Medical Marijuana and Spasticity: MS, Spinal Cord Injury, and the Nabiximols Evidence

If there's one therapeutic application where medical marijuana has the strongest clinical evidence, it's spasticity. Not pain — though the pain evidence is solid. Not nausea — though that's well-established too. Spasticity, particularly from multiple sclerosis, is where the cannabinoid research is most mature, most replicated, and closest to mainstream medical acceptance.

Nabiximols (brand name Sativex) — an oromucosal spray containing THC and CBD in a 1:1 ratio, extracted from standardized cannabis plants — is approved for MS spasticity in over 25 countries. Not the United States, where it remains unapproved due to Schedule I complications, but in the UK, Germany, Spain, Italy, Canada, Australia, and most of Europe.

The fact that a cannabis-derived medication is standard treatment for spasticity throughout the developed world — while American patients must navigate state medical marijuana programs for the same compound — is one of the more absurd consequences of U.S. scheduling policy.

Understanding Spasticity

Spasticity is a motor disorder characterized by velocity-dependent increases in muscle tone — muscles that resist stretching, contract involuntarily, and produce stiffness, spasms, and pain. It results from damage to the upper motor neurons in the brain or spinal cord.

The mechanism: normally, inhibitory signals from the brain modulate spinal motor neuron excitability, keeping muscle tone in balance. When these descending pathways are damaged — by MS plaques, spinal cord injury, stroke, cerebral palsy, or traumatic brain injury — the balance shifts toward excitation. Motor neurons fire more readily, muscles contract when they shouldn't, and the result is the stiffness, clonus, and painful spasms that characterize spasticity.

Current treatments include:

• Baclofen: A GABA-B receptor agonist. Effective but causes drowsiness, cognitive dulling, and weakness at higher doses.
• Tizanidine: An alpha-2 agonist. Similar efficacy to baclofen with different side effects (dry mouth, sedation, liver toxicity risk).
• Dantrolene: Acts directly on muscle. Less CNS side effects but can cause hepatotoxicity.
• Botulinum toxin: Injected locally for focal spasticity. Effective but requires repeated injections and targets only specific muscles.
• Intrathecal baclofen pump: For severe spasticity. Surgically implanted, delivering baclofen directly to the spinal fluid. Effective but invasive and carries risks of pump malfunction and withdrawal syndrome.

These treatments help many patients but leave a substantial gap. A 2012 survey of MS patients found that 44% reported inadequate spasticity control despite pharmacological treatment.

The Nabiximols Evidence Base

Nabiximols is the most extensively studied cannabis-based medicine for any indication. The evidence base includes:

Phase III Randomized Controlled Trials

Novotna et al., 2011 (European Journal of Neurology): 572 MS patients with treatment-resistant spasticity. After a 4-week single-blind trial period, responders (patients who achieved at least 20% improvement) were randomized to nabiximols or placebo for 12 weeks. The nabiximols group showed significantly greater improvement on the NRS (Numerical Rating Scale) for spasticity compared to placebo (p = 0.0002).

Langford et al., 2013 (Journal of Neurology, Neurosurgery & Psychiatry): 335 MS patients randomized to nabiximols or placebo for 48 weeks — one of the longest cannabis-medicine trials conducted. Nabiximols showed sustained benefit in spasticity control with no evidence of tolerance development.

Collin et al., 2007 (Neurology): 189 patients. Nabiximols produced statistically significant improvement in spasticity NRS compared to placebo. Secondary outcomes including sleep quality and carer-assessed functional improvement also favored nabiximols.

Meta-Analyses and Systematic Reviews

Whiting et al., 2015 (JAMA): The landmark systematic review of cannabinoids for medical use. For spasticity in MS, the review found moderate-quality evidence supporting the use of nabiximols, with an average reduction in spasticity NRS of approximately 0.76 points compared to placebo. The number needed to treat (NNT) for a clinically significant response was approximately 8.

Nielsen et al., 2022 (JAMA Network Open): Updated meta-analysis confirming nabiximols efficacy for MS spasticity, with effect sizes consistent across trials and subgroups.

The National Academies of Sciences, Engineering, and Medicine (2017): Concluded that there is "conclusive or substantial evidence" that cannabis is effective for the treatment of spasticity in MS — one of only three therapeutic areas receiving this highest evidence rating.

Long-Term Data

Real-world evidence from post-marketing surveillance in countries where nabiximols is approved shows:

• Sustained efficacy over 12+ months without dose escalation in most patients
• Favorable safety profile with the most common adverse events being dizziness, fatigue, and dry mouth
• No evidence of cannabis use disorder development at therapeutic doses
• Improved quality of life metrics and reduced concomitant antispasticity medication use

How Cannabinoids Work on Spasticity

The endocannabinoid system is directly involved in motor control and muscle tone regulation. The mechanism for spasticity reduction involves multiple pathways:

Presynaptic Inhibition at the Spinal Level

CB1 receptors are located on presynaptic terminals in the spinal cord. When activated by THC or endocannabinoids, they reduce neurotransmitter release from excitatory neurons — effectively dampening the excessive motor neuron firing that produces spasticity. This is a direct, pharmacologically elegant mechanism: cannabinoids modulate the same inhibitory circuits that are impaired by the upper motor neuron damage causing spasticity.

Supraspinal Motor Modulation

CB1 receptors in the basal ganglia, cerebellum, and motor cortex modulate descending motor control signals. THC's effects on these circuits contribute to the muscle relaxation and reduced spasm frequency patients report.

Anti-inflammatory Effects at Lesion Sites

In MS specifically, spasticity severity correlates with active demyelination and inflammation. CBD's anti-inflammatory properties — mediated through CB2 receptors, TRPV1 activation, and adenosine reuptake inhibition — may reduce inflammation at MS lesion sites, potentially addressing a root cause of worsening spasticity rather than just the symptom.

Pain Modulation

Spasticity is rarely painless. The muscle spasms themselves are painful, and many spasticity-causing conditions involve concomitant neuropathic pain. Cannabinoids' analgesic properties address both the spasticity and the pain simultaneously — something that baclofen and tizanidine do less effectively.

Beyond MS: Other Spasticity Conditions

Spinal Cord Injury

Spinal cord injury (SCI) affects approximately 300,000 Americans, with spasticity developing in 65-78% of patients within the first year. The spasticity of SCI is often severe, painful, and disruptive to sleep and functional independence.

A 2007 randomized crossover trial by Pooyania et al. in Spinal Cord found that nabilone (a synthetic THC analog) significantly reduced spasticity in SCI patients compared to placebo, as measured by the Ashworth Scale. A 2015 observational study by Andresen et al. in Spinal Cord reported that 71% of SCI patients using medical cannabis experienced improvement in spasticity, with 38% reducing their use of other antispasticity medications.

The American Academy of Neurology's 2014 systematic review concluded that oral cannabis extract was "probably effective" for MS spasticity as measured by patient-reported outcomes and "possibly effective" for SCI spasticity, noting the smaller evidence base for SCI.

Cerebral Palsy

Cerebral palsy (CP) is the most common motor disability in childhood, and spasticity is its most prevalent feature. Evidence for cannabinoid treatment of CP-related spasticity is limited but growing:

• A 2020 case series published in Developmental Medicine & Child Neurology reported that CBD-enriched medical cannabis improved spasticity and quality of life in pediatric CP patients
• Preclinical models suggest that cannabinoids' neuroprotective and anti-inflammatory properties could benefit CP-related brain injury

The ethical and regulatory complexities of studying medical marijuana in children make this a slow-moving research area, but the mechanistic rationale is strong.

Stroke-Related Spasticity

Post-stroke spasticity affects approximately 20-40% of stroke survivors, typically developing in the weeks to months following the event. No clinical trials specifically examine cannabinoids for post-stroke spasticity, but:

• The pathophysiology (upper motor neuron damage) is mechanistically similar to MS and SCI spasticity
• Cannabinoids' neuroprotective properties may be relevant in the post-acute stroke period
• Case reports describe benefit, though controlled data is lacking

Practical Considerations for Spasticity Patients

Product Selection

The nabiximols data supports a 1:1 THC:CBD ratio as the evidence-based starting point for spasticity. In the Florida medical marijuana program, patients can access:

• Tinctures with calibrated THC:CBD ratios
• Capsules with standardized cannabinoid content
• Vaporized products for acute spasm relief (faster onset than oral)

Dosing

Nabiximols clinical trials used a self-titration protocol:

1. Start with 1 spray (2.7 mg THC + 2.5 mg CBD)
2. Increase by 1 spray per day
3. Maximum 12 sprays per day
4. Most patients stabilized at 8-12 sprays daily

Translating this to available medical marijuana products: the daily therapeutic THC range for spasticity is approximately 15-30 mg THC combined with 15-30 mg CBD, divided into 3-4 doses throughout the day. At CORAL, Dr. Kim helps patients develop a titration schedule appropriate for their specific product and condition.

Timing

Spasticity often worsens at night — nocturnal spasms are a common complaint and a major contributor to sleep disruption. Many patients benefit from a slightly higher dose before bed, using a longer-acting formulation (tincture, capsule, or edible) to maintain effect through the night.

Drug Interactions

Baclofen, tizanidine, and benzodiazepines all have CNS depressant effects that can be additive with THC. Patients on these medications should start at lower medical marijuana doses and titrate slowly under physician guidance. The goal for many patients is partial substitution — reducing the dose of conventional antispasticity medications as medical marijuana provides additional benefit — rather than abrupt switching.

The Gap Between Evidence and Access

The irony of medical marijuana for spasticity is stark: the evidence base is stronger than for many FDA-approved medications. Nabiximols is approved in countries with some of the most rigorous pharmaceutical regulatory standards in the world. Yet in the United States, patients must navigate state medical marijuana programs to access what is, in much of the developed world, a standard prescription.

This isn't a failure of evidence. It's a failure of federal drug policy. And until that policy changes, state programs remain the practical access pathway.

In Florida, MS, spinal cord injury, and comparable conditions qualify for medical marijuana certification. At CORAL, Dr. Kim provides telehealth evaluations for patients with spasticity from any qualifying neurological condition.

Dealing with spasticity that conventional medications aren't adequately controlling? [Start your evaluation at coral.clinic/start](https://coral.clinic/start).