Plasma exchange in polyneuropathy associated with monoclonal gammopathy of undetermined significance

A pathologically expanded, clonal lineage of IL-21 producing CD4+ T cells drives Inflammatory neuropathy

Inflammatory neuropathies, which include CIDP (chronic inflammatory demyelinating polyneuropathy) and GBS (Guillain Barre Syndrome), result from autoimmune destruction of the peripheral nervous system (PNS) and are characterized by progressive weakness and sensory loss. CD4+ T cells play a key role in the autoimmune destruction of the PNS. Yet, key properties of pathogenic CD4+ T cells remain incompletely understood. Here, we use paired scRNAseq and scTCRseq of peripheral nerves from an inflammatory neuropathy mouse model to identify IL-21 expressing CD4+ T cells that are clonally expanded and multifunctional. These IL-21-expressing CD4+ T cells are comprised of two transcriptionally distinct expanded populations, which express genes associated with Tfh and Tph subsets. Remarkably, TCR clonotypes are shared between these two IL-21-expressing populations, suggesting a common lineage differentiation pathway. Finally, we demonstrate that IL-21 signaling is required for neuropathy development and pathogenic T cell infiltration into peripheral nerves. IL-21 signaling upregulates CXCR6, a chemokine receptor that promotes CD4+ T cell localization in peripheral nerves. Together, these findings point to IL-21 signaling, Tfh/Tph differentiation, and CXCR6-mediated cellular localization as potential therapeutic targets in inflammatory neuropathies.

Autoimmune polyneuropathies

The autoimmune peripheral neuropathies with prominent motor manifestations are a diverse collection of unusual peripheral neuropathies that are appreciated in vast clinical settings. This chapter highlights the most common immune-mediated, motor predominant neuropathies excluding acute, and chronic inflammatory demyelinating polyradiculoneuropathy (AIDP and CIDP, respectively). Other acquired demyelinating neuropathies such as distal CIDP and multifocal motor neuropathy will be covered. Additionally, the radiculoplexus neuropathies, resulting from microvasculitis-induced injury to nerve roots, plexuses, and nerves, including diabetic and nondiabetic lumbosacral radiculoplexus neuropathy and neuralgic amyotrophy (i.e., Parsonage-Turner syndrome), will be included. Finally, the motor predominant peripheral neuropathies encountered in association with rheumatological disease, particularly Sjögren's syndrome and rheumatoid arthritis, are covered. Early recognition of these distinct motor predominant autoimmune neuropathies and initiation of immunomodulatory and immunosuppressant treatment likely result in improved outcomes.

Polyneuropathy Associated with IgM Monoclonal Gammopathy; Advances in Genetics and Treatment, Focusing on Anti-MAG Antibodies

With increasing age, the chances of developing either MGUS or polyneuropathy increase as well. In some cases, there is a causative relationship between the IgM M-protein and polyneuropathy. In approximately half of these cases, IgM targets the myelin-associated glycoprotein (MAG). This results in chronic polyneuropathy with slowly progressive, predominantly sensory neurological deficits and distally demyelinating features in nerve conduction studies. Despite the disease being chronic and developing slowly, it can cause considerable impairment. We reviewed English medical publications between 1980 and May 2022 on IgM gammopathy-associated polyneuropathy, with special attention to studies addressing the pathophysiology or treatment of anti-MAG polyneuropathy. Treatment options have been limited to a temporizing effect of intravenous immunoglobulins in some patients and a more sustained effect of rituximab but in only 30 to 55 percent of patients. An increase in our knowledge concerning genetic mutations, particularly the MYD88L265P mutation, led to the development of novel targeted treatment options such as BTK inhibitors. Similarly, due to the increasing knowledge of the pathophysiology of anti-MAG polyneuropathy, new treatment options are emerging. Since anti-MAG polyneuropathy is a rare disease with diverse symptomatology, large trials with good outcome measures are a challenge.

Assessing efficacy and safety of replacement fluids in therapeutic plasma exchange: A systematic scoping review of outcome measures used

OBJECTIVE

The aim of this systematic scoping review is to identify and categorize the outcome measures that have been reported in clinical studies, where therapeutic plasma exchange (TPE) has been used as an intervention in any clinical settings, excluding thrombotic thrombocytopenic purpura (TTP).

METHODS

We searched electronic databases using a predefined search strategy from inception to October 9, 2020. Two reviewers independently screened and extracted data.

RESULTS

We included 42 studies (37 RCTs and 5 prospective cohort studies) grouped into six main categories (neurology, immunology, renal, rheumatology, hematology, and dermatology). Primary outcomes were defined in eight studies (19%, 8/42) and were categorized as efficacy (five studies) or patient reported outcomes (three studies). A power calculation was reported in six studies (75%, 6/8): five neurology studies (mainly patient reported outcomes) and a single immunological study (efficacy outcome). Disease-specific efficacy outcomes were dependent on the clinical setting of the population receiving TPE. Most of the trials (43%, 18/42) were undertaken in patients with neurology conditions where clear, disease-specific, clinical outcome measures were used, including neurological disability scales (11/18, 61%), change in neurological examination (9/18, 50%), and functional improvement scores (7/18, 39%). For other conditions, the reporting of disease-specific outcomes was poorly reported. Safety outcomes were mainly related to replacement fluid type rather than being disease-specific. The most common outcome reported was hypotension (19%, 8/42), and this was primarily in patients exchanged with albumin.

CONCLUSION

Future clinical studies to determine which fluid replacement option is most efficacious and safe should use disease-specific outcomes, as a trial in one therapeutic area may not necessarily translate to another therapeutic area. Patient reported outcomes are not universally reported for all disease areas. Safety measures focused primarily on fluid safety.

Immunoglobulin M Monoclonal Gammopathies of Clinical Significance

Immunoglobulin M monoclonal gammopathy of undetermined significance (MGUS) comprises 15-20% of all cases of MGUS. IgM MGUS is distinct from other forms of MGUS in that the typical primary progression events include Waldenstrom macroglobulinaemia and light chain amyloidosis. Owing to its large pentameric structure, IgM molecules have high intrinsic viscosity and precipitate more readily than other immunoglobulin subtypes. They are also more commonly associated with autoimmune phenomena, resulting in unique clinical manifestations. Organ damage attributable to the paraprotein, not fulfilling criteria for a lymphoid or plasma cell malignancy has recently been termed monoclonal gammopathy of clinical significance (MGCS) and encompasses an important family of disorders for which diagnostic and treatment algorithms are evolving. IgM related MGCS include unique entities such as cold haemagglutinin disease, IgM related neuropathies, renal manifestations and Schnitzler's syndrome. The diagnostic approach to, and management of these disorders differs significantly from other categories of MGCS. We describe a practical approach to the evaluation of these patients and our approach to their treatment. We will also elaborate on the key unmet needs in IgM MGCS and highlight potential areas for future research.

Decrease in Serum Anti-MAG Autoantibodies Is Associated With Therapy Response in Patients With Anti-MAG Neuropathy: Retrospective Study

Background and Objectives

The objective of the retrospective analysis was to test the hypothesis that changes in serum anti-myelin-associated glycoprotein (MAG) autoantibodies are associated with clinical response to immunotherapy in patients with anti-MAG neuropathy.

Methods

As of January 29, 2020, we used anti-myelin-associated glycoprotein-related search strings in the Medline database to identify studies that provided information on anti-MAG immunoglobulin M (IgM) autoantibodies and clinical outcomes during immunotherapies. The relative change in anti-MAG IgM titers, paraprotein levels, or total IgM was determined before, during, or posttreatment, and the patients were assigned to “responder,” “nonresponder,”’ or “acute deteriorating” category depending on their clinical response to treatment. The studies were qualified as “supportive” or “not supportive” depending on the percentage of patients exhibiting an association between relative change of anti-MAG antibody titers or levels and change in clinical outcomes.

Results

Fifty studies with 410 patients with anti-MAG neuropathy were included in the analysis. Forty studies with 303 patients supported the hypothesis that a “responder” patient had a relative reduction of anti-MAG antibody titers or levels that is associated with clinical improvements and “nonresponder” patients exhibited no significant change in anti-MAG IgM antibodies. Six studies with 93 patients partly supported, and 4 studies with 26 patients did not support the hypothesis.

Discussion

The retrospective analysis confirmed the hypothesis that a relative reduction in serum anti-MAG IgM antibodies is associated with a clinical response to immunotherapies; a sustained reduction of at least 50% compared with pretreatment titers or levels could be a valuable indicator for therapeutic response.

Management of Myeloma Manifestations and Complications: The Cornerstone of Supportive Care: Recommendation of the Canadian Myeloma Research Group (formerly Myeloma Canada Research Network) Consensus Guideline Consortium

Multiple myeloma (MM) is a hematological cancer associated with significant symptomatic burden. Bone disease, renal insufficiency, cytopenias, infection, and peripheral neuropathy, among other disease manifestations and complications, impair patients' quality of life. The Canadian Myeloma Research Group Consensus Guideline Consortium, formerly Myeloma Canada Research Network Consensus Guideline Consortium, proposes national consensus recommendations for the management of MM-related manifestations and complications. To address the needs of Canadian physicians and people living with MM across the country, this document focuses on the improvement and maintenance of patient care by clarifying best-practice approaches for the prevention, detection and management of disease manifestations and complications. The Canadian Myeloma Research Group Consensus Guideline Consortium will periodically review the recommendations herein and update as necessary.

Monoclonal Gammopathies of 'Neurological Significance': Paraproteinemic Neuropathies

OBJECTIVES

To study the clinical profile and outcomes of patients with paraproteinemic neuropathy (PPN) and to explore the utility of nerve conduction studies (NCSs) to differentiate between the demyelinating subtypes.

METHODS

We did a retrospective analysis of patients diagnosed with PPN between January 2010 and December 2019 in an inpatient setting. The study population consisted of patients above 16 years of age presenting with clinical features suggestive of chronic peripheral neuropathy and on evaluation was found to have PPN.

RESULTS

A total of 74 patients were identified. The patients were predominantly in the 6th decade, and the majority were males. The subtypes of PPN were monoclonal gammopathy of undetermined significance (MGUS) (45.9%), POEMS syndrome (polyneuropathy, organomegaly, endocrinopathy, monoclonal plasma cell disorder, and skin changes) (24.3%), solitary plasmacytoma (17.6%), multiple myeloma (8.1%), and AL amyloidosis (4.1%). There are specific features on NCS which can help in identifying POEMS syndrome and IgM MGUS. The majority of patients with PPN tend to stabilize or improve with treatment; however, many have a severe residual disability. New terminology and classification of these entities as 'monoclonal gammopathies of neurological significance' can aid in early diagnosis and the development of effective treatment, to prevent residual disability.

CONCLUSION

PPN has a heterogeneous spectrum of clinical, biochemical, and electrophysiological features. NCS can help distinguish POEMS syndrome and IgM MGUS from other demyelinating subtypes.

The Spectrum of Monoclonal Immunoglobulin-Associated Diseases

The spectrum of immunoglobulin paraprotein-associated diseases requiring therapy extends beyond multiple myeloma and AL amyloidosis. Awareness of these is essential in ensuring timely accurate diagnosis and appropriate treatment. As most paraprotein-associated diseases are fairly uncommon, therapeutic decisions must often be made in the absence of data from randomized controlled trials. Treatment is generally directed at the underlying clonal cell population. This review focuses on the spectrum of the less common paraprotein-associated disorders. In most instances, the monoclonal immunoglobulin plays a direct role in the pathophysiology of the disease course; in a select few, the paraprotein may be a disease marker.

Immunoglobulin M Paraproteinaemias

Monoclonal paraproteinaemia is an increasingly common reason for referral to haematology services. Paraproteinaemias may be associated with life-threatening haematologic malignancies but can also be an incidental finding requiring only observation. Immunoglobulin M (IgM) paraproteinaemias comprise 15–20% of monoclonal proteins but pose unique clinical challenges. IgM paraproteins are more commonly associated with lymphoplasmacytic lymphoma than multiple myeloma and can occur in a variety of other mature B-cell neoplasms. The large molecular weight of the IgM multimer leads to a spectrum of clinical manifestations more commonly seen with IgM paraproteins than others. The differential diagnosis of B-cell and plasma cell dyscrasias associated with IgM gammopathies can be challenging. Although the discovery of MYD88 L265P and other mutations has shed light on the molecular biology of IgM paraproteinaemias, clinical and histopathologic findings still play a vital role in the diagnostic process. IgM secreting clones are also associated with a number of “monoclonal gammopathy of clinical significance” entities. These disorders pose a novel challenge from both a diagnostic and therapeutic perspective. In this review we provide a clinical overview of IgM paraproteinaemias while discussing the key advances which may affect how we manage these patients in the future.

Development of measures of polyneuropathy impairment in hATTR amyloidosis: From NIS to mNIS + 7

Hereditary transthyretin-mediated amyloidosis (hATTR amyloidosis) is a rare, life-threatening disease, caused by point mutations in the transthyretin gene. It is a heterogeneous, multisystem disease with rapidly progressing polyneuropathy (including sensory, motor, and autonomic impairments) and cardiac dysfunction. Measures used to assess polyneuropathy in other diseases have been tested as endpoints in hATTR amyloidosis clinical trials (i.e. Neuropathy Impairment Score [NIS], NIS-lower limb, and NIS + 7), yet the unique nature of the polyneuropathy in this disease has necessitated modifications to these scales. In particular, the heterogeneous impairment and the aggressive disease course have been key drivers in developing scales that better capture the disease burden and progression of polyneuropathy in hATTR amyloidosis. The modified NIS + 7 (mNIS + 7) scale was specifically designed to assess polyneuropathy impairment in patients with hATTR amyloidosis, and has been the primary endpoint in two recent, phase III studies in this disease. The mNIS + 7 uses highly standardized, quantitative, and referenced assessments to quantify decreased muscle weakness, muscle stretch reflexes, sensory loss, and autonomic impairment. Physicians using this scale in clinical trials should be specifically trained and monitored to minimize variability. This article discusses the different scales that have been/are being used to assess polyneuropathy in patients with hATTR amyloidosis, their correlation with other disease assessments, and reflects on how and why scales have evolved to the latest iteration of mNIS + 7.

Plasma exchange in neurological disease

Plasma exchange is a highly efficient technique to remove circulating autoantibodies and other humoral factors rapidly from the vascular compartment. It was the first effective acute treatment for peripheral disorders such as Guillain-Barré syndrome and myasthenia gravis before intravenous immunoglobulin became available. The recent recognition of rapidly progressive severe antibody-mediated central nervous system disorders, such as neuromyelitis optica spectrum disorders and anti-N-methyl-D-aspartate-receptor encephalitis, has renewed interest in using plasma exchange for their acute treatment also. In this review we explain the principles and technical aspects of plasma exchange, review its current indications, and discuss the implications for its provision in the UK.

Peripheral Nervous System Involvement in Lymphoproliferative Disorders

Peripheral neuropathies are a vast group of diseases with heterogeneous aetiologies, including genetic and acquired causes. Several haematological disorders may cause an impairment of the peripheral nervous system, with diverse mechanisms and variable clinical, electrophysiological and pathological manifestations. In this practical review, we considered the main phenotypes of peripheral nervous system diseases associated with lymphoproliferative disorders.

The area of intersection of neurological and haematological fields is of particular complexity and raises specific problems in the clinical practice of lymphoproliferative disorders. The personal crosstalk between neurologists and haematologists remains a fundamental tool for a proper diagnostic process which may lead to successful treatments in most cases.

Immune Axonal Polyneuropathy

PURPOSE OF REVIEW

Immune axonal polyneuropathy is caused by a diverse group of disorders that share similar presentations and treatment regimens. This article focuses on the clinical findings, evaluation, and management of immune-mediated causes of axonal polyneuropathy, focusing primarily on large fiber sensorimotor polyneuropathy.

RECENT FINDINGS

Specific characteristics of an immune-mediated polyneuropathy have been incorporated in a new diagnostic screening tool that is highly sensitive and can easily be used in the outpatient clinic setting. New insights into autoantibodies may help identify the presence of an underlying autoimmune or paraneoplastic disease as the cause of a polyneuropathy.

SUMMARY

This article provides readers with further understanding into the autoimmune causes of axonal polyneuropathy and will help the clinician recognize key clinical features that may lead to timely diagnosis and treatment.

Plasma-exchange in Chronic Peripheral Neurological Disorders

We investigated 19 patients affected by chronic peripheral neurological disorders treated with therapeutic plasma exchange (TPE) to verify the efficacy of the therapeutic protocol used in these diseases.

Every patient was clinically considered after 5 TPE. Those who showed an improvement started chemotherapy and continued TPE at the rate of 2 procedures/week for 2 weeks, then 1 procedure/week for 1 month and finally 1 procedure every 2 weeks for 2 months. Intravenous immunoglobulins (IVIg) were infused at the end of apheretic treatment in one of the patients affected by neurological disorders due to monoclonal gammopathy undetermined significance. HCV-positive patients with cryoglobulins were treated with α-interferon (α-IFN) for 6 months before TPE. Eleven patients (58%) had a symptomatic improvement, 2 (1.5%) stopped TPE treatment owing to side effects and 6 (31.5%) did not respond to apheretic therapy.

In order to improve the advantages of TPE we suggest using IVIg at the end of apheretic therapy, while in HCV-positive patients, at least one year of α-IFN therapy is required before initiating TPE.

Monoclonal Gammopathy-Associated Peripheral Neuropathy: Diagnosis and Management

Monoclonal gammopathies comprise a spectrum of clonal plasma cell disorders that include monoclonal gammopathy of undetermined significance, multiple myeloma, and Waldenström macroglobulinemia. In this review, we outline the epidemiology, etiology, classification, diagnosis, and treatment of monoclonal gammopathy-associated peripheral neuropathy. Monoclonal gammopathy of undetermined significance is relatively common in the general population, with a prevalence of 3% to 4% among individuals older than age 50 years. Therefore, the presence of M protein in a patient with neuropathy does not automatically indicate a causal relationship. Monoclonal gammopathy-associated peripheral neuropathy is often a difficult diagnosis with limited treatment options. Studies addressing the optimal approach to diagnosis and management of this entity are limited. In addition to a review of the literature, we present a diagnostic approach to patients with monoclonal gammopathy-associated peripheral neuropathy and discuss available data and options for treatment.

Diagnosis and management of neuropathies associated with plasma cell dyscrasias

Neuropathies associated with plasma cell dyscrasias are a major cause of morbidity for patients managed by medical oncologists. Because of similarities in clinical presentation and on nerve conduction studies, identifying the underlying disease leading to a paraproteinemic neuropathy can often be difficult. In addition, the degree of neurologic deficit does not strictly correlate with the extent of abnormalities on common clinical laboratory testing. Fortunately, with increasing understanding into the biologic mechanisms of underlying hematologic diseases, additional biomarkers have recently been developed, thus improving our diagnostic capacity. Neuropathies associated with plasma cells dyscrasias are seen with Monoclonal gammopathy of undetermined significance (MGUS) particularly IgM subtype, followed by IgG and IgA MGUS, multiple myeloma, Waldenström's macroglobulinemia, amyloid, Castleman's disease, and POEMS syndrome. The mechanisms of neuronal injury associated with plasma cell dyscrasia vary based on underlying diagnosis and include malignant infiltration, immune-mediated antibody deposition, or local compression of nerve roots. The polyneuropathies are frequently demyelinating, although axonal and mixed neuropathies can also be seen. As demonstrated by the cases included in this review, patients frequently present with symmetric sensory disturbance, followed by progressive motor weakness. Unfortunately, because of the complexity of diagnostic testing, patients are frequently examined late, often after receiving several ineffective therapies. The aim of this case-based review is to provide clinicians with insight on how to properly recognize these atypical neuropathies and send the appropriate diagnostic work, increasing the likelihood of accurately classify the patient's underlying hematologic disorder.

Assessing mNIS+7Ionis and international neurologists' proficiency in a familial amyloidotic polyneuropathy trial

INTRODUCTION

Polyneuropathy signs (Neuropathy Impairment Score, NIS), neurophysiologic tests (m+7_Ionis ), disability, and health scores were assessed in baseline evaluations of 100 patients entered into an oligonucleotide familial amyloidotic polyneuropathy (FAP) trial.

METHODS

We assessed: (1) Proficiency of grading neurologic signs and correlation with neurophysiologic tests, and (2) clinometric performance of modified NIS+7 neurophysiologic tests (mNIS+7_Ionis ) and its subscores and correlation with disability and health scores.

RESULTS

The mNIS+7_Ionis sensitively detected, characterized, and broadly scaled diverse polyneuropathy impairments. Polyneuropathy signs (NIS and subscores) correlated with neurophysiology tests, disability, and health scores. Smart Somatotopic Quantitative Sensation Testing of heat as pain 5 provided a needed measure of small fiber involvement not adequately assessed by other tests.

CONCLUSIONS

Specially trained neurologists accurately assessed neuropathy signs as compared to referenced neurophysiologic tests. The score, mNIS+7_Ionis , broadly detected, characterized, and scaled polyneuropathy abnormality in FAP, which correlated with disability and health scores. Muscle Nerve 56: 901-911, 2017.

Treatments for chronic inflammatory demyelinating polyradiculoneuropathy (CIDP): an overview of systematic reviews

BACKGROUND

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is a chronic progressive or relapsing and remitting disease that usually causes weakness and sensory loss. The symptoms are due to autoimmune inflammation of peripheral nerves. CIPD affects about 2 to 3 per 100,000 of the population. More than half of affected people cannot walk unaided when symptoms are at their worst. CIDP usually responds to treatments that reduce inflammation, but there is disagreement about which treatment is most effective.

OBJECTIVES

To summarise the evidence from Cochrane systematic reviews (CSRs) and non-Cochrane systematic reviews of any treatment for CIDP and to compare the effects of treatments.

METHODS

We considered all systematic reviews of randomised controlled trials (RCTs) of any treatment for any form of CIDP. We reported their primary outcomes, giving priority to change in disability after 12 months.Two overview authors independently identified published systematic reviews for inclusion and collected data. We reported the quality of evidence using GRADE criteria. Two other review authors independently checked review selection, data extraction and quality assessments.On 31 October 2016, we searched the Cochrane Database of Systematic Reviews, the Database of Abstracts of Reviews of Effects (in theCochrane Library), MEDLINE, Embase, and CINAHL Plus for systematic reviews of CIDP. We supplemented the RCTs in the existing CSRs by searching on the same date for RCTs of any treatment of CIDP (including treatment of fatigue or pain in CIDP), in the Cochrane Neuromuscular Specialised Register, CENTRAL, MEDLINE, Embase, and CINAHL Plus.

MAIN RESULTS

Five CSRs met our inclusion criteria. We identified 23 randomised trials, of which 15 had been included in these CSRs. We were unable to compare treatments as originally planned, because outcomes and outcome intervals differed. CorticosteroidsIt is uncertain whether daily oral prednisone improved impairment compared to no treatment because the quality of the evidence was very low (1 trial, 28 participants). According to moderate-quality evidence (1 trial, 41 participants), six months' treatment with high-dose monthly oral dexamethasone did not improve disability more than daily oral prednisolone. Observational studies tell us that prolonged use of corticosteroids sometimes causes serious side-effects. Plasma exchangeAccording to moderate-quality evidence (2 trials, 59 participants), twice-weekly plasma exchange produced more short-term improvement in disability than sham exchange. In the largest observational study, 3.9% of plasma exchange procedures had complications. Intravenous immunoglobulinAccording to high-quality evidence (5 trials, 269 participants), intravenous immunoglobulin (IVIg) produced more short-term improvement than placebo. Adverse events were more common with IVIg than placebo (high-quality evidence), but serious adverse events were not (moderate-quality evidence, 3 trials, 315 participants). One trial with 19 participants provided moderate-quality evidence of little or no difference in short-term improvement of impairment with plasma exchange in comparison to IVIg. There was little or no difference in short-term improvement of disability with IVIg in comparison to oral prednisolone (moderate-quality evidence; 1 trial, 29 participants) or intravenous methylprednisolone (high-quality evidence; 1 trial, 45 participants). One unpublished randomised open trial with 35 participants found little or no difference in disability after three months of IVIg compared to oral prednisone; this trial has not yet been included in a CSR. We know from observational studies that serious adverse events related to IVIg do occur. Other immunomodulatory treatmentsIt is uncertain whether the addition of azathioprine (2 mg/kg) to prednisone improved impairment in comparison to prednisone alone, as the quality of the evidence is very low (1 trial, 27 participants). Observational studies show that adverse effects truncate treatment in 10% of people.According to low-quality evidence (1 trial, 60 participants), compared to placebo, methotrexate 15 mg/kg did not allow more participants to reduce corticosteroid or IVIg doses by 20%. Serious adverse events were no more common with methotrexate than with placebo, but observational studies show that methotrexate can cause teratogenicity, abnormal liver function, and pulmonary fibrosis.According to moderate-quality evidence (2 trials, 77 participants), interferon beta-1a (IFN beta-1a) in comparison to placebo, did not allow more people to withdraw from IVIg. According to moderate-quality evidence, serious adverse events were no more common with IFN beta-1a than with placebo.We know of no other completed trials of immunosuppressant or immunomodulatory agents for CIDP. Other treatmentsWe identified no trials of treatments for fatigue or pain in CIDP. Adverse effectsNot all trials routinely collected adverse event data; when they did, the quality of evidence was variable. Adverse effects in the short, medium, and long term occur with all interventions. We are not able to make reliable comparisons of adverse events between the interventions included in CSRs.

AUTHORS' CONCLUSIONS

We cannot be certain based on available evidence whether daily oral prednisone improves impairment compared to no treatment. However, corticosteroids are commonly used, based on widespread availability, low cost, very low-quality evidence from observational studies, and clinical experience. The weakness of the evidence does not necessarily mean that corticosteroids are ineffective. High-dose monthly oral dexamethasone for six months is probably no more or less effective than daily oral prednisolone. Plasma exchange produces short-term improvement in impairment as determined by neurological examination, and probably produces short-term improvement in disability. IVIg produces more short-term improvement in disability than placebo and more adverse events, although serious side effects are probably no more common than with placebo. There is no clear difference in short-term improvement in impairment with IVIg when compared with intravenous methylprednisolone and probably no improvement when compared with either oral prednisolone or plasma exchange. According to observational studies, adverse events related to difficult venous access, use of citrate, and haemodynamic changes occur in 3% to17% of plasma exchange procedures.It is uncertain whether azathioprine is of benefit as the quality of evidence is very low. Methotrexate may not be of benefit and IFN beta-1a is probably not of benefit.We need further research to identify predictors of response to different treatments and to compare their long-term benefits, safety and cost-effectiveness. There is a need for more randomised trials of immunosuppressive and immunomodulatory agents, routes of administration, and treatments for symptoms of CIDP.

Immunotherapy for IgM anti-myelin-associated glycoprotein paraprotein-associated peripheral neuropathies

BACKGROUND

Serum monoclonal anti-myelin-associated glycoprotein (anti-MAG) antibodies may be pathogenic in some people with immunoglobulin M (IgM) paraprotein and demyelinating neuropathy. Immunotherapies aimed at reducing the level of these antibodies might be expected to be beneficial. This is an update of a review first published in 2003 and previously updated in 2006 and 2012.

OBJECTIVES

To assess the effects of immunotherapy for IgM anti-MAG paraprotein-associated demyelinating peripheral neuropathy.

SEARCH METHODS

On 1 February 2016 we searched the Cochrane Neuromuscular Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, and Embase for randomised controlled trials (RCTs). We also checked trials registers and bibliographies, and contacted authors and experts in the field.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) or quasi-RCTs involving participants of any age treated with any type of immunotherapy for anti-MAG antibody-associated demyelinating peripheral neuropathy with monoclonal gammopathy of undetermined significance and of any severity.Our primary outcome measures were numbers of participants improved in disability assessed with either or both of the Neuropathy Impairment Scale (NIS) or the modified Rankin Scale (mRS) at six months after randomisation. Secondary outcome measures were: mean improvement in disability, assessed with either the NIS or the mRS, 12 months after randomisation; change in impairment as measured by improvement in the 10-metre walk time, change in a validated linear disability measure such as the Rasch-built Overall Disability Scale (R-ODS) at six and 12 months after randomisation, change in subjective clinical scores and electrophysiological parameters at six and 12 months after randomisation; change in serum IgM paraprotein concentration or anti-MAG antibody titre at six months after randomisation; and adverse effects of treatments.

DATA COLLECTION AND ANALYSIS

We followed standard methodological procedures expected by Cochrane.

MAIN RESULTS

We identified eight eligible trials (236 participants), which tested intravenous immunoglobulin (IVIg), interferon alfa-2a, plasma exchange, cyclophosphamide and steroids, and rituximab. Two trials of IVIg (22 and 11 participants, including 20 with antibodies against MAG), had comparable interventions and outcomes, but both were short-term trials. We also included two trials of rituximab with comparable interventions and outcomes.There were very few clinical or statistically significant benefits of the treatments used on the outcomes predefined for this review, but not all the predefined outcomes were used in every included trial and more responsive outcomes are being developed. A well-performed trial of IVIg, which was at low risk of bias, showed a statistical benefit in terms of improvement in mRS at two weeks and 10-metre walk time at four weeks, but these short-term outcomes are of questionable clinical significance. Cyclophosphamide failed to show any benefit in the single trial's primary outcome, and showed a barely significant benefit in the primary outcome specified here, but some toxic adverse events were identified.Two trials of rituximab (80 participants) have been published, one of which (26 participants) was at high risk of bias. In the meta-analysis, although the data are of low quality, rituximab is beneficial in improving disability scales (Inflammatory Neuropathy Cause and Treatment (INCAT) improved at eight to 12 months (risk ratio (RR) 3.51, 95% confidence interval (CI) 1.30 to 9.45; 73 participants)) and significantly more participants improve in the global impression of change score (RR 1.86, 95% CI 1.27 to 2.71; 70 participants). Other measures did not improve significantly, but wide CIs do not preclude some effect. Reported adverse effects of rituximab were few, and mostly minor.There were few serious adverse events in the other trials.

AUTHORS' CONCLUSIONS

There is inadequate reliable evidence from trials of immunotherapies in anti-MAG paraproteinaemic neuropathy to form an evidence base supporting any particular immunotherapy treatment. IVIg has a statistically but probably not clinically significant benefit in the short term. The meta-analysis of two trials of rituximab provides, however, low-quality evidence of a benefit from this agent. The conclusions of this meta-analysis await confirmation, as one of the two included studies is of very low quality. We require large well-designed randomised trials of at least 12 months' duration to assess existing or novel therapies, preferably employing unified, consistent, well-designed, responsive, and valid outcome measures.

[A case of sensory ataxic axonal polyneuropathy with IgGλ monoclonal gammopathy successfully treated with intravenous immunoglobulin therapy]

We report the case of an 84-year-old man with sensory ataxic polyneuropathy and IgGλ monoclonal gammopathy of undetermined significance (MGUS), which was successfully treated with intravenous immunoglobulin (IVIG) therapy. He had developed progressive ataxic gait over the span of 2 years before he was admitted to our hospital. On admission, he was unable to walk without assistance because of severe sensory ataxia. He performed poorly on the finger-nose-finger and heel-knee tests, and his vibration and position sense in the feet was remarkably diminished. However, motor involvement was not remarkable. Serum immunoelectrophoresis revealed IgGλ monoclonal gammopathy, and MGUS was diagnosed. Nerve conduction studies revealed sensory-dominant axonal polyneuropathy. The patient was successfully treated with IVIG (400 mg/kg/day, for 5 days). He regained his capacity to walk independently after treatment, but his nerve conduction results remained unchanged. This sensory ataxia might be partially due to underlying cervical spondylotic myelopathy. To our knowledge, this is the first report in our country of the successful use of IVIG therapy to treat a patient with IgGλ monoclonal gammopathy and related sensory ataxic axonal polyneuropathy.

Monoclonal gammopathy of undeterminated significance and endoneurial IgG deposition: A case report

BACKGROUND

Monoclonal gammopathy of undeterminated significance is the most common form of plasma cell dyscrasia, usually considered as benign. In rare cases it may have a malignant course, sometimes limited to an organ such as peripheral nerves.

METHODS

We describe clinical, electrophysiological and pathological findings in a patient presenting a immunoglobulin G (IgG) paraproteinemic polyneuropathy clinically mimicking a chronic inflammatory demyelinating polyneuropathy.

RESULTS

Immuno-electron microscopy (immune-EM) demonstrated that the widenings of the myelin lamellae resulted from the infiltration of IgG between a significant number of myelin lamellae (with absence of inflammatory cells in the epineurium, endoneurium, and perineurium, and the lack signs of vasculitis). This patient was finally treated successfully with lenalidomide then mycophenolate mofetil.

CONCLUSIONS

In polyneuropathies associated to a monoclonal gammopathy, a nerve biopsy may clinch the diagnosis. Immuno-EM may be required to determine the role of the pathological immunoglobulin in the destruction of the peripheral nerve parenchyma. Diagnosis of such a direct involvement of peripheral nerve can endorse more aggressive treatment of real efficiency.

The Spectrum and Pathogenesis of Antibody-mediated Neuropathies

Antibodies reacting with carbohydrate epitopes on neural glycoconjugates are present in several forms of neuropathy. These include monoclonal antibodies to the myelin-associated glycoprotein (MAG) and to gan gliosides in patients with neuropathy in association with IgM gammopathy, as well as polyclonal antibodies to gangliosides in inflammatory polyneuropathies, such as Guillain-Barré syndrome and multifocal motor neuropathy. There are several correlations between antibody specificity and clinical symptoms, including anti-MAG antibodies with demyelinating sensory or sensorimotor neuropathy, anti-GM1 ganglioside anti bodies with motor nerve disorders, anti-GQ1b ganglioside antibodies with Miller-Fisher syndrome, and antibodies to gangliosides containing disialosyl moieties with sensory ataxic neuropathy. This review will emphasize recent developments concerning the origins of the anti-glycoconjugate antibodies in patients, pathogenic mechanisms by which the antibodies may cause the neuropathies, and the implications of these findings for therapy. NEUROSCIENTIST 3:195-204, 1997

Long-term disability and prognostic factors in polyneuropathy associated with anti-myelin-associated glycoprotein (MAG) antibodies

AIM OF THE STUDY

Neuropathy associated with IgM monoclonal gammopathy (MGUS) represents distinctive clinical syndrome, characterized by male predominance, late age of onset, slow progression, predominantly sensory symptoms, deep sensory loss, ataxia, minor motor impairment. More than 50% of patients with neuropathy-associated MGUS possess antibodies against myelin-associated glycoprotein (MAG). Purpose of our study was to assess effects on disease progression of demographic, clinical and neurophysiological variables in our large cohort of patients.

MATERIALS AND METHODS

Forty-three Caucasians patients were followed every eight months for median duration time of 93 months. Extremity strength was assessed with Medical Research Council (MRC) Scale, disability with overall disability status scale (ODSS), modified Rankin Scale and sensory function with Inflammatory Neuropathy Cause and Treatment (INCAT) sensory scale (ISS). Statistical analyses were conducted with parametric or non-parametric measures as appropriate. Survival analysis was used to test predictive value of clinical, demographical and neurophysiological variables. Variance analysis was conducted to explain difference on MRC between patients and groups at different time from onset.

RESULTS

Results showed that demyelinating pattern, older age and absence of treatment were significant risk factors for disability worsening. No other factors emerged as predictors including gender, ataxia and tremor at baseline, level of anti-MAG and IgM protein concentration in serum. Despite worsening of all outcome measures between first and last visit, quality of life (HRQol) judged by patients did not vary significantly.

CONCLUSIONS

Our study provides evidence that electrophysiologic pattern, age of onset and absence of treatment are strong predictor of prognosis in anti-MAG polyneuropathy.

Office immunotherapy in chronic inflammatory demyelinating polyneuropathy and multifocal motor neuropathy

Intravenous immunoglobulin [IVIg], plasma exchange [PE], and corticosteroids are efficacious treatment in chronic inflammatory demyelinating polyneuropathy [CIDP]. IVIg is effective in multifocal motor neuropathy [MMN]. NIS, NIS-weakness, sum scores of raw amplitudes of motor fiber (CMAPs) amplitudes, and Dyck/Rankin score provided reliable measures to detect and scale abnormality and reflect change; they are therefore ideal for office management of response-based immunotherapy (R-IRx) of CIDP. Using efficacious R-IRx, a large early and late therapeutic response (≥ one-fourth were in remission or had recovered) was demonstrated in CIDP. In MMN only an early improvement with late non-significant worsening was observed. The difference in immunotherapy response supports a fundamental difference between CIDP (immune attack on Schwann cells and myelin) and MMN (attack on nodes of Ranvier and axons).

Paraproteinemic neuropathies

PURPOSE OF REVIEW

Monoclonal gammopathies are common in the general population and occur in 10% of patients with peripheral neuropathy. It is important for the clinician to be able to determine whether an association exists between the paraprotein and the neuropathy. The clinical phenotype of the neuropathy, as well as the type of monoclonal protein, provides clues for the diagnosis. Optimal management of paraproteinemic neuropathies requires appropriate evaluation of the monoclonal protein for an underlying hematologic disorder.

RECENT FINDINGS

Clinical studies in paraproteinemic neuropathies have provided a better understanding of these disorders, but much is still unknown regarding the pathophysiologic mechanisms. Recent clinical trials in immunoglobulin M (IgM) neuropathy have shown that better outcome measures and treatment approaches are needed. Peripheral blood stem cell transplantation has shown promising improvements in the treatment of polyneuropathy, organomegaly, endocrinopathy, monoclonal plasma cell disorder, and skin changes (POEMS) syndrome and immunoglobulin light chain (AL) amyloidosis.

SUMMARY

Recognizing the frequent association of neuropathy with monoclonal proteins and evaluating for a hematologic malignancy should enable physicians to find better treatments and ultimately improve neuropathy outcome.

Treatment for IgG and IgA paraproteinaemic neuropathy

BACKGROUND

Paraproteinaemic neuropathy refers to those neuropathies associated with a monoclonal gammopathy or paraprotein. The most common of these present with a chronic, predominantly sensory, symmetrical neuropathy, similar to chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) but with relatively more sensory involvement, both clinically and neurophysiologically. The optimal treatment for neuropathies associated with IgG and IgA monoclonal gammopathy of uncertain significance is not known. This is an update of a review first published in 2007.

OBJECTIVES

To assess the effects of any treatment for IgG or IgA paraproteinaemic peripheral neuropathy.

SEARCH METHODS

On 18 January 2014 we searched the Cochrane Neuromuscular Disease Group Trials Specialized Register, CENTRAL, MEDLINE and EMBASE. We also checked bibliographies for controlled trials of treatments for IgG or IgA paraproteinaemic peripheral neuropathy. We checked clinical trials registries for ongoing studies in November 2014.

SELECTION CRITERIA

We considered for inclusion randomised controlled trials (RCTs) and quasi-RCTs using any treatment for IgG or IgA paraproteinaemic peripheral neuropathy. We excluded people with IgM paraproteins. We excluded people where the monoclonal gammopathy was considered secondary to an underlying disorder. We included participants of any age with a diagnosis of monoclonal gammopathy of uncertain significance with a paraprotein of the IgG or IgA class and a neuropathy. Included participants were not required to fulfil specific electrophysiological diagnostic criteria.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methodology to select studies, extract data and analyse results. One trial author provided additional data and clarification.

MAIN RESULTS

We identified one RCT, with 18 participants, that fulfilled the predetermined inclusion criteria. The trial compared plasma exchange to sham plasma exchange in participants with IgG or IgA paraproteinaemic neuropathy over a three-week follow-up period. We identified four other studies but these were not RCTs or quasi-RCTs. The included RCT did not report our predefined primary outcome measure, change in disability six months after randomisation. The trial revealed a modest benefit of plasma exchange in the weakness component of the Neuropathy Disability Score (NDS, now the Neuropathy Impairment Score); the mean improvement with plasma exchange was 17 points (95% confidence interval (CI) 5.2 to 28.8 points) versus 1 point (95% CI -7.7 to 9.7 points) in the sham exchange group at three weeks' follow-up (mean difference (MD) 16.00; 95% CI 1.37 to 30.63, low quality evidence). There was no statistically significant difference in the overall NDS (MD 18.00; 95% CI -2.03 to 38.03, low quality evidence), vibration thresholds or neurophysiological indices. Adverse events were not reported. The trial was at low risk of bias overall, although limitations of trial size and duration reduce the quality of the evidence in support of its conclusions.

AUTHORS' CONCLUSIONS

The evidence from RCTs for the treatment of IgG or IgA paraproteinaemic neuropathy is currently inadequate. More RCTs of treatments are required. These should have adequate follow-up periods and contain larger numbers of participants, perhaps through multicentre collaboration, considering the relative infrequency of this condition. Observational or open trial data provide limited support for the use of treatments such as plasma exchange, cyclophosphamide combined with prednisolone, intravenous immunoglobulin, and corticosteroids. These interventions show potential therapeutic promise but the potential benefits must be weighed against adverse effects. Their optimal use and the long-term benefits need to be considered and validated with well-designed RCTs.

Cellular targets and mechanistic strategies of remyelination-promoting IgMs as part of the naturally occurring autoantibody repertoire

Immunoglobulins with germline sequences occur in invertebrates and vertebrates and are named naturally occurring autoantibodies (NAbs). NAbs may target foreign antigens, self- or altered self-components and are part of the normal immunoglobulin repertoire. Accumulating evidence indicates that naturally occurring antibodies can act as systemic surveillance molecules, which tag, damaged or stressed cells, invading pathogens and toxic cellular debris for elimination by the immune system. In addition to acting as detecting molecules, certain types of NAbs actively signal in different cell types with a broad range of responses from induction of apoptosis in cancer cells to stimulation of remyelination in glial cells. This review emphasizes functions and characteristics of NAbs with focus on remyelination-promoting mouse and human antibodies. Human remyelination-promoting NAbs are potential therapeutics to combat a wide spectrum of disease processes including demyelinating diseases like multiple sclerosis. We will highlight the identified glycosphingolipid (SL) antigens of polyreactive remyelination-promoting antibodies and their proposed mechanism(s) of action. The nature of the identified antigens suggests a lipid raft-based mechanism for remyelination-promoting antibodies with SLs as most essential raft components. However, accumulating evidence also suggests involvement of other antigens in stimulation of remyelination, which will be discussed in the text.

Rituximab in the treatment of peripheral neuropathy associated with monoclonal gammopathy

Peripheral neuropathy associated with immunoglobulin (Ig)M gammopathy and anti-myelin-associated glycoprotein antibodies is frequently treatment-resistant and different treatment regimens carry substantial toxicity and side effects. More recently, the chimeric anti-CD20 monoclonal antibody rituximab has shown benefits in the treatment of peripheral neuropathy associated with IgM gammopathy with a favorable side-effect profile. There are no published reports of its use in the treatment of neuropathy associated with IgG and IgA gammopathies. Rituximab is usually given at 375 mg/m(2) intravenously with four weekly doses that may be repeated after 6-12 months. Large controlled studies are still pending but rituximab is an exciting and promising treatment offering another option in the treatment of peripheral neuropathy associated with IgM monoclonal gammopathy.

Predicting treatment response in chronic, acquired demyelinating neuropathies

Chronic inflammatory demyelinating polyradiculopathy is an immune-mediated neuropathy that was first described approximately 30 years ago. Since that time an increasingly wide spectrum of chronic acquired demyelinating polyneuropathies exhibiting different phenotypes, clinical course and treatment responses to immunomodulatory treatment have been described. Several new therapeutic agents have been prescribed for such conditions, some with promising results. This review summarizes what is presently known about the clinical courses, treatment responses and predictors of response of the chronic inflammatory demyelinating polyradiculopathy subgroups.

Repurposing diflunisal for familial amyloid polyneuropathy: a randomized clinical trial

IMPORTANCE

Familial amyloid polyneuropathy, a lethal genetic disease caused by aggregation of variant transthyretin, induces progressive peripheral nerve deficits and disability. Diflunisal, a nonsteroidal anti-inflammatory agent, stabilizes transthyretin tetramers and prevents amyloid fibril formation in vitro.

OBJECTIVE

To determine the effect of diflunisal on polyneuropathy progression in patients with familial amyloid polyneuropathy.

DESIGN, SETTING, AND PARTICIPANTS

International randomized, double-blind, placebo-controlled study conducted among 130 patients with familial amyloid polyneuropathy exhibiting clinically detectable peripheral or autonomic neuropathy at amyloid centers in Sweden (Umeå), Italy (Pavia), Japan (Matsumoto and Kumamoto), England (London), and the United States (Boston, Massachusetts; New York, New York; and Rochester, Minnesota) from 2006 through 2012.

INTERVENTION

Participants were randomly assigned to receive diflunisal, 250 mg (n=64), or placebo (n=66) twice daily for 2 years.

MAIN OUTCOMES AND MEASURES

The primary end point, the difference in polyneuropathy progression between treatments, was measured by the Neuropathy Impairment Score plus 7 nerve tests (NIS+7) which ranges from 0 (no neurological deficits) to 270 points (no detectable peripheral nerve function). Secondary outcomes included a quality-of-life questionnaire (36-Item Short-Form Health Survey [SF-36]) and modified body mass index. Because of attrition, we used likelihood-based modeling and multiple imputation analysis of baseline to 2-year data.

RESULTS

By multiple imputation, the NIS+7 score increased by 25.0 (95% CI, 18.4-31.6) points in the placebo group and by 8.7 (95% CI, 3.3-14.1) points in the diflunisal group, a difference of 16.3 points (95% CI, 8.1-24.5 points; P < .001). Mean SF-36 physical scores decreased by 4.9 (95% CI, -7.6 to -2.2) points in the placebo group and increased by 1.5 (95% CI, -0.8 to 3.7) points in the diflunisal group (P < .001). Mean SF-36 mental scores declined by 1.1 (95% CI, -4.3 to 2.0) points in the placebo group while increasing by 3.7 (95% CI, 1.0-6.4) points in the diflunisal group (P = .02). By responder analysis, 29.7% of the diflunisal group and 9.4% of the placebo group exhibited neurological stability at 2 years (<2-point increase in NIS+7 score; P = .007).

CONCLUSIONS AND RELEVANCE

Among patients with familial amyloid polyneuropathy, the use of diflunisal compared with placebo for 2 years reduced the rate of progression of neurological impairment and preserved quality of life. Although longer-term follow-up studies are needed, these findings suggest benefit of this treatment for familial amyloid polyneuropathy.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00294671.

Paraproteinemic neuropathies

The term paraproteinemic neuropathy refers to a heterogeneous group of neuropathies, which share the common feature of a homogeneous immunoglobulin in the serum. The presence of a monoclonal gammopathy indicates an underlying clonal B-cell expansion, which may appear in the context of a lymphoproliferative disorder. If a neoplastic origin of the gammopathy is identified, the treatment should be targeted to the neoplasm. In most patients, however, the monoclonal gammopathy is not associated with malignant haematological disorders, and is defined as monoclonal gammopathy of undetermined significance.

Multifocal motor neuropathy, multifocal acquired demyelinating sensory and motor neuropathy, and other chronic acquired demyelinating polyneuropathy variants

Chronic acquired demyelinating neuropathies (CADP) constitute an important group of immune neuromuscular disorders affecting myelin. This article discusses CADP with emphasis on multifocal motor neuropathy, multifocal acquired demyelinating sensory and motor neuropathy, distal acquired demyelinating symmetric neuropathy, and less common variants. Although each of these entities has distinctive laboratory and electrodiagnostic features that aid in their diagnosis, clinical characteristics are of paramount importance in diagnosing specific conditions and determining the most appropriate therapies. Knowledge regarding pathogenesis, diagnosis, and management of these disorders continues to expand, resulting in improved opportunities for identification and treatment.

Neuropathy and monoclonal gammopathy

The association of neuropathy with monoclonal gammopathy has been known for several years, even if the clinical and pathogenetic relevance of this association is not completely defined. This is not a marginal problem since monoclonal gammopathy is present in 1-3% of the population above 50 years in whom it is often asymptomatic, and in at least 8% of patients is associated with a symptomatic neuropathy, representing one of the leading causes of neuropathy in aged people. Monoclonal gammopathy may result from malignant lymphoproliferative diseases including multiple myeloma or solitary plasmocytoma, Waldenström's macroglobulinemia (WM), other IgM-secreting lymphoma or chronic lymphocytic leukemia, and primary systemic amyloidosis (AL). In most instances it is not associated with any of these disorders and is defined monoclonal gammopathy of undetermined significance (MGUS) for its possible, though infrequent, evolution into malignant forms. Several data support the pathogenetic role of the monoclonal gammopathy in the neuropathy particularly when of IgM isotype where IgM reactivity to several neural antigens has been reported. Increased levels of VEGF have been implicated in POEMS syndrome. However, there are as yet no defined therapies for these neuropathies, as their efficacy has not been confirmed in randomized trials.

Acute and chronic polyradiculopathies

Polyradiculopathies are uncommon peripheral nervous system syndromes that result from a variety of conditions. The clinical manifestations are variable but often include symmetric or asymmetric distal and proximal weakness with a variable degree of sensory loss and reduction or loss of reflexes. The most common cause of an acute polyradiculopathy is acute inflammatory demyelinating polyradiculopathy (also known as Guillain-Barré syndrome); however, other inflammatory, infectious, or neoplastic causes can present with similar features. Chronic polyradiculopathies include chronic inflammatory demyelinating polyradiculopathy as well as paraprotein-related syndromes and other inflammatory and infectious causes. Evaluation using a combination of serologic studies, electrodiagnostic testing, and CSF evaluation can help to identify the underlying etiology and implement the appropriate treatment. This article reviews the approach to patients with suspected polyradiculopathy and the features of the more common causes of acute and chronic polyradiculopathies.

Autoimmune neuromuscular disorders

Autoimmune neuromuscular disorders affecting peripheral nerves, neuromuscular junction or muscle have a wide clinical spectrum with diverse pathogenetic mechanisms. Peripheral nervous system may be targeted in the context of complex immune reactions involving different cytokines, antigen-presenting cells, B cells and different types of T cells. Various immunomodulating and cytotoxic treatments block proliferation or activation of immune cells by different mechanisms attempting to control the response of the immune system and limit target organ injury. Most treatment protocols for autoimmune neuromuscular disorders are based on the use of corticosteroids, intravenous immunoglobulins and plasmapheresis, with cytotoxic agents mostly used as steroid-sparing medications. More recently, development of specific monoclonal antibodies targeting individual cell types allowed a different approach targeting specific immune pathways, but these new treatments are also associated with various adverse effects and their long-term efficacy is still unknown.

Immunotherapy for IgM anti-myelin-associated glycoprotein paraprotein-associated peripheral neuropathies

BACKGROUND

Serum monoclonal anti-myelin-associated glycoprotein antibodies may be pathogenic in some people with immunoglobulin M (IgM) paraprotein and demyelinating neuropathy. Immunotherapies aimed at reducing the level of these antibodies might be expected to be beneficial. This is an update of a review first published in 2003 and previously updated in 2006.

OBJECTIVES

To assess the effects of immunotherapy for IgM anti-myelin-associated glycoprotein paraprotein-associated demyelinating peripheral neuropathy.

SEARCH METHODS

We searched the Cochrane Neuromuscular Disease Group Specialized Register 6 June 2011), CENTRAL (2011, Issue 2), MEDLINE (January 1966 to May 2011) and EMBASE (January 1980 to May 2011) for controlled trials. We also checked bibliographies and contacted authors and experts in the field.

SELECTION CRITERIA

We included randomised or quasi-randomised controlled trials involving participants of any age treated with any type of immunotherapy for anti-myelin-associated glycoprotein antibody-associated demyelinating peripheral neuropathy with monoclonal gammopathy of undetermined significance and of any severity.Our primary outcome measure was change in the Neuropathy Impairment Scale or Modified Rankin Scale at six months after randomisation. Secondary outcome measures were: Neuropathy Impairment Scale or the Modified Rankin Score at 12 months after randomisation; 10-metre walk time, subjective clinical scores and electrophysiological parameters at six and 12 months after randomisation; IgM paraprotein levels and anti-myelin-associated glycoprotein antibody titres at six months after randomisation; and adverse effects of treatments.

DATA COLLECTION AND ANALYSIS

The two authors independently selected studies. Two authors independently assessed the risk of bias in included studies.

MAIN RESULTS

We identified seven eligible trials (182 participants), which tested intravenous immunoglobulin, alfa interferon alfa-2a, plasma exchange, cyclophosphamide and steroids, and rituximab. Only two trials, of intravenous immunoglobulin (with 33 participants, including 20 with antibodies against myelin-associated glycoprotein), had comparable interventions and outcomes, but both were short-term trials.There were no clinical or statistically significant benefits of the treatments used on the outcomes predefined for this review, but not all the predefined outcomes were used in every included trial. Intravenous immunoglobulin showed a statistical benefit in terms of improvement in Modified Rankin Scale at two weeks and 10-metre walk time at four weeks. Cyclophosphamide failed to show any benefit in the trial's primary outcome, and showed a barely significant benefit in the primary outcome specified here, but some toxic adverse events were identified. A trial of rituximab was of poor methodological quality with a high risk of bias and a further larger study is awaited. Serious adverse events were few in the other trials.

AUTHORS' CONCLUSIONS

There is inadequate reliable evidence from trials of immunotherapies in anti-myelin-associated glycoprotein paraproteinaemic neuropathy to form an evidence base supporting any particular immunotherapy treatment. There is very low quality evidence of benefit from rituximab. Large well designed randomised trials of at least six to 12 months duration are required to assess existing or novel therapies, preferably employing unified, consistent, well designed, responsive and valid outcome measures.

An update on monoclonal gammopathy and neuropathy

Peripheral neuropathy associated with monoclonal gammopathy is a rare but important cause of neuropathy that can herald serious underlying disease. IgM monoclonal gammopathy of undetermined significance (MGUS) is the most commonly found monoclonal gammopathy associated with neuropathy, with characteristic clinical, electrophysiologic, and pathologic features. The IgG and IgA monoclonal gammopathies are rarely associated with specific neuropathies. Standard immunomodulatory agents including steroids, intravenous immunoglobulin, and plasmapheresis have shown limited efficacy in IgM MGUS. Neuropathies associated with specific lymphoproliferative disorders may not respond to treatments aimed at that disorder. Case series had shown promising results with rituximab, a monoclonal antibody that targets the B cell surface antigen CD20 and results in a rapid and sustained depletion of B cells; however, two recent randomized controlled trials with rituximab failed to provide evidence of efficacy in primary outcome measures, despite reduction in antibody levels. Long-term studies looking at the association between specific immunologic markers and disease recurrence are needed to ultimately develop targeted therapies.