores measured 45 minutes after smoking were down 8.67 points more with cannabis than with placebo (P=0.003).

However, “the clinical significance of this result is uncertain; despite the transient decrease in scores, patients were still within normal ranges for their ages and levels of education,” the investigators pointed out.

“It is worth noting that conventional treatments, such as baclofen and tizanidine hydrochloride, may also affect cognition, although published data are scarce,” they added.

Nevertheless, further attention to the issue is warranted, the group acknowledged.

“Larger, long-term studies are needed to confirm our findings and determine whether lower doses can result in beneficial effects with less cognitive impact,” they suggested.

The researchers cautioned that many of the study participants had previously used cannabis — 80% overall and one-third in the prior year, which raised the question of self-selection bias and may have limited generalizability.

Another limitation was the difficulty of completely blinding participants to the psychoactive substance, although that wasn’t likely to have impacted objectively assessed spasticity scores.

By comparison, in a previous study, sublingual tizanidine hydrochloride (Zanaflex) resulted in a 3-point decline in Ashworth scores after a week of treatment; oral tizanidine showed a 1.81-point decline compared with 1.19-point decline with placebo in prior studies.

A separate trial of intrathecal baclofen (Lioresal) for unresponsive patients demonstrated that intrathecal delivery resulted in a change in mean Ashworth scores from 4 to 1.2.

The study was funded by a grant from the University of California Center for Medicinal Cannabis Research.

The researchers reported having no conflicts of interest.

Primary source: CMAJ
Source reference:
Corey-Bloom J, et al “Smoked cannabis for spasticity in multiple sclerosis: a randomized, placebo-controlled trial” CMAJ 2012; DOI: 10.1503/cmaj.110837.

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