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ABSTRACT: In some anti-ganglioside antibody-mediated neuropathies, human and experimental data suggest a common pathogenic mechanism of dysfunction/disruption at the node of Ranvier resulting in a pathophysiologic continuum from transitory nerve conduction failure to axonal degeneration. The traditional classification of polyneuropathies into demyelinating or axonal may generate some confusion in the electrophysiological diagnosis of Guillain-Barré syndrome subtypes associated with anti-ganglioside antibodies. The axonal forms show, besides axonal degeneration, promptly reversible nerve conduction failure. This may be interpreted, by a single electrophysiological study, as demyelinating conduction block or distal axonal degeneration leading to errors in classification and in establishing prognosis. Moreover the term axonal may be misleading as it is commonly associated to axonal degeneration and not to a transitory, promptly reversible, dysfunction of the excitable axolemma. To focus on the site of nerve injury and overcome the classification difficulties, we propose the new category of nodo-paranodopathy which seems appropriate to various acute and chronic neuropathies associated with anti-ganglioside antibodies and we think better systematizes the neuropathies characterized by an autoimmune attack targeting the nodal region.
Clinical neurophysiology: official journal of the International Federation of Clinical Neurophysiology 04/2013; · 3.12 Impact Factor
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ABSTRACT: Natura non facit saltus (Latin for "nature does not make jumps"). This maxim expresses the idea that natural things and properties change gradually, in a continuum, rather than suddenly. In biomedical sciences, for taxonomic purposes, we make jumps that emphasize differences more than similarities. In dysimmune neuropathies 2 disorders characterized by the presence of antibodies to gangliosides GM1 and GD1a and a peculiar exclusive motor involvement: acute motor axonal neuropathy (AMAN) and multifocal motor neuropathy (MMN) have been identified. However anti-GM1 or -GD1a antibodies are also associated with acute motor and sensory axonal motor neuropathy (AMSAN). We review the results of recent clinical and experimental studies which indicating that AMAN and MMN are not exclusively motor. We discuss the possible explanations of the greater resistance of sensory fibers to antibody attack to finally suggest that AMAN, AMSAN, and MMN belong to a continuous spectrum with a common pathophysiological mechanism. © 2013 Wiley Periodicals, Inc.
Muscle & Nerve 04/2013; · 2.37 Impact Factor
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Clinical neurophysiology: official journal of the International Federation of Clinical Neurophysiology 09/2012; · 3.12 Impact Factor
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ABSTRACT: In thalamic lesions a pseudocortical syndrome has been occasionally described but the effect of the lesion on the cortical network of tactile recognition has never been studied. We report a patient who developed tactile agnosia in the left hand after right thalamic stroke, configuring a pseudocortical sensory syndrome. The discriminative sensory dysfunction was dissociate because only tactile agnosia and mild pseudoathetosis were present. A functional magnetic resonance imaging (fMRI) study showed that tactile recognition with the unaffected hand recruited a bilateral fronto-parietal network. During recognition with the left hand the activation was restricted and lateralized to the ipsilateral hemisphere. In this patient with pseudocortical discriminative sensory dysfunction the lack of activation of the whole cortical network, implicated in tactile recognition, demonstrates that pseudocortical is functionally equivalent to cortical tactile agnosia.
Cortex 08/2012; · 6.08 Impact Factor
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Clinical neurophysiology: official journal of the International Federation of Clinical Neurophysiology 06/2012; · 3.12 Impact Factor
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ABSTRACT: Despite the use of plasma exchanges and intravenous immunoglobulins, Guillain-Barré syndrome (GBS) still carries non-negligible morbidity and mortality. Furthermore, the psychosocial consequences of GBS may persist longer than expected. Various aetiological, clinical, electrophysiological and immunological factors may carry prognostic predictive value. The objective of this article was to perform a summary of the current knowledge-base on outcome and its determinants in adequately-treated adult-onset GBS. Relevant prospective literature was reviewed through a Medline search of English-language articles published between 1966 and March 2012. GBS causes severe persistent disability in 14% of patients at 1 year. Loss of full strength, persistent pain and need for professional change occurs in about 40%. Mortality is of about 4% within the first year. Analysis of prognostic predictors consistently demonstrates the negative impact of higher age, preceding diarrhoea, greater disability/weaker muscles at admission, short interval between symptom-onset and admission, mechanical ventilation and absent/low amplitude compound muscle action potentials. Further outcome studies will soon be underway and may in future contribute to adequately integrate all potential factors in more reliable predictive models.
Journal of neurology, neurosurgery, and psychiatry 05/2012; 83(7):711-8. · 4.87 Impact Factor
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ABSTRACT: Electrophysiology plays a determinant role in Guillain-Barré syndrome (GBS) diagnosis, classification of the subtypes and in establishing prognosis. In the last three decades, different electrodiagnostic criteria sets have been proposed for acute inflammatory demyelinating neuropathy (AIDP), acute motor axonal neuropathy (AMAN) and acute motor and sensory axonal neuropathy (AMSAN). Criteria sets for AIDP varied for the parameters indicative of demyelination considered, for the cut-off limits and the number of required abnormalities (all a priori established) showing different sensitivities. Criteria sets for AMAN and AMSAN were proposed on the initial assumption that these subtypes were pathologically characterised by simple axonal degeneration. However, some AMAN patients show transient conduction block/slowing in intermediate and distal nerve segments, mimicking demyelination but without the development of abnormal temporal dispersion, named reversible conduction failure (RCF). The lack of distinction between RCF and demyelinating conduction block leads to fallaciously classify AMAN patients with RCF as AIDP or AMAN with axonal degeneration. Serial electrophysiological studies are mandatory for proper diagnosis of GBS subtypes, identification of pathophysiological mechanisms and prognosis. More reliable electrodiagnostic criteria should be devised to distinguish axonal and demyelinating subtypes of GBS, taking into consideration the RCF pattern and focussing on temporal dispersion.
Clinical neurophysiology: official journal of the International Federation of Clinical Neurophysiology 04/2012; 123(8):1487-95. · 3.12 Impact Factor
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ABSTRACT: The possibility that some patients diagnosed with an acute sensory neuropathy could actually have Guillain-Barré syndrome (GBS) has been repeatedly advanced in the literature, but the number of cases reported is small. The reports have shown different clinical presentations and electrophysiological findings and are variously named, thus generating terminological and nosological confusion. We operatively defined sensory GBS as an acute, monophasic, widespread neuropathy characterized clinically by exclusive sensory symptoms and signs that reach their nadir in a maximum of 6 weeks without related systemic disorders and other diseases or conditions. We reviewed the literature through searches of PubMed from 1980 to March 2011 and our own files. On the basis of the size of fibers involved and the possible site of primary damage, we propose tentatively classifying sensory GBS and related disorders into three subtypes: acute sensory demyelinating polyneuropathy; acute sensory large-fiber axonopathy-ganglionopathy; and acute sensory small-fiber neuropathy-ganglionopathy.
Muscle & Nerve 04/2012; 45(4):464-70. · 2.37 Impact Factor
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Yukari Sekiguchi, Antonino Uncini,
Nobuhiro Yuki,
Sonoko Misawa,
Francesca Notturno,
Saiko Nasu,
Kazuaki Kanai,
Yu-ichi Noto,
Yumi Fujimaki,
Kazumoto Shibuya,
Shigeki Ohmori,
Yasunori Sato,
Satoshi Kuwabara
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ABSTRACT: Whether or not antiganglioside antibodies are related to axonal or demyelinating Guillain-Barré syndrome (GBS) is still a matter of controversy, as detailed in previous studies conducted in Western and Asian countries.
To clarify whether antiganglioside antibodies are associated with axonal dysfunction in Japanese and Italian GBS patient cohorts.
Clinical and electrophysiological profiles were reviewed for 156 GBS patients collected from Japan (n=103) and Italy (n=53). Serum IgG antibodies against GM1, GM1b, GD1a and GalNAc-GD1a were measured by ELISA in the same laboratory. Electrodiagnostic criteria and results of serial electrophysiological studies were used for classification of GBS subtypes: acute inflammatory demyelinating polyneuropathy (AIDP) and acute motor axonal neuropathy (AMAN).
In both Japanese and Italian cohorts, any of the antibodies were positive in 36% of the patients, and antibody positivity had a significant association with the AMAN electrodiagnosis. Approximately 30% of Japanese and Italian antiganglioside positive patients showed the AIDP pattern at the first examination whereas sequential studies showed that most finally showed the AMAN pattern. Clinically, seropositive patients more frequently had preceding diarrhoea and pure motor neuropathy in both Japanese and Italian cohorts; vibratory sensation was normal in 97% of Japanese and in 94% of Italian seropositive patients.
In GBS, clinical and electrophysiological features appear to be determined by antiganglioside antibodies, and the antibodies are associated with motor axonal GBS in both Japan and Italy. Classification of the GBS subtypes as a disease entity should be made, combining the results of antiganglioside assays and serial electrodiagnostic studies.
Journal of neurology, neurosurgery, and psychiatry 01/2012; 83(1):23-8. · 4.87 Impact Factor
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ABSTRACT: Areflexia is part one of the clinical criteria required to make a diagnosis of Guillain-Barré syndrome (GBS). The diagnostic criteria were stringently developed to exclude non-GBS cases but there have been reports of patients with GBS following Campylobacter jejuni enteritis with normal and exaggerated deep tendon reflexes (DTRs). The aim of this study is to expand the existing diagnostic criteria to preserved DTRs. From the cohort of patients referred for anti-ganglioside antibody testing from hospitals throughout Japan, 48 GBS patients presented with preserved DTR at admission. Thirty-two patients had normal or exaggerated DTR throughout the course of illness whereas in 16 patients the DTR became absent or diminished during the course of the illness. IgG antibodies against GM1, GM1b, GD1a, or GalNAc-GD1a were frequently present in either group (84 vs. 94%), suggesting a close relationship between the two groups. We then investigated the clinical and laboratory findings of 213 GBS patients from three hospital cohorts. In 23 patients, eight presented with normal tendon reflexes throughout the clinical course of the illness. Twelve showed hyperreflexia, with at least one of the jerks experienced even at nadir, and exaggerated reflexes returning to normal at recovery. The other three had hyperreflexia throughout the disease course. Compared to 190 GBS patients with reduced or absent DTR, the 23 DTR-preserved patients more frequently presented with pure motor limb weakness (87 vs. 47%, p = 0.00026), could walk 5 m independently at the nadir (70 vs. 33%, p = 0.0012), more frequently had antibodies against GM1, GM1b, GD1a, or GalNAc-GD1a (74 vs. 47%, p = 0.014) and were more commonly diagnosed with acute motor axonal neuropathy (65 vs. 34%, p = 0.0075) than with acute inflammatory demyelinating polyneuropathy (13 vs. 43%, p = 0.0011). This study demonstrated that DTRs could be normal or hyperexcitable during the entire clinical course in approximately 10% of GBS patients. This possibility should be added in the diagnostic criteria for GBS to avoid delays in diagnosis and effective treatment to these patients.
Journal of Neurology 12/2011; 259(6):1181-90. · 3.47 Impact Factor
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ABSTRACT: Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) affects various components and segments of the peripheral nervous system differently, and thus there can be phenotypic heterogeneity. We report a 47-year-old woman with chronic sensory disturbances and proximal weakness limited to the legs. Motor and sensory nerve conduction studies were normal. Somatosensory evoked potentials and imaging indicated a demyelinating process involving the lumbosacral roots. The patient responded favorably to IVIg. Although she did not fulfill the diagnostic criteria for CIDP we believe this patient represents a restricted regional CIDP variant.
Muscle & Nerve 11/2011; 44(5):833-7. · 2.37 Impact Factor
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ABSTRACT: In the quest for susceptibility factors of inflammatory neuropathies, many genes implicated in the pathogenesis of autoimmune diseases have been investigated with negative or conflicting results. We studied, with a gene candidate approach, the CD1 system specialized in capturing and presenting glycolipids to antigen-specific T cells, and the SH2D2A gene encoding for a T-cell-specific adapter protein implicated in control of early T-cell activation. In Guillain-Barré syndrome, an initially positive association study with polymorphism of CD1A and CD1E genes was not confirmed. In chronic inflammatory demyelinating polyneuropathy, we did not find an association with CD1 genes, but we found an association with a homozygous genotype for a low repeat number of tandem GA in the SH2D2A gene. This genotype could result in defective control and elimination of autoreactive T cells. All the studies were performed on relatively small size populations. Confirmation in larger sized studies is required both for CD1 and SH2D2A genes. Considering the relative rarity of patients with inflammatory neuropathies, this can only be accomplished by international collaboration.
Journal of the Peripheral Nervous System 06/2011; 16 Suppl 1:48-51. · 2.80 Impact Factor
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Movement Disorders 04/2011; 26(8):1567-9. · 4.51 Impact Factor
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ABSTRACT: Acute motor axonal neuropathy (AMAN) and acute motor and sensory axonal neuropathy (AMSAN) are due to an antiganglioside antibody mediated attack, thought to be restricted to motor fibres in AMAN. Sensory symptoms and minor sensory conduction abnormalities, however, have been reported in some AMAN patients.
To verify whether sensory fibres are truly spared in AMAN and whether AMAN and AMSAN represent a continuum.
Serial conduction studies in 13 AMAN and three AMSAN patients were reviewed. To evaluate the variation in sensory nerve action potential (SNAP) amplitude in serial recordings, the least significant change in a test-retest study of 20 controls was calculated. Least significant change for median, ulnar and sural nerves were 44%, 47% and 58%, respectively.
In 34% of initially normal sensory nerves of six AMAN patients, SNAP amplitude significantly increased by 57-518%. In three nerves of three AMAN patients, SNAP significantly decreased by 50-69%. Overall, serial recordings allowed detection of sensory fibre involvement in 49% of nerves and in 69% of AMAN patients. In one AMSAN patient, SNAP increased in two nerves by 150-300%; in another patient, SNAPs, unrecordable at baseline in six nerves, reappeared during follow-up and normalised in three nerves. In five nerves of three AMAN and in eight nerves of two AMSAN patients, SNAP amplitudes increased rapidly, suggesting reversible conduction failure of sensory fibres. In other nerves, SNAP increased over months, as for axonal regeneration.
Sensory fibres are often involved subclinically in AMAN. Reversible conduction failure may develop in sensory as well as motor fibres in both AMAN and AMSAN. AMAN and AMSAN represent a continuum in axonal GBS.
Journal of neurology, neurosurgery, and psychiatry 03/2011; 82(6):664-70. · 4.87 Impact Factor
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ABSTRACT: We report 2 patients diagnosed simultaneously with an overlap of Guillain-Barré syndrome (GBS) and Miller Fisher syndrome (MFS), who had anti-GT1a, anti-GQ1b, anti-GD1a and anti-GD1b antibodies. There was no identifiable specific preceding infection. Both patients presented with upper and lower limb paresthesias and severe weakness, bulbar and facial weakness, ophthalmoparesis and areflexia. In one, electrophysiology demonstrated multifocal conduction blocks (CBs) and mild motor conduction velocity slowing in intermediate segments and absent sensory nerve action potentials (SNAPs). The patient improved rapidly and fully recovered within 18 days from onset. CBs resolved, distal compound muscle action potential (CMAP) amplitudes increased and SNAPs normalized on subsequent testing. In the other patient, initial studies showed low/normal CMAPs, with absent SNAPs, without demyelinating features. This patient fully recovered within 21 days from onset. CMAPs markedly increased, SNAPs improved marginally. These 2 patients exhibited features indicative of the pathophysiological mechanism of conduction failure in motor and sensory fibers. This phenomenon relates to rapidly resolving CBs possibly induced by the transitory and limited attack of antiganglioside antibodies at the axolemma of the nodes of Ranvier not progressing to axonal degeneration. These cases widen the range of GBS subtypes in which reversible conduction failure has been described, to include overlap syndromes with MFS. The factors determining the electrophysiology, as well as the rate, degree and quality of recovery in GBS subtypes remain uncertain at the present time.
Journal of the neurological sciences 02/2011; 303(1-2):35-8. · 2.32 Impact Factor
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ABSTRACT: Guillain-Barré syndrome is divided into two major subtypes, acute inflammatory demyelinating polyneuropathy and acute motor axonal neuropathy. The characteristic electrophysiological features of acute motor axonal neuropathy are reduced amplitude or absence of distal compound muscle action potentials indicating axonal degeneration. In contrast, autopsy study results show early nodal changes in acute motor axonal neuropathy that may produce motor nerve conduction block. Because the presence of conduction block in acute motor axonal neuropathy has yet to be fully recognized, we reviewed how often conduction block occurred and how frequently it either reversed or was followed by axonal degeneration. Based on Ho's criteria, acute motor axonal neuropathy was electrodiagnosed in 18 patients, and repeated motor nerve conduction studies were carried out on their median and ulnar nerves. Forearm segments of these nerves and the across-elbow segments of the ulnar nerve were examined to evaluate conduction block based on the consensus criteria of the American Association of Electrodiagnostic Medicine. Twelve (67%) of the 18 patients with acute motor axonal neuropathy had definite (n=7) or probable (n=5) conduction blocks. Definite conduction block was detected for one patient (6%) in the forearm segments of both nerves and probable conduction block was detected for five patients (28%). Definite conduction block was present across the elbow segment of the ulnar nerve in seven patients (39%) and probable conduction block in two patients (11%). Conduction block was reversible in seven of 12 patients and was followed by axonal degeneration in six. All conduction blocks had disappeared or begun to resolve within three weeks with no electrophysiological evidence of remyelination. One patient showed both reversible conduction block and conduction block followed by axonal degeneration. Clinical features and anti-ganglioside antibody profiles were similar in the patients with (n=12) and without (n=6) conduction block as well as in those with (n=7) and without (n=5) reversible conduction block, indicating that both conditions form a continuum; a pathophysiological spectrum ranging from reversible conduction failure to axonal degeneration, possibly mediated by antibody attack on gangliosides at the axolemma of the nodes of Ranvier, indicating that reversible conduction block and conduction block followed by axonal degeneration and axonal degeneration without conduction block constitute continuous electrophysiological conditions in acute motor axonal neuropathy.
Brain 10/2010; 133(10):2897-908. · 9.46 Impact Factor
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ABSTRACT: To electrophysiologically classify an Italian Guillain-Barré syndrome (GBS) population into demyelinating and axonal subtypes, to investigate how serial recordings changed the classification and to underline the pitfalls in electrodiagnosis of GBS subtypes.
The authors applied two current electrodiagnostic criteria sets for demyelinating and axonal GBS subtypes in 55 patients who had at least two serial recordings in three motor and sensory nerves.
At first test, the electrodiagnosis was almost identical with both criteria: 65-67% of patients were classifiable as acute inflammatory demyelinating polyradiculoneuropathy (AIDP), 18% were classifiable as axonal GBS, and 14-16% were equivocal. At follow-up, 24% of patients changed classification: AIDP decreased to 58%, axonal GBS increased to 38%, and equivocal patients decreased to 4%. The majority of shifts were from AIDP and equivocal groups to axonal GBS, and the main reason was the recognition by serial recordings of the reversible conduction failure and of the length-dependent compound muscle action potential amplitude reduction patterns as expression of axonal pathology.
Axonal GBS is pathophysiologically characterised not only by axonal degeneration but also by reversible conduction failure at the axolemma of the Ranvier node. The lack of distinction among demyelinating conduction block, reversible conduction failure and length-dependent compound muscle action potential amplitude reduction may fallaciously classify patients with axonal GBS as having AIDP. Serial electrophysiological studies are mandatory for proper diagnosis of GBS subtypes and the identification of pathophysiological mechanisms of muscle weakness. More reliable electrodiagnostic criteria taking into consideration the reversible conduction failure pattern should be devised.
Journal of neurology, neurosurgery, and psychiatry 10/2010; 81(10):1157-63. · 4.87 Impact Factor
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ABSTRACT: In two patients with the pharyngeal-cervical-brachial variant (PCB) of Guillain-Barré syndrome (GBS), low amplitude distal compound muscle action potentials and partial motor conduction blocks normalized without development of excessive temporal dispersion within 4 weeks. Sensory nerve action potentials significantly improved in amplitude or, when absent, rapidly became recordable at follow-up. Besides axonal degeneration, PCB is characterized by reversible conduction failure in both motor and sensory fibers and is in the continuous spectrum of axonal GBS subtypes.
Muscle & Nerve 10/2010; 42(4):608-12. · 2.37 Impact Factor
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ABSTRACT: It has been difficult to replicate consistently the experimental model of axonal Guillain-Barré syndrome (GBS). We immunized rabbits with two lipo-oligosaccharides (LOS1 and LOS2) derived from the same C. jejuni strain and purified in a slightly different way. LOS1 did not contain proteins whereas several proteins were present in LOS2. In spite of a robust anti-GM1 antibody response in all animals the neuropathy developed only in rabbits immunized with LOS1. To explain this discrepancy we investigated fine specificity, affinity and ability to activate the complement of anti-GM1 antibodies. Only rabbits immunized with LOS1 showed monospecific high-affinity antibodies which activated more effectively the complement. Although it is not well understood how monospecific high-affinity antibodies are induced these are crucial for the induction of experimental axonal neuropathy. Only a strict adherence to the protocols demonstrated to be successful may guarantee the reproducibility and increase the confidence in the animal model as a reliable tool for the study of the human axonal GBS.
Journal of the neurological sciences 04/2010; 293(1-2):76-81. · 2.32 Impact Factor
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Muscle & Nerve 02/2010; 41(2):283-5; author reply 285. · 2.37 Impact Factor
