Chronic pain from failed back surgery is notoriously difficult to manage. Might medical marijuana hold promise?
A 52-year-old man with chronic low back pain and hypertension (controlled) comes to see you for his annual physical. Approximately 15 years ago he underwent spinal fusion after a bulging disc at L4-L5 was found on an MRI. The surgery provided him a bit of relief for a few months but his back pain soon returned to the presurgery level. He has used various analgesic medications including acetaminophen and NSAIDs over the years and at best these have offered him some mild relief. Several years ago another physician prescribed hydrocodone/acetaminophen (Vicodin) and then oxycodone/acetaminophen (Percocet) but the patient reports that while they each offered him a bit more relief than the other medications, he found these too sedating.
He has heard about medical marijuana and lives in a state where it has been approved for the management of chronic pain. His only experience with marijuana was smoking it while in college more than 30 years ago. He is willing to try it if it would help his pain but he’d like to know whether you think there is a likelihood that it would be beneficial for his low back pain.
1. You tell him that, based on currently available medical evidence:
A. There is a very good chance that marijuana would be beneficial for his pain.
B. There is limited evidence that marijuana would be beneficial for his pain.
C. You refuse to discuss the use of marijuana as it is still against Federal law.
D. Although marijuana may be beneficial for chronic pain, the evidence is far stronger supporting its use for other medical conditions.
Answer: B. There is limited evidence that marijuana would be beneficial for his pain.
There are a limited number of studies on use of any of the cannabinoids for pain and those that have been performed indicate that they are most likely to be beneficial for neuropathic pain. Despite claims that cannabinoids are effective for a wide range of conditions including depression, glaucoma, and epilepsy, the evidence supporting their use for these conditions is of an even lower quality than that for chronic pain.
The patient asks you whether marijuana is likely to provide more analgesia than the acetaminophen and NSAIDs he is currently taking or the opioids he took in the past.
2. You respond:A. It is very likely that marijuana will provide more analgesia than these other medications.
B. No other analgesic medications are ever more effective than opioids.
C. There is too little research for you to make an informed statement regarding this.
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Answer: C. There is too little research for you to make an informed statement regarding this.
There are very few studies comparing cannabinoids to other analgesics. In the one that compared it to an opioid (dihydrocodeine), the opioid was found to be more effective.
When he used marijuana in college, he had no problems with it as far as he can recall. He has heard that it is essentially side-effect free and asks you if this is true.
3. You respond that:
A. There is an increased risk of a number of adverse events associated with the use of cannabinoids including dizziness, nausea, fatigue, euphoria, and drowsiness.
B. If he had no problems when he previously used it, it is unlikely he would have any problems with it now.
C. It would be dangerous to try it in light of his hypertension.
Answer: A. Multiple adverse events can occur with the use of cannabinoids including those listed.
As to the predictive value of his previous experience with marijuana, it is impossible to know the strength or dose of the marijuana he had used. Thus there is no feasible way to determine whether or not he would have problems with a cannabinoid he would be prescribed now.
Would you consider prescribing medical cannabis if it becomes legal to do so in your state? What are your thoughts on this politicotherapeutic groundswell?
Whiting PF, Wolff RF, Deshpande S, et al. Cannabinoids for medical use: a systematic review and meta-analysis. JAMA. 2015;313:2456-2473.
Hill KP. Medical marijuana for treatment of chronic pain and other medical and psychiatric problems: a clinical review. JAMA. 2015;313:2474-2483.