Multifocal motor neuropathy

Intravenous Immunoglobulin Treatment in Autoimmune Neurological Disorders—Effects on Quality of Life

Autoimmune neurological disorders are very common. Health-related quality-of-life measures, obtained through a patient-oriented tool (a self-administered questionnaire), are now considered essential in the evaluation of therapies, especially for pathologies that may affect patients' general status. We reviewed the most common autoimmune neurological disorders and their treatment, and we report on our experience on intravenous immunoglobulin (IVIG) administration and the relationship between IVIG and health-related quality of life. Generally, IVIG administration is effective in the most common autoimmune neurological diseases. Concerning the relationship between IVIG treatment and health-related quality of life, our results reveal an improvement of physical aspects of patients' health-related quality of life after IVIG administration. Conversely, the comparison of mental scores between the evaluation at baseline and the evaluation at follow-up exhibited no difference. Although the use of IVIG is effective for autoimmune neurological disorders, there are no commonly accepted protocols for the use of IVIG treatment. Further controlled studies on IVIG, including quality-of-life assessments, are necessary to develop needed evidence on the use of IVIG in clinical practice.

Antiglycolipid antibodies in Guillain-Barré syndrome and related diseases: Review of clinical features and antibody specificities

Guillain-Barré syndrome (GBS) is an acute inflammatory polyradiculoneuropathy that usually develops following a respiratory or intestinal infection. Although the pathogenic mechanisms of GBS have not been fully established, both humoral and cell-mediated immune factors have been shown to contribute to the disease process. Several antiglycosphingolipid (anti-GSL) antibodies have been found in the sera of patients with GBS or related diseases. Measurements of these antibody titers are very important in the diagnosis of GBS and in evaluating the effectiveness of treatments in clinical trials. The most common treatment strategies for these disorders involve plasmapheresis and the use of steroids for reducing anti-GSL antibody titers to ameliorate patients' clinical symptoms. Administration of intravenous immunoglobulin may also be beneficial in the treatment of neuropathies by suppressing the immune-mediated processes that are directed against antigenic targets in myelin and axons. In certain demyelinating neuropathies, the destruction or malfunctioning of the blood-nerve barrier, which results in the leakage of circulating antibodies into the peripheral nerve parenchyma, has been considered to be an initial step in development of the disease process. In addition, anti-GSL antibodies, such as anti-GM1, may cause nerve dysfunction and injury by interfering with the ion channel function at the nodes of Ranvier, where carbohydrate epitopes of glycoconjugates are located. These malfunctions thus contribute to the pathogenic mechanisms of certain demyelinating neuropathies.

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.

Cytotoxic drugs and interferons for chronic inflammatory demyelinating polyradiculoneuropathy

BACKGROUND

Chronic inflammatory demyelinating polyradiculoneuropathy is a disease causing progressive or relapsing and remitting weakness and numbness. It is probably due to an autoimmune inflammatory process. Immunosuppressive or immunomodulatory drugs would be expected to be beneficial.

OBJECTIVES

We aimed to review systematically the evidence from randomised trials concerning cytotoxic drugs and interferons for chronic inflammatory demyelinating polyradiculoneuropathy.

SEARCH STRATEGY

We searched the Cochrane Neuromuscular Disease Group trials register (searched May 2004), MEDLINE (searched January 1977 to May 2004), EMBASE (January 1980 to May 2004), CINAHL (searched January 1982 to December 2001) and LILACS (searched January 1982 to December 2001). We contacted the authors of the trials identified and other disease experts seeking other published and unpublished trials.

SELECTION CRITERIA

We sought randomised and quasi-randomised trials of all immunosuppressive agents such as azathioprine, cyclophosphamide, methotrexate, cyclosporin A, mycophenolate mofetil, and rituximab and all immunomodulatory agents such as alpha interferon and beta interferon in participants fulfilling standard diagnostic criteria for chronic inflammatory demyelinating polyradiculoneuropathy.

DATA COLLECTION AND ANALYSIS

Two of us independently selected the trials which met our criteria, judged their methodological quality and extracted the data onto specially designed forms. We wanted to measure the change in disability after one year as our primary outcome measure.

MAIN RESULTS

We found one parallel group open trial of azathioprine for nine months involving 27 participants and another of interferon beta involving 10 participants in a double blind crossover trial with each treatment period lasting 12 weeks. Neither trial provided our primary outcome measure and neither showed a significant beneficial effect on any of the outcome measures selected by the authors or ourselves in the protocol for this review.

REVIEWERS' CONCLUSIONS

The evidence is inadequate to decide whether azathioprine, interferon beta or any other immunosuppressive drug or interferon is beneficial in chronic inflammatory demyelinating polyradiculoneuropathy.

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.

Pure motor mononeuropathy with distal conduction block: an unusual presentation of multifocal motor neuropathy with conduction blocks

OBJECTIVE

To report an hitherto undescribed presentation of Motor Neuropathy with Multifocal Conduction Block (MMNCB).

METHODS

Description of two patients presenting with complete paralysis of the 3 heads of the trapezius muscle (case one) and progressive weakness of finger extension (case 2).

RESULTS

Nerve conduction studies (NCS) established that the corresponding nerves were distally inexcitable. In the affected muscles, no voluntary activity was elicited in both patients with spontaneous activity noted in patient 2. Systematic NCSs documented an asymptomatic, partial conduction block (CB) in a median nerve forearm segment in both patients. Neurophysiological follow-up after a dramatic response to intravenous immunoglobulins demonstrated recovery of the initially unobtainable motor responses.

CONCLUSIONS

This indicates that a complete, distal CB of the motor fibers destined to the trapezius muscle in patient 1, and to the extensor indicis proprius in patient 2, had caused the heralding deficits.

SIGNIFICANCE

These findings underscore the possibility of distal CB in this disorder and the need for extensive NCSs, including asymptomatic nerves, for an accurate diagnosis.

Multifocal motor neuropathy presenting as chronic progressive proximal leg weakness

We report on a 47-year-old man with a 12-year history of progressive and ultimately severe proximal weakness of his right lower limb. Motor conduction block at the unaffected tibial nerve and positive IgM antibodies against GM1 gangliosides lead us to suggest a diagnosis of oligosymptomatic multifocal motor neuropathy. He rapidly responded to intravenous immunoglobulins, with complete remission lasting 4 weeks, and had a repeated treatment response to intravenous immunoglobulins during subsequent exacerbations. The proximal involvement may represent another unusual clinical manifestation of multifocal motor neuropathy.

Multifocal motor neuropathy: pathologic alterations at the site of conduction block

The pathologic changes of nerves in multifocal motor neuropathy (MMN), a rare neuropathy with selective focal conduction block of motor fibers in mixed nerves, remain essentially unstudied. Fascicular nerve biopsy of 8 forearm or arm nerves in 7 patients with typical MMN was undertaken for diagnostic reasons at the site of the conduction block. Abnormalities were seen in 7 of 8 nerves, including a varying degree of multifocal fiber degeneration and loss, an altered fiber size distribution with fewer large fibers, an increased frequency of remyelinated fiber profiles, and frequent and prominent regenerating fiber clusters. Small epineurial perivascular inflammatory infiltrates were observed in 2 nerves. We did not observe overt segmental demyelination or onion bulb formation. We hypothesize that an antibody-mediated attack directed against components of axolemma at nodes of Ranvier could cause conduction block, transitory paranodal demyelination and remyelination, and axonal degeneration and regeneration. Alternatively, the antibody attack could be directed at components of paranodal myelin. We favor the first hypothesis because in nerves studied by us, axonal pathological alteration predominated over myelin pathology. Irrespective of which mechanism is involved, we conclude that the unequivocal multifocal fiber degeneration and loss and regenerative clusters at sites of conduction block explains the observed clinical muscle weakness and atrophy and alterations of motor unit potentials. The occurrence of conduction block and multifocal fiber degeneration and regeneration at the same sites suggests that the processes of conduction block and fiber degeneration and regeneration are linked. Finding discrete multifocal fiber degeneration may also provide an explanation for why the functional abnormalities remain unchanged over long periods of time at discrete proximal to distal levels of nerve and may emphasize a need for early intervention (assuming that efficacious treatment is available).

Acquisitions récentes dans le traitement des polyneuropathies dysimmunitaires chroniques

Chronic immune-mediated polyneuropathies encompass chronic inflammatory demyelinating polyneuropathies, polyneuropathies associated with monoclonal gammopathy and multifocal motor neuropathy with persistent conduction blocks. Their diagnosis is made on clinical, electrophysiological and sometimes immunochemical and pathological criteria. The efficacy of intravenous immunoglobulins has been reported in the short-term treatment of these neuropathies in the same way than corticosteroids and plasma exchanges, depending on the type of the polyneuropathy. The efficacy of long-term treatments needs further evaluation.

Plasma exchange for chronic inflammatory demyelinating polyradiculoneuropathy

BACKGROUND

Chronic inflammatory demyelinating polyradiculoneuropathy is an uncommon progressive or relapsing paralysing disease caused by inflammation of the peripheral nerves. If the hypothesis that it is due to autoimmunity is correct, removal of autoantibodies in the blood by plasma exchange should be beneficial.

OBJECTIVES

To evaluate the efficacy of plasma exchange in chronic inflammatory demyelinating polyradiculoneuropathy.

SEARCH STRATEGY

We searched the Neuromuscular Disease Group Register (December 2003), and MEDLINE (January 1966 to January 2003), EMBASE (January 1980 to January 2003), CINAHL (January 1982 to December 2002) and LILACS (January 1982 to January 2003). We also scrutinised the bibliographies of the trials, and contacted the trial authors and other disease experts.

SELECTION CRITERIA

Randomised or quasi-randomised controlled trials in participants of any age comparing plasma exchange with sham treatment or no treatment. A trial showing no significant difference in the benefit from plasma exchange with intravenous immunoglobulin has been included in a separate Cochrane review.

DATA COLLECTION AND ANALYSIS

Two authors selected the trials, extracted the data and assessed methodological quality independently. Where possible data were combined according to the methods of the Cochrane Neuromuscular Disease Review Group.

PRIMARY OUTCOME MEASURE

one crossover trial including 18 participants showed 2 (95% confidence interval (CI) 0.8 to 3.0) points more improvement after four weeks in an 11-point disability scale with plasma exchange (10 exchanges over four weeks) than with sham exchange. Rapid deterioration after plasma exchange occurred in eight of 12 who had improved.

SECONDARY OUTCOME MEASURES

when the results of this trial and another with 29 participants treated in a parallel group design trial were combined, there were 31 points (95% CI 16 to 45) more improvement in an impairment scale after plasma exchange (six exchanges over three weeks) than after sham exchange. There were significant improvements in both trials in an electrophysiological measure, the proximally evoked compound muscle action potential, after three or four weeks. Non-randomised evidence indicates that plasma exchange induces adverse events in 3% to 17% of procedures. These are sometimes serious.

REVIEWERS' CONCLUSIONS

Evidence from two small trials showed that plasma exchange provides significant short-term benefit in about two-thirds of patients with chronic inflammatory demyelinating polyradiculoneuropathy but rapid deterioration may occur afterwards. Adverse events related to difficulty with venous access, use of citrate and haemodynamic changes are not uncommon. More research is needed to identify agents which will prolong the beneficial action of plasma exchange.

Advances in understanding and treatment of immune-mediated disorders of the peripheral nervous system

During recent years, novel insights in basic immunology and advances in biotechnology have contributed to an increased understanding of the pathogenetic mechanisms of immune-mediated disorders of the peripheral nervous system. This increased knowledge has an impact on the management of patients with this class of disorders. Current advances are outlined and their implication for therapeutic approaches addressed. As a prototypic immune-mediated neuropathy, special emphasis is placed on the pathogenesis and treatment of the Guillain-Barré syndrome and its variants. Moreover, neuropathies of the chronic inflammatory demyelinating, multifocal motor, and nonsystemic vasculitic types are discussed. This review summarizes recent progress with currently available therapies and--on the basis of present immunopathogenetic concepts--outlines future treatment strategies.

Surface electromyographic recording of volitional activity: a technique to detect partial motor conduction block

Partial motor conduction block, an electrophysiological hallmark of demyelination, helps to identify acquired demyelinating neuropathies but its electrophysiological detection can be difficult. We report a technique that may be helpful in this regard. Twenty-five patients with partial motor conduction block secondary to acquired demyelinating polyneuropathy (ADP), 7 with amyotrophic lateral sclerosis (ALS), 7 with stroke, and 11 control subjects, were studied. Amplitude of compound muscle action potentials was recorded after distal electrical (E) stimulation and for volitionally (V) induced responses in 82 muscles. Mean +/- SD V/E ratio was 12.3 +/- 6.6 for ADP patients, 58.1 +/- 17 for ALS patients, 11.4 +/- 9 for stroke patients, and 55.4 +/- 12.3 for controls. The V/E ratios for patients with partial motor conduction block and stroke were significantly reduced compared with ALS patients and healthy controls (P < 0.05). Surface electromyographic (EMG) recording for determination of the V/E ratio may be a useful technique for detection of a proximal conduction block if a central lesion or poor effort can be excluded. Further study of this novel technique is necessary.

Peripheral neuropathies in clinical practice

Based on the history and physical examination, it is often possible to arrive at a relatively specific diagnosis of peripheral neuropathy. The clinical history and examination are often sufficient to create a more focused and appropriate laboratory evaluation, counseling for the patient as to long-term prognosis, and options for clinical management.

Management of chronic inflammatory demyelinating polyradiculoneuropathy

This review briefly describes current concepts concerning the nosological status, pathogenesis and management of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). CIDP is an uncommon variable disorder of unknown but probably autoimmune aetiology. The commonest form of CIDP causes more or less symmetrical progressive or relapsing weakness affecting proximal and distal muscles. Against this background the review describes the short-term responses to corticosteroids, intravenous immunoglobulin (IVIg) and plasma exchange that have been confirmed in randomised trials. In the absence of better evidence about long-term efficacy, corticosteroids or IVIg are usually favoured because of convenience. Benefit following introduction of azathioprine, cyclophosphamide, cyclosporin, other immunosuppressive agents, and interferon-beta and -alpha has been reported but randomised trials are needed to confirm these benefits. In patients with pure motor CIDP and multifocal motor neuropathy, corticosteroids may cause worsening and IVIg is more likely to be effective. General measures to rehabilitate patients and manage symptoms, including foot drop, weak hands, fatigue and pain, are important.

Plasmapheresis in immunologically mediated polyneuropathies

One of the most common uses of therapeutic plasmapheresis is for the treatment of immunologically mediated polyneuropathies. This paper discusses the use of plasmapheresis in Guillain-Barré syndrome, chronic inflammatory demyelinating polyneuropathy, polyneuropathies associated with paraproteins, lower motor neuron syndromes, and polyneuropathies associated with HIV. As the pathogenesis of immunologically mediated polyneuropathies becomes better understood, newer therapies for these syndromes will evolve: however, therapeutic plasmapheresis is likely to continue to play a central role in the treatment of many of these diseases.

Treatment of IgM antibody associated polyneuropathies using rituximab

OBJECTIVES

Polyneuropathies with associated serum IgM antibodies are often difficult to treat. Rituximab is a monoclonal antibody directed against the B cell surface membrane marker CD20. Rituximab eliminates B cells from the circulation, and, over time, could reduce cells producing autoantibodies. This study tested the ability of rituximab to produce changes in serum antibody titres, and improvement in strength, in patients with neuromuscular disorders and IgM autoantibodies.

METHODS

Over a period of two years, the authors evaluated changes in strength, measured by quantitative dynamometry, and concentrations of several types of serum antibodies in patients with polyneuropathies and serum IgM autoantibodies. Twenty one patients treated with rituximab were compared with 13 untreated controls.

RESULTS

Treatment with rituximab was followed by improved strength (an increase of mean (SEM) 23% (2%)of normal levels of strength), a reduction in serum IgM autoantibodies (to 43% (4%) of initial values), and a reduction in total levels of IgM (to 55% (4%) of initial values). There was no change in levels of serum IgG antibodies. There were no major side effects, even though B cells were virtually eliminated from the circulation for periods up to two years.

CONCLUSIONS

In patients with IgM autoantibody associated peripheral neuropathies, rituximab treatment is followed by reduced serum concentrations of IgM, but not IgG, antibodies, and by improvement in strength. Additional studies, with placebo controls and blinded outcome measures, are warranted to further test the efficacy of rituximab treatment of IgM associated polyneuropathies.

Demyelination and axonal loss in multifocal motor neuropathy: distribution and relation to weakness

Multifocal motor neuropathy (MMN) is characterized by a slowly progressive, asymmetric weakness of the limbs without sensory loss. The arms are usually affected to a greater extent than the legs, and distal muscles more than proximal muscles. The distribution of electrophysiological abnormalities and its correlation with weak muscle groups in MMN have not been investigated systematically. The aim of the present study was to assess whether electrophysiological abnormalities have a preferential or random distribution, whether electrophysiological abnormalities in a nerve correlate with weakness in the innervated muscles, and whether these results are relevant for the development of optimal electrodiagnostic protocols. We compared the pattern of weakness and electrophysiological abnormalities in 39 patients with a lower motoneuron syndrome and a positive response to intravenous immunoglobulins. All patients underwent an extensive standardized electrophysiological examination. Electrophysiological evidence of demyelination was found more often in the nerves of the arms and was distributed randomly over lower arm, upper arm and shoulder segments. Electrophysiological evidence of axonal loss presented more frequently in longer nerves, occurring most often in the leg nerves. For the arm nerves, it is possible that the length dependence of axonal loss is due to the random distribution of demyelinating lesions that lead to axonal degeneration. Weakness was associated with features of demyelination and axonal loss in the nerves of the arm, and with features of axonal loss in leg nerves. However, a substantial number (approximately one-third) of electrophysiological abnormalities were found in nerves innervating non-weakened muscles. These results imply that in MMN, conduction block is most likely to be found in long arm nerves innervating weakened muscles, but if conduction block cannot be detected in these nerves, the electrophysiological examination should be extended to other arm nerves including those innervating non-weakened muscles.

Cytotoxic drugs and interferons for chronic inflammatory demyelinating polyradiculoneuropathy

BACKGROUND

Chronic inflammatory demyelinating polyradiculoneuropathy is a disease causing progressive or relapsing and remitting weakness and numbness. It is probably due to an autoimmune inflammatory process. Immunosuppressive or immunomodulatory drugs would be expected to be beneficial.

OBJECTIVES

We aimed to review systematically the evidence from randomised trials concerning cytotoxic drugs and interferons for chronic inflammatory demyelinating polyradiculoneuropathy.

SEARCH STRATEGY

We searched the Cochrane Neuromuscular Disease Group trials register (searched December 2001), MEDLINE (searched January 1977 to December 2001), EMBASE (January 1980 to December 2001), CINAHL (searched January 1982 to December 2001) and LILACS (searched January 1982 to December 2001). We contacted the authors of the trials identified and other disease experts seeking other published and unpublished trials.

SELECTION CRITERIA

We sought randomised and quasi-randomised trials of all immunosuppressive agents such as azathioprine, cyclophosphamide, methotrexate, cyclosporin A, mycophenolate mofetil, and rituximab and all immunomodulatory agents such as alpha interferon and beta interferon in participants fulfilling standard diagnostic criteria for chronic inflammatory demyelinating polyradiculoneuropathy.

DATA COLLECTION AND ANALYSIS

Two of us independently selected the trials which met our criteria, judged their methodological quality and extracted the data onto specially designed forms. We wanted to measure the change in disability after one year as our primary outcome measure.

MAIN RESULTS

We found one parallel group open trial of azathioprine for nine months involving 27 participants and another of interferon beta involving 10 participants in a double blind crossover trial with each treatment period lasting 12 weeks. Neither trial provided our primary outcome measure and neither showed a significant beneficial effect on any of the outcome measures selected by the authors or ourselves in the protocol for this review.

REVIEWER'S CONCLUSIONS

The evidence is inadequate to decide whether azathioprine, interferon beta or any other immunosuppressive drug or interferon is beneficial in chronic inflammatory demyelinating polyradiculoneuropathy.

Anterior interosseous nerve and multifocal motor neuropathy

We report the case of a 47-year-old woman with a left anterior interosseous nerve palsy. Surgical release of the anterior interosseous nerve was initially proposed, but electrodiagnostic evaluation demonstrated that the neuropathy was due not to compression or to neuralgic amyotrophy but to a proximal conduction block. At that time, the conduction block could be defined only by indirect electrodiagnostic criteria. A multifocal motor neuropathy with persistent conduction block was subsequently diagnosed, and the patient was treated with intravenous immunoglobulins. The efficacy of this treatment and the subsequent disclosure of conduction block in the right posterior interosseous and peroneal nerves definitively confirmed the multifocal motor neuropathy.

Nerve conduction studies in selected peripheral nerve disorders

PURPOSE OF REVIEW

The physiological properties of nerve and muscle are influenced by pathological changes and the aim of this review is to discuss recent contributions of electrophysiological studies to the understanding and diagnosis of selected peripheral nerve disorders. The relationships between pathology and physiology emphasize the close interdependence between electrophysiological studies, clinical deficits and other laboratory information. Attention should be paid to the strengths and limitations of electrophysiological methods, considering their impact on diagnosis and treatment of patients.

RECENT FINDINGS

Several studies have shown particular pathophysiological profiles associated with different antibody subtypes in autoimmune peripheral neuropathies and this association further supports the suggestion of pathological specificity in both acute and chronic neuropathy. The sensitivity and specificity of physiological profiles therefore become increasingly important since some of these neuropathies are accessible to treatment. On the other hand, the pathophysiological and clinical profiles may be heterogeneous in patients with some disorders. This could be related to a more indistinct division between different types of pathology with increased understanding of pathogenetic mechanisms. Moreover, new insights into disturbed axonal function have stimulated attempts to develop methods to explore normal and diseased human nerve function.

SUMMARY

The exploration of axonal membrane and ion-channel function has become accessible using studies of excitability and are of potential value where conventional studies only provide nonspecific evidence of the number of fibers and the integrity of myelin. These studies will presumably become increasingly important in the years ahead considering the lack of understanding of the functional disturbances in axonal neuropathies.

Multifocal motor neuropathy and asymptomatic Hashimoto's thyroiditis: first report of an association

Motor neuropathy with multifocal conduction blocks represents a recently identified autoimmune disorder of the peripheral nerve myelin. Association of motor neuropathies or neuronopathies with thyroid disorders, such as hyperthyroidism, hypothyroidism or thyroid neoplasms has been rarely described. We studied a 61-year-old man with a 2-year-history of slowly progressive weakness of the left limbs with atrophy and fasciculations. Nerve conduction velocity studies revealed multifocal motor conduction blocks. Serum IgM titer of antibodies against GM1 was elevated (1:1280; n.v. up to 1:640). Thyroid studies were compatible with Hashimoto's thyroiditis. Therapy with high dose intravenous immunoglobulins was followed by a prompt clinical recovery. Then the disease assumed an intravenous immunoglobulins dependent course with a full clinical, but transient, recovery. This is the first observation of an association of multifocal motor neuropathy with high titers of GM1 and Hashimoto's thyroiditis and reinforces the multifocal motor neuropathy autoimmune origin as well as the repeated clinical recoveries after intravenous immunoglobulins. This case also suggests to deeply investigate the thyroid function in patients with multifocal motor neuropathy.

Multifocal motor neuropathy and Campylobacter jejuni reactivity

In some patients, Campylobacter jejuni infection has been associated with the development of multifocal motor neuropathy (MMN) and high titers of antiganglioside antibodies. The authors measured anti-C. jejuni antibodies by ELISA and immunoblot in 20 patients with MMN, and correlated their presence with antiganglioside reactivity and a history of recent diarrhea. Only one patient had high titers of anti-C. jejuni antibodies, indicating that C. jejuni is unlikely to be involved in the pathogenesis of MMN in most patients.

Multifocal motor neuropathy: clinical and immunological features and response to IVIg in relation to the presence and degree of motor conduction block

OBJECTIVE

To determine whether patients with clinically typical multifocal motor neuropathy (MMN) with or without definite or probable conduction block (CB) differ in terms of clinical presentation, immunological findings, or response to treatment with intravenous immunoglobulin (IVIg).

METHODS

23 consecutive patients were studied with the typical clinical features of MMN, consisting of a progressive multineuropathic motor impairment with minimal or no sensory loss. In 14 patients, electrophysiological studies disclosed the presence of a definite or probable CB according to the criteria proposed by the American Association of Electrodiagnostic Medicine (AAEM) in at least one motor nerve. Six patients had possible CB, defined as a degree of CB 10% less than that required by the AAEM for probable CB, while no CB was detected in three patients.

RESULTS

Patients with possible CB did not differ from those with a definite or probable CB in terms of age at disease onset (mean 38.8 v 38.2 years, respectively), distribution and severity of limb weakness, clinical impairment (mean Rankin score 2.2 in both), and frequency of antiganglioside antibodies (33% v 29%). Patients with possible CB had a longer mean disease duration (9 v 5.9 years, p < 0.05) and a less frequent consistent response to IVIg (67% v 86%) than those with a definite or probable CB. Patients without a detectable CB had a similar frequency of antiganglioside antibodies (33%) but had a longer disease duration (20.3 years), greater impairment (Rankin score 2.7), and more frequent signs of axonal degeneration (41% of examined motor nerves) than patients with CB (13-15%, p < 0.005). Only one patient without detectable CB (33%) consistently improved with IVIg.

CONCLUSIONS

Patients with possible CB were clinically and immunologically indistinguishable from those with definite or probable CB, albeit with a slightly less frequent response to IVIg. This finding suggests that failure to fulfil AAEM criteria for CB in patients with otherwise clinically typical MMN should not preclude this diagnosis and consequently a treatment trial with IVIg. Whether the longer duration and greater severity of the disease and more frequent axonal impairment in patients without detectable CB than in those with CB explain their lower response to IVIg remains to be established.

Sialosyl-galactose: a common denominator of Guillain-Barré and related disorders?

The immune reactivity implicated in the pathogenesis of Guillain-Barré syndrome (GBS) and related diseases, which occur following infection with specific strains of Campylobacter jejuni bearing sialylated lipopolysaccharide structures that cross-react with specific gangliosides, is consistent with provocation of inflammation via molecular mimicry. In this review, we have focused upon microbial characteristics and structures, the fine structure of the essential carbohydrate determinants, and the application of our proposed criteria, modified from those of Koch for causation of infectious and of Witebsky for autoimmune diseases, to the circumstance of infectious induction of autoimmune disorder.

Systematic reviews of treatment for inflammatory demyelinating neuropathy

This review describes the progress made in preparing Cochrane systematic reviews of randomized controlled trials for Guillain-Barré syndrome (GBS), chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), multifocal motor neuropathy (MMN) and the demyelinating neuropathies associated with paraproteins. The discovery of antibodies against myelin and axolemmal glycolipids and proteins has not yet replaced the clinicopathological classification on which treatment trials have been based. Systematic reviews have endorsed the equivalence of plasma exchange (PE) and intravenous immunoglobulin (IVIg) and the lack of efficacy of steroids in GBS. Systematic reviews have also endorsed the value of steroids, PE and IVIg in CIDP but randomized controlled trials have only shown benefit from IVIg in MMN. There is a paucity of evidence concerning the efficacy of treatments in paraproteinaemic demyelinating neuropathy apartment from small trials showing short-term benefit from PE or IVIg. There is a lack of good quality controlled trials of immunosuppressive agents in any of these conditions. As the number of treatment trials increases, Cochrane systematic reviews will be an increasingly valuable resource for summarizing the evidence from randomised controlled trials on which to base clinical practice. They already demonstrate major deficiencies in the existing evidence base.