Marijuana May Help Ease Nerve Pain
But evidence for using pot to treat other types of pain or post-traumatic stress remains inconclusive
By Randy Dotinga
MONDAY, Aug. 14, 2017 (HealthDay News) — Marijuana may be slightly effective at reducing chronic nerve pain known as neuropathy. But there’s little evidence on whether or not pot helps treat other types of pain or post-traumatic stress disorder (PTSD), a pair of new studies suggests.
The findings on neuropathy “fit generally well with what we know,” said Dr. Sachin Patel of the Vanderbilt Psychiatric Hospital in Nashville. Patel wrote a commentary accompanying the review in the Aug. 15 online edition of Annals of Internal Medicine.
Medical marijuana is legal in almost all states and the District of Columbia for certain medical purposes. Some states may have laws that haven’t yet been implemented, according to NORML, a pro-marijuana legalization group.
But research into the medical uses of marijuana remains controversial. Plus, it’s difficult for scientists to study the drug because it is illegal on the federal level.
However, some research has found positive results. Earlier this year, the National Academy of Sciences released a report saying there is conclusive or substantial scientific evidence that marijuana is effective at treating chronic pain, calming muscle spasms caused by multiple sclerosis, and easing nausea from chemotherapy.
The new reviews into pain and PTSD were commissioned by the U.S. Department of Veterans Affairs. The department refused to allow the authors of the reviews to be interviewed to discuss the findings.
Curt Cashour, a spokesman for the department, declined to provide any comment about the reviews.
However, Cashour did provide a written statement with a comment from David Shulkin, the secretary of the Department of Veterans Affairs. The statement said the VA system will not prescribe medical marijuana although “there may be some evidence that this is beginning to be helpful.”
For the review of research into chronic nerve pain and marijuana, the researchers examined 27 studies. The investigators determined that there’s “low strength” evidence that marijuana can help nerve pain. But there’s just not enough reliable research to come to a conclusion about whether marijuana is useful for other types of pain, the study authors determined.
The researchers also looked at 32 studies and 11 reviews of research on side effects. They noted several potential risks of marijuana use such as car accidents, psychotic symptoms and “short-term cognitive impairment.”
However, the review noted that research into risks and side effects is limited.
The researchers said their findings may have “limited applicability to older, chronically ill populations and patients who use cannabis heavily.”
Paul Armentano, deputy director of NORML, said the review findings are consistent with other research reviews. He added that the findings are also consistent with “anecdotal reports of patients, many of whom are seeking a safer alternative to the use of deadly opioids. And it is inconsistent with the federal government’s classification of the marijuana plant as a schedule I controlled substance with ‘no currently accepted medical use in treatment in the United States.’ “
In the second review, researchers looked at three studies and two reviews of marijuana as a treatment for PTSD. The investigators found only a very low level of research. In addition, they said, the research had a “medium- to high-risk of bias.”
There’s no way to come to conclusions based on the few studies currently available. But “several ongoing studies may soon provide important results,” the study authors wrote.
Why is there so little research into medical marijuana?
“Much of the lack of evidence may have to do with difficulty accessing cannabis and funding for clinical studies,” Patel said.
NORML’s Armentano said anti-pot laws and politics have “greatly impeded researchers’ ability to conduct the sort of robust, large-scale, prolonged clinical trials that are typically associated with eventual U.S. Food and Drug Administration drug approval.”
Armentano added that most large studies are funded by pharmaceutical companies trying to get a drug to market.
Patel advised patients to be cautious about medical pot.
“Just because states list certain conditions for which medical cannabis can be prescribed does not mean there is strong or rigorous scientific data supporting its use,” he said.
Patel advised doctors to “follow the data and inform patients about the state of the evidence. Make sure patients are aware of potential benefits, but also potential harms.”
But evidence for using pot to treat other types of pain or post-traumatic stress remains inconclusive
Tingling. Burning. Shooting. Stabbing. If you suffer from neuropathic pain, these unfortunate adjectives are all too familiar.
Neuropathic pain, or neuropathy, is a catch-all term for pain caused by damage to the nervous system. It’s one of the most common forms of chronic pain, affecting one to two per cent of the population and producing feelings of weakness, numbness, tingling and burning.
“Neuropathic pain is something we see a lot in our older patients,” says Natural Care’s Director of Patient Care, Karen Newell, who is also a registered practical nurse. “It’s fairly common in seniors because they are likely to be dealing with one or more of the conditions that cause it.”
What causes neuropathic pain?
Neuropathy has many causes, including:
- Autoimmune diseases (including diabetes, multiple sclerosis, lupus, rheumatoid arthritis and thyroid disorders)
- Chemotherapy treatment
- Exposure to toxins
How long does neuropathic pain last?
Neuropathic pain can come and go over the course of a day, or even come and go over weeks and months. There’s no one set path for the journey through neuropathic pain. For most, it’s a chronic companion, for some, it’s a temporary travelling partner who can be kicked to the curb.
Can cannabis help neuropathic pain?
Anecdotally, several of our patients report that cannabis helps with their neuropathic pain, but so far the evidence is mixed.
A review published in the AMA Journal of Ethics concluded that cannabis is comparably effective to the traditional agents used to treat neuropathic pain. The review looked at studies conducted with vaporized or smoked cannabis flower of low to medium THC concentration (two to nine per cent). Study subjects ranged from HIV patients dealing with neuropathy to healthy volunteers who had been purposefully injected with pain-inducing capsaicin (the ingredient that makes peppers hot).
Another review, which looked at studies conducted with a range of cannabis products – from synthetic cannabinoids, to sprays containing a mix of THC and CBD, to inhaled flower and more found “no high-quality evidence” to support the use of cannabis for neuropathic pain, citing side effects of sleepiness, dizziness and mental problems compared with placebo.
These reviews are interesting because they both draw their conclusions from a mixed bag of studies, often featuring multiple and diverse cannabis products used to treat neuropathy of multiple and diverse origins. Imagine a sommelier saying “wine never pairs with meat” or “wine always pairs with meat” and you can easily understand the problem we face in interpreting these kind of broad reviews.
Determining the right cannabis product for a specific health goal is more complicated than choosing the right wine for dinner: cannabis comes in many different strains, strengths and formats (vaporized, ingested capsules and oils, etc), and every person processes it differently, making it difficult to generate conclusive prescriptions.
Interestingly, smaller studies looking at specific products and dosages tend to generate more promising results:
A 2013 double-blind, placebo-controlled study published in the Journal of Pain found that low-dose cannabis (1.29 per cent THC or less) significantly improved neuropathic pain when compared with medium-dose and placebo cannabis. Most of the subjects in this study had already experienced poor results with conventional neuropathic pain treatments, leading its authors to conclude that “vaporized cannabis, even at low doses, may present an effective option for patients with treatment-resistant neuropathic pain.”
Similarly, a 2010 trial published in the Canadian Medical Association Journal looked at 23 patients who were assigned three different strengths of cannabis to manage post-traumatic and post-surgical neuropathic pain. The conclusion? “A single inhalation of 25 mg of 9.4% tetrahydrocannabinol herbal cannabis three times daily for five days reduced the intensity of pain, improved sleep and was well tolerated. Further long-term safety and efficacy studies are indicated.”
Cannabis Pharmacy author Michael Backes writes that this study is particularly significant because the best results were observed at the lowest dose, highlighting “the unexpected medical effectiveness of cannabis dosages that are far below those commonly consumed within the medical community.”
Finding the right product and dose for your neuropathic pain
Backes suggests that a variety of cannabis products, from topicals to oils to flower, may help a variety of neuropathy-related symptoms.
Natural Care nurse practitioner Lynn Haslam says she typically starts neuropathic pain patients on a low nighttime dose of a balanced CBD to THC oil. “We really want the pain managed so they can sleep,” she says. “Neuropathic pain typically gets worse at night, electric shock-like. We may not be able to diminish all of these sensations, but if we can restore sleep, which will help decrease pain during the day, that may be a reasonable goal.”
Setting realistic goals and weighing risks versus benefits is important when working with any medication, adds Haslam. “First-line therapy for neuropathic pain can be nortriptyline or amitriptyline,” she says, “and these medications can cause issues with older adults. This is the same with the other medications commonly used – gabapentin or pregabalin. I think cannabis is usually worth trying.”
In the absence of research that conclusively says which dose and product will work for which type of patient, Natural Care takes a conservative, personalized approach.
“Of course, we follow the latest cannabis research with great interest,” says Newell. “The more studies the better. But on a day to day basis, we weigh potential risks and benefits in a highly individual way – what medications is the patient taking? Are they at risk for drug interactions or falls? Have they had good or bad experiences with cannabis already? What is the nature of their pain, and have they tried other treatments? Then we start at the lowest dose possible and see if it helps. For many of our neuropathic pain patients, that’s enough.”
Natural Care Tingling. Burning. Shooting. Stabbing. If you suffer from neuropathic pain, these unfortunate adjectives are all too familiar. Neuropathic pain, or neuropathy, is a catch-all term