RESUMO
The endocannabinoid system (ECS) is an essential endogenous signaling system that may be involved in the pathophysiology of chronic widespread pain (CWP) and fibromyalgia syndrome (FMS). Further research is required to understand the role of ECS in the development and maintenance of CWP and FMS. We provided the first systematic review and meta-analysis exploring the clinical relevance of ECS alterations in patients with CWP and FMS by comparing plasma and interstitial levels of endocannabinoids and N-acylethanolamines in patients and healthy controls. A systematic search was conducted to identify studies that measured plasma and/or interstitial levels of endocannabinoids and N-acylethanolamines in patients with CWP or FMS and healthy controls. A total of 8 studies were included for qualitative review, and 7 studies were included for meta-analysis. The findings identified increased plasma levels of oleoylethanolamide and stearoylethanolamide in patients with FMS compared with those in controls (P = 0.005 and P < 0.0001, respectively) and increased plasma levels of palmitoylethanolamide and interstitial levels of stearoylethanolamide in patients with CWP compared with those in controls (P = 0.05 and P = 0.001, respectively). There were no significant differences in other ECS parameters. Most studies did not account for variables that may influence ECS function, including cannabis use, concomitant medication, comorbidities, physical activity, stress levels, circadian rhythm, sleep quality, and dietary factors, suggesting that future studies should explore the correlation between these variables and endocannabinoid activity. We highlight the importance of investigating endocannabinoid activity in CWP and FMS because it will underpin future translational research in the area.
RESUMO
Background: Fibromyalgia (FMS) is a complex condition that is characterized by various pain syndromes and fatigue, among other symptoms experienced. Current medical treatment of FMS involves both pharmacological and nonpharmacological approaches, but often with ineffective outcomes. Medicinal cannabis has the potential to be a therapeutic option for patients with FMS due to the positive research in chronic pain management. In addition, it has been found to have fewer adverse effects compared with currently available pain medications. This literature review aims at answering whether medicinal cannabis is reported to be safe and effective for the treatment of pain and symptomology experienced by people with FMS. Methods: A systematic review was conducted on human trials utilizing cannabis in FMS. MEDLINE, Embase, CINAHL, AMED, Scopus, and Cochrane CENTRAL were used for databases search, and mesh terms were used for cannabis and FMS. The search was limited to studies conducted from 2000 to 2020. Results: From the 181 citations identified, 10 studies were included after title, abstract, and full text screening occurred. A total of 1136 of patients (intervention n = 945, control n = 108, crossover n = 83) participated in the 10 studies ranging from 9 to 383 patients (mean = 114, median = 36). Of these studies, there were three randomized controlled trials, six observational studies, and one study that compared the management of chronic pain patients with FMS patients. Cannabis was found to be safe and well tolerated in FMS. The main adverse events identified included feeling "high," dizziness/vertigo, dry mouth, cough, red eyes, and drowsiness with no serious adverse events reported. Conclusions: This literature review identified that medical cannabis may be beneficial for some people with FMS. Further studies are required to confirm its efficacy, what type of cannabis is the most effective form to use, and what assessment tools need to be utilized to understand how to quantify clinical outcomes.
