Multifocal motor neuropathy: response to human immune globulin

Immunoglobulin for multifocal motor neuropathy

BACKGROUND

Multifocal motor neuropathy (MMN) is a rare, probably immune-mediated disorder characterised by slowly progressive, asymmetric, distal weakness of one or more limbs with no objective loss of sensation. It may cause prolonged periods of disability. Treatment options for MMN are few. People with MMN do not usually respond to steroids or plasma exchange. Uncontrolled studies have suggested a beneficial effect of intravenous immunoglobulin (IVIg). This is an update of a Cochrane Review first published in 2005, with an amendment in 2007. We updated the review to incorporate new evidence.

OBJECTIVES

To assess the efficacy and safety of intravenous and subcutaneous immunoglobulin in people with MMN.

SEARCH METHODS

We searched the following databases on 20 April 2021: the Cochrane Neuromuscular Specialised Register, CENTRAL, MEDLINE, Embase, ClinicalTrials.gov, and WHO ICTRP for randomised controlled trials (RCTs) and quasi-RCTs, and checked the reference lists of included studies.

SELECTION CRITERIA

We considered RCTs and quasi-RCTs examining the effects of any dose of IVIg and subcutaneous immunoglobulin (SCIg) in people with definite or probable MMN for inclusion in the review. Eligible studies had to have measured at least one of the following outcomes: disability, muscle strength, or electrophysiological conduction block. We used studies that reported the frequency of adverse effects to assess safety.

DATA COLLECTION AND ANALYSIS

Two review authors independently reviewed the literature searches to identify potentially relevant trials, assessed risk of bias of included studies, and extracted data. We followed standard Cochrane methodology.

MAIN RESULTS

Six cross-over RCTs including a total of 90 participants were suitable for inclusion in the review. Five RCTs compared IVIg to placebo, and one compared IVIg to SCIg. Four of the trials comparing IVIg versus placebo involved IVIg-naive participants (induction treatment). In the other two trials, participants were known IVIg responders receiving maintencance IVIg at baseline and were then randomised to maintenance treatment with IVIg or placebo in one trial, and IVIg or SCIg in the other. Risk of bias was variable in the included studies, with three studies at high risk of bias in at least one risk of bias domain. IVIg versus placebo (induction treatment): three RCTs including IVIg-naive participants reported a disability measure. Disability improved in seven out of 18 (39%) participants after IVIg treatment and in two out of 18 (11%) participants after placebo (risk ratio (RR) 3.00, 95% confidence interval (CI) 0.89 to 10.12; 3 RCTs, 18 participants; low-certainty evidence). The proportion of participants with an improvement in disability at 12 months was not reported. Strength improved in 21 out of 27 (78%) IVIg-naive participants treated with IVIg and one out of 27 (4%) participants who received placebo (RR 11.00, 95% CI 2.86 to 42.25; 3 RCTs, 27 participants; low-certainty evidence). IVIg treatment may increase the proportion of people with resolution of at least one conduction block; however, the results were also consistent with no effect (RR 7.00, 95% CI 0.95 to 51.70; 4 RCTs, 28 participants; low-certainty evidence). IVIg versus placebo (maintenance treatment): a trial that included participants on maintenance IVIg treatment reported an increase in disability in 17 out of 42 (40%) people switching to placebo and seven out of 42 (17%) remaining on IVIg (RR 2.43, 95% CI 1.13 to 5.24; 1 RCT, 42 participants; moderate-certainty evidence) and a decrease in grip strength in 20 out of 42 (48%) participants after a switch to placebo treatment compared to four out of 42 (10%) remaining on IVIg (RR 0.20, 95% CI 0.07 to 0.54; 1 RCT, 42 participants; moderate-certainty evidence). Adverse events, IVIg versus placebo (induction or maintenance): four trials comparing IVIg and placebo reported adverse events, of which data from two studies could be meta-analysed. Transient side effects were reported in 71% of IVIg-treated participants versus 4.8% of placebo-treated participants in these studies. The pooled RR for the development of side effects was 10.33 (95% CI 2.15 to 49.77; 2 RCTs, 21 participants; very low-certainty evidence). There was only one serious side effect (pulmonary embolism) during IVIg treatment. IVIg versus SCIg (maintenance treatment): the trial that compared continuation of IVIg maintenance versus SCIg maintenance did not measure disability. The evidence was very uncertain for muscle strength (standardised mean difference 0.08, 95% CI -0.84 to 1.00; 1 RCT, 9 participants; very low-certainty evidence). The evidence was very uncertain for the number of people with side effects attributable to treatment (RR 0.50, 95% CI 0.18 to 1.40; 1 RCT, 9 participants; very low-certainty evidence).

AUTHORS' CONCLUSIONS

Low-certainty evidence from three small RCTs shows that IVIg may improve muscle strength in people with MMN, and low-certainty evidence indicates that it may improve disability; the estimate of the magnitude of improvement of disability has wide CIs and needs further studies to secure its significance. Based on moderate-certainty evidence, it is probable that most IVIg responders deteriorate in disability and muscle strength after IVIg withdrawal. SCIg might be an alternative treatment to IVIg, but the evidence is very uncertain. More research is needed to identify people in whom IVIg withdrawal is possible and to confirm efficacy of SCIg as an alternative maintenance treatment.

10% liquid human immunoglobulin (KIOVIG®) for immunomodulation in autoimmune disorders

Intravenous immunoglobulins have been used to treat autoimmune disorders (ADs) for over 50 years. The etiologies of various ADs are not fully understood and although intravenous immunoglobulin treatment has proved its immunomodulatory properties, the roles of proposed mechanisms of action also remain a matter of speculation. A systemic search of the literature regarding KIOVIG® (Baxalta US, Inc., MA, USA) use in clinical trials on patients with ADs and a detailed review of retrieved articles revealed eight relevant publications. These articles reported KIOVIG use in multifocal motor neuropathy, chronic inflammatory demyelinating polyneuropathy, idiopathic thrombocytopenic purpura, Kawasaki disease, Guillain–Barré syndrome and other autoimmune and neurologic disorders and showed that KIOVIG is an effective, safe and well-tolerated treatment in the studied populations. Nevertheless, further studies on larger patient cohorts are needed.

Therapeutic Plasma Exchange in Patients with Neurologic Disorders: Review of 63 Cases

Therapeutic plasma exchange (TPE) is a procedure that reduces circulating autoantibodies of the patients. TPE is commonly used in neurological disorders where autoimmunity plays a major role. We report our experience with regard to the indications, adverse events and outcomes of plasma exchange in neurological disorders. Sixty-three patients were included to this retrospective study. Median age was 48 years (range 1-85), there was a predominance of males. Neurological indications included Guillain-Barrè syndrome (n = 22), myasthenia gravis (n = 21), chronic inflammatory demyelinating polyneuropathy (n = 7), polymyositis (n = 3), multifocal motor neuropathy (n = 2), acute disseminated encephalomyelitis (n = 2), neuromyelitis optica (n = 2), multiple sclerosis (n = 2), limbic encephalitis (n = 1) and transverse myelitis (n = 1). TPE was frontline therapy in 57 % of the patients (n = 36). Total number of TPE sessions was 517; median number of sessions per patient was 8 (range 1-66). TPE was done through a central venous access in 97 % and through a peripheral venous access in 3 % of the patients. Human albumin was used as replacement fluid in 49 %, hydroxyethyl starch (HES) in 49 % and fresh frozen plasma in 2 % of the cases. Adverse reactions were recorded in 60 % of the patients. Total ratio of complications in 517 TPE procedures was 10.8 % and these were mild and manageable such as allergic reactions and hypotension. Overall response rate was 81 %. Interestingly, complication and response rates were similar in both HES and human albumin groups. We conclude that TPE is an effective treatment in neurologic diseases in which autoimmunity plays an important role in the pathogenesis and HES can be used instead of albumin as replacement fluid in these disorders, since it is cost-effective, has similar efficacy and complication rates.

Efficacy of Intravenous Immunoglobulin in Neurological Diseases

Owing to its anti-inflammatory efficacy in various autoimmune disease conditions, intravenous immunoglobulin (IVIG)-pooled IgG obtained from the plasma of several thousands individuals-has been used for nearly three decades and is proving to be efficient in a growing number of neurological diseases. IVIG therapy has been firmly established for the treatment of Guillain-Barré syndrome, chronic inflammatory demyelinating polyneuropathy, and multifocal motor neuropathy, either as first-line therapy or adjunctive treatment. IVIG is also recommended as rescue therapy in patients with worsening myasthenia gravis and is beneficial as a second-line therapy for dermatomyositis and stiff-person syndrome. Subcutaneous rather than intravenous administration of IgG is gaining momentum because of its effectiveness in patients with primary immunodeficiency and the ease with which it can be administered independently from hospital-based infusions. The demand for IVIG therapy is growing, resulting in rising costs and supply shortages. Strategies to replace IVIG with recombinant products have been developed based on proposed mechanisms that confer the anti-inflammatory activity of IVIG, but their efficacy has not been tested in clinical trials. This review covers new developments in the immunobiology and clinical applications of IVIG in neurological diseases.

Drugs for the treatment of peripheral neuropathies

Peripheral neuropathies are frequent in association with systemic diseases as well as isolated disorders. Recent advances in the therapy of specific neuropathies led to the approval of new drugs/treatments. This review selected those peripheral neuropathies where the most recent approvals were provided and revised the potential future developments in diabetic and toxic-induced neuropathies, although they do not have a currently available causal therapy in view of their epidemiological and social relevance. Data have been extracted from the most important published trials and from clinical experience. In addition, data from the Food and Drug Administration and European Medicine Agency indications on the treatment of the selected peripheral neuropathies and from recently updated international guidelines have also been included. The website of the U.S. National Institutes of Health www.clinicaltrials.gov registry has been used as the reference database for phase III clinical trials not yet published or ongoing. This review gives a general overview of the most recent advances in the treatment of amyloid, inflammatory, and paraproteinemic peripheral neuropathies. Moreover, it briefly describes the unmet medical need in disabling and frequent conditions, such as diabetic and chemotherapy-induced neuropathy, highlighting the most promising therapeutic approaches to their treatment.

Immunosuppressant and immunomodulatory treatments for multifocal motor neuropathy

BACKGROUND

Multifocal motor neuropathy (MMN) is characterised by progressive, predominantly distal, asymmetrical limb weakness and usually multiple partial motor nerve conduction blocks. Intravenous immunoglobulin (IVIg) is beneficial but the role of immunosuppressive agents is uncertain. This is an update of a review first published in 2002 and previously updated in 2003, 2005, 2008 and 2011.

OBJECTIVES

To assess the effects of immunosuppressive agents for the treatment of multifocal motor neuropathy.

SEARCH METHODS

On 22 September 2014 we searched the Cochrane Neuromuscular Disease Group Specialized Register, CENTRAL, MEDLINE, EMBASE and LILACS for trials of MMN. We also searched two trials registers for ongoing studies.

SELECTION CRITERIA

We planned to include randomised controlled trials (RCTs) and quasi-RCTs. We considered prospective and retrospective case series and case reports in the Discussion.

DATA COLLECTION AND ANALYSIS

Two review authors searched the titles and abstracts of the articles identified and extracted the data independently.

MAIN RESULTS

Only one RCT of an immunosuppressive or immunomodulatory agent has been performed in MMN. This study randomised 28 participants and showed that mycophenolate mofetil, when used with IVIg, did not significantly improve strength, function or reduce the need for IVIg. No serious adverse events were observed. The study was deemed at low risk of bias. We summarised the results of retrospective and prospective case series in the discussion.

AUTHORS' CONCLUSIONS

According to moderate quality evidence, mycophenolate mofetil did not produce significant benefit in terms of reducing need for IVIg or improving muscle strength in MMN. Trials of other immunosuppressants should be undertaken.

Optimizing IgG therapy in chronic autoimmune neuropathies: a hypothesis driven approach

Prolonged intravenous immunoglobulin (IVIG) therapy is used for the chronic autoimmune neuropathies chronic idiopathic demyelinating polyneuropathy and multifocal motor neuropathy, but the doses and treatment intervals are usually chosen empirically due to a paucity of data from dose-response studies. Recent studies of the electrophysiology and immunology of these diseases suggest that antibody-induced reversible dysfunction of nodes of Ranvier may play a role in conduction block and disability which responds to immunotherapy more rapidly than would be expected for demyelination or axonal damage per se. Clinical reports suggest that in some cases, the effects of each dose of IVIG may be transient, wearing-off before the next dose is due. These observations lead us to hypothesize that that therapeutic IgG acts by competing with pathologic autoantibodies and that individual patients may require different IgG levels for optimal therapeutic effects. Frequent IVIG dosing and weekly subcutaneous IgG have been tried as ways of continuously maintaining high serum IgG levels, resulting in stabilization of neuromuscular function in small case series. Frequent grip strength and disability measurements, performed by the patient at home and reported electronically, can be used to assess the extent and duration of responses to IgG doses. Individualization of IgG treatment regimens may optimize efficacy, minimize disability, and identify nonresponders.

Subcutaneous immunoglobulin therapy for inflammatory neuropathy: current evidence base and future prospects

Intravenous immunoglobulin therapy is of proven effect in chronic inflammatory neuropathies, including chronic inflammatory demyelinating polyneuropathy (CIDP) and multifocal motor neuropathy (MMN). In more recent years, there have been a number of anecdotal case reports and small series, followed by a few trials of variable design, of subcutaneous immunoglobulin therapy in these neuropathies. To date, limited evidence suggests that the subcutaneous route may be a more clinically effective, better-tolerated, at least cost-equivalent and a more patient-friendly option than the still more used intravenous alternative. Long-term efficacy is not as yet established in neuropathic indications by randomised controlled clinical trial evidence, and it is likely that the subcutaneous route may not be suitable in all cases with some hints to this effect appearing from the limited data available to date. Further studies are ongoing, including those of dose comparison, and more are likely to be planned in future. The literature on the use of subcutaneous immunoglobulin therapy in chronic inflammatory neuropathy is reviewed here. The current use in clinical practice, day-to-day benefits, including quality of life measures and health economics as published thus far, are evaluated. The limitations of this form of treatment in CIDP and MMN are also analysed in the light of current literature and taking into account the remaining unknowns. Future prospects and research with this mode of immunoglobulin therapy administration are discussed.

Sera from patients with multifocal motor neuropathy disrupt the blood-nerve barrier

OBJECTIVE

In multifocal motor neuropathy (MMN), the destruction of the blood-nerve barrier (BNB) has been considered to be the key step in the disease process. The purpose of the present study was to ascertain whether sera from patients with MMN can open the BNB, and which component of patient sera is the most important for this disruption.

METHODS

We evaluated the effects of sera from patients with MMN, patients with amyotrophic lateral sclerosis, and control subjects on the expression of tight junction proteins and vascular cell adhesion molecule-1 (VCAM-1), and on the transendothelial electrical resistance (TEER) in human peripheral nerve microvascular endothelial cells (PnMECs).

RESULTS

The sera from patients with MMN decreased the claudin-5 protein expression and the TEER in PnMECs. However, this effect was reversed after application of an anti-vascular endothelial growth factor (anti-VEGF) neutralising antibody. The VEGF secreted by PnMECs was significantly increased after exposure to the sera from patients with MMN. The sera from patients with MMN also increased the VCAM-1 protein expression by upregulating the nuclear factor kappa-B (NF-κB) signalling. The immunoglobulin G purified from MMN sera decreased the expression of claudin-5 and increased the VCAM-1 expression in PnMECs.

CONCLUSIONS

The sera from MMN patients may disrupt the BNB function via the autocrine secretion of VEGF in PnMECs, or the exposure to autoantibodies against PnMECs that are contained in the MMN sera. Autoantibodies against PnMECs in MMN sera may activate the BNB by upregulating the VCAM-1 expression, thereby allowing for the entry of a large number of circulating inflammatory cells into the peripheral nervous system.

Multifocal motor neuropathy: current therapies and novel strategies

Multifocal motor neuropathy (MMN) is a purely motor mononeuritis multiplex characterized by the presence of conduction block on motor but not on sensory nerves and by the presence of high titers of anti-GM1 antibodies. Several data point to a pathogenetic role of the immune system in this neuropathy, although this has not yet been proved. Several uncontrolled studies and randomized controlled trials have demonstrated the efficacy of therapy with high-dose intravenous immunoglobulin (IVIg) in MMN. However, this therapy has a short-lasting effect that needs to be maintained with periodic infusions. This can be partly overcome by the use of subcutaneous immunoglobulin (SCIg) at the same dose. The high cost and need for repeated infusions have led to the search for other immune therapies, the efficacy of which have not yet been confirmed in randomized trials. In addition, some therapies, including corticosteroids and plasma exchange, are not only ineffective but have been associated with clinical worsening. More recently, a number of novel therapies have been investigated in MMN, including interferon-β1a, the anti-CD20 monoclonal antibody rituximab and the complement inhibitor eculizumab. Preliminary data from open-label uncontrolled studies show that some patients improve after these therapies; however, randomized controlled trials are needed to confirm efficacy. Until then, IVIg (and SCIg) remains the mainstay of treatment in MMN, and the use of other immune therapies should only be considered for patients not responding to, or becoming resistant to, IVIg.

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.

Treatment of multifocal motor neuropathy

OPINION STATEMENT

Multifocal motor neuropathy (MMN) is a treatable immune disorder of the peripheral nerves that is characterized clinically by slowly progressive or stepwise asymmetric distal > proximal, upper > lower limb weakness in multiple motor nerve distributions; electrophysiologically by multifocal motor demyelination, specifically partial motor conduction block; laboratory evidence of high serum anti-GM1 IgM antibodies; and remarkable treatment response to intravenous immunoglobulin (IVIG). IVIG has become the treatment of choice, and the U.S. Food and Drug Administration (FDA) has approved Gammagard Liquid 10 % [immune globulin infusion (human)] as a treatment for multifocal motor neuropathy (MMN). Response to IVIG in MMN is dose- and frequency-dependent, most patients needing high (2 g/kg) and frequent (every 4-8 weeks) doses for several years. Over time, response to IVIG may decrease despite higher and more frequent dosing of IVIG treatment. Subcutaneous immunoglobulin (dose equivalent to IVIG) given in weekly fashion has recently been used with equal efficacy and fewer side effects. There are some case reports and non-randomized trials suggesting variable results from therapeutic or adjunctive use of other immunosuppressive or immunomodulatory agents such as cyclophosphamide, cyclosporine, methotrexate, azathioprine, interferon beta-1a, and rituximab. Of these, cyclophosphamide and rituximab are the only immune treatments that have shown some benefits in case reports. One randomized controlled trial of mycophenolate mofetil used as adjunctive agent did not prove efficacious in altering the disease course. Although MMN, like chronic inflammatory demyelinating polyneuropathy (CIDP), is a chronic immune-mediated demyelinating neuropathy, the use of corticosteroids and plasma exchange - two other therapies used in CIDP - is not beneficial for MMN. Further investigations are warranted to evaluate the immunopathogenesis of MMN and to explore options for dose, frequency, and duration of IVIG treatment as well as the use of alternative immunomodulatory agents either as primary therapeutic or adjunctive agents.

Multifocal motor neuropathy: a review of pathogenesis, diagnosis, and treatment

Multifocal motor neuropathy (MMN) is an uncommon, purely motor neuropathy associated with asymmetric deficits with predilection for upper limb involvement. Even in the early descriptions of MMN, the associations of anti-GM1 antibodies and robust response to immunomodulatory treatment were recognized. These features highlight the likelihood of an underlying autoimmune etiology of MMN. The clinical presentation of MMN can closely mimic several neurological conditions including those with more malignant prognoses such as motor neuron disease. Therefore early and rapid recognition of MMN is critical. Serological evidence of anti GM-1 antibodies and electrodiagnostic findings of conduction block are helpful diagnostic clues for MMN. Importantly, these diagnostic features are not universally present, and patients lacking these characteristic findings can demonstrate similar robust response to immunodulatory treatment. In the current review, recent research in the areas of diagnosis, pathogenesis, and treatment of MMN and needs for the future are discussed. The characteristic findings of MMN and treatment implications are reviewed and contrasted with other mimicking disorders.

Susac syndrome and multifocal motor neuropathy first manifesting in pregnancy

Susac Syndrome (SS) and multifocal motor neuropathy (MMN) are rare autoimmune neurological conditions which can affect women of childbearing years. The effect of pregnancy on these disorders is poorly characterised. We report a case of SS first manifesting in pregnancy with challenges in diagnosis and management and a poor clinical outcome, and a case of MMN manifesting in pregnancy then relapsing in a subsequent pregnancy. A summary of other cases in the literature and the postulated underlying immune mechanisms is presented.

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.

A rational diagnostic approach to peripheral neuropathy

Peripheral neuropathies are among the most common disorders encountered by neuromuscular specialists and their evaluation can be challenging. The first part of this review outlined an algorithm based on anatomy, pathology, electrodiagnosis, and clinical localization that leads to a full characterization of the peripheral neuropathy. In the second part, we apply this approach, emphasizing recognition of atypical features and formulation of a focused differential diagnosis, thus reducing the number of uninformative tests. We review evidence supporting the routine use of commonly ordered laboratory tests and recommend a panel of tests that should be performed in patients with symmetric, distal, sensory-predominant peripheral neuropathy. Using this diagnostic approach, a diagnosis could be made in two thirds of patients.

Multifocal motor neuropathy

Multifocal motor neuropathy (MMN) was first described in 1988 as a purely motor neuropathy affecting multiple motor nerves. The diagnosis was based entirely on demonstrating electrophysiological evidence of a conduction block (CB) that selectively affected motor axons, with sparing of sensory axons even through the site of motor CB. Subsequently, a similar disorder was reported but with absence of demonstrable CB on routine nerve conduction studies and there is still some debate as to whether MMN without CB is related to MMN. MMN is thought to be an inflammatory neuropathy related to an immune attack on motor nerves. The conventional hypothesis is that the primary pathology is segmental demyelination, but recent research raises the possibility of a primary axonopathy. Anti-GM1 antibodies can be found in some patients but it is unclear whether these antibodies are pathogenic. Intravenous immunoglobulin is the mainstay of treatment but other immunosuppressive treatments can also be effective.

Immunosuppressant and immunomodulatory treatments for multifocal motor neuropathy

BACKGROUND

Multifocal motor neuropathy is characterised by progressive, predominantly distal, asymmetrical limb weakness and usually multiple partial motor nerve conduction blocks. Intravenous immunoglobulin is beneficial but the role of immunosuppressive agents is uncertain. This is an update of a review first published in 2002 and previously updated in 2003, 2005 and 2008.

OBJECTIVES

To provide the best available evidence from randomised controlled trials on the role of immunosuppressive agents for the treatment of multifocal motor neuropathy.

SEARCH METHODS

We searched the Cochrane Neuromuscular Disease Group Specialized Register (4 October 2011), the Cochrane Central Register of Controlled Trials (CENTRAL) (2011, Issue 3 in The Cochrane Library), MEDLINE (January 1966 to September 2011), EMBASE (January 1980 to September 2011), and LILACS (January 1982 to September 2011) for trials of multifocal motor neuropathy.

SELECTION CRITERIA

We planned to include randomised and quasi-randomised controlled trials. We considered prospective and retrospective case series and case reports in the Discussion.

DATA COLLECTION AND ANALYSIS

Two review authors searched the titles and abstracts of the articles identified and extracted the data independently.

MAIN RESULTS

Only one randomised controlled trial of an immunosuppressive or immunomodulatory agent has been performed in multifocal motor neuropathy. This study randomised 28 participants and showed that mycophenolate mofetil, when used with intravenous immunoglobulin, did not significantly improve strength, function or reduce the need for intravenous immunoglobulin. No serious adverse events were observed. The study was deemed at low risk of bias. We summarised the results of retrospective and prospective case series in the discussion.

AUTHORS' CONCLUSIONS

According to moderate quality evidence, mycophenolate mofetil did not produce significant benefit in terms of reducing need for intravenous immunoglobulin or improving muscle strength. Trials of other immunosuppressants should be undertaken.

Pathogenesis and treatment of immune-mediated neuropathies

Immune-mediated neuropathies represent a heterogeneous spectrum of peripheral nerve disorders that can be classified according to time course, predominant involvement of motor/sensory fibers, distribution of deficits and paraclinical parameters such as electrophysiology and serum antibodies. In the last few years, significant advances have been achieved in elucidating underlying pathomechanisms, which made it possible to identify potential therapeutic targets. In this review, we discuss the latest development in pathogenesis and treatment of immune-mediated neuropathies.

Immunosuppressant and immunomodulatory treatments for multifocal motor neuropathy

BACKGROUND

Multifocal motor neuropathy is characterised by progressive, predominantly distal, asymmetrical limb weakness and usually multiple partial motor nerve conduction blocks. Intravenous immunoglobulin is beneficial but the role of immunosuppressive agents is uncertain.

OBJECTIVES

To provide the best available evidence from randomised controlled trials on the role of immunosuppressive agents for the treatment of multifocal motor neuropathy.

SEARCH STRATEGY

For this update, we searched the Cochrane Neuromuscular Disease Group Trials Register (October 8 2008), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2008, Issue 4), MEDLINE (from January 1966 to October 8 2008), and EMBASE (from January 1980 to October 8 2008), for trials of multifocal motor neuropathy.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials were to be included and one was found. Prospective and retrospective case series and case reports were considered in the Discussion.

DATA COLLECTION AND ANALYSIS

Two review authors searched the titles and abstracts of the articles identified and extracted the data independently.

MAIN RESULTS

In this update, we found the first randomised controlled trial of multifocal motor neuropathy. This study, which randomised 28 patients, showed that mycophenolate mofetil did not significantly improve strength or function or reduce the need for intravenous immunoglobulin. We summarised the results of retrospective and prospective case series in the discussion.

AUTHORS' CONCLUSIONS

In the only randomised placebo-controlled trial of any immunosuppressive agent, mycophenolate mofetil did not produce significant benefit. Trials of other immunosuppressants should be undertaken.

European Federation of Neurological Societies/Peripheral Nerve Society guideline on management of multifocal motor neuropathy

Several diagnostic criteria for multifocal motor neuropathy have been proposed in recent years and a beneficial effect of intravenous immunoglobulin (IVIg) and various other immunomodulatory drugs has been suggested in several trials and uncontrolled studies. The objectives were to prepare consensus guidelines on the definition, investigation and treatment of multifocal motor neuropathy. Disease experts and a patient representative considered references retrieved from MEDLINE and the Cochrane Library in July 2004 and prepared statements which were agreed in an iterative fashion. The Task Force agreed good practice points to define clinical and electrophysiological diagnostic criteria for multifocal motor neuropathy and investigations to be considered. The principal recommendations and good practice points were: (i) IVIg (2 g/kg given over 2-5 days) should be considered as the first line treatment (level A recommendation) when disability is sufficiently severe to warrant treatment. (ii) Corticosteroids are not recommended (good practice point). (iii) If initial treatment with IVIg is effective, repeated IVIg treatment should be considered (level C recommendation). The frequency of IVIg maintenance therapy should be guided by the individual response (good practice point). Typical treatment regimens are 1 g/kg every 2-4 weeks or 2 g/kg every 4-8 weeks (good practice point). (iv) If IVIg is not or not sufficiently effective then immunosuppressive treatment may be considered. Cyclophosphamide, ciclosporin, azathioprine, interferon beta1a, or rituximab are possible agents (good practice point). (v) Toxicity makes cyclophosphamide a less desirable option (good practice point).

European Federation of Neurological Societies/Peripheral Nerve Society Guideline on management of multifocal motor neuropathy. Report of a joint task force of the European Federation of Neurological Societies and the Peripheral Nerve Society

BACKGROUND

Several diagnostic criteria for multifocal motor neuropathy (MMN) have been proposed in recent years, and a beneficial effect of intravenous immunoglobulin (IVIg) and various other immunomodulatory drugs has been suggested in several trials and uncontrolled studies.

OBJECTIVES

The aim of this guideline was to prepare consensus guidelines on the definition, investigation, and treatment of MMN.

METHODS

Disease experts and a representative of patients considered references retrieved from MEDLINE and the Cochrane Library in July 2004 and prepared statements that were agreed in an iterative fashion.

RECOMMENDATIONS

The Task Force agreed on good practice points to define clinical and electrophysiological diagnostic criteria for MMN and investigations to be considered. The principal recommendations and good practice points were as follows: (1) IVIg (2 g/kg given over 2-5 days) should be considered as the first line of treatment (level A recommendation) when disability is sufficiently severe to warrant treatment; (2) corticosteroids are not recommended (good practice point); (3) if initial treatment with IVIg is effective, repeated IVIg treatment should be considered (level C recommendation). The frequency of IVIg maintenance therapy should be guided by the individual response (good practice point). Typical treatment regimens are 1 g/kg every 2-4 weeks or 2 g/kg every 4-8 weeks (good practice point); (4) if IVIg is not (or not sufficiently) effective, then immunosuppressive treatment may be considered. Cyclophosphamide, cyclosporine, azathioprine, interferon-beta1a, or rituximab are possible agents (good practice point); and (5) toxicity makes cyclophosphamide a less desirable option (good practice point).

High-dose cyclophosphamide without stem cell rescue for refractory multifocal motor neuropathy

Patients with multifocal motor neuropathy (MMN) respond to intravenous immune globulin (IVIg) and cyclophosphamide, although the benefit is not sustained. High-dose cyclophosphamide can induce a remission in patients with autoimmune diseases, including chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). We describe a patient with refractory MMN who improved with high-dose cyclophosphamide (50 mg/kg for 4 days) without stem cell rescue. Following treatment she discontinued IVIg. At a 6-month examination, her strength had improved and she had regained the ability to write. High-dose cyclophosphamide may be a successful treatment for patients with MMN refractory to other therapies.

Long term prognosis of chronic inflammatory demyelinating polyneuropathy: a five year follow up of 38 cases

BACKGROUND

Little is known about long term prognosis and course after immune treatments in chronic inflammatory demyelinating polyneuropathy (CIDP).

OBJECTIVE

To study long term outcomes and prognostic factors in patients with CIDP.

METHODS

Clinical and electrophysiological findings, responses to immune modulating treatments, and outcomes five years after the start of treatment were reviewed in 38 CIDP patients.

RESULTS

Patients were treated with corticosteroids (89%), immunoglobulin infusion (45%), or plasmapheresis (34%), and 58% received combined therapy. Five years after treatment was begun, 10 (26%) of the patients had complete remission (lasting >2 years with normal nerve conduction studies), and 23 (61%) had partial remission (able to walk) with (26%) or without (34%) immune treatments. The remaining five patients (13%) still had severe disability (unable to walk) or treatment dependent relapses. Patients with complete remission more often had subacute onset, symmetrical symptoms, good response to initial corticosteroid treatment, and nerve conduction abnormalities predominant in the distal nerve terminals. In contrast, insidious onset, asymmetrical symptoms, and electrophysiological evidence of demyelination in the intermediate nerve segments were associated with refractoriness to treatment or treatment dependent relapse.

CONCLUSIONS

The long term prognosis of CIDP patients was generally favourable, but 39% of patients still required immune treatments and 13% had severe disabilities. Mode of onset, distribution of symptoms, and electrophysiological characteristics may be prognostic factors for predicting a favourable outcome.

A practical definition of conduction block in IvIg responsive multifocal motor neuropathy

BACKGROUND

Multifocal motor neuropathy with conduction block (MMN) can be mistaken for motor neurone disease or other lower motor neurone syndromes, but is treatable with intravenous immunoglobulin (IvIg). Formal electrophysiological criteria for conduction block (CB) are so stringent that substantial numbers of patients may miss out on appropriate treatment.

METHODS

Electrophysiological data were collected from 10 healthy volunteers and compared to data from 10 patients who satisfied the clinical criteria for MMN and who responded to IvIg. This produced a definition of CB in MMN patients which was compared with existing definitions to assess "miss rates".

RESULTS

Mean values for compound muscle action potential area, amplitude, and duration were calculated in normal subjects. Results beyond 3 SD of their respective means were considered abnormal. Using these criteria, CB in the context of MMN was defined as a reduction in negative peak area >23% along a distal nerve segment or >29% across a proximal segment; or a reduction in amplitude >32% across a distal segment or >33% across a proximal segment. All IvIg responsive patients had at least one nerve segment showing such CB. Employing some criteria from the literature would have denied treatment to over 30% of responsive patients.

CONCLUSION

In the clinical setting of suspected MMN, less stringent criteria for CB can improve the diagnosis of this treatable disorder. Exclusions on grounds of temporal dispersion may be over-restrictive. A little over one third of CBs occur proximally.

The effect of treatment upon temporal dispersion in IvIg responsive multifocal motor neuropathy

BACKGROUND

Multifocal motor neuropathy with conduction block (MMN) is a treatable disorder that can be mistaken for other lower motor neurone syndromes. Existing electrophysiological diagnostic criteria for MMN are restrictive. In particular, many are cautious about diagnosing conduction block (CB) in the presence of abnormal temporal dispersion (TD).

OBJECTIVE

To study the significance of TD in MMN, its relationship to CB in intravenous immunoglobulin (IvIg) responsive patients, and its utility in detecting a treatment response.

METHODS

We compared pre- and post-treatment changes in CB and TD in nine patients who satisfied clinical and electrophysiological criteria for MMN and responded to IvIg.

RESULTS

TD improved in one or more nerve segments in eight of nine patients tested. There was marked improvement in 65% of all nerve segments, and 60% of those segments with CB. By comparison, significant improvement in CB occurred in only 33% of segments. Of segments with significantly better CB after treatment, all but one showed similar improvements in TD. Such changes were not related to the degree of TD before treatment, being seen in segments with abnormal as well as normal TD. There was no correlation between improvements seen in TD and CB.

CONCLUSION

We believe that TD should be considered an inherent feature of MMN. Improvement in TD is an independent marker of electrophysiological improvement in this disorder and is likely to be more useful than CB. When MMN is clinically suspected, the use of stringent criteria for CB in the presence of TD should be avoided.

Immunosuppressant and immunomodulatory treatments for multifocal motor neuropathy

BACKGROUND

Multifocal motor neuropathy is a distinct clinical entity characterised by progressive, predominantly distal, asymmetrical limb weakness and minimal sensory abnormality. The diagnostic feature of this condition is the presence of multiple partial motor nerve conduction blocks. Controlled trials have demonstrated the efficacy of regular intravenous immunoglobulin infusions. Immunosuppressive agents have been used as primary, second-line or adjunctive agents for its treatment. This review was undertaken to identify and review systematically randomised controlled trials of immunosuppressive agents. The use of intravenous immunoglobulin will be the subject of a separate review.

OBJECTIVES

To provide the best available evidence from randomised controlled trials on the role of immunosuppressive agents for the treatment of multifocal motor neuropathy.

SEARCH STRATEGY

We searched the Cochrane Neuromuscular Disease Group trials register for all trials of multifocal motor neuropathy published, using 'multifocal motor neuropathy' OR 'chronic inflammatory demyelinating polyradiculoneuropathy' OR ' conduction block' OR ' motor neuropathy' AND 'immunosuppressive agents', 'immunosuppressants', 'corticosteroids', 'plasma exchange', 'azathioprine', 'cyclophosphamide', 'cyclosporin', 'ciclosporin', 'methotrexate', and 'mycophenolate', 'immunomodulatory agents', 'interferon', 'total lymphoid irradiation' or 'bone marrow transplantation' as search terms. In addition we searched MEDLINE, EMBASE for 2000 and 2001 and CINAHL, LILACS for all years. We updated the register search in February 2004 and searched MEDLINE (January 1966 to end May 2004) and EMBASE (January 1980 to end May 2004).

SELECTION CRITERIA

All randomised controlled trials and quasi-randomised clinical trials in which allocation was not random but was intended to be unbiased (e.g. alternate allocation) were to have been selected. Since no such trials were discovered, all prospective and retrospective case series were included in the 'background' or 'discussion' sections of the review.

DATA COLLECTION AND ANALYSIS

All studies on multifocal motor neuropathy or lower motor neuron weakness with conduction block and no sensory abnormality were scrutinised for data on patients treated with any form of immunosuppressive agents besides intravenous immunoglobulin. The information on the outcome of treatment was then collated and summarised.

MAIN RESULTS

We found no randomised controlled trials of any immunosuppressive agents for multifocal motor neuropathy. We summarised the results of retrospective and prospective case series in the discussion of the review.

AUTHORS' CONCLUSIONS

There are no randomised controlled trials to indicate whether immunosuppressive agents are beneficial in multifocal motor neuropathy.

Multifocal motor neuropathy: current concepts and controversies

Multifocal motor neuropathy (MMN) is now a well-defined purely motor multineuropathy characterized by the presence of multifocal partial motor conduction blocks (CB), frequent association with anti-GM1 IgM antibodies, and usually a good response to high-dose intravenous immunoglobulin (IVIg) therapy. However, several issues remain to be clarified in the diagnosis, pathogenesis, and therapy of this condition including its nosological position and its relation to other chronic dysimmune neuropathies; the degree of CB necessary for the diagnosis of MMN; the existence of an axonal form of MMN; the pathophysiological basis of CB; the pathogenetic role of antiganglioside antibodies; the mechanism of action of IVIg treatments in MMN and the most effective regimen; and the treatment to be used in unresponsive patients. These issues are addressed in this review of the main clinical, electrophysiological, immunological, and therapeutic features of this neuropathy.

Multifocal motor neuropathy

Multifocal motor neuropathy (MMN) is an immune-mediated disorder characterised by slowly progressive, asymmetrical weakness of limbs without sensory loss. The clinical presentation of MMN mimics that of lower-motor-neuron disease, but in nerve-conduction studies of patients with MMN motor-conduction block has been found. By contrast with chronic inflammatory demyelinating polyneuropathy, treatment with prednisolone and plasma exchange is generally ineffective in MMN and even associated with clinical worsening in some patients. Of the immunosuppressants, cyclophosphamide has been reported as effective but only anecdotally. Various open trials and four placebo-controlled trials have shown that treatment with high-dose intravenous immunoglobulin leads to improvement of muscle strength in patients with MMN. Although clinical, pathological, imaging, immunological, and electrophysiological studies have improved our understanding of MMN over the past 15 years, further research is needed to elucidate pathogenetic disease mechanisms in the disorder.

CD16+CD57– Natural Killer Cells in Multifocal Motor Neuropathy

We analyzed the CD16+CD57- lymphocyte subset, which is considered to have strong natural killer (NK) cell activity, in peripheral blood from patients with chronic immune-mediated neuropathies and patients with other neurological diseases. We found that the ratio of CD16+CD57- NK cells to total lymphocytes was increased in 4 of 6 patients with multifocal motor neuropathy (MMN) with persistent conduction block. Since the CD16 molecule is an Fc receptor for immunoglobulin G (IgG), high-dose intravenous immunoglobulin (IVIg) may interfere with CD16+CD57- NK cells via Fc receptor blockade. In addition, cyclophosphamide (Cy) is often used to suppress NK cells. Therefore, our findings may partly account for the effectiveness of IVIg or Cy, which is the current treatment of choice for MMN.

IVIg in idiopathic autoimmune neuropathies: analysis in the light of the latest results

High-dose intravenous immunoglobulin (IVIg) is effective in the treatment of idiopathic autoimmune neuropathies including Guillain-Barré syndrome (GBS), chronic inflammatory demyelinating neuropathy (CIDP) and multifocal motor neuropathy (MMN), representing a useful option or, as in MMN, the gold standard for their treatment. In GBS, two randomised, controlled trials (RCT) showed that IVIg is at least as effective as plasma exchange (PE). IVIg may however be preferred due to its low number of contraindications and complications and the fact that it can be administered at any time, in any department, including patients with contraindications to PE, or in intensive care units. In CIDP, at least four RCTs have demonstrated the efficacy of IVIg in over 60% of CIDP patients, while two additional RCTs have shown a comparable effect to steroids and PE as initial treatment. As with PE, the effects of IVIg usually last a few weeks meaning that the majority of patients require periodic maintenance infusions. The lower cost and easier administration of oral steroids compared to IVIg may be partly compensated by the safer long-term profile of IVIg over steroids. In MMN, almost 80% of patients improve with IVIg, the efficacy of which has been confirmed by four RCTs, making of IVIg the first-choice therapy in MMN, for which steroids and PE are ineffective or even detrimental. Also in these patients, IVIg induces a rapid improvement that usually lasts only a few weeks and has to be maintained with periodic IVIg infusions for long periods of time, if not indefinitely.

A review of the medical management of chronic inflammatory demyelinating polyradiculoneuropathy

Chronic idiopathic demyelinating polyradiculoneuropathy (CIDP) is a rare condition, but merits consideration due to its disabling consequences for patients and the growing existence of efficacious therapies during the last few decades. The first step is to characterise this neuropathy among the chronic dysimmune polyneuropathies, according to clinical, electrophysiologicalal and sometimes pathologicalal and immunochemical criteria. Typical CIDP is currently defined by criteria which have progressively improved since the first attempt made by an Ad Hoc Subcommittee of the American Academy of Neurology in 1991. However, CIDP may be associated with several concurrent diseases, and other chronic demyelinating polyneuropathies may be considered as either subtypes of CIDP, such as sensory CIDP and multifocal acquired sensory and motor neuropathy, or frontiers of CIDP, such as multi-focal motor neuropathy and polyneuropathy associated with monoclonal gammopathy. These considerations are helpful in the choice of treatments, as the response to immunomodulatory agents is different according to the type of the dysimmune neuropathy. CIDP is considered to be an immune-mediated disorder and may respond dramatically to numerous short-term therapies, such as corticosteroids, plasma exchanges, or intravenous immunoglobulin. The aim of this review is both to summarise the main results of the published open and randomised controlled trials for CIDP, and to provide some information about randomised controlled trials currently in progress. The objectives of the current and future trials are firstly, to choose the best regimen for short-term treatments, and secondly, to test new immunosuppressants in long-term therapy, if the neurological condition requires it.

Intravenous immunoglobulin for multifocal motor neuropathy

BACKGROUND

Multifocal motor neuropathy is a rare, probably immune mediated disorder characterised by slowly progressive, asymmetric, distal weakness of one or more limbs with no objective loss of sensation. It may cause prolonged periods of disability. The treatment options for multifocal motor neuropathy are sparse. Patients with multifocal motor neuropathy do not usually respond to steroids or plasma exchange, and may even worsen with these treatments. Many uncontrolled studies have suggested a beneficial effect of intravenous immunoglobulin.

OBJECTIVES

To review systematically the evidence from randomised controlled trials concerning the efficacy and safety of intravenous immunoglobulin in multifocal motor neuropathy.

SEARCH STRATEGY

We used the search strategy of the Cochrane Neuromuscular Disease Review Group to search the Disease Group register (searched September 2003), MEDLINE (January 1990 to September 2003), EMBASE (January 1990 to September 2003) and ISI (January 1990 to September 2003) databases for randomised controlled trials.

SELECTION CRITERIA

Randomised controlled studies examining the effects of any dose of intravenous immunoglobulin versus placebo in patients with definite or probable multifocal motor neuropathy. Outcome measures had to include one of the following: disability, strength, or conduction block. Studies which reported the frequency of adverse effects were used to assess safety.

DATA COLLECTION AND ANALYSIS

Two authors reviewed literature searches to identify potentially relevant trials, scored their quality and extracted data independently. For dichotomous data, we calculated relative risks, and for continuous data, effect sizes and weighted pooled effect sizes. Statistical uncertainty was expressed with 95% confidence intervals.

MAIN RESULTS

Four randomised controlled trials including a total of 34 patients were suitable for this systematic review. Strength improved in 78% of patients treated with intravenous immunoglobulin and only 4% of placebo-treated patients. Disability improved in 39% of patients after intravenous immunoglobulin treatment and in 11% after placebo (statistically not significantly different). Mild, transient side effects were reported in 71% of intravenous immunoglobulin treated patients. Serious side effects were not encountered.

AUTHORS' CONCLUSIONS

Limited evidence from randomised controlled trials shows that intravenous immunoglobulin has a beneficial effect on strength. There was a non-significant trend towards improvement in disability. More research is needed to discover whether intravenous immunoglobulin improves disability and is cost-effective.

Treatment of dysimmune neuropathies

Several therapies are currently used in dys-immune neuropathies including steroids,plasma exchange (PE), high-dose intravenous immunoglobulins(IVIg), and immuno-suppressive agents (IS). Even if there is substantial evidence that these treatments may improve the course of the neuropathy, their effectiveness is far from being complete and is sometime hampered by the occurrence of associated side effects. In Guillain-Barré syndrome (GBS),IVIg and PE are similarly effective in accelerating the recovery but there is still little evidence that they can reduce mortality or long-term disability. Recent reports on the association of intravenous methylprednisolone or interferon-beta (IFN-beta) to IVIg did not result in significant further improvement. In chronic inflammatory demyelinating polyradiculoneuropathy(CIDP) steroids, PE, and IVIG are initially similarly effective. The short-term effect of PE and IVIgand the side effects associated with the long-term use of steroids have prompted the use of several IS, interferon and,more recently, the anti-CD20 monoclonal-antibody Rituximab, but their efficacy has still to be proved in controlled studies. The recent identification of multifocal motor neuropathy(MMN) was shortly followed by the finding of an effective therapy. Almost 80% of patients respond toIVIg whose effect needs to be maintained with periodic infusions for long periods of time, and tends to decrease after several years. Also in this condition a number of immune modulating agents have been used to reduce the frequency or improve the effectiveness of IVIg,but their efficacy has not been sofar confirmed in randomized trials. Similar conclusions can be drawn for neuropathies associated with monoclonal gammopathies where only PE and IVIg have proved to be effective in controlled studies,while the promising initial results obtained with Rituximab in neuropathy associated IgM monoclonal gammopathy awaits confirmation from controlled trials.

Magnetic stimulation using a triple-stimulation technique in patients with multifocal neuropathy without conduction block

It has been suggested previously that multifocal motor neuropathy (MMN) without conduction block (CB) or other features of demyelination is axonal in nature. Conventional transcranial magnetic stimulation (TMS) and the triple-stimulation technique (TST) performed on 10 MMN patients without CB revealed a proximal focal CB in 4 patients. In 3 other patients, the amplitude ratio obtained in response to conventional TMS was abnormally low, but the area ratio was normal. The TST amplitude ratio and area ratio were normal in these 3 patients. This pattern suggested the occurrence of temporal dispersion without CB. The occurrence of temporal dispersion or CB was associated with a relatively satisfactory response to intravenous immunoglobulins. These findings suggest that some forms of MMN previously thought to be axonal are in fact proximal variants of MMN with CB.

The use of intravenous immunoglobulin in the treatment of autoimmune neuromuscular diseases: evidence-based indications and safety profile

Intravenous immunoglobulin (i.v.Ig) has multiple actions on the immunoregulatory network that operate in concert with each other. For each autoimmune neuromuscular disease, however, there is a predominant mechanism of action that relates to the underlying immunopathogenetic cause of the respective disorder. The best understood actions of i.v.Ig include the following: (a) modulation of pathogenic autoantibodies, an effect relevant in myasthenia gravis (MG), Lambert-Eaton myasthenic syndrome (LEMS), Guillain-Barré syndrome (GBS), chronic inflammatory demyelinating polyneuropathy (CIDP), and stiff-person syndrome (SPS); (b) inhibition of complement activation and interception of membranolytic attack complex (MAC) formation, an action relevant to the complement-mediated mechanisms involved in GBS, CIDP, MG, and dermatomyositis (DM); (c) modulation of the inhibitory or activation Fc receptors on macrophages invading targeted tissues in nerve and muscle, as seen in CIDP, GBS, and inflammatory myopathies; (d) down-regulation of pathogenic cytokines and adhesion molecules; (e) suppression of T-cell functions; and (f) interference with antigen recognition. Controlled clinical trials have shown that i.v.Ig is effective as first-line therapy in patients with GBS, CIDP, and multifocal motor neuropathy (MMN), and as second-line therapy in DM, MG, LEMS, and SPS. In paraproteinemic IgM anti-MAG (myelin-associated glycoprotein) demyelinating polyneuropathies and inclusion body myositis (IBM), the benefit is variable, marginal, and not statistically significant. i.v.Ig has a remarkably good safety record for long-term administration, however, the following side effects have been observed: mild, infusion-rate-related reactions, such as headaches, myalgia, or fever; moderate but inconsequential events, such as aseptic meningitis and skin rash; and severe, but rare, complications, such as thromboembolic events and renal tubular necrosis. Future studies are needed to (a) find the appropriate dose and frequency of infusions that maintain a response; (b) address pharmacoeconomics, comparing the high cost of i.v.Ig to the cost of the other therapies, which, although less expensive, cause significantly more long-term side effects; (c) determine why some patients respond better than others; and (d) examine the merits of combining i.v.Ig with other immunosuppressive drugs.

Neuropathies motrices multifocales avec blocs de conduction persistants : 18 ans après

Multifocal motor neuropathy with persistent conduction blocks was firstly reported in 1986 and outlined from the group of purely motor diseases of the peripheral nervous system. The main criterion is the presence of conduction blocks located only on the motor nerves; additionally 30 percent of patients have IgM subclass serum antibodies directed against GM1 ganglioside. The clinical picture is a multifocal, asymmetrical, neuropathy, starting and predominant in the upper limbs, occurring in males aged 50 years and more, and having a progressive course. There is no biological sign besides elevated anti-GM1 antibodies. CSF analysis discloses mild increased protein count. The course is unpredictable, the neuropathy may be strictly limited to one or two motor nerves, or spread to other motor nerves in the four limbs. There is no involvement of the sensory and the cranial nerves, no involvement of the autonomic and the central nervous system. The pathophysiology is unknown, animal models do not allow to confirm the role of humoral immunity, and the role of anti-GM1 antibodies is controversial. Randomized controlled trials have assessed the efficacy of intravenous immunoglobulins which dramatically improve strength in 70-80 percent of patients in the short term, but remain unable to prevent motor deterioration in most patients, together with the occurrence of new conduction blocks. Corticosteroids and plasma exchanges do not improve the patients and may be followed by transient worsening. Long-term efficacy of immunosuppressive agents is not known.