Immunoglobulin Responsive Chronic Pain

Intravenous Immunoglobulin Therapy in Patients With Painful Idiopathic Small Fiber Neuropathy

Objective

This is the first double-blind randomized controlled trial evaluating the efficacy and safety of IV immunoglobulin (IVIG) vs placebo in patients with idiopathic small fiber neuropathy (I-SFN).

Methods

Between July 2016 and November 2018, 60 Dutch patients with skin biopsy–proven I-SFN randomly received a starting dose of IVIG (2 g/kg body weight) or matching placebo (0.9% saline). Subsequently, 3 additional infusions of IVIG (1 g/kg) or placebo were administered at 3-week intervals. The primary outcome was a 1-point change in Pain Intensity Numerical Rating Scale score at 12 weeks compared to baseline.

Results

Thirty patients received IVIG, and 30 received placebo. In both groups, 29 patients completed the trial. In 40% of patients receiving IVIG, the mean average pain was decreased by at least 1 point compared to 30% of the patients receiving placebo (p = 0.588, odds ratio 1.56, 95% confidence interval 0.53–4.53). No significant differences were found on any of the other prespecified outcomes, including general well-being, autonomic symptoms, and overall functioning and disability.

Conclusions

This randomized controlled trial showed that IVIG treatment had no significant effect on pain in patients with painful I-SFN.

Trial Registration Information

ClinicalTrials.gov Identifier: NCT02637700, EudraCT 2015-002624-31.

Classification of Evidence

This study provides Class I evidence that for patients with painful I-SFN, IVIG did not significantly reduce pain compared to placebo.

Human Intravenous Immunoglobulin Alleviates Neuropathic Symptoms in a Rat Model of Paclitaxel-Induced Peripheral Neurotoxicity

The onset of chemotherapy-induced peripheral neurotoxicity (CIPN) is a leading cause of the dose reduction or discontinuation of cancer treatment due to sensory symptoms. Paclitaxel (PTX) can cause painful peripheral neuropathy, with a negative impact on cancer survivors' quality of life. While recent studies have shown that neuroinflammation is involved in PTX-induced peripheral neurotoxicity (PIPN), the pathophysiology of this disabling side effect remains largely unclear and no effective therapies are available. Therefore, here we investigated the effects of human intravenous immunoglobulin (IVIg) on a PIPN rat model. PTX-treated rats showed mechanical allodynia and neurophysiological alterations consistent with a severe sensory axonal polyneuropathy. In addition, morphological evaluation showed a reduction of intra-epidermal nerve fiber (IENF) density and evidenced axonopathy with macrophage infiltration, which was more prominent in the distal segment of caudal nerves. Three weeks after the last PTX injection, mechanical allodynia was still present in PTX-treated rats, while the full recovery in the group of animals co-treated with IVIg was observed. At the pathological level, this behavioral result was paralleled by prevention of the reduction in IENF density induced by PTX in IVIg co-treated rats. These results suggest that the immunomodulating effect of IVIg co-treatment can alleviate PIPN neurotoxic manifestations, probably through a partial reduction of neuroinflammation.

Effectiveness of Intravenous Immunoglobulin for Management of Neuropathic Pain: A Narrative Review

Administrations of intravenous immunoglobulin (IVIG), an immune-modulating blood-derived product, may be beneficial for managing neuropathic pain. Here, we review previous studies to investigate the effectiveness of IVIG in managing neuropathic pain due to various neurological disorders. The electronic databases PubMed, Scopus, Embase, and the Cochrane Library were searched for studies published up to February 2020. Two reviewers independently assessed the studies using strict inclusion criteria. Ten studies were included and qualitatively analyzed. The review included patients with pain due to complex regional pain syndrome (CRPS), diabetic polyneuropathy, and others, such as postherpetic neuralgia and trigeminal neuralgia. We found that IVIG may be one of the beneficial options for managing neuropathic pain from various neurological disorders. In the four articles reviewed, no major adverse effects were reported, and the trend was toward a positive pain-reducing effect in eight articles. However, to confirm the benefits of IVIG on reducing neuropathic pain, more high-quality studies are required.

Serum proteome profiles revealed dysregulated proteins and mechanisms associated with fibromyalgia syndrome in women

Fibromyalgia syndrome (FM) is a multifactorial disorder whose pathogenesis and diagnosis are poorly understood. This study investigated differential serum proteome profiles in patients with FM and healthy pain-free controls and explored the association between serum proteome and clinical profiles in patients with FM. Twenty patients with FM (according to the American College of Rheumatology criteria, 2010) and 20 healthy pain-free controls were recruited for optimized quantitative serum proteomics analysis. The levels of pain, pressure pain threshold, sleep, anxiety, depression, and functional status were evaluated for patients with FM. We identified 22 proteins differentially expressed in FM when compared with healthy pain-free controls and propose a panel of methyltransferase-like 18 (METTL18), immunoglobulin lambda variable 3–25 (IGLV3–25), interleukin-1 receptor accessory protein (IL1RAP), and IGHV1OR21-1 for differentiating FM from controls by using a decision tree model (accuracy: 0.97). In addition, we noted several proteins involved in coagulation and inflammation pathways with distinct expression patterns in patients with FM. Novel proteins were also observed to be correlated with the levels of pain, depression, and dysautonomia in patients with FM. We suggest that upregulated inflammation can play a major role in the pathomechanism of FM. The differentially expressed proteins identified may serve as useful biomarkers for diagnosis and evaluation of FM in the future.

A medical mystery of complex regional pain syndrome

Complex regional pain syndrome (CRPS) is a condition of neuropathic pain, which is characterized by significant autonomic and inflammatory features. CRPS occurs in patients who have limb surgery, limb fractures, or trauma. Many patients may have pain resolve within twelve months of the inciting incident; however, a small subset progresses to the chronic form. This transitional process often happens by changing from warm CRPS with dominant inflammatory phase to cold CRPS, in which autonomic characteristics or manifestations dominate. Several peripheral and central mechanisms are involved, which might vary among individuals over a period of time. Other contributors include peripheral and central sensitization, autonomic alterations, inflammatory and immune changes, neurochemical changes, and psychological and genetic factors. Although effective management of the chronic CRPS form is often challenging, there are a few high quality randomized controlled trials that support the efficacy of the most commonly used therapeutic approaches.

Impact of mast cells in fibromyalgia and low-grade chronic inflammation: Can IL-37 play a role?

Fibromyalgia (FM) is a disease characterized by chronic widespread pain, fatigue, aches, joint stiffness, depression, cognitive dysfunction, and nonrestorative sleep. In FM, neurotransmission and glial activation can occur with an increase in inflammatory cytokines and involvement of mast cells (MCs) in the skin. FM skin biopsies show an increase in the number of MCs, as well as the production of corticotropin releasing hormone and substance P (SP) by the neurons, which in turn activate MCs to release neurosensitizing proinflammatory substances, such as cytokines, secreted preformed mediators, and lipids, which can exacerbate low-grade inflammation. In fact, certain proinflammatory cytokines are higher in FM and mediate muscle pain, the mechanism of which is not yet clear. MC-derived tumor necrosis factor (TNF) induces nerve growth factor (NGF) and participates in nerve fiber elongation in skin hypersensitivity. IL-37 is an inhibitor of proinflammatory IL-1 family members, which are generated and released by MCs. The goal of this article is to demonstrate that inflammatory cytokines and MC products play a role in FM and that inflammation may be inhibited by IL-37. Here, we propose IL-37 as a cytokine that contributes to improve the pathogenesis of FM by blocking IL-1 family members.

Update on the use of immunoglobulin in human disease: A review of evidence

Human immunoglobulin preparations for intravenous or subcutaneous administration are the cornerstone of treatment in patients with primary immunodeficiency diseases affecting the humoral immune system. Intravenous preparations have a number of important uses in the treatment of other diseases in humans as well, some for which acceptable treatment alternatives do not exist. We provide an update of the evidence-based guideline on immunoglobulin therapy, last published in 2006. Given the potential risks and inherent scarcity of human immunoglobulin, careful consideration of its indications and administration is warranted.

Intravenous immunoglobulin therapy for small fiber neuropathy: study protocol for a randomized controlled trial

Background

Small fiber neuropathy is the most common cause of neuropathic pain in peripheral neuropathies, with a minimum prevalence of 53/100,000. Patients experience excruciating pain, and currently available anti-neuropathic and other pain drugs do not relieve the pain substantially. Several open-label studies have suggested an immunological basis in small fiber neuropathy and have reported efficacy of treatment with intravenous immunoglobulin. Therefore, immunological mechanisms conceivably may play a role in small fiber neuropathy. To date, no randomized controlled study with intravenous immunoglobulin in patients with small fiber neuropathy has been performed.

Methods/design

This study is a randomized, double-blind, placebo-controlled, clinical trial in patients with idiopathic small fiber neuropathy. The primary objective is to investigate the efficacy of intravenous immunoglobulin versus placebo on pain alleviation. A 1-point change in the PI-NRS compared to baseline is considered the minimum clinically important difference. In the IVIg-treated group, we assume a response rate of approximately 60 % based on the criteria composed by the IMMPACT group for measurement of pain. Based on this, a sample size of 60 patients is needed. Eligible patients fulfilling the inclusion/exclusion criteria will be randomized to receive either intravenous immunoglobulin or placebo (0.9 % saline). The treatment regimen will start with a loading dose of 2 g/kg body weight over 2–4 consecutive days, followed by a maintenance dose of 1 g/kg body weight over 1–2 consecutive days given three times at a 3-week interval. The primary endpoint is the comparison of the percentage of responder subjects between the two treatment groups from the first randomization during the 12 weeks of treatment. A responder is defined as ≥ 1-point Pain Intensity Numerical Rating Scale improvement on the mean weekly peak pain relative to baseline. The secondary outcomes are pain intensity, pain qualities, other small fiber neuropathy-related complaints, daily and social functioning, as well as quality of life. In addition, safety assessments will be performed for adverse events, vital signs, and laboratory values outside the normal range. Responders during the 12-week treatment period will be followed during a 3-month extension phase.

Discussion

This is the first randomized, double-blind, placebo-controlled clinical trial with intravenous immunoglobulin in patients with idiopathic small fiber neuropathy. Positive findings will result in a new treatment option for small fiber neuropathy and support an immunological role in this condition.

Trial registration

ClinicalTrials.gov, NCT02637700. Registered on 16 December 2015.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-016-1450-x) contains supplementary material, which is available to authorized users.

Intravenous Therapies for Complex Regional Pain Syndrome: A Systematic Review

Complex regional pain syndrome (CRPS) remains a challenging clinical pain condition. Multidisciplinary approaches have been advocated for managing CRPS. Compared with spinal cord stimulation and intrathecal targeted therapy, IV treatments are less invasive and less costly. We aimed to systemically review the literature on IV therapies and determine the level of evidence to guide the management of CRPS. We searched PubMed, Embase, Scopus, and the Cochrane databases for articles published on IV therapies of CRPS up through February 2015. The search yielded 299 articles, of which 101 were deemed relevant by reading the titles and 63 by reading abstracts. All these 63 articles were retrieved for analysis and discussion. We evaluated the relevant studies and provided recommendations according to the level of evidence. We conclude that there is evidence to support the use of IV bisphosphonates, immunoglobulin, ketamine, or lidocaine as valuable interventions in selected patients with CRPS. However, high-quality studies are required to further evaluate the safety, efficacy, and cost-effectiveness of IV therapies for CRPS.

Low-dose intravenous immunoglobulin treatment for complex regional pain syndrome (LIPS): study protocol for a randomized controlled trial

Background

Longstanding complex regional pain syndrome (CRPS) is refractory to treatment with established analgesic drugs in most cases, and for many patients, alternative pain treatment approaches, such as with neuromodulation devices or rehabilitation methods, also do not work. The development of novel, effective treatment technologies is, therefore, important. There are preliminary data suggesting that low-dose immunoglobulin treatment may significantly reduce pain from longstanding CRPS.

Methods/Design

LIPS is a multicentre (United Kingdom), double-blind, randomised parallel group, placebo-controlled trial, designed to evaluate the efficacy, safety, and tolerability of intravenous immunoglobulin (IVIg) 0.5 g/kg plus standard treatment, versus matched placebo plus standard treatment in 108 patients with longstanding complex regional pain syndrome. Participants with moderate or severe CRPS of between 1 and 5 years duration will be randomly allocated to receive IVIg 0.5 g/kg (IntratectTM 50 g/l solution for infusion) or matching placebo administered day 1 and day 22 after randomisation, followed by two optional doses of open-label medication on day 43 after randomisation and on day 64 after randomisation. The primary outcome is the patients’ pain intensity in the IVIG group compared with the placebo group, between 6 and 42 days after randomisation. The primary trial objective is to confirm the efficacy and confidently determine the effect size of the IVIG treatment technology in this group of patients.

Trial registration

ISRCTN42179756 (Registered 28 June 13).

Electronic supplementary material

The online version of this article (doi:10.1186/1745-6215-15-404) contains supplementary material, which is available to authorized users.

Treatment of spinal cord injury with intravenous immunoglobulin G: preliminary evidence and future perspectives

Neuroinflammation plays an important role in the secondary pathophysiological mechanisms of spinal cord injury (SCI) and can exacerbate the primary trauma and thus worsen recovery. Although some aspects of the immune response are beneficial, it is thought that leukocyte recruitment and activation in the acute phase of injury results in the production of cytotoxic substances that are harmful to the nervous tissue. Therefore, suppression of excessive inflammation in the spinal cord could serve as a therapeutic strategy to attenuate tissue damage. The immunosuppressant methylprednisolone has been used in the setting of SCI, but there are complications which have attenuated the initial enthusiasm. Hence, there is interest in other immunomodulatory approaches, such as intravenous Immunoglobulin G (IVIg). Importantly, IVIg is used clinically for the treatment of several auto-immune neuropathies, such as Guillain-Barre syndrome, chronic inflammatory demyelinating polyneuropathy (CIPD) and Kawasaki disease, with a good safety profile. Thus, it is a promising treatment candidate for SCI. Indeed, IVIg has been shown by our team to attenuate the immune response and result in improved neurobehavioral recovery following cervical SCI in rats through a mechanism that involves the attenuation of neutrophil recruitment and reduction in the levels of cytokines and cytotoxic enzymes Nguyen et al. (J Neuroinflammation 9:224, 2012). Here we review published data in the context of relevant mechanisms of action that have been proposed for IVIg in other conditions. We hope that this discussion will trigger future research to provide supporting evidence for the efficiency and detailed mechanisms of action of this promising drug in the treatment of SCI, and to facilitate its clinical translation.

Immunoglobulin g for the treatment of chronic pain: report of an expert workshop

BACKGROUND

The treatment of chronic pain is still unsatisfactory. Despite the availability of different drugs, most patients with chronic pain do not receive satisfactory pain relief or report side effects. Converging evidence implicates involvement of the immune system in the pathogenesis of different types of nociceptive and neuropathic chronic pain.

DESIGN

At a workshop in Liverpool, UK (October 2012), experts presented evidence suggesting immunological involvement in chronic pain and recent data supporting the concept that the established immune-modulating drug, polyvalent immunoglobulin G (IgG), either given intravenously (IVIg) or subcutaneously (SCIg), may reduce pain in some peripheral neuropathies and a range of other pain disorders. Workshop's attendees discussed the practicalities of using IVIg and SCIg in these disorders, including indications, cost-effectiveness, and side effects.

RESULTS

IgG may reduce pain in a range of nociceptive and neuropathic chronic pain conditions, including diabetes mellitus, Sjögren's syndrome, fibromyalgia, complex regional pain syndrome, post-polio syndrome, and pain secondary to pathological autoantibodies.

CONCLUSIONS

IgG is a promising treatment in several chronic pain conditions. IgG is a relatively safe therapeutic strategy, with uncommon and mild side effects but high costs. Randomized, controlled trials and predictive tests are needed to better support the use of IgG for refractory chronic pain.

Subcutaneous IgG in neurologic diseases

Subcutaneous administration of IgG (SCIG) has become widely used in primary immune deficiency diseases but it has only recently been studied for maintenance therapy in autoimmune peripheral neuropathies, such as chronic idiopathic demyelinating polyneuropathy and multifocal motor neuropathy. Weekly self-administration of SCIG is safe and well-tolerated, and results in steady-state serum IgG levels, as contrasted with the peaks and troughs of monthly immune globulin (human) for intravenous use. Freedom from the need for venous access or medical personnel for infusions, flexibility in scheduling, convenience of home therapy, and improved clinical stability due to the steady-state IgG levels, lead many patients to prefer SCIG to immune globulin (human) for intravenous use. Long-term studies are needed to determine if the constant IgG levels and clinical stability translate into better long-term outcomes.

Long-term response of neuropathic pain to intravenous immunoglobulin in relapsing diabetic lumbosacral radiculoplexus neuropathy. A case report

Diabetic lumbosacral radiculoplexus neuropathy (DLRPN) is a rare painful peripheral neuropathic complication of diabetes mellitus. The clinical features of DLRPN include severe neuropathic pain, weakness, atrophy, and sensory loss in the lower limbs with asymmetrical distribution. Nerve ischemia due to inflammation and microvasculitis has been suggested as the pathophysiological mechanism for DLRPN. Analgesics and drugs for neuropathic pain often cannot achieve adequate pain control in DLRPN. Some reports suggest that intravenous immunoglobulin (IVIg) may reduce pain in DLRPN, but the mechanisms of this effect are unclear. We report a patient with relapsing DLRPN who was followed up for 8 years and whose pain improved after IVIg on nine occasions. We measured serum cytokines before and after IVIg; serum tumor necrosis factor α was increased when the patient reported pain and normalized after IVIg in parallel with pain improvement. Our data extend the notion that some types of pain, including peripheral neuropathic pain, may respond to IVIg and give some clue on the mechanism of this therapeutic effect. They are also consistent with the suggested role of the immune system in the pathophysiology of neuropathic pain and offer support to the hypothesis that cytokines may contribute to the pathogenesis of neuropathic pain.

Improving the diagnosis and treatment of CRPS: insights from a clinical immunologist's personal experience with an underrecognized neuroinflammatory disorder

Complex regional pain syndrome is a neuroinflammatory condition associated with overactive glial cells that can be challenging to diagnose and treat. Early recognition and treatment are thought to be critical for good outcomes, yet many patients experience a delay in diagnosis and have difficulty accessing expert medical care. While there are no universally effective treatments, there are several promising new therapies, but these are not widely available. Some of the specific barriers to diagnosis and treatment are reviewed, with suggestions as to how they might be eliminated, leading to better care for all patients with CRPS.