There has been a lot of buzz about cannabis being a great option for pain management, but for cannabis consumers, there are still a lot of unknowns when it comes to understanding the biology of pain and how cannabis interacts with our bodies to reduce that pain. That’s why it’s important to understand some fundamental details about pain. We’ve broken down the different types of pain and the way cannabis interacts with each type so you can better understand how cannabis can benefit you.
Pain is Multifactorial
Pain is caused or influenced by many “factors.” Some people are able to walk on a hotbed of coals, while others are unable to tolerate a bed sheet touching their toes. The varying sensitivity to pain is due to the many factors that contribute to pain. Fundamentally, pain happens when an injury sends a nerve signal to the brain. The brain then interprets the pain. This is why pain from the same source will affect people differently. Alongside the actual pain signal, a person’s mental or emotional condition will affect how pain is interpreted.
It is also true that pain is different depending on the location of the injury. An injury on the skin will feel different than an injury on the nerve and different than an injury in the brain. The active ingredients in cannabis products reduce pain in many ways. Cannabis reduces inflammation, reduces nerve transmission, relaxes muscles and reduces the anxiety causes by pain. Some people also claim that cannabis helps them to not pay attention to pain. By attacking pain in many ways, cannabis addresses the multifactorial nature of pain.
Biology of Pain
From itch to burning pain, the skin is the source of pain in many patients. The skin has many free nerve endings that signal pain to the brain. Scientists have described free nerve endings like the root endings to a plant. Injuries at the skin release a set of neurotransmitters or chemicals that attach to receptors located at the free nerve endings. A signal is created that travels via the nerve to the spinal cord and then to the brain where it is interpreted.
One of the more important receptors that signal the transmission of pain is called the TRP receptor. Preclinical studies conclude that CBD, an active ingredient in cannabis binds to the TRP receptor blocking pain transmission. This may be one of the ways cannabis products reduce pain. It’s also understood that components of cannabis attach to cannabinoid receptors and reduce inflammation – another major aspect of pain. Finally, it’s well known that both THC and CBD reduce anxiety and improve depression, both important emotional components of pain. Therefore, pain is seen to be affected in three major ways while most prescription medicines address only one aspect of pain.
Muscle, Ligament, or Tendon Pain
Damaged tissue or overused body parts result in muscle, ligament or tendon pain. Sports related trauma and work related repetitive actions are common causes of this type of tissue injury. Bones fall out of alignment, ligaments and tendons tear and get inflamed, and muscles contract or spasm causing immobility and pain. This happens frequently in people who have neck and low back problems.
Damaged muscle repairs quickly and is not generally the source of pain. However, damaged ligaments and tendons are slow to repair and can be a source of chronic pain. Tendonitis is frequently the diagnosis in repetitive overuse injuries. Free nerve endings are found on ligaments, tendons and the outer fibrous capsule of the muscle bed. As in the skin, a signal is sent via the TRP receptor and interpreted in the brain. Topical cannabis products are an excellent resource for muscle, tendon or ligament pain. The thicker the salve or lotion, the longer it stays on and the longer it works. Some topical product manufacturers add penetrants for fast relief. It may be difficult to get topical cannabis products to penetrate these deeper tissues so inhaling or ingesting cannabis products may the necessary to alleviate muscle, tendon or ligament pain.
Remember that pain signals travel from injury via the nerves, up the spinal cord and are interpreted by the brain. So, what happens when the nerve itself is damaged? That result is nerve pain or neuropathy. Damaged nerves continue to send signals of pain. As the damage increases, a person will feel numbness change to tingling or burning to a deeper ache or sharp pain. If the nerve is completely severed, as in amputees, the brain also continues to interpret pain in the area of the amputation. This type of pain is called phantom pain.
Diabetes damages small nerves and causes a neuropathy that results in pain in hands and feet. Sciatica is a type of nerve pain caused when discs or bones in the lower back pinch or put pressure on a nerves exiting the spinal cord resulting in pain or numbness down the leg foot or toes. Cannabis products reduce nerve pain by blocking the transmission of the pain signal coupled with relieving anxiety or depression caused by chronic nerve pain. Patients have claimed successful reduction of pain with all methods of use.
Osteoarthritis and fractures are the most common forms of bone pain. Osteoarthritis occurs in the joint space between bones. Free nerve endings are prevalent on the outer surface of bones sending pain signals to the brain via the spinal cord. Repetitive movement and pressure at the joint space wears down the protective cartilage exposing bone surface. Rather than cell death, damaged or exposed bones cells grow in an awkward fashion creating bone spurs, also called osteophytes. The spurs will enter a joint space or push into a tendon or ligament resulting in pain. Bone spurs are sign of Osteoarthritis. Osteoarthritis is common in the elderly because, over time, moving parts wear down cartilage. In the case of Osteoarthritis, moving parts result in bone spurs. Fractures, gout and rheumatoid arthritis are other common forms of bone pain in which the treatment is to use anti-inflammatory medication. Cannabis products are anti-inflammatory and as a consequence are useful for bone pain. As with muscle, tendon or ligament tissue damage, deeper pain may require ingesting or inhaling cannabis products.
When pain signals reach the brain that is when a patient experiences emotional pain. The signals enter the thalamus, which relays to different parts of the brain. The relayed signals enter the sensory cortex where they are interpreted as sharp or dull, aching pain. The thalamus also sends signals to the limbic area of the brain where emotions are felt. The thalamus sends signals back down the spinal cord where pain sensation can be amplified or dampened. The dampening of pain via the spinal cord is called descending neural inhibitory control and is how athletes or traumatic accident victims block out pain.
The emotional experience of pain will be different depending on childhood experiences and culture. As pain persists and becomes chronic, pain signals dissipate and persist to a point where the source is less obvious. Chronic pain also creates anxiety and depression, which in turn causes the vicious cycle of increased pain. In this way, pain alters mood and mood alters the experience of pain. CBD specifically binds to 5HTa (serotonin) receptor reducing anxiety, depression and emotional pain.
Recent studies show that people with chronic pain who use cannabis products reduce their opiate use. Cannabinoids bind to cannabinoid receptors while opiates bind to mu receptors. The two pain substances work through different biochemical mechanisms. Opiate overdose occurs when mu receptors in the brain stem are activated reducing the body’s natural respiratory drive. As a result, victims stop breathing and die. In 2015, opiate overdoses were responsible for more than 33,000 deaths according to the Center for Disease Control.
There are no cannabinoid receptors in the brain stem and thus respiratory arrest is not a side effect of cannabis use. Pharmaceutical companies are investigating the combination of cannabis-derived compounds with opiates as a way to improve pain control and reduce opiate overdose. Non-steroidal anti-inflammatories such as ibuprofen or naproxen are commonly prescribed for pain; however, with chronic use they can cause bleeding ulcers and kidney damage. Other pain medicines such as gabapentin alter the transmission of nerve signals. Other than cannabis products, there are no known medicines that affect pain in multiple ways and address the multifactorial nature of pain.
Cannabis Dosage for Pain
There are at least four or five active ingredients produced by cannabis that affect pain. Alone, each active ingredient may reduce pain. But, it is the synergy of multiple active ingredients that is likely to be most effective for pain. Typically THCA or CBD are used in the daytime because they are non-sedating and non-psychoactive. THC or CBN are used at night for sleep.
The CESC, a non-profit research group recently released the first clues on dosage of smoked cannabis flower for pain. In an observational study called The Dosing Project, Participants reported a significant reduction in pain of smoking or vaporizing ½ to ¾ of a gram of cannabis flower. Dr. Raphael Mechoulam, founder of the Endocannabinoid System recommends 10 milligrams per kilogram body weight of CBD per day to maximize the anti-inflammatory effect. The average adult would need 100 mg to 200 mg doses of CBD to approach the recommended amount. Scientists are still in an investigational phase in our understanding of cannabis product dosing. With more study and better products, pain relief will improve using cannabis products.
Whether you are looking to incorporate cannabis into your pain management regimen, have been using it for many years, or would like to reduce your use of pharmaceutical drugs, understanding different forms of pain and how they interact with medicine is key in determining your next steps.
Jean Talleyrand, MD
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