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

Update on therapy of chronic immune-mediated neuropathies

Chronic immune-mediated neuropathies, including chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), neuropathies associated with monoclonal gammopathy, and multifocal motor neuropathy (MMN), are a group of disorders deemed to be caused by an immune response against peripheral nerve antigens. Several immune therapies have been reported to be variably effective in these neuropathies including steroids, plasma exchange, and high-dose intravenous (IVIg) or subcutaneous (SCIg) immunoglobulins. These therapies are however far from being invariably effective and may be associated with a number of side effects leading to the use of immunosuppressive agents whose efficacy has not been so far confirmed in randomized trials. More recently, new biological agents, such as rituximab, have proved to be effective in patients with neuropathy associated with IgM monoclonal gammopathy and are currently tested in CIDP.

One nerve suffices: A clinically guided nerve ultrasound protocol for the differentiation of multifocal motor neuropathy (MMN) and amyotrophic lateral sclerosis (ALS)

OBJECTIVE

To investigate diagnostic accuracy of a nerve ultrasound (US) protocol that is individualized to a patient's clinical deficits for the differentiation of amyotrophic lateral sclerosis with predominant lower motoneuron disease (ALS/LMND) and multifocal motor neuropathy (MMN).

METHODS

Single-center, prospective, examiner-blinded, diagnostic study in two cohorts. Cohort I (model development): Convenience sample of subjects with ALS/LMND or MMN according to revised El-Escorial or EFNS guidelines. Cohort II (model validation): Consecutively recruited treatment-naïve subjects with suspected diagnosis of ALS/LMND or MMN. Cutoffs for 28 different US values were determined by Receiver Operating Curve (ROC) in cohort I. Area Under The Curve (AUC) of US was compared to nerve conduction studies (NCS). Diagnostic accuracy of US protocols, individualized according to clinical deficits, was compared to former rigid non-individualized protocols and to random examination site selection in cohort II.

RESULTS

48 patients were recruited. In cohort I (28 patients), US had higher ROC AUCs than NCS, US 0.82 (0.12) (mean (standard deviation)), NCS (compound muscle action potential (CMAP) 0.60 (0.09), p < .001; two-sided t-test). US models based on the nerve innervating the clinically most affected muscles had higher correct classification rates (CCRs, 93%) in cohort II than former rigid protocols (85% and 80%), or models with random measurement site selection (66% and 80%).

CONCLUSIONS

Clinically guided US protocols for differentiation of ALS/LMND from MMN increase diagnostic accuracy when compared to clinically unguided protocols. They also require less measurements sites to achieve this accuracy.

Intravenous Immunoglobulin Therapy in Patients With Painful Idiopathic Small Fiber Neuropathy

Objective

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

Methods

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

Results

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

Conclusions

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

Trial Registration Information

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

Classification of Evidence

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

Clinical cases of amyotrophic lateral sclerosis concurrent with hydromyelia

A comprehensive work-up, clinical correlation, and differential diagnosis are needed to determine if abnormal findings such us hydromyelia in ALS patients are causative or incidental in order to rule out other, more curable conditions that resemble ALS.

Difference in distribution of fasciculations between multifocal motor neuropathy and amyotrophic lateral sclerosis

OBJECTIVE

To examine differences in fasciculation distribution between patients with multifocal motor neuropathy (MMN) and amyotrophic lateral sclerosis (ALS) based on muscle ultrasound.

METHODS

Forty-one muscles (tongue muscle and 40 muscles of the trunk and limbs on both sides) in 5 MMN patients and 21 muscles (tongue muscle and 20 muscles on the onset side) in 21 ALS patients were subjected to muscle ultrasound individually for 60 seconds to detect the presence of fasciculations.

RESULTS

Fasciculation detection rates on the onset side were significantly higher in ALS (42.4 ± 18.3%, mean ± SD) than in MMN (21.9 ± 8.8%) patients (p < 0.05). In MMN patients, no fasciculation was detected in the tongue or truncal muscles. There was no difference in the fasciculation detection rate between the onset and non-onset sides or between upper and lower limbs in MMN patients.

CONCLUSIONS

In MMN patients, fasciculations were detected extensively in the limbs. However, the detection rate in patients with MMN was lower than in those with ALS.

SIGNIFICANCE

Demonstration of the absence of fasciculations in the tongue and truncal muscles in MMN patients by extensive muscle ultrasound examination may help distinguish MMN from ALS.

Quality of life in inflammatory neuropathies: the IN-QoL

BACKGROUND

No consensus exists which quality of life (QoL) measure should be used in patients with inflammatory neuropathies. Moreover, most QoL measures are ordinal-based scales with their known deficiencies.

OBJECTIVES

To establish a new disease-specific interval-based QoL questionnaire in inflammatory neuropathies (IN-QoL) using the Rasch model and evaluate its scientific properties (validity, reliability and responsiveness).

METHODS

264 patients with inflammatory neuropathies completed six commonly used QoL questionnaires. The obtained data were stacked and subjected to Rasch analysis. Responsiveness was determined by using the concept of minimum clinically important differences related to varying individually obtained SEs (responsiveness definition: MCID-SE≥1.96 after 1-year follow-up compared with baseline).

RESULTS

The IN-QoL fulfilled all Rasch's model requirements with high internal reliability values (patient separation index of 0.94), except being multidimensional. Additional factor analysis resulted in two (functional and mental) subsets that were unidimensional on their own. The IN-QoL showed good correlation with the EuroQol-health quality visual analogue scale (EQ-VAS) (Spearman's rho 0.72). It demonstrated acceptable responsiveness in patients with Guillain-Barré syndrome (GBS) and chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), as did the EQ-VAS. In patients with monoclonal gammopathy-related neuropathy and multifocal motor neuropathy, hardly any changes were seen over time.

CONCLUSION

The IN-QoL questionnaire fulfils modern clinimetric requirements and correlates strongly with a patient's self-assessment of their own quality of health, while also showing responsiveness in patients with GBS and CIDP. We propose using the IN-QoL and the EQ-VAS for assessing the QoL of patients with inflammatory neuropathies in future studies.

Nerve ultrasound as follow-up tool in treated multifocal motor neuropathy

BACKGROUND AND PURPOSE

High-resolution ultrasound is a valuable tool in supporting the diagnosis of multifocal motor neuropathy (MMN) but longitudinal data under therapy are lacking.

METHODS

The change in peripheral nerve ultrasound pattern in patients with MMN was assessed over time. Patients with MMN received a thorough initial examination and follow-up over a period of 6-12 months using high-resolution ultrasound of the cervical roots and the nerves of the arms and legs, nerve conduction studies, Medical Research Council Sum Score (MRCSS) and Rotterdam Inflammatory Neuropathy Cause and Treatment Group (INCAT) score to evaluate changes under treatment. The Ultrasound Pattern Sum Score (UPSS) was used as standardized peripheral nerve ultrasound protocol.

RESULTS

Seventeen patients with MMN received initial examinations of whom 12 were successfully followed up. All patients with MMN showed at least localized but often multifocal peripheral nerve enlargement. An enlarged overall cross-sectional area as well as enlarged single fascicles (>3 mm²) in clinically and electrophysiologically affected (>90%) and unaffected (>70%) nerves were found. The UPSS did not correlate with clinical disability at both visits. However, the change in clinical disability (evaluated as difference in MRCSS) and the change in UPSS correlated significantly inversely (P = 0.004).

CONCLUSIONS

High-resolution sonography of peripheral nerves revealed multifocal nerve enlargement in MMN. Distinct enlargement patterns may support the diagnosis. Ultrasound findings did not correlate well with clinical severity or electrophysiological findings at initial presentation. As changes in UPSS correlated significantly with the clinical course in terms of muscle strength (MRCSS), sonographic assessment may represent a useful tool for therapeutic monitoring.

High-dose Ig VENA is well tolerated and efficacious in patients with multifocal motor neuropathy

Multifocal motor neuropathy (MMN) is a rare, chronic, motor neuropathy that progressively impairs physical functioning and quality of life. Randomised controlled trials have shown that high-dose intravenous immunoglobulin (IVIg) is superior to placebo in improving muscle strength and disability, but many patients require periodic infusions to maintain long-term improvement. This observational, multicentre, retrospective study investigated the efficacy and tolerability of human normal immunoglobulin (Ig VENA) at high intravenous infusion rates in 20 MMN patients (14 male, 6 female). Thirty days after the first infusion, there was an improvement of at least 1 point in two muscles compared to baseline on the Medical Research Council (MRC) scale and of 1 point in the ONLS (Overall Neuropathy Limitation Scale) scale in 15 patients (75%) and 10 patients (50%), respectively; 45% improved on both scales. At 6 months, 100% of 12 patients had improved on the MRC and 79% of 14 patients had improved on the ONLS scale; 83% improved on both scales. All reported adverse drug reactions (ADR) were mild, transient and possibly related to the study drug. Four patients (20%) reported ADRs, three reported headache and one fever. There were no serious or unexpected ADRs. By confirming that high-dose Ig VENA is efficacious and well tolerated, this study adds to the evidence base for IVIg in MMN and potentially increases clinicians' and patients' choice of therapy.

Nerve ultrasound in the differentiation of multifocal motor neuropathy (MMN) and amyotrophic lateral sclerosis with predominant lower motor neuron disease (ALS/LMND)

The objective of the study was to investigate nerve ultrasound (US) in comparison to nerve conduction studies (NCS) for differential diagnosis of amyotrophic lateral sclerosis with predominant lower motoneuron disease(ALS/LMND) and multifocal motor neuropathy(MMN). A single-center, prospective, examiner-blinded cross-sectional diagnostic study in two cohorts was carried out. Cohort I: convenience sample of subjects diagnosed with ALS/LMND or MMN (minimal diagnostic criteria:possible ALS (revised EL-Escorial criteria), possible MMN (European Federation of Neurosciences guidelines).Cohort II: consecutive subjects with suspected diagnosis of either ALS/LMND or MMN. Diagnostic US and NCS models were developed based on ROC analysis of 28 different US and 32 different NCS values measured in cohort I. Main outcome criterion was sensitivity/specificity of these models between ALS/LMND and MMN in cohort II.Cohort I consisted of 16 patients with ALS/LMND and 8 patients with MMN. For cohort II, 30 patients were recruited, 8 with ALS/LMND, 5 with MMN, and 17 with other diseases. In cohort I, the three best US measures showed higher mean ± SD areas under the curve than the respective NCS measures (0.99 ± 0.01 vs. 0.79 ± 0.03, p<0.001; two-sided t test). The US model with highest measurement efficacy (8 values) and diagnostic quality reached 100 % sensitivity and 92 % specificity for MMN in cohort II, while the respective NCS model (6 values, including presence of conduction blocks) reached 100 and 52 %. Nerve US is of high diagnostic accuracy for differential diagnosis of ALS/LMND and MMN. It might be superior to NCS in the diagnosis of MMN in hospital-admitted patients with this differential diagnosis.

Efficacy of Various Intravenous Immunoglobulin Therapy Protocols in Autoimmune and Chronic Inflammatory Disorders

Objective:

To determine the efficacy of various intravenous immunoglobulin (IVIG) protocols used in the treatment of autoimmune and chronic inflammatory disorders.

Data Sources:

Literature retrieval was accessed through MEDLINE (November 1984–March 2007) and a search was conducted using the term intravenous immunoglobulin. References cited in the selected articles were also reviewed.

Study Selection and Data Extraction:

Inclusion criteria for studies were (1) English language, (2) randomized controlled trials, (3) defined protocols, (4) a minimum of 15 patients, and (5) objective criteria provided to assess clinical outcomes and course.

Data Synthesis:

The therapeutic efficacy of IVIG therapy is well established, and defined protocols exist for treatment of Kawasaki disease, immune thrombocytopenic purpura, Guillain–Barré syndrome, chronic inflammatory demyelinating polyneuropathy, multifocal motor neuropathy, and autoimmune mucocutaneous blistering diseases. In the absence of a defined protocol, studies have demonstrated that IVIG therapy is effective in the treatment of myasthenia gravis, dermatomyositis, stiff person syndrome, antineutrophil cytoplasmic antibody positive systemic vasculitides, Graves' ophthalmopathy, and certain forms of systemic lupus erythematosus. It might also be of benefit in some patients with relapsing–remitting multiple sclerosis. The outcomes are variable in these studies. In toxic epidermal necrolysis and Stevens–Johnson syndrome, use of IVIG has dramatically influenced clinical response and reduced mortality.

Conclusions:

The cumulative evidence suggests that the clinical outcomes observed are significantly influenced by the use of a defined protocol. There is a need for multicenter trials approved by the Food and Drug Administration to better define the role of IVIG in many disease states. Such studies would be able to establish the indications for use, optimal dose, frequency of infusions, duration of therapy, and need for gradual withdrawal versus sudden cessation. Defined protocols resulting from the study of a large cohort of patients often convince insurance companies to create policies that provide access to IVIG therapy.

Regarding the past, what is the trial you have always been dreaming of in CIDP?

Chronic inflammatory demyelinating polyradiculoneuropathy is an orphan disease of poorly understood cause. While first line treatments with corticosteroids, intravenous immunoglobulin and plasma exchange have at least short-term efficacy, no trial has shown that immunosuppressants work. In our dream, we will take advantage of the recently improved EU regulations to launch a Europe wide trial which will investigate the cause of the disease. It will compare three parallel groups, the anti-B cell agent rituximab, the anti-T cell agent abatacept and usual care. The trial will not be blinded and the design will be very simple. The primary outcome measure will be improvement from baseline of the overall neuropathy limitations scale (ONLS) score by 1 or more grades at 12 weeks without increase in concomitant corticosteroids or IVIg or use of plasma exchange. There will be an option to substitute improvement in the Rasch-built overall disability scale depending on future experience with that scale as the primary outcome measure. The trial will require 3 groups of 60 participants to detect an increase from 20% in the usual care group to 30% with one of the other agents with a power of 90% and P-value of 5%. It will be larger than any trial of an immunosuppressant agent so far performed in CIDP. However, recruitment will be easier because inclusion criteria will be broad and allow randomisation of any patient in whom their neurologist wishes to introduce an immunosuppressant. Avoidance of blinding and use of simple monitoring with facetime will simplify running the trial and reduce expense. The trial will follow participants and measure outcomes at 12 months. Other outcomes will consist only of grip strength, time to walk 10 m and Euroqol, the last allowing us to estimate the cost per QALY of rituximab or abatacept. Even including central analysis of key biomarkers, the trial will only cost 3 million euros, a fraction of the cost of the usual phase III pharmaceutical company trial.

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

Background

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

Methods/design

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

Discussion

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

Trial registration

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

Electronic supplementary material

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

Treatment of patients with multifocal motor neuropathy with immunoglobulins in clinical practice: the SIGNS registry

OBJECTIVES

The management of patients with multifocal motor neuropathy (MMN) under everyday clinical conditions has been insufficiently studied. We therefore collected comprehensive observational data on patients with MMN who received intravenous (IV) or subcutaneous (SC) immunoglobulins (IGs) as maintenance therapy.

METHODS

This was a prospective, noninterventional study (registry) in neurological centres (hospitals and offices) throughout Germany.

RESULTS

As of 1 December 2015, 80 patients with MMN were included (mean age 55.4 ± 9.8 years, 67% males, mean disease duration 10.7 ± 10.2 years). The affected limb regions were predominantly distal muscle groups of the upper extremities. On the inflammatory neuropathy cause and treatment (INCAT) scale, 94% of the patients had some disability in the arms and 61% in the legs. At inclusion, 98.8% received IVIG and 1.3% SCIG. Substantial variation was observed between IVIG treatment intervals (every 0.7 to 17.3 weeks) and dosage (0.2-2.1 g/kg body weight received during a single administration; mean monthly dosage, 0.9 g/kg body weight). However, the mean monthly dosage was steady over time. At 1-year follow up, improvement was seen in muscle strength, INCAT and quality of life (QoL) scores (SF-36 questionnaire).

CONCLUSIONS

The management of patients with MMN in everyday clinical practice demonstrates a wide range of absolute dosages and treatment intervals of IG, supporting the recommended practice of determining treatment dose on an individual patient basis. The improvements in muscle strength and reduction in disability, accompanied by increased QoL, strengthen the case for use of IG as a maintenance treatment for MMN.

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.

Streptococcal IdeS: therapeutic potential for Guillain-Barré syndrome

Plasma exchange and intravenous immunoglobulin are effective in treating Guillain–Barré syndrome (GBS) probably because the former removes IgG autoantibodies and complement and the latter inhibits complement activation subsequent to the autoantibody binding to peripheral nerve antigens. IgG degrading enzyme of Streptococcus pyogenes (IdeS) can cleave the pathogenic autoantibodies into F(ab’)₂ and Fc. The purpose of this study is to show whether IdeS has novel therapeutic potential for GBS. Sera with anti-ganglioside IgG antibodies from 15 patients with GBS or Miller Fisher syndrome were used. We tested whether IdeS cleaved the anti-ganglioside IgG antibodies and inhibited deposition of activated complement component on ELISA plates. IdeS efficiently cleaved IgG and blocked complement activation mediated by anti-GM1, anti-GD1a and anti-GQ1b IgG antibodies. IdeS has therapeutic potential for GBS and related conditions.

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.

Practical rules for electrodiagnosis in suspected multifocal motor neuropathy

Multifocal motor neuropathy (MMN) with conduction block (CB) is a rare chronic immune-mediated neuropathy, but important to diagnose as it is treatable. The key features in prototypic MMN are electrodiagnostic demonstration of focal CB away from common sites of entrapment and normal sensory conduction across these sites. However, there are challenges in distinguishing CB from the effects of abnormal temporal dispersion. Consensus electrodiagnostic criteria, reinforced by modeling studies, are available to support definite or probable CB. In addition, consideration of technical issues can guard against false-positive and false-negative conclusions. These include limb temperature, stimulus site, inadvertent stimulating electrode movement, and supramaximal and submaximal responses, as well as the possibility of Martin-Gruber anastamosis. Robust evidence supports the treatment of MMN with intravenous immunoglobulin, and guidelines have been developed. Application of practical and simple rules including a 4-step diagnostic algorithm can help practitioners correctly diagnose this treatable condition and improve patient outcomes.

Antibodies to heteromeric glycolipid complexes in multifocal motor neuropathy

BACKGROUND

Measurement of anti-GM1 IgM antibodies in multifocal motor neuropathy (MMN) sera is confounded by relatively low sensitivity that limits clinical usefulness. Combinatorial assay methods, in which antibodies react to heteromeric complexes of two or more glycolipids, are being increasingly applied to this area of diagnostic testing.

METHODS

A newly developed combinatorial glycoarray able to identify antibodies to 45 different heteromeric glycolipid complexes and their 10 individual glycolipid components was applied to a randomly selected population of 33 MMN cases and 57 normal or disease controls. Comparison with an enzyme-linked immunosorbent assay (ELISA) was conducted for selected single glycolipids and their complexes.

RESULTS

By ELISA, 22/33 MMN cases had detectable anti-GM1 IgM antibodies, whereas 19/33 MMN samples were positive for anti-GM1 antibodies by glycoarray. Analysis of variance (anova) revealed that of the 55 possible single glycolipids and their 1:1 complexes, antibodies to the GM1:galactocerebroside (GM1:GalC) complex were most significantly associated with MMN, returning 33/33 MMN samples as positive by glycoarray and 29/33 positive by ELISA. Regression analysis revealed a high correlation in absolute values between ELISA and glycoarray. Receiver operator characteristic analysis revealed insignificantly different diagnostic performance between the two methods. However, the glycoarray appeared to offer slightly improved sensitivity by identifying antibodies in four ELISA-negative samples.

CONCLUSIONS

The use of combinatorial glycoarray or ELISA increased the diagnostic sensitivity of anti-glycolipid antibody testing in this cohort of MMN cases, without significantly affecting specificity, and may be a useful assay modification for routine clinical screening.

Fulminant multifocal motor neuropathy: a report of two cases

Multifocal motor neuropathy (MMN) shows stepwise progression over decades. The multifocal weakness usually remains asymmetric, confined to distal limb muscles, while sparing cranial, phrenic, and sensory nerves. One electrophysiological hallmark is partial motor conduction block (CB) at sites not exposed to compression; whether CB is an essential feature remains debatable. High titer of anti-GM1 antibodies is found with figures usually between 40% and 50% of patients. Intravenous immuneglobulin (IVIg) is effective in almost 80%, but plasmapheresis and steroids are not. The condition is reported as lethal exceptionally, mimicking motor neuron diseases (MND). We have studied two patients who failed to respond to treatment and who died with respiratory failure; one of the two had high titer of IgM antibody to the ganglioside GM1. Our cases confirm that great attention should be paid in order to define the borderland between MMN and MND and the entity of their clinical and electrophysiological overlaps.

Predicting a positive response to intravenous immunoglobulin in isolated lower motor neuron syndromes

OBJECTIVE

To determine clinically related characteristics in patients with pure lower motor neuron (LMN) syndromes, not fulfilling accepted diagnostic criteria, who were likely to respond to intravenous immunoglobulin (IVIg) treatment.

METHODS

Demographic, clinical, laboratory and neurophysiological characteristics were prospectively collected from patients with undifferentiated isolated LMN syndromes who were then treated with IVIg. Patients were classified as either responders or non-responders to therapy with IVIg based on clinical data and the two groups were compared.

RESULTS

From a total cohort of 42 patients (30 males, 12 females, aged 18-83 years), 31 patients responded to IVIg and 11 did not. Compared to patients that developed progressive neurological decline, responders were typically younger (45.8 compared to 56.0 years, P<0.05) and had upper limb (83.9% compared to 63.6%, NS), unilateral (80.6% compared to 45.5%, P<0.05), and isolated distal (54.1% compared to 9.1%, P<0.05) weakness. Patients with predominantly upper limb, asymmetrical, and distal weakness were more likely to respond to IVIg therapy. Of the patients who responded to treatment, only 12.9% had detectable GM(1) antibodies and conduction block (not fulfilling diagnostic criteria) was only identified in 22.6%.

CONCLUSIONS

More than 70% of patients with pure LMN syndromes from the present series responded to treatment with IVIg therapy, despite a low prevalence of detectable GM(1) antibodies and conduction block. Patients with isolated LMN presentations, not fulfilling accepted diagnostic criteria, may respond to IVIg therapy, irrespective of the presence of conduction block or GM(1) antibodies, and should be given an empirical trial of IVIg to determine treatment responsiveness.

Thromboembolic complications of intravenous immunoglobulin therapy in patients with neuropathy: a two-year study

BACKGROUND

The incidence and determinants of thromboembolic complications (TEC) of intravenous immunoglobulin (IVIg) therapy in patients with dysimmune neuropathy are uncertain.

METHODS

We performed a retrospective study of patients with dysimmune neuropathy seen at our institution and treated with IVIg, over a 24-month period.

RESULTS

Sixty-two patients were treated with a total of 616 courses of IVIg. TEC occurred in 7 patients. In 5, these occurred within 14 days after IVIg infusion ("early TEC"). Early TEC were significantly more frequent after courses administered to IVIg-naïve patients (3/25 vs. 2/591 courses; p<0.001), but incidences were comparable in newly- vs. previously-treated patients (3/25 vs. 2/44 patients; p=0.34). Early TEC included 2 cases of myocardial infarction, one of acute coronary syndrome, one of deep vein thrombosis (DVT) with pulmonary embolism and one of isolated DVT. Mean dose per course was comparable in affected and unaffected patients (p=0.47), but administration of daily doses ≥ 35 g correlated significantly with occurrence of early TEC (p=0.028). Previous coronary disease (p=0.037) and immobility at time of treatment (p=0.049) were independent predictors of early TEC. Patients with early TEC had significantly more risk factors (p<0.001), and were significantly more likely to have ≥ 4 risk factors (p=0.006), than those without early TEC.

CONCLUSION

The risk of TEC with IVIg is not negligible in patients with neuropathy. Although higher with a first-ever infusion, the general risk may be comparable in IVIg-naïve and previously-treated patients. Administration of daily doses ≥ 35 g of IVIg may carry a greater risk of early TEC. Coronary disease, immobility at time of treatment, presence of ≥ 4 risk factors, should lead to caution and consideration of alternative treatments.

Occurrence and characterization of Pain in immune-mediated neuropathies: a multicentre prospective study

BACKGROUND

pain is a common symptom of peripheral neuropathies that may severely affect patients' Quality of Life. Pain questionnaires, based on verbal descriptors, are a useful way to investigate it.

METHODS

we performed a multicentre study through validated measures to characterize pain in a sample of consecutive patients affected by immune-mediated neuropathies.

RESULTS

ninety-three patients were enrolled in 16 Italian centres. Based on the numeric rating scale, almost half of the patients complained of moderate pain and one-third of the patients severe pain. Overall, up to 50% of our patients with immune-mediated neuropathies complained of neuropathic pain. The most common neuropathic symptoms were paraesthesia/dysesthesia and superficial spontaneous pain. Surprisingly, also patients with neuropathies commonly thought to be painless (such as multifocal motor neuropathy) reported discomfort and painful symptoms.

CONCLUSIONS

pain questionnaires should be considered in the clinical evaluation of immune-mediated neuropathies, also when evaluating therapy efficacy, because they may provide clinicians with useful information on painful symptoms and patients' quality of life.

[Advances and perspectives in treatment for refractory neuropathies with special reference to immune-mediated neuropathies and Crow-Fukase syndrome]

There are significant advances in immune-modulating treatments for Guillain-Barré syndrome (GBS) and chronic inflammatory demyelinating polyneuropathy (CIDP) in the past 20 years. GBS, however, is still a serious disease with a mortality rate of 8% and 20% of the patients being unable to walk independently a year after onset For CIDP and related disorders such as multifocal motor neuropathy, and demyeinating neuropathy with anti-myelin-associated-glycoprotein (MAG) antibody, treatments should be based on individual pathophysiology. Rituximab could be a promising agent for the subtypes of CIDP refractory to conventional immune treatments. Crow-Fukase syndrome is a rare cause of demyelinating neuropathy with multiorgan involvement Overproduction of vascular endothelial growth factor (VEGF), probably mediated by monoclonal proliferation of plasma cells, is likely to be responsible for most of the characteristic symptoms. There is no established treatment regimen for Crow-Fukase syndrome. In appropriate candidates, high-dose chemotherapies with autologous peripheral blood stem cell transplantation is highly recommended, because this treatment could result in obvious improvement in neuropathy as well as other symptoms. Indication of this treatment has not yet been established, and long-term prognosis is unclear at present. Treatments that should be considered as future therapy against Crow-Fukase syndrome include thalidomide, and anti-VEGF monoclonal antibody (bevacizumab).

Treatment in inflammatory neuropathies

This review focuses on recent developments in the treatment of inflammatory neuropathies arising from immune dysregulation, rather than from infectious causes. The dysimmune inflammatory neuropathies are diseases of the peripheral nerves that have varying etiologies and may respond to immunomodulatory therapies. They are characterized by inflammatory changes in the nerve with associated destruction of myelin and axons. The underlying immune mechanisms are better understood in some of these conditions than others. Correct diagnosis and treatment is important to prevent clinical progression. Randomized controlled trials of some treatments in the more common inflammatory neuropathies have clarified their effectiveness; however, there are still groups of patients who are resistant to currently available treatments and for whom little effective treatment is available. Newer, targeted biologics and larger controlled trials of existing and novel therapies in these conditions offer promise of improved morbidity and mortality in this group of diseases.

6th International Immunoglobulin Symposium: poster presentations

The posters presented at the 6th International Immunoglobulin Symposium covered a wide range of fields and included both basic science and clinical research. From the abstracts accepted for poster presentation, 12 abstracts were selected for oral presentations in three parallel sessions on immunodeficiencies, autoimmunity and basic research. The immunodeficiency presentations dealt with novel, rare class-switch recombination (CSR) deficiencies, attenuation of adverse events following IVIg treatment, association of immunoglobulin (Ig)G trough levels and protection against acute infection in patients with X-linked agammaglobulinaemia (XLA) and common variable immunodeficiency (CVID), and the reduction of class-switched memory B cells in patients with specific antibody deficiency (SAD). The impact of intravenous immunoglobulin on fetal alloimmune thrombocytopenia, pregnancy and postpartum-related relapses in multiple sclerosis and refractory myositis, as well as experiences with subcutaneous immunoglobulin in patients with multi-focal motor neuropathy, were the topics presented in the autoimmunity session. The interaction of dendritic cell (DC)-SIGN and alpha2,6-sialylated IgG Fc and its impact on human DCs, the enrichment of sialylated IgG in plasma-derived IgG, as wells as prion surveillance and monitoring of anti-measles titres in immunoglobulin products, were covered in the basic science session. In summary, the presentations illustrated the breadth of immunoglobulin therapy usage and highlighted the progress that is being made in diverse areas of basic and clinical research, extending our understanding of the mechanisms of immunoglobulin action and contributing to improved patient care.

Subcutaneous immunoglobulin: opportunities and outlook

Immunoglobulin (Ig) administration via the subcutaneous (s.c.) route has become increasingly popular in recent years. The method does not require venous access, is associated with few systemic side effects and has been reported to improve patients' quality of life. One current limitation to its use is the large volumes which need to be administered. Due to the inability of tissue to accept such large volumes, frequent administration at multiple sites is necessary. Most studies conducted to date have investigated the use of subcutaneous immunoglobulin (SCIg) in patients treated previously with the intravenous (i.v.) formulation. New data now support the use of s.c. administration in previously untreated patients with primary immunodeficiencies. SCIg treatment may further be beneficial in the treatment of autoimmune neurological conditions, such as multi-focal motor neuropathy; however, controlled trials directly comparing the s.c. and i.v. routes are still to be performed for this indication. New developments may further improve and facilitate the s.c. administration route. For example, hyaluronidase-facilitated administration increases the bioavailability of SCIg, and may allow for the administration of larger volumes at a single site. Alternatively, more concentrated formulations may reduce the volume required for administration, and a rapid-push technique may allow for shorter administration times. As these developments translate into clinical practice, more physicians and patients may choose the s.c. administration route in the future.

Diagnosis and treatment in inflammatory neuropathies

The inflammatory neuropathies are a large diverse group of immune-mediated neuropathies that are amenable to treatment and may be reversible. Their accurate diagnosis is essential for informing the patient of the likely course and prognosis of the disease, informing the treating physician of the appropriate therapy and informing the scientific community of the results of well-targeted, designed and performed clinical trials. With the advent of biological therapies able to manipulate the immune response more specifically, an understanding of the pathogenesis of these conditions is increasingly important. This review presents a broad overview of the pathogenesis, diagnosis and therapy of inflammatory neuropathies, concentrating on the most commonly encountered conditions.

Subcutaneous versus intravenous immunoglobulin in multifocal motor neuropathy: a randomized, single-blinded cross-over trial

BACKGROUND AND PURPOSE

For treatment of multifocal motor neuropathy (MMN), we hypothesized that (i) infusion of equivalent dosages of subcutaneous immunoglobulin (SCIG) is as effective as intravenous immunoglobulin (IVIG) and that (ii) subcutaneous infusion at home is associated with a better quality of life.

METHODS

In a randomized single-blinded cross-over study, nine IVIG responsive patients were allocated to receive either SCIG or IVIG for a period equivalent to three IVIG treatment intervals and, subsequently, crossed over to the other treatment. Primary end-points were (i) dynamometric strength of affected muscles and (ii) the SF-36 quality of life questionnaire.

RESULTS

The two treatments were equally effective, the mean change in muscle strength after SCIG being 3.6% (95% CI -3.6% to 10.9%) vs. 4.3% (-1.3% to 10.0%) after IVIG (P = 0.86). One patient had sustained erythema and oedema at the injection sites for a few weeks. All other adverse effects during SCIG were mild and transient. No differences between treatments of health-related quality of life occurred.

CONCLUSION

In MMN, short-term subcutaneous infusion of immunoglobulin is feasible, safe and as effective as intravenous infusion. Subcutaneous administration is an alternative option that adds flexibility to the treatment schedule.