Identification and Treatment of New Inflammatory Triggers for Complex Regional Pain Syndrome: Small Intestinal Bacterial Overgrowth and Obstructive Sleep Apnea

A Utilization Review of Patients That Respond to Low-Dose Naltrexone (LDN) for Chronic Pain at a Single Institution

Studies have demonstrated the benefits of LDN for various pain indications. This review describes the utilization of and response to LDN in patients with chronic pain within the William S. Middleton Memorial Veterans Hospital (Madison VA). This was a retrospective, single center, chart review of patients that were prescribed LDN for chronic pain. The primary outcome, change in subjective pain report via numeric rating scale (NRS), was analyzed through Wilcoxon Signed Rank Test and descriptive statistics. A total of 136 participants were included. Patients had an average pain score of 7.1 per NRS at baseline. At the initial follow up visit, participants had an average pain of 6.4 (p < 0.001). Additionally, 17.1% of patients had a greater than or equal to 30% pain reduction from baseline. At subsequent follow up, patients reported an average pain of 5.5 (p < 0.0001) per NRS. At the end of the study, 31.6% of patients were maintained on LDN at an average dose of 3.8 mg. This retrospective review demonstrated that LDN may be an effective modality for some chronic pain indications. Reported pain scores were significantly lower at initial follow up compared to baseline for the total population, and for patients with fibromyalgia (FM) specifically.

Microbiota-Accessible Boron-Containing Compounds in Complex Regional Pain Syndrome

The microbiota-gut-brain axis has garnered increasing attention in recent years for its role in various health conditions, including neuroinflammatory disorders like complex regional pain syndrome (CRPS). CRPS is a debilitating condition characterized by chronic neuropathic pain, and its etiology and pathophysiology remain elusive. Emerging research suggests that alterations in the gut microbiota composition and function could play a significant role in CRPS development and progression. Our paper explores the implications of microbiota in CRPS and the potential therapeutic role of boron (B). Studies have demonstrated that individuals with CRPS often exhibit dysbiosis, with imbalances in beneficial and pathogenic gut bacteria. Dysbiosis can lead to increased gut permeability and systemic inflammation, contributing to the chronic pain experienced in CRPS. B, an essential trace element, has shown promise in modulating the gut microbiome positively and exerting anti-inflammatory effects. Recent preclinical and clinical studies suggest that B supplementation may alleviate neuropathic pain and improve CRPS symptoms by restoring microbiota balance and reducing inflammation. Our review highlights the complex interplay between microbiota, inflammation, and neuropathic pain in CRPS and underscores the potential of B as a novel therapeutic approach to target the microbiota-gut-brain axis, offering hope for improved management of this challenging condition.

Low-dose naltrexone's utility for non-cancer centralized pain conditions: a scoping review

BACKGROUND

At low doses, naltrexone (LDN) has been shown to modulate inflammation through the interruption of microglial cell activation within the central nervous system. One of the most likely contributors to centralized pain is changes in microglial cell processing. Therefore, it has been postulated that LDN can be used to manage patients with pain resulting from central sensitization due to this relationship. This scoping review aims to synthesize the relevant study data for LDN as a novel treatment strategy for various centralized pain conditions.

METHODS

A comprehensive literature search was conducted in PubMed, Embase, and Google Scholar, guided by the Scale for Assessment of Narrative Review Articles (SANRA) criteria.

RESULTS

Forty-seven studies related to centralized pain conditions were identified. Many of the studies were case reports/series and narrative reviews, but a few randomized control trials have been conducted. Overall, the body of evidence revealed improvement in patient-reported pain severity and in outcomes related to hyperalgesia, physical function, quality of life, and sleep. Variability in dosing paradigms and the time to patient response was present in the reviewed studies.

CONCLUSIONS

Evidence synthesized for this scoping review supports the ongoing use of LDN for the treatment of refractory pain in various centralized chronic pain conditions. Upon review of the currently available published studies, it is apparent that further high-quality, well-powered randomized control trials need to be conducted to establish efficacy, standardization for dosing, and response times. In summary, LDN continues to offer promising results in the management of pain and other distressing symptoms in patients with chronic centralized pain conditions.

Multiple Sclerosis and the Endogenous Opioid System

Multiple sclerosis (MS) is an autoimmune disease characterized by chronic inflammation, neuronal degeneration and demyelinating lesions within the central nervous system. The mechanisms that underlie the pathogenesis and progression of MS are not fully known and current therapies have limited efficacy. Preclinical investigations using the murine experimental autoimmune encephalomyelitis (EAE) model of MS, as well as clinical observations in patients with MS, provide converging lines of evidence implicating the endogenous opioid system in the pathogenesis of this disease. In recent years, it has become increasingly clear that endogenous opioid peptides, binding μ- (MOR), κ- (KOR) and δ-opioid receptors (DOR), function as immunomodulatory molecules within both the immune and nervous systems. The endogenous opioid system is also well known to play a role in the development of chronic pain and negative affect, both of which are common comorbidities in MS. As such, dysregulation of the opioid system may be a mechanism that contributes to the pathogenesis of MS and associated symptoms. Here, we review the evidence for a connection between the endogenous opioid system and MS. We further explore the mechanisms by which opioidergic signaling might contribute to the pathophysiology and symptomatology of MS.

Mast Cell Activation Syndrome: A Primer for the Gastroenterologist

Mast cell activation syndrome is thought to be a common, yet under-recognized, chronic multi-system disorder caused by inappropriate mast cell activation. Gastrointestinal symptoms are frequently reported by these patients and are often mistaken by physicians as functional gastrointestinal disorders. This syndrome can be diagnosed by the medical history and measurable biomarkers. Gastroenterologists manage diseases associated with active inflammatory cells including neutrophils, lymphocytes, macrophages, and eosinophils. The mast cell has only recently been recognized as a major player in our specialty. Gastrointestinal disorders from mast cell mediators often present with apparent irritable bowel syndrome, dyspepsia, chronic or cyclical nausea, and heartburn. Individuals with mast cell activation syndrome experience significant delays in diagnosis. The gastrointestinal symptoms are often refractory to symptom-targeted prescription medications. Beyond avoiding triggers, the best therapy is directed at modulating mast cell activation and the effects of the mediators. Many of these therapies are simple over-the-counter medications. In this article, we review mast cell function and dysfunction and the gastrointestinal symptoms, comorbid conditions, diagnosis, and management of mast cell activation syndrome. Gastroenterologists who become aware of this syndrome can dramatically improve the quality of life for their patients who previously have been labeled with a functional gastrointestinal disorder.

Risk of Postoperative Hyperalgesia in Adult Patients with Preoperative Poor Sleep Quality Undergoing Open-heart Valve Surgery

Purpose

Studies have reported that preoperative poor sleep quality could decrease the pain threshold in patients undergoing noncardiac surgery. However, the risk of postoperative hyperalgesia (HA) in cardiac surgery patients with preoperative poor sleep quality remains unclear.

Patients and Methods

We retrospectively collected clinical data from patients undergoing open-heart valve surgery between May 1 and October 31, 2019, in Fuwai Hospital (Beijing). We assessed preoperative sleep quality and postoperative pain severity using the Pittsburgh sleep quality index (PSQI) and numerical pain rating scale (NPRS), respectively. A PSQI of six or greater was considered to indicate poor sleep quality, and a NPRS of four or greater was considered to indicate HA. Multivariable logistic regression analysis was used to study the risk of postoperative HA in patients with preoperative poor sleep quality.

Results

We divided 214 eligible patients into two groups based on postoperative HA; HA group: n=61 (28.5%) and nonHA group: n=153 (71.5%). Compared with nonHA patients, patients with postoperative HA showed a higher percentage of history of smoking, 17 (11.1%) vs 15 (24.6%) and alcohol abuse, 5 (3.3%) vs 6 (9.8%), higher intraoperative dose of sufentanil (median, 1.02 vs 1.12 μg/kg/h), and longer duration of ventilation with tracheal catheter (median, 760 vs 934 min). Preoperative poor sleep quality was associated independently with an increased risk of postoperative HA (adjusted odds ratio [AOR]: 2.66; 95%CI: 1.31–5.39, P=0.007). Stratification by history of smoking revealed a stronger risk of postoperative HA in nonsmoking patients with preoperative poor sleep quality (AOR: 3.40; 95%CI: 1.51–7.66, P=0.003). No risk was found in patients who had history of smoking (AOR: 0.83; 95%CI: 0.14–4.75, P=0.832).

Conclusion

Preoperative poor sleep quality is an independent risk factor for postoperative HA in adult patients undergoing open-heart valve surgery who had no history of smoking.

Low-Dose Naltrexone for Chronic Pain: Update and Systemic Review

PURPOSE OF REVIEW

The purpose of this review is to evaluate and explain our current understanding of the clinical use of low-dose naltrexone in the treatment of chronic pain.

RECENT FINDINGS

Recent pre-clinical uses and clinical studies further elucidate the use of low-dose naltrexone in the treatment of chronic pain. Low-dose naltrexone (LDN) has shown promise to reduce symptoms related to chronic pain conditions such as fibromyalgia, inflammatory bowel conditions, and multiple sclerosis. The mechanism of LDN appears to be modulation of neuro-inflammation, specifically, the modulation of the glial cells and release of inflammatory chemicals in the central nervous system. These effects appear to unique at low dosage compared to dosage for food and drug administration approved use for alcohol and opioid dependence. We review the evidence that LDN has shown more than promise and should be further investigated in clinical practice.

A role for the microbiota in complex regional pain syndrome?

Complex regional pain syndrome (CRPS) is a debilitating neuroinflammatory condition of unknown etiology. Symptoms include excruciating pain and trophic changes in the limbs as defined by the Budapest criteria. The severity and functional recovery of CRPS, unlike most pain conditions, is quantifiable using a variation of the Budapest criteria known as the CRPS severity score. Like many chronic pain conditions, CRPS is difficult to treat once pain has been present for more than 12 months. However, previous work has demonstrated that a subset of patients with new-onset CRPS (~50%) improve if treated within one year, while the rest have minimal to no symptom improvement. Unfortunately, this leads to permanent disability and often requires invasive and costly treatments such as spinal cord stimulation or long-term opioid therapy. Because the etiology is unknown, treatment is multimodal, and often supportive. Biomarkers that predict severity or resolution of symptoms would significantly change treatment but have not yet been identified. Interestingly, there are case reports of remission or resolution of CRPS symptoms with the use of antibiotics known to affect the gut flora. Mouse studies have demonstrated that modulation of the gut microbiome is anti-nociceptive in visceral, inflammatory and neuropathic pain models. We hypothesize that the variable clinical potential for recovery and response to therapy in CRPS may be secondary to or reflected in changes in the gut microbiota. We suggest that the microbiota may mediate or reflect clinical status via the metabolome, activation of the immune system and/or microglial activation. We hypothesize that the gut microbiome is a potential mediator in development and persistence of CRPS symptoms and propose that the clinical condition of CRPS could provide a unique opportunity to identify biomarkers of the microbiota and potential therapies to prevent pain chronification.

Low-Dose Naltrexone (LDN)-Review of Therapeutic Utilization

Naltrexone and naloxone are classical opioid antagonists. In substantially lower than standard doses, they exert different pharmacodynamics. Low-dose naltrexone (LDN), considered in a daily dose of 1 to 5 mg, has been shown to reduce glial inflammatory response by modulating Toll-like receptor 4 signaling in addition to systemically upregulating endogenous opioid signaling by transient opioid-receptor blockade. Clinical reports of LDN have demonstrated possible benefits in diseases such as fibromyalgia, Crohn’s disease, multiple sclerosis, complex-regional pain syndrome, Hailey-Hailey disease, and cancer. In a dosing range at less than 1 μg per day, oral naltrexone or intravenous naloxone potentiate opioid analgesia by acting on filamin A, a scaffolding protein involved in μ-opioid receptor signaling. This dose is termed ultra low-dose naltrexone/naloxone (ULDN). It has been of use in postoperative control of analgesia by reducing the need for the total amount of opioids following surgery, as well as ameliorating certain side-effects of opioid-related treatment. A dosing range between 1 μg and 1 mg comprises very low-dose naltrexone (VLDN), which has primarily been used as an experimental adjunct treatment for boosting tolerability of opioid-weaning methadone taper. In general, all of the low-dose features regarding naltrexone and naloxone have been only recently and still scarcely scientifically evaluated. This review aims to present an overview of the current knowledge on these topics and summarize the key findings published in peer-review sources. The existing potential of LDN, VLDN, and ULDN for various areas of biomedicine has still not been thoroughly and comprehensively addressed.

Successful treatment of postural orthostatic tachycardia and mast cell activation syndromes using naltrexone, immunoglobulin and antibiotic treatment

A patient with severe postural orthostatic tachycardia syndrome (POTS) and mast cell activation syndrome (MCAS) received immunotherapy with low-dose naltrexone (LDN) and intravenous immunoglobulin (IVIg) and antibiotic therapy for small intestinal bacterial overgrowth (SIBO). A dramatic and sustained response was documented. The utility of IVIg in autoimmune neuromuscular diseases has been published, but clinical experience with POTS is relatively unknown and has not been reported in MCAS. As a short-acting mu-opioid antagonist, LDN paradoxically increases endorphins which then bind to regulatory T cells which regulate T-lymphocyte and B-lymphocyte production and this reduces cytokine and antibody production. IVIg is emerging as a promising therapy for POTS. Diagnosis and treatment of SIBO in POTS is a new concept and appears to play an important role.

Low-dose Naltrexone for the treatment of sarcoidosis

Systemic therapy is administered to 50% of patients and the need for long-term use of therapy is quite variable (1,2). Prednisone is often administered for many months with risk for multiple side effects, immunomodulators as steroid sparing agents have a delayed onset of action and have risks for infection and malignancies, and infliximab increases the risk for infection (1). In light of these issues, alternative options for therapy are desirable. We made a comparison between sarcoidosis and Crohn's disease in that in each disease there is unregulated lymphocyte activity, a common unique pathological finding of non-caseating granulomas, and a similar approach to medical therapy (3,4). Low dose naltrexone (LDN) has been utilized for many conditions (5). Efficacy has been documented in Crohn's disease with randomized controlled studies showing mucosal healing and histologic improvement (6-7). LDN is compounded in 1/10^th to 1/20^th the dose used for the FDA-approved indications of narcotic and alcohol dependence (8). Neuropeptides (e.g., enkephalins and endorphins) are present in the gastrointestinal tract and endocrine cells and modulate immune responses (9). Up-regulation of met-enkephelin and opioid receptors can be induced by a rebound effect by short-acting LDN (10). Higher levels of endogenous opioids and receptors inhibit cell proliferation which suppress T and B lymphocyte responses (11,12) and decrease production of pro-inflammatory interleukins-6 and -12 (13). In light of the Crohn's disease LDN literature and similar experiences with other inflammatory conditions in our clinic (14,15), LDN was administered to a sarcoidosis patient with severe fatigue, sarcoid rash, and marked radiographic evidence of gastrointestinal involvement. (Sarcoidosis Vasc Diffuse Lung Dis 2017; 34: 184-187).