Spinal cord injury can result in serious neuropathic pain, but new research suggests cannabis may help.
It is a little known phenomena that injury to the spinal cord may lead to the loss of full functioning in the neurons responsible for pain processing. Most comprehend that there can be loss in nerve transmission, resulting in paralysis. But, spinal cord injury can also result in severe and chronic pain. One major risk factor is subsequent injury.
What happens is that the circuitry that would normally stop sensory inputs, including pain. Functions of the intact spinal cord become deranged in the damaged spinal cord. The result is debilitating neuropathic pain. It is very difficult to treat spinal cord injury and new approaches to treatment are constantly being sought because the available strategies are largely ineffective. Recent research suggests that patients may find relief in treatments that target support cells of the central nervous system.
Cannabinoid Therapy for Spinal Cord Injury
Researchers discovered that targeting support cells, like glial cells, could modulate pain. The most abundant cell type in the central nervous system are these glial cells. While these are not able to conduct electrical current, glial cells provide support and cushioning for cells that do. Different types of glial cells also support neuronal cells by conducting surveillance (as an immune function) and monitoring inflammatory response.
Cannabinoids are known to alter glial function and several clinical studies, involving administration of cannabis, demonstrated the ability of these support cells to block neuropathic pain. Recently, a new study, published in the Journal of Pain (2016), compared the painkilling abilities of different strengths of vaporized cannabis in 42 participants who suffered from spinal cord injury related to traumatic injury or disease.
The participants were between eighteen and seventy years old, with a self-reported pain level of at least four on a ten scale. All participants began with a seven day ‘wash out period.’ During this time, they were to refrain from cannabis. Participants continued prescribed medications. The study was a randomized, double-blind, placebo controlled, crossover clinical trial. This is the ‘gold standard’ in research medicine.
The tests involved two different strengths of cannabis. The strengths for two test groups were 2.9 percent and 6.7 percent THC. A third group was the placebo (0% THC). Each session was eight hours, separated by seven days. Each session involved vaping cannabis or a placebo. The researchers assigned such that each participant was their own control.
Study Finds Better Pain Relief With High Potency Cannabis
The researchers found a significant improvement in pain scores that correlated with the higher doses of THC. There was virtually no improvement with placebo, but significantly less pain with 2.9% THC vaporized cannabis, and then even less pain with 6.7% THC vaporized cannabis. Additionally, they also found that the analgesic effects were long lasting. Pain intensity was significantly less even one hour after administration.
Successful Phase I Clinical Trial on Glial Cell Cannabinoid Therapy
The authors recognized that this was a phase I clinical study, involving only 3 treatment session. Phase I involves healthy subjects in a clinical setting. It has the purpose of determining if the medicine is safe to check for efficacy. Positive results also imply efficacy.
In support of these findings, patients with spinal cord injuries report consumption in other parts of the world. These patients report that they consume cannabis for symptom relief. For example, a recent evaluation of recreational and medical cannabis consumption in individuals with traumatic spinal cord injury in Denmark was published. This survey revealed that sixty-five percent of the patients use cannabis for spinal cord injury related consequences, and that almost all of them reported at least a good effect on pain and spasticity.
The addition of cellular targets, such as glial cells, in designing therapeutic strategies for spinal cord injury may be exactly what will revolutionize this treatment field. Cannabinoid signaling was already described in glial cells almost two decades ago when it was found that these neuronal support cells have CB receptors. The mode of action for THC and pain relief is the binding and activating of THC to CB2 receptors. Therefore, CB2 receptor activation on glial cells may provide this analgesic effect.
Cannabinoid Therapy May Reduce Opioid Use
If THC is able to effectively manage the pain of spinal cord injury, this could also lead to the much needed reduction in opioid use. This would, not only mitigate addiction concerns for these chronic pain patients, it was also improve overall health by eliminating associated side effects of opioid painkillers.