Can you help with nerve pain?

The researchers reported that the psychoactive component of marijuana, delta-9-tetrahydrocannabinol (THC), was associated with a reduction in neuropathic pain and corresponding functional brain changes.

Haggai Sharon, MD, of the Haggai Sharon study, the small Tel Aviv Medical Center lab in Israel and his colleagues from Neurology.

The graph theory analyzes also showed reduced network connectivity in the areas involved in the treatment of pain, particularly in the dorsolateral lateral prefrontal cortex. Connectivity changes were correlated with less pain.

"We have found a reduction in functional connectivity, a major measure of brain networking, between areas of the brain that treat aspects of sensation to those that deal with the emotional and cognitive aspects of pain," he said. Sharon. MedPage today. "It may mean that the analgesic effects of cannabis are caused by a break in the pain experience, rather than by a simple influence on the sensation of pain."

Previous research has shown that THC reduces experimentally induced pain in healthy participants and that this analgesic effect correlates with reduced activity of the anterior cingulate cortex. Sharon and co-authors noted that the anterior cingulate cortex was densely populated with THC-activated cannabinoid-1 receptors.

In this study, 15 young men with chronic lumbar radicular neuropathic pain participated in a randomized, double-blind, placebo-controlled trial with a cross pattern. The average age of the patients was 33.3 years; they had moderate to severe chronic pain – more than 40 on a 100-point visual analogue scale (VAS) – and no other known comorbidity. The researchers excluded the women from the trial because evidence suggested that menstrual hormonal fluctuations could alter sensitivity to pain.

Before treatment, participants had a clinical assessment including pain assessment on a scale of 0 to 100 VAS. They had resting fMRI and then received sublingual THC oil or placebo oil (0.2 mg / kg, mean THC dose = 15.4 mg).

The resting scan lasted 6 minutes and patients were asked to keep their eyes closed and to relax, but not to sleep. There was then a second fMRI about 2 hours after the drug or placebo administration.

Nine patients received THC in one session and placebo at a second session; six patients received treatment in the reverse treatment order. Sessions were separated by at least one week to allow for a weaning period (mean interval of weeks = 2.9).

On average, patients rated their pain level at 53 at the beginning of the study. Two hours after using THC, patients rated their pain at an average of 35, compared with an average of 43 for placebo.

The extent of individual pain relief was associated with reduced functional connectivity between the anterior cingulate cortex and the sensorimotor cortex. "The higher the positive functional connectivity at baseline, the greater the benefits of THC administration were important," the authors note.

They reported decreases in the right dorsolateral prefrontal cortical group and in the chronic pain network, which were also associated with a reduction in pain. "These measurements show that, on average, the whole network has become locally less connected and, in particular, the right dorsolateral prefrontal cortex is less linked to it."

Larger studies need to confirm the results, Sharon noted, and research is needed to see if a combination of THC and cannabidiol is superior to THC alone, as some studies have shown on cancer patients. Future work, the researchers said, should include women and should be extended to other chronic pain states to determine if the findings are specific to neuropathy.

2018-05-09T00: 00: 00-0400

Last update 09/05/2018