What is Chronic Neuropathic Pain?
Pain is our bodies’ acute response to danger – that knee-jerk, instinctual reaction that causes us to recoil when we stub our toes or touch a hot stove. But for some pain is something more permanent, often lasting months or even years, despite continuous attempts at diagnosing, treating, and resolving it.
This is known as chronic neuropathic pain, a condition that is usually chronic. It is typically caused by chronic progressive nerve disease, but can also result from injury, trauma, or infection. With neuropathic pain, the pain is usually not triggered by an event or injury like stubbing your toe. Instead, pain signals are sent to the brain unprompted and without any clear cause.
People with a chronic neuropathic pain condition can experience anything from shooting pains to burning sensations or throbbing that is often also accompanied by numbness or a loss of sensation. The pain may be constant or intermittent and lasts for 12 weeks or longer. Chronic neuropathic pain is often debilitating, rendering the individual unable to work, exercise, or go about life’s basic activities, compromising overall health, and mental well-being.
Symptoms of Chronic Neuropathic Pain
Symptoms may differ slightly from individual to individual, but the following symptoms are considered common:
- Shooting, burning or stabbing pain
- Tingling sensations or a “pins and needles” feeling
- Numbness or a loss of sensation
- Spontaneous pain or pain that occurs without a trigger
- Evoked pain, or pain that’s caused by events that are typically not painful — such as rubbing against something, being in cold temperatures, or hair brushing
- A chronic sensation of feeling unpleasant or abnormal
- Difficulty with sleeping or resting, and loss of sleep
- An inability to perform normal daily activities, work, or exercise
- Emotional problems as a result of chronic pain and difficulty expressing feelings
Chronic Neuropathic Pain Medications & Treatment
The main goals of neuropathic pain treatment are twofold. Firstly and where possible, the physician will try to identify and treat the underlying condition causing it. The second goal is to provide pain relief, helping to improve the quality of life for the patient while attempting to help them maintain their typical daily activities despite the pain.
The usual first step is to use non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen, naproxen, and diclofenac to help relieve pain and inflammation. In the event of these not being effective, or in more severe cases, nerve block injections are used to interrupt pain signals using local anesthesia. Most often prescription pain medications such as opioids are prescribed. However, these come with severe side-effects of which abuse and addiction are the most problematic, but also include sedation, dizziness, nausea, vomiting, constipation, and respiratory depression.
Often times, non-pharmaceutical interventions can also help, either as an adjunct therapy to medications or on their own. Physical therapy is often recommended to increase strength, flexibility, and range of motion in the body while acupuncture can stimulate blood flow and help your body release pain-fighting chemicals into the brain. Similarly, electrical stimulation (aka TENS therapy) applied to muscles helps relieve pain and biofeedback can train the mind to regulate bodily reactions such as tension, mood, depression, and chronic pain. Other relaxation techniques including meditation, hypnosis, breathing exercises and yoga can help lessen pain and improve overall physical and emotional well-being.
CBD for Chronic Neuropathic Pain
Research & Scientific Evidence
Research involving cannabidiol (CBD) for the treatment of chronic neuropathic pain is in its infancy, with most studies investigating the combined effects of Δ9-tetrahydrocannabinol (THC) and CBD, using nabiximols which is a combined product of THC/CBD in a 1:1 ratio. However, a handful of CBD-only neuropathic pain studies do exist, often investigated in conjunction with inflammatory pain.
One such study is from 2007, published in the European Journal of Pharmacology. The study investigated the therapeutic potential of CBD on neuropathic pain and inflammatory pain in rats.
Neuropathic and inflamed rats received oral cannabidiol, with the neuropathic rats receiving four different cannabidiol doses of 2.5 mg/kg, 5 mg/kg, 10 mg/kg, and 20 mg/kg. Treatment was administered orally once a day for a week. The efficacy of the CBD was evaluated using various measures including behavioral tests as well as the testing of specific cannabinoids and TRPV1 receptor antagonists.
Based on the results of these measures, the researchers concluded that CBD reverses an increased sensitivity to pain via two mechanisms: Firstly by inhibiting the uptake of anandamide which is involved in pain control through activation of cannabinoid CB1 and CB2 receptors; and secondly by acting as an agonist and desensitization of the vanilloid TRPV1 receptors implicated in pain. However, this was only the case for repeated oral treatments and not acute, single-dose treatments, suggesting that repeated doses are necessary for pain improvement.
In another, more recent, an animal study from 2019 published in Brain Research scientists evaluated the pain-blocking potential of CBD on neuropathic pain in diabetic rats.
The scientists divided diabetic rats into three groups; a control group, an experimental group treated acutely in a single dose, and another experimental group that was chronically for 14 days. The experimental groups were either given 0.1 mg/kg, 0.3 mg/kg, or 3 mg/kg of pure CBD which was administered intraperitoneally. Measures such as cannabinoid, glycine, and 5-HT1A receptor activation, as well as mechanical pain sensitization (allodynia) confirmation and spinal levels of serotonin, were evaluated.
From the data, the researchers found that CBD shows significant anti-allodynic effects for chronic neuropathic pain, without altering locomotor activity in diabetic animals. They hypothesize that CBD does this by activating the serotonergic system and blocking pain signals via the 5-HT1A receptors thought to be involved in the sensation of pain.
In a randomized controlled clinical trial from 2019 published in Current Pharmaceutical Biotechnology, researchers evaluated the effectiveness of topically applied CBD oil for symptomatic relief of chronic peripheral neuropathic pain in non-cancer patients.
A total of 29 patients with symptomatic peripheral neuropathy were recruited with 15 randomized to the experimental CBD group and 14 to the control group. A treatment product containing 250 mg CBD/3 fl oz. was administered for four weeks. Treatment efficacy was evaluated using the neuropathic pain scale (NPS) and administered bi-weekly to assess change from baseline during the treatment period.
The researchers demonstrated that topical, transdermal application of CBD oil significantly reduced sensations of chronic neuropathic pain in the CBD group when compared to the placebo group. In particular, the largest reduction in ratings was for intense pain, sharp pain, and itchy sensations. However, although a reduction was noted for hot, dull, sensitive, unpleasant, deep, and surface pain in the CBD group, the scores did not reach statistical significance. They speculate that this may be due to the small sample size and/or the inclusion of multiple conditions that resulted in a lack of clinical heterogeneity.
There is substantial anecdotal evidence suggesting that cannabis and cannabinoids such as CBD and THC have beneficial effects on chronic pain – especially for patients suffering chronic neuropathic pain resulting from diabetes, complications from surgery, and Multiple Sclerosis.
CBD as a complementary treatment
In addition to potentially reducing chronic neuropathic pain by inhibiting anandamide uptake, desensitization of the pain receptors, and blocking pain signals directly, CBD can help patients in other ways as well.
CBD can help reduce reliance on pain medication when used as an adjunct or complementary therapy, especially in conjunction with other non-pharmaceutical interventions. Similarly, it can help reduce some of the negative side-effects associated with NSAIDs and opioids, including relieving nausea, aiding with drug addiction, and aiding recovery from opioid dependence, while helping with gastrointestinal irritation and bowel inflammation from NSAID use. Moreover, CBD can also help patients improve overall mood, reduce anxiety, aid in relieving feelings of depression, and help improve sleep.
Chronic neuropathic pain can be debilitating if left untreated, impacting almost every part of life. However, from the little we know about using CBD to treat neuropathic pain, the scientific evidence shows promise as being a potentially effective anti-allodynic and analgesic effects by interacting with various vanilloid, serotonergic, and endocannabinoid pathways and mechanisms. However, no matter how severe your symptoms are, always consult a medical practitioner before using CBD as it can interact negatively with other medications. Your physician can monitor dosage, symptom severity, and other clinical parameters to ensure that your CBD treatment is both safe and effective and provide you with a long-term non-habit-forming solution.