Category Archives: Neuropathic Pain

Suppression of neuropathic pain in the circadian clock-deficient Per2m/m mice involves up-regulation of endocannabinoid system

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“Neuropathic pain often results from injuries and diseases that affect the somatosensory system. Disruption of the circadian clock has been implicated in the exacerbation of the neuropathic pain state. However, in this study, we report that mice deficient in a core clock component Period2 (Per2m/m mice) fail to develop tactile pain hypersensitivity even following peripheral nerve injury. Similar to male wild-type mice, partial sciatic nerve ligation (PSL)-Per2m/m male mice showed activation of glial cells in the dorsal horn of the spinal cord and increased expression of pain-related genes. Interestingly, α1D-adrenergic receptor (α1D-AR) expression was up-regulated in the spinal cord of Per2m/m mice, leading to increased production of 2-arachidonoylglycerol (2-AG), an endocannabinoid receptor ligand. This increase in 2-AG suppressed the PSL-induced tactile pain hypersensitivity. Furthermore, intraspinal dorsal horn injection of adeno-associated viral vectors expressing α1D-AR also attenuated pain hypersensitivity in PSL-wild-type male mice by increasing 2-AG production.

Our findings reveal an uncovered role of the circadian clock in neuropathic pain disorders and suggest a link between α1D-AR signaling and the endocannabinoid system.”

https://pubmed.ncbi.nlm.nih.gov/38239754/

https://academic.oup.com/pnasnexus/article/3/1/pgad482/7564865?login=false

A preliminary study evaluating self-reported effects of cannabis and cannabinoids on neuropathic pain and pain medication use in people with spinal cord injury

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“Approximately 60% of individuals with a spinal cord injury (SCI) experience neuropathic pain, which often persists despite the use of various pharmacological treatments. Increasingly, the potential analgesic effects of cannabis and cannabinoid products have been studied; however, little research has been conducted among those with SCI-related neuropathic pain. Therefore, the primary objective of the study was to investigate the perceived effects of cannabis and cannabinoid use on neuropathic pain among those who were currently or had previously used these approaches. Additionally, the study aimed to determine if common pain medications are being substituted by cannabis and cannabinoids. Participants (N = 342) were recruited from existing opt-in listserv sources within the United States. Of those, 227 met the inclusion criteria and were enrolled in the study. The participants took part in an anonymous online survey regarding past and current use of cannabis and their perceived effects on neuropathic pain, including the use of pain medication. Those in the sample reported average neuropathic pain intensity scores over the past week of 6.8 ± 2.1 (0 to 10 scale), reflecting a high moderate to severe level of pain. Additionally, 87.9% noted that cannabis reduced their neuropathic pain intensity by more than 30%, and 92.3% reported that cannabis helped them to better deal with their neuropathic pain symptoms. Most participants (83.3%) also reported substituting their pain medications with cannabis, with the most substituted medication categories being opioids (47.0%), gabapentinoids (42.8%) and over-the-counter pain medications (42.2%). These preliminary results suggest that cannabis and cannabinoids may be effective in reducing neuropathic pain among those with SCI and may help to limit the need for certain pain medications.”

https://pubmed.ncbi.nlm.nih.gov/38188193/

https://www.frontiersin.org/articles/10.3389/fpain.2023.1297223/full

Phytocannabinoids for the Treatment of Neuropathic Pain: A Scoping Review of Randomised Controlled Trials Published Between 2012 and 2023

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“Purpose of review: Neuropathic pain (NP) remains a challenge to treat, with 50% of patients experiencing limited efficacy from current treatments. Medicinal cannabis, which contains tetrahydrocannabinol (THC), cannabidiol (CBD) and other minor cannabinoids, is garnering attention as an alternative treatment for NP. This paper reviews the clinical evidence for phytocannabinoid treatment of NP.

Recent findings: Seventeen randomised controlled trials (RCT) were identified for inclusion in this review. Of these, ten studies using phytocannabinoid preparations containing THC alone had the most evidence for pain relief. Four studies investigating THC/CBD combinations showed some reductions in pain scores, although not all findings were statistically significant, whereas studies investigating CBD (two studies) or cannabidivarin (one study) showed no analgesic effect over placebo. However, CBD studies were of small sample size when compared to other studies in the review and short duration. Results for treatment of diabetic peripheral neuropathy patients with THC showed better improvements over those for NP induced by chemotherapy and multiple sclerosis, with these trials using vaporised whole plant cannabis. This formulation may have trace amounts of other minor cannabinoids, compared with synthetic cannabinoids such as dronabinol or nabilone that were investigated in other studies. This review provides an overview of RCTs that have investigated phytocannabinoid use for the treatment of NP. There appears to be evidence to necessitate further high quality RCTs into novel formulations of phytocannabinoids for the treatment of NP.”

https://pubmed.ncbi.nlm.nih.gov/38095748/

https://link.springer.com/article/10.1007/s11916-023-01196-1

Medical Cannabis: A Review from the American Society of Pain and Neuroscience

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“Cannabinoids have recently gained a renewed interest due to their potential applicability to various medical conditions, specifically the management of chronic pain conditions.

Unlike many other medications, medical cannabis is not associated with serious adverse events, and no overdose deaths have been reported.

However, both safety and efficacy data for medical cannabis treatment of chronic, nonmalignant pain conditions are lacking. Therefore, representatives from the American Society of Pain and Neuroscience summarize the evidence, according to level and grade, for medical cannabis treatment of several different pain conditions. Treatment of cancer-related pain has prospective evidentiary support for the use of medical cannabis. Although 3 large and well-designed randomized controlled trials investigated cannabis treatment of cancer-related pain, the evidence yielded only a grade D recommendation. Neuropathic pain has been investigated in prospective studies, but a lack of high-quality evidence renders cannabis treatment for this indication a grade C recommendation. Both safety and efficacy data are lacking for use of medical cannabis to treat chronic nonmalignant pain conditions.”

https://pubmed.ncbi.nlm.nih.gov/38094100/

https://www.dovepress.com/medical-cannabis-a-review-from-the-american-society-of-pain-and-neuros-peer-reviewed-fulltext-article-JPR

Relief of nocturnal neuropathic pain with the use of cannabis in a patient with Fabry disease

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“Neuropathic pain is one of the most invalidating symptoms in patients with Fabry disease (FD), affecting their quality of life, it is linked to small fiber neuropathy and it may not respond to available disease specific treatments. We report the case of a 32 years old man with classic FD and severe neuropathic pain who, after the failure of several standard pharmaceutical approaches, was treated with medical cannabis with relief of nocturnal pain and sleep improvement.”

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10694749/

“In conclusion: although more evidence is needed, this case report suggests that the use of medical cannabis could be considered as a pain treatment option for patient with FD, in particular for nocturnal pain relief, when other pharmacological approaches have failed.”

https://www.sciencedirect.com/science/article/pii/S2214426923000563?via%3Dihub


The holistic effects of medical cannabis compared to opioids on pain experience in Finnish patients with chronic pain

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“Background: Medical cannabis (MC) is increasingly used for chronic pain, but it is unclear how it aids in pain management. Previous literature suggests that MC could holistically alter the pain experience instead of only targeting pain intensity. However, this hypothesis has not been previously systematically tested.

Method: A retrospective internet survey was used in a sample of Finnish chronic pain patients (40 MC users and 161 opioid users). The patients evaluated statements describing positive and negative phenomenological effects of the medicine. The two groups were propensity score matched to control for possible confounding factors.

Results: Exploratory factor analysis revealed three experience factors: Negative Side Effects, Positive Holistic Effects, and Positive Emotional Effects. The MC group (matched n = 39) received higher scores than the opioid group (matched n = 39) in Positive Emotional Effects with large effect size (Rank-Biserial Correlation RBC = .71, p < .001), and in Holistic Positive Effects with medium effect size (RBC = .47, p < .001), with no difference in Negative Side Effects (p = .13). MC and opioids were perceived as equally efficacious in reducing pain intensity. Ratings of individual statements were exploratively examined in a post hoc analysis.

Conclusion: MC and opioids were perceived to be equally efficacious in reducing pain intensity, but MC additionally positively affected broader pain-related factors such as emotion, functionality, and overall sense of wellbeing. This supports the hypothesis that MC alleviates pain through holistically altering the pain experience.”

https://pubmed.ncbi.nlm.nih.gov/37941019/

“The results of the present study support the hypothesis that the effects of MC on pain experience are more holistic than those of opioids. MC may alleviate pain through affecting a broad range of pain-related experience experiental factors such as relaxation, improved sleep and mood, being able not to react to the pain, as well as a sense of control. These holistic effects of MC could explain the inconsistencies in clinical trials, where focus has mainly been on pain intensity instead of broader pain phenomenology. The results highlight the importance of taking these holistic effects into account in treating patients with MC, considering them as part of the therapeutic process.”

https://jcannabisresearch.biomedcentral.com/articles/10.1186/s42238-023-00207-7

Complex Regional Pain Syndrome Type I: Evidence for the CB1 and CB2 Receptors Immunocontent and Beneficial Effect of Local Administration of Cannabidiol in Mice

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“Introduction: Complex regional pain syndrome type I (CRPS-I) is a debilitating neuropathic painful condition associated with allodynia, hyperalgesia, sudomotor and/or vasomotor dysfunctions, turning investigation of its pathophysiology and new therapeutic strategies into an essential topic. We aim to investigate the impact of ischemia/reperfusion injury on the immunocontent of CB1 and CB2 cannabinoid receptor isoforms in the paws of mice submitted to a chronic postischemia pain (CPIP) model and the effects of local administration of cannabidiol (CBD) on mechanical hyperalgesia. 

Methods: Female Swiss mice, 30-35 g, were submitted to the CPIP model on the right hind paw. Skin and muscle samples were removed at different periods for western blot analysis. 

Results: No changes in the immunocontent of CB1 and CB2 receptors in paw muscle tissues after ischemia-reperfusion were observed. CBD promoted an antihyperalgesic effect in both phases. AM281 reversed the effect of CBD, whereas ruthenium red abolished the late phase. 

Conclusion: Our results point to the possible beneficial effects of local administration of CBD in modulating CRPS-I in humans. As possible targets for CBD antihyperalgesia in this model, the contribution of cannabinoid receptor CB1, in addition to TRPM8 is suggested.”

https://pubmed.ncbi.nlm.nih.gov/37903029/

https://www.liebertpub.com/doi/10.1089/can.2023.0093

Chronic Cannabigerol as an Effective Therapeutic for Cisplatin-Induced Neuropathic Pain

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“Cannabigerol (CBG), derived from the cannabis plant, acts as an acute analgesic in a model of cisplatin-induced peripheral neuropathy (CIPN) in mice. There are no curative, long-lasting treatments for CIPN available to humans. We investigated the ability of chronic CBG to alleviate mechanical hypersensitivity due to CIPN in mice by measuring responses to 7 and 14 days of daily CBG. We found that CBG treatment (i.p.) for 7 and 14 consecutive days significantly reduced mechanical hypersensitivity in male and female mice with CIPN and reduced pain sensitivity up to 60-70% of baseline levels (p < 0.001 for all), 24 h after the last injection. Additionally, we found that daily treatment with CBG did not evoke tolerance and did not incur significant weight change or adverse events. The efficacy of CBG was independent of the estrous cycle phase. Therefore, chronic CBG administration can provide at least 24 h of antinociceptive effect in mice. These findings support the study of CBG as a long-lasting neuropathic pain therapy, which acts without tolerance in both males and females.”

https://pubmed.ncbi.nlm.nih.gov/37895913/

https://www.mdpi.com/1424-8247/16/10/1442

Medical Cannabis Alleviates Chronic Neuropathic Pain Effectively and Sustainably without Severe Adverse Effect: A Retrospective Study on 99 Cases

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“Introduction: Medical cannabis may provide a treatment option for chronic neuropathic pain. However, empirical disease-specific data are scarce.

Methods: This is a retrospective observational study including 99 patients with chronic neuropathic pain. These patients received medical cannabis by means of inhaling dried flowers with tetrahydrocannabinol content of <12-22% at a maximal daily dose of 0.15-1 g. Up to six follow-ups were carried out at intervals of 4-6 weeks. Pain severity, sleep disturbance, general improvement, side effects, and therapy tolerance at the follow-up consultations were assessed in interviews and compared with the baseline data using non-parametric Wilcoxon signed-rank test.

Results: Within 6 weeks on the therapy, median of the pain scores decreased significantly from 7.5 to 4.0 (p < 0.001). The proportion of patients with severe pain (score >6) decreased from 96% to 16% (p < 0.001). Sleep disturbance was significantly improved with the median of the scores decreased from 8.0 to 2.0 (p < 0.001). These improvements were sustained over a period of up to 6 months. There were no severe adverse events reported. Mild side effects reported were dryness in mucous tissue (5.4%), fatigue (4.8%), and increased appetite (2.7%). Therapy tolerance was reported in 91% of the interviews.

Conclusion: Medical cannabis is safe and highly effective for treating neuropathic pain and concomitant sleep disturbance.”

https://pubmed.ncbi.nlm.nih.gov/37900896/

https://karger.com/mca/article/6/1/89/860557/Medical-Cannabis-Alleviates-Chronic-Neuropathic

Applications of Cannabinoids in Neuropathic Pain: An Updated Review

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“Neuropathic pain is experienced due to injury to the nerves, underlying disease conditions or toxicity induced by chemotherapeutics. Multiple factors can contribute to neuropathic pain such as central nervous system (CNS)-related autoimmune and metabolic disorders, nerve injury, multiple sclerosis and diabetes. Hence, development of pharmacological interventions to reduce the drawbacks of existing chemotherapeutics and counter neuropathic pain is an urgent unmet clinical need.

Cannabinoid treatment has been reported to be beneficial for several disease conditions including neuropathic pain.

Cannabinoids act by inhibiting the release of neurotransmitters from presynaptic nerve endings, modulating the excitation of postsynaptic neurons, activating descending inhibitory pain pathways, reducing neural inflammation and oxidative stress and also correcting autophagy defects. This review provides insights on the various preclinical and clinical therapeutic applications of cannabidiol (CBD), cannabigerol (CBG), and cannabinol (CBN) in various diseases and the ongoing clinical trials for the treatment of chronic and acute pain with cannabinoids.

Pharmacological and genetic experimental strategies have well demonstrated the potential neuroprotective effects of cannabinoids and also elaborated their mechanism of action for the therapy of neuropathic pain.”

https://pubmed.ncbi.nlm.nih.gov/37824417/

https://www.dl.begellhouse.com/journals/3667c4ae6e8fd136,7ec6441519bff684,786cb61f3f1ec955.html