BACKGROUND: Complex regional pain syndrome is a rare, neuropathic disorder that affects fewer than 200,000 individuals in the United States annually. Current treatments often focus on pain management and fall short of relieving symptoms of pain and dystonia in patients.
OBJECTIVE: The goal of this systematic qualitative review is to evaluate the evidence for the use of low-dose naltrexone in the treatment of chronic pain syndromes.
STUDY DESIGN: This is a systematic review.
METHODS: PubMed, Embase, and Web of Science were searched for articles containing the keywords "low-dose naltrexone" AND ("pain" OR "chronic pain" OR "fibromyalgia" OR "complex regional pain syndrome" OR "neuropathic pain" OR "nociceptive pain") between 1950 and July 17, 2020. A total of 30 publications were systematically reviewed. Exclusion criteria were articles that were unavailable in English, focused on acute pain only, and evaluated only animal models. Case studies were included for the purposes of our qualitative review.
RESULTS: Out of 29 articles, we reviewed 11 prospective studies, 10 case studies, 3 systematic reviews, 2 retrospective studies, 2 simulation models, and one combination study. Articles focused on chronic pain syndromes as well as painful rheumatologic disorders and neurological disorders. We found that low-dose naltrexone treatment was positively associated with symptom relief in patients experiencing chronic pain, dystonia, and sleep disturbances.
LIMITATIONS: Due to the limited number of available articles focusing on the treatment of complex regional pain syndrome with low-dose naltrexone, the majority of studies analyzed focused on other chronic pain syndromes.
CONCLUSIONS: There is a need for additional prospective and interventional studies addressing the use of low-dose naltrexone in the treatment of complex regional pain syndrome symptoms.
The review of individual articles seems quite superficial and diagnoses questionable. Exemplary is fibromyalgia, when the summary of symptoms suggest allodynia. All the article reveals is the need for a carefully designed, controlled study.
This systematic review aimed at reviewing the published studies on the use of low dose Naltrexone in the management of chronic regional pain syndrome types I and II. The rationale for use of low dose Naltrexone in these conditions relates to the reported upregulation of toll like receptor 4 in these conditions. Unfortunately, most of the studies included in this systematic review involved the use of low dose Naltrexone in other chronic pain conditions, in particular Fibromyalgia, rather than the intended subject of this systematic review, patients with chronic regional pain syndrome types I and II. As a result, while the review does suggest some efficacy for low dose Naltrexone in the management of chronic pain, it doesn’t really address the role of low dose Naltrexone in the intended patient group.
Interesting article that concludes that more research is needed on the topic.