Can Cannabis Help Neuropathy Patients ?
Dec 26, 2019
Can cannabis help with neuropathy? The evidence seems to point to yes, and many US states and other countries now have approved the use of cannabis to treat it.
Research is ongoing, but there is a large and encouraging body of evidence suggesting that cannabis, with its impact on the endocannabinoid system — which is involved in neuropathic pain — is helpful.
By modulating the endocannabinoid system, cannabis may be effective at both reducing pains associated with neuropathy and promoting neurogenesis.
How Cannabis Works on Neuropathy
While the body produces its own natural cannabinoids that interact with the endocannabinoid system, the cannabinoids found in cannabis (such as THC and CBD) are also capable of activating endocannabinoid receptors.
There is strong evidence that the endocannabinoid system is involved in the expression of neuropathy. In animal models, ECS dysfunction has been shown to correlate with neuropathic pain. One study showed that when activity of CB1 — the primary ECS receptor in the central nervous — system was deleted, mice showed signs of increased pain. In another study, deletion of the CB2 receptor — primarily found in our immune system — also led to more pain in mice.
The more CB2 receptors we find in the central nervous system, the more we find a reduction in neuropathic pain. In animal studies of diabetic-induced neuropathic pain, along with chemotherapy-induced neuropathy, activating the CB1 and CB2 receptors also reduced pain. It is noteworthy that other studies using mice whose CB1 or CB2 receptors were blocked did not show changes in pain behavior in animals.
Rat models of neuropathic pain have also found reduced pain responses when CB1 and CB2 were activated. These researchers found that activation of these receptors before an injury could actually prevent the development of pain.
In addition, activation of CB1 and CB2 receptors has been found to promote neurogenesis — the process by which new neurons are formed in the brain. CB1 and CB2 activators increased cell proliferation and survival of brain cells and even restore changes that come with age in the brain. Since neurogenesis is decreased in patients with neuropathic pain, it is possible that increasing neurogenesis could be helpful for neuropathic pain.
Some studies also showed that activation of cannabinoid receptors allowed people to benefit from pain relief from a smaller dose of opiates.
Medical Studies on Cannabis and Neuropathy
There is a large body of preclinical research that suggests cannabis is effective at reducing neuropathic pain in rodents. But what about humans?
Thankfully, there are a few studies — and even some systematic reviews with meta-analysis — that look at whether cannabis might help with neuropathy. The results are generally positive.
A 2015 meta-review covering multiple studies found that several clinical studies demonstrated the pain-relieving effects of cannabis, particularly for pain associated with diabetes, multiple sclerosis, and chemotherapy — three common sources of neuropathic pain.
A 2017 meta-review on cannabis also found that there was conclusive evidence that cannabis is an effective treatment for chronic pain. While this review looked at studies on a variety of different types of chronic pain (including neuropathy), they found cannabis helped for all types of chronic pain studied — regardless of the condition. Acute pain however — like that experienced during surgery or immediately after an injury — was not helped by cannabis. Even more recently, a 2018 meta-review looking specifically at neuropathic pain found that cannabis performed similarly to other pharmaceutical options for pain relief.
One study found that patients who smoked cannabis with low doses of THC showed improvements in neuropathic pain relative to the placebo. A similar study using smoked cannabis with low doses of THC also found pain relief compared to the placebo for multiple sclerosis related pain. In addition, a randomized, double-blinded, placebo controlled study using inhaled cannabis showed a significant dose-dependent effect on pain in patients with diabetic peripheral neuropathy.
Taking cannabis orally can also be helpful. Studies on Sativex — a sublingual spray with equal parts THC and CBD — show it can provide relief from neuropathic pain. In one study on MS patients, Sativex showed pain relief when compared to a placebo at 10 weeks. However at 14 weeks there was no longer a difference between the placebo and Sativex — perhaps suggesting development of a tolerance to cannabis’ pain relieving effects.
Studies of Nabilone — a synthetic version of THC approved by the FDA have also shown positive results. One study found it was significantly more effective at treating diabetic neuropathy than the placebo.
While CBD isn’t as widely studied for neuropathic pain as THC, some studies have also shown that CBD leads to reductions of neuropathy for patients with diabetes.
Despite the positive potential for cannabis treating neuropathy, cannabis comes with a wide array of potential side effects and these can be a deterrent for some patients.
In studies on patients with neuropathy, side effects were generally modest but included symptoms like light-headedness, mild difficulties in concentration and memory, tachycardia, dry mouth, nausea, and fatigue. These usually resolve within a few hours.
The Cannigma content is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Always consult with an experienced medical professional with a background in cannabis before beginning treatment.
Peripheral neuropathy is when your peripheral nerves, the nerves outside of your brain and spinal cord, are damaged. These nerves send information back and forth between your central nervous system in your brain and spinal cord, and various parts of your body like your fingers, toes, lungs, and digestive system.
Each type of peripheral neuropathy has its own symptoms, depending on which nerves are damaged and how bad the damage is. Sometimes, peripheral neuropathy can get better on its own, but other times it gets progressively worse.
Peripheral neuropathy is not usually life-threatening, but it can be very uncomfortable, and can cause pain, weakness, and loss of feeling in the affected areas of the body. It can also be one of the first symptoms of a chronic or progressive underlying condition, so a workup is always important.
There are many potential causes of peripheral neuropathy, including diabetes, infections, and traumatic injuries. There are over 100 types of peripheral neuropathy, and taken all together they are a very common set of conditions, affecting more than 20 million Americans. As you get older, it becomes more common, affecting 3-5% of Americans aged over 55, and 10% of this age group in the UK.
The symptoms of peripheral neuropathy can vary a lot, depending on which nerves are affected. There are three main types of nerves:
- Sensory nerves, which receive and transmit information about sensations like heat and cold, touch, and pain
- Motor nerves, which control muscle movement
- Autonomic nerves, which control involuntary bodily functions like your digestion, bladder, blood pressure and heart rate
Sensory neuropathy symptoms include:
- Numbness and loss of sensation in the affected part of the body
- Pins and needles
- Extreme sensitivity when touched lightly
- A burning or sharp pain
- Loss of balance or coordination, because you can’t tell where your hands or feet are
The symptoms of motor neuropathy include:
- Weak or paralyzed muscles
- Muscles wasting away
- Twitching and muscle cramps
- Foot drop, when you have trouble lifting up your toes and the front of your foot
Autonomic neuropathy symptoms include:
- Sweating too much, or not being able to sweat
- Loss of control over the bowels and bladder
- Digestive difficulties that make you feel sick or bloated
- Rapid heart rate (tachycardia)
- Dizziness or lightheadedness due to change in blood pressure
It’s possible to have more than one type of peripheral neuropathy at the same time, like sensorimotor neuropathy, which is quite common.
Finally, you could have mononeuropathy, which is when only one nerve is damaged, or polyneuropathy, when two or more nerves are affected. Most people with peripheral neuropathy have polyneuropathy, but carpal tunnel syndrome is a common example of mononeuropathy.
The loss of sensation through peripheral neuropathy increases your risk of getting burns, cuts, or infection, without being aware of them. Peripheral neuropathy can also cause more falls due to loss of balance and weakness. Autonomic neuropathy can disrupt your circulation and heart rate.
Peripheral neuropathy often goes undiagnosed or misdiagnosed, because there are so many different types. Diagnosing neuropathy begins with a full physical exam and medical history. Your doctor might also order tests like:
- Blood tests to check for diabetes, vitamin deficiencies, infections, liver or kidney dysfunction, metabolic disorders, and abnormal immune function, which could cause peripheral neuropathy
- CT or MRI scans to look for herniated disks and other abnormalities that could cause neuropathy
- Nerve function tests, like an EMG or a nerve conduction test, to detect electrical activity and signal strength and speed along the nerves
- Autonomic nerve tests to check your sweat levels, reaction to temperature and touch
- Nerve biopsy, examining a sample of nerve fiber for damage
- Skin biopsy, examining a small amount of skin to check for nerve fiber endings
Peripheral neuropathy is caused by damage to the nerves that run from the central nervous system to various parts of the body, but there are many ways that damage can happen. Sometimes it’s genetic, but more often it’s acquired, meaning that it develops because of a condition or injury. Very often, acquired peripheral neuropathy is idiopathic, which means that it’s not known what caused it.
Diabetes is the most common cause of peripheral neuropathy, and it affects 25% of people with diabetes. If you also smoke, drink a lot of alcohol, or are aged over 40, your risk rises even more.
Other common causes include:
- Autoimmune disorders, like lupus, rheumatoid arthritis, Guillain-Barre syndrome, and vasculitis
- Infections, like HIV, hepatitis B and C, shingles, Lyme disease, and other viral or bacterial infections
- Tumors that develop or press on the nerves (chemotherapy can also cause peripheral neuropathy)
- Drinking too much alcohol
- Exposure to toxins, like arsenic, lead, or mercury
- Traumatic injury to the nerve from a car accident, sports injury, or a fall, or from repetitive strain injury (RSI)
- Vitamin deficiencies, particularly of vitamin B12
- Underactive thyroid (hypothyroidism)
- Chronic liver or kidney disease
- Bone marrow disorders, including myeloma, lymphoma, amyloidosis, and the presence of monoclonal gammopathy of undetermined significance, (MGUS), a rare protein, in the blood
There are many treatment options for peripheral neuropathy. The treatment that you get will depend on the cause, progression, and symptoms of your neuropathy.
The first approach is to treat the underlying cause of neuropathy. Often, this is enough to help the nerves regenerate and recover on their own. Treatments include:
- Lifestyle changes to control diabetes
- Stopping smoking
- Reducing alcohol intake
- Getting more exercise
- Taking vitamins to correct vitamin deficiencies
- Avoiding exposure to toxins
Medications used to treat neuropathy include:
- Neuropathic agents such as Gabapentin (Neurontin), Pregabalin (Lyrica), and Duloxetine (Cymbalta) are often given to control the symptoms of neuropathy
- Anticonvulsants if the above medications are not effective enough
- Antidepressants like amitriptyline, doxepin, nortriptyline, and newer serotonin-norepinephrine reuptake inhibitors
- Topical pain relief like lidocaine patches and capsaicin cream
- Over the counter or prescription pain relief, like NSAIDs, or opioids when very strong pain relief is needed
- Immunosuppressive drugs, like prednisone, cyclosporine, ,and azathioprine, that control inflammatory and autoimmune disorders
You might be prescribed other medications to deal with certain conditions caused by peripheral neuropathy, like for constipation.
- Physical therapy can strengthen muscles affected by peripheral neuropathy.
- Occupational therapists can provide hand and leg braces, orthopedic inserts, splints, and other aids that relieve pressure on the nerves.
- Transcutaneous electrical nerve stimulation (TENS) involves using electrodes to deliver a mild electrical current to the body, which can help with pain relief.
- Plasmapheresis is when the blood is removed from the body, cleaned of immune system cells and antibodies, and then returned.
Some types of peripheral neuropathy are helped by surgery like to move a protruding disk or tumors that are pressing on a nerve.