Researchers show benefits of medical cannabis for chronic pain

For years the use of cannabis as medicine has been debated by governments, doctors and the public. A new study from McGill University shows real evidence that cannabis offers relief for patients with chronic neuropathic pain.

The study, Smoked cannabis for chronic neuropathic pain: a randomized controlled trial authored by Mark A. Ware MBBS, Tongtong Wang PhD, Stan Shapiro PhD, Ann Robinson RN, Thierry Ducruet MSc, Thao Huynh MD, Ann Gamsa PhD, Gary J. Bennett PhD, Jean-Paul Collet MD PhD is in the current issue of the Canadian Medical Association Journal.

Lead author Dr. Mark Ware said that this trial was the first time that allowed patients to smoke cannabis at home and to daily monitor their responses. The subjects were given low doses (25 mg) of inhaled cannabis containing approximately 10% THC smoked as a single inhalation using a pipe three time daily over a period of five days. Within the first few days the chronic neuropathic pain patients found modest pain reduction. Patients also were found to be in better moods and had improvements to their sleep. When subjects were given cannabis strains containing less than 10% THC the benefits were lessened.

"The patients we followed suffered from pain caused by injuries to the nervous system from post-traumatic (e.g. traffic accidents) or post-surgical (e.g. cut nerves) events, and which was not controlled using standard therapies" explains Dr. Ware in a press release. "This kind of pain occurs more frequently than many people recognize, and there are few effective treatments available. For these patients, medical cannabis is sometimes seen as their last hope."

The trial consisted of 23 subjects with a mean age of 45.4, all were over the age of 18, 12 of the subjects were women. The subjects all suffered from neuropathic pain of at least three months in duration caused by trauma or surgery, with allodynia or hyperalgesia, and with an average weekly pain intensity score greater than 4 on a 10-cm visual analogue scale.

Prairie Plant Systems provided the herbal cannabis for the study. Longer time frame studies are needed to further evaluate the long-term safety of medical cannabis. These studies will need to study higher doses of THC.

"Our challenge as researchers is to continue to conduct rigorous clinical studies on the medical use of cannabis with strict attention to details such as quality and dosage," says Dr. Ware. "This will allow us to move the debate forward by providing reliable scientific clinical data."

These studies are needed as current treatments for pain management do not help all patients with neuropathic pain. Cannabis can produce moderate relief for these patients and the analgesic effect is more pronounced could be more pronounced in central, as opposed to peripheral, neuropathic pain.