Fine specificity of anti-GQ1b IgG and clinical features

Guillain-Barré syndrome with overlap between the finger drop variant and acute bulbar palsy: a case report

BACKGROUND

Guillain-Barré syndrome (GBS) is a clinically heterogenous disease and encompasses several distinct clinical variants. Overlap between these variants can pose a diagnostic challenge. We report a case of finger drop variant and acute bulbar palsy overlap as an unusual manifestation of GBS.

CASE PRESENTATION

An 81-year-old man presented with dysarthria, dysphagia, and upper limb weakness. Neurological examination revealed impaired tongue protrusion, the finger drop sign, and diminished brachioradial and triceps muscle reflexes. Nerve conduction studies showed reduced amplitudes and decreased velocities in the median and ulnar nerves. Cerebrospinal fluid analysis revealed albuminocytological dissociation and an anti-ganglioside antibody study revealed positivity for GM1, asialo-GM1, GT1a, GD1b, and GQ1b. As GBS was suspected, we initiated intravenous immunoglobulin treatment, resulting in gradual improvement within the next 3 weeks.

CONCLUSION

To the best of our knowledge, this is the first reported case of an overlap between the finger drop variant and acute bulbar palsy in GBS, highlighting the importance of considering GBS when patients present with a combination of atypical symptoms. Anti-ganglioside antibodies can be helpful and add diagnostic value in these complex cases.

The spectrum of anti-GQ1B antibody syndrome: beyond Miller Fisher syndrome and Bickerstaff brainstem encephalitis

INTRODUCTION

Since the initial identification of Miller Fisher syndrome (MFS) and Bickerstaff brainstem encephalitis (BBE),significant milestones have been achieved in understanding these diseases.Discoveries of common serum antibodies (IgG anti-GQ1b), antecedent infections, neurophysiological data, andneuroimaging suggested a shared autoimmune pathogenetic mechanism rather than distinct pathogenesis, leadingto the hypothesis that both diseases are part of a unified syndrome, termed "Fisher-Bickerstaff syndrome". The subsequent identification of atypical anti-GQ1b-positive forms expanded the classification to a broader condition known as "Anti-GQ1b-Antibody syndrome".

METHODS

An exhaustive literature review was conducted, analyzing a substantial body of research spanning from the initialdescriptions of the syndrome's components to recent developments in diagnostic classification and researchperspectives.

RESULTS

Anti-GQ1b syndrome encompasses a continuous spectrum of conditions defined by a common serological profilewith varying degrees of peripheral (PNS) and central nervous system (CNS) involvement. MFS and BBE represent theopposite ends of this spectrum, with MFS primarily affecting the PNS and BBE predominantly involving the CNS.Recently identified atypical forms, such as acute ophthalmoparesis, acute ataxic neuropathy withoutophthalmoparesis, Guillain-Barré syndrome (GBS) with ophthalmoparesis, MFS-GBS and BBE-GBS overlap syndromes,have broadened this spectrum.

CONCLUSION

This work aims to provide an extensive, detailed, and updated overview of all aspects of the anti-GQ1b syndromewith the intention of serving as a stepping stone for further shaping thereof. Special attention was given to therecently identified atypical forms, underscoring their significance in redefining the boundaries of the syndrome.

Expanding Clinical Spectrum of Anti-GQ1b Antibody Syndrome: A Review

Importance

The discovery of the anti-GQ1b antibody has expanded the nosology of classic Miller Fisher syndrome to include Bickerstaff brainstem encephalitis, Guillain-Barré syndrome with ophthalmoplegia, and acute ophthalmoplegia without ataxia, which have been brought under the umbrella term anti-GQ1b antibody syndrome. It seems timely to define the phenotypes of anti-GQ1b antibody syndrome for the proper diagnosis of this syndrome with diverse clinical presentations. This review summarizes these syndromes and introduces recently identified subtypes.

Observations

Although ophthalmoplegia is a hallmark of anti-GQ1b antibody syndrome, recent studies have identified this antibody in patients with acute vestibular syndrome, optic neuropathy with disc swelling, and acute sensory ataxic neuropathy of atypical presentation. Ophthalmoplegia associated with anti-GQ1b antibody positivity is complete in more than half of the patients but may be monocular or comitant. The prognosis is mostly favorable; however, approximately 14% of patients experience relapse.

Conclusions and Relevance

Anti-GQ1b antibody syndrome may present diverse neurological manifestations, including ophthalmoplegia, ataxia, areflexia, central or peripheral vestibulopathy, and optic neuropathy. Understanding the wide clinical spectrum may aid in the differentiation and management of immune-mediated neuropathies with multiple presentations.

A Case with Anti-ganglioside Antibodies Showing Multiple Cranial Nerve Palsies Detected on Gadolinium-enhanced Magnetic Resonance Imaging

The anti-GQ1b IgG antibody is often accompanied by other anti-ganglioside antibodies, which induces various neurological symptoms. We herein report a patient with anti-ganglioside antibodies, including anti-GQ1b IgG and anti-GT1a IgG antibodies, showing bilateral ophthalmoplegia, facial nerve palsies, dysarthria, dysphagia, dysesthesia in both hands, and enhancement of the bilateral oculomotor, abducens, and facial nerves on gadolinium (Gd)-enhanced T1-weighted brain magnetic resonance imaging (MRI). He was first treated with intravenous immunoglobulin, which improved ophthalmoplegia, bulbar palsies, and dysesthesia of hands, but the facial nerve palsies worsened, and Gd enhancement of the brain nerves persisted. High-dose methylprednisolone therapy subsequently improved the facial nerve palsies and Gd enhancement of the cranial nerves. This is the first case with anti-ganglioside antibodies presenting with multiple cranial nerve palsies that was followed to track the changes in the Gd enhancement of cranial nerves on MRI.

An Oculopharyngeal Subtype of Guillain-Barré Syndrome Sparing the Trochlear and Abducens Nerves

Guillain-Barré syndrome (GBS) comprises a group of polyneuropathies characterized by rapid progression of limb paralysis. Various subtypes of GBS have been reported. The oculopharyngeal subtype of GBS is currently understood to be primarily a cranial polyneuropathy without limb weakness or cerebellar ataxia. In our case of 62-year-old man, gastrointestinal infection was followed by paranesthesia of the hands. He had bilateral ptosis, pharyngeal disorder, and tongue and bifacial weakness. We diagnosed oculopharyngeal subtype of GBS. It responded to intravenous immunoglobulin. This case highlights the need for further characterization of unusual GBS subtypes.

Clinical characterization of anti-GQ1b antibody syndrome in Korean children

Anti-GQ1b antibody syndrome encompasses Miller Fisher syndrome and its related disorders. We retrospectively identified 11 pediatric patients (5.4-18 years old) with anti-GQ1b antibody syndrome. Diagnoses of patients included acute ophthalmoparesis (n = 6), classical Miller Fisher syndrome (n = 2), Miller Fisher syndrome/Guillain-Barré syndrome (n = 1), acute ataxic neuropathy (n = 1), and pharyngeal-cervical-brachial weakness (n = 1). Nine patients (81.8%) fully recovered. Maturational change in GQ1b antigen expression and the accessibility of anti-GQ1b antibodies might be the cause of the difference of clinical manifestations in children with anti-GQ1b antibody syndrome.

Whole Genome Sequencing and Multiplex qPCR Methods to Identify Campylobacter jejuni Encoding cst-II or cst-III Sialyltransferase

Campylobacter jejuni causes more than 2 million cases of gastroenteritis annually in the United States, and is also linked to the autoimmune sequelae Guillan-Barre syndrome (GBS). GBS often results in flaccid paralysis, as the myelin sheaths of nerve cells are degraded by the adaptive immune response. Certain strains of C. jejuni modify their lipooligosaccharide (LOS) with the addition of neuraminic acid, resulting in LOS moieties that are structurally similar to gangliosides present on nerve cells. This can trigger GBS in a susceptible host, as antibodies generated against C. jejuni can cross-react with gangliosides, leading to demyelination of nerves and a loss of signal transduction. The goal of this study was to develop a quantitative PCR (qPCR) method and use whole genome sequencing data to detect the Campylobacter sialyltransferase (cst) genes responsible for the addition of neuraminic acid to LOS. The qPCR method was used to screen a library of 89 C. jejuni field samples collected by the Food and Drug Administration Pacific Northwest Lab (PNL) as well as clinical isolates transferred to PNL. In silico analysis was used to screen 827 C. jejuni genomes in the FDA GenomeTrakr SRA database. The results indicate that a majority of C. jejuni strains could produce LOS with ganglioside mimicry, as 43.8% of PNL isolates and 46.9% of the GenomeTrakr isolates lacked the cst genes. The methods described in this study can be used by public health laboratories to rapidly determine whether a C. jejuni isolate has the potential to induce GBS. Based on these results, a majority of C. jejuni in the PNL collection and submitted to GenomeTrakr have the potential to produce LOS that mimics human gangliosides.

Ophthalmoplegic Guillain-Barré syndrome: An independent entity or a transitional spectrum?

Ophthalmoplegia can occur in both Miller Fisher syndrome (MFS) and Guillain-Barré syndrome (GBS) with typical limb involvement. However, ophthalmoplegic GBS (OGBS) has been poorly defined. We aimed to characterize OGBS and clarify the pathophysiological implications across the overall GBS spectrum. Twenty GBS and seven MFS patients from three university based teaching hospitals in Korea were enrolled and analyzed. Six GBS patients who were classified as OGBS commonly also had facial diplegia (50%) and bulbar palsy (50%), while only a small portion of non-ophthalmoplegic GBS (NOGBS) patients had facial diplegia (21%). None of the patients had bulbar palsy in the NOGBS or MFS groups. The most frequent anti-ganglioside antibody in OGBS was the IgG anti-GT1a antibody (50%). The IgG anti-GM1 antibody was found mainly in NOGBS (57%) with high concordance with the pure motor type classification on electrophysiology. IgG anti-GQ1b antibody was positive uniquely in MFS (100%), although some patients were also positive for anti-GT1a antibody (71%). OGBS had distinct clinical features, including bulbar palsy, as well as ophthalmoplegia and limb weakness for both GBS and MFS. Relevant immunological factors were anti-GT1a antibody. Whether OGBS is an independent entity or a transitional spectrum remains to be established and further study will be needed.

Recurrent Diplopia in a Pediatric Patient with Bickerstaff Brainstem Encephalitis

Introduction. Acute complete external ophthalmoplegia is a rare finding in clinical practice that is associated with diseases affecting the neuromuscular junction, the oculomotor nerves, or the brainstem. Ophthalmoplegia has been reported with acute ataxia in Miller Fisher syndrome (MFS) and Bickerstaff brainstem encephalitis (BBE). Up to 95% of these cases are associated with anti-GQ1b antibodies. Only a small number of cases of anti-GQ1b negative MFS have been documented in pediatric patients. This is the first case reporting a recurrence of ocular symptoms in an anti-GQ1b antibody negative patient with BBE. Case Presentation. An 8-year-old Caucasian boy presented with complete external ophthalmoplegia without ptosis, cerebellar ataxia, and a disturbance of consciousness. He had recently recovered from a confirmed Campylobacter jejuni infection. On subsequent laboratory testing he was anti-GQ1b antibody negative. He had a recurrence of diplopia at four-week follow-up. Conclusions. This patient's recurrence of diplopia was treated with a five-week course of oral corticosteroids which did not worsen his condition, and this may be a therapeutic option for similar patients. We will discuss the symptoms and treatment of reported pediatric cases of anti-GQ1b antibody negative cases of MFS and the variation between cases representing a spectrum of illness.

Anti-GQ1b antibody syndrome: anti-ganglioside complex reactivity determines clinical spectrum

BACKGROUND AND PURPOSE

Anti-GQ1b antibodies have been found in patients with Miller Fisher syndrome as well as its related conditions. Our aim was to identify the mechanism by which autoantibodies produce various clinical presentations in 'anti-GQ1b antibody syndrome'.

METHODS

Immunoglobulin G antibodies to ganglioside complex (GSC) of GQ1b or GT1a with GM1, GD1a, GD1b or GT1b were tested in sera from patients with anti-GQ1b (n = 708) or anti-GT1a (n = 696) IgG antibodies. Optical densities of the single anti-GQ1b or anti-GT1a antibodies were used as reference (100%), and those of anti-GSC antibodies were expressed in percentages to reference. The relationships between anti-GSC antibody reactivity and the corresponding clinical features were assessed by multivariate logistic regression analysis.

RESULTS

Ophthalmoplegia and hypersomnolence were significantly associated with complex-attenuated anti-GQ1b and anti-GT1a antibodies. Ataxia was associated with GD1b- and GT1b-enhanced anti-GQ1b antibodies or GM1-enhanced anti-GT1a antibodies. Bulbar palsy was associated with GT1b-enhanced anti-GQ1b antibodies. Neck weakness was associated with GD1a-enhanced anti-GQ1b antibodies. Arm weakness was associated with GD1b-enhanced anti-GQ1b and GD1a-enhanced anti-GT1a antibodies. Leg weakness was associated with GD1a-enhanced anti-GQ1b and anti-GT1a antibodies.

CONCLUSIONS

Differences in fine specificity of anti-GQ1b antibodies are associated with clinical features, possibly due to the different expression of gangliosides in different parts of the nervous system.

Miller Fisher syndrome is a nodo-paranodopathy, but not a myelinopathy

ABSTRACT 

Miller Fisher syndrome, characterized by ophthalmoplegia, ataxia and areflexia, is a variant of Guillain–Barré syndrome. There have been controversies over the electrophysiological studies of Miller Fisher syndrome, as both demyelinating and axonal changes have been reported. In recent years, reversible conduction failure has been reported in patients with Miller Fisher syndrome with the use of serial nerve conduction studies. The similarity between Miller Fisher syndrome and axonal Guillain–Barré syndrome has led to the suggestion of a common autoimmune mechanism at the nodes and paranodes.

Infectious and noninfectious triggers in Guillain-Barré syndrome

Guillain-Barré syndrome (GBS) is the commonest cause of acquired flaccid paralysis in the world and regarded by many as the prototype for postinfectious autoimmunity. Here the authors consider both infectious and noninfectious triggers of GBS and determine where possible what immunological mechanisms may account for this association. In approximately two-thirds of cases, an infectious trigger is reported in the weeks that lead up to disease onset, indicating that the host's response to infection must play an important role in disease pathogenesis. The most frequently identified bacteria, Campylobacter jejuni, through a process known as molecular mimicry, has been shown to induce cross-reactive anti-ganglioside antibodies, which can lead to the development of axonal-type GBS in some patients. Whether this paradigm can be extended to other infectious organisms or vaccines remains an important area of research and has public health implications. GBS has also been reported rarely in patients with underlying systemic diseases and immunocompromised states and although the exact mechanism is yet to be established, increased susceptibility to known infectious triggers should be considered most likely.

Fisher syndrome: clinical features, immunopathogenesis and management

Since Miller Fisher's first report in 1956, evidence has accumulated about clinical and laboratory features, immunopathogenesis and treatment of Fisher syndrome (FS). Our literature review revealed the nature of FS. It has relatively uniform clinical and laboratory features. Ophthalmoplegia, ataxia and areflexia are essential prerequisites for an FS diagnosis, but there are several clinical variants with isolated ophthalmoplegia or ataxia. The discovery of serum anti-GQ1b antibody in FS has led to breakthroughs in FS research. The antibody is thought to be a key factor in the pathogenesis of FS, the understanding of which has progressed owing to the discovery of molecular mimicry between GQ1b and the lipo-oligosaccharides of Campylobacter jejuni and Haemophilus influenzae. The lesions responsible for the clinical symptoms have been debated but are close to clarification. Hence, the pathogenesis of FS has been made much clearer, although there are still some unanswered questions.

The repertoire of glycan determinants in the human glycome

The number of glycan determinants that comprise the human glycome is not known. This uncertainty arises from limited knowledge of the total number of distinct glycans and glycan structures in the human glycome, as well as limited information about the glycan determinants recognized by glycan-binding proteins (GBPs), which include lectins, receptors, toxins, microbial adhesins, antibodies, and enzymes. Available evidence indicates that GBP binding sites may accommodate glycan determinants made up of 2 to 6 linear monosaccharides, together with their potential side chains containing other sugars and modifications, such as sulfation, phosphorylation, and acetylation. Glycosaminoglycans, including heparin and heparan sulfate, comprise repeating disaccharide motifs, where a linear sequence of 5 to 6 monosaccharides may be required for recognition. Based on our current knowledge of the composition of the glycome and the size of GBP binding sites, glycoproteins and glycolipids may contain approximately 3000 glycan determinants with an additional approximately 4000 theoretical pentasaccharide sequences in glycosaminoglycans. These numbers provide an achievable target for new chemical and/or enzymatic syntheses, and raise new challenges for defining the total glycome and the determinants recognized by GBPs.

Polyneuritis cranialis presenting with anti-GQ1b IgG antibody

A 52-year-old man developed diplopia, a nasal voice, dysphagia, hoarseness and slight bilateral facial palsies. There was no ataxia, areflexia, limb weakness or sensory involvement. Serum anti-GQ1b IgG antibody was present. Treatment with intravenous immunoglobulin started, and the patient responded with a rapid resolution of symptoms. The diagnosis is consistent with polyneuritis cranialis which is considered to be a Guillain-Barre syndrome variant, a forme fruste, but very rare. The diagnosis can be difficult and a thorough investigation is required. Electrophysiological examination, laboratory evaluations, imaging and cerebrospinal fluid examination are often required in the investigations. Cranial neuropathy can be the presentation of many disorders. Determination of anti-ganglioside antibodies as anti-GQ1b is valuable to the diagnosis, and shows the association with the Guillain-Barre syndrome.

Clinical and immunological spectrum of the Miller Fisher syndrome

The Miller Fisher syndrome (MFS), characterized by ataxia, areflexia, and ophthalmoplegia, was first recognized as a distinct clinical entity in 1956. MFS is mostly an acute, self-limiting condition, but there is anecdotal evidence of benefit with immunotherapy. Pathological data remain scarce. MFS can be associated with infectious, autoimmune, and neoplastic disorders. Radiological findings have suggested both central and peripheral involvement. The anti-GQ1b IgG antibody titer is most commonly elevated in MFS, but may also be increased in Guillain-Barré syndrome (GBS) and Bickerstaff's brainstem encephalitis (BBE). Molecular mimicry, particularly in relation to antecedent Campylobacter jejuni and Hemophilus influenzae infections, is likely the predominant pathogenic mechanism, but the roles of other biological factors remain to be established. Recent studies have demonstrated the presence of neuromuscular transmission defects in association with anti-GQ1b IgG antibody, both in vitro and in vivo. Collective findings from clinical, radiological, immunological, and electrophysiological techniques have helped to define MFS, GBS, and BBE as major disorders within the proposed spectrum of anti-GQ1b IgG antibody syndrome.

Anti-GM1 antibodies as a model of the immune response to self-glycans

Glycans are a class of molecules with high structural variability, frequently found in the plasma membrane facing the extracellular space. Because of these characteristics, glycans are often considered as recognition molecules involved in cell social functions, and as targets of pathogenic factors. Induction of anti-glycan antibodies is one of the early events in immunological defense against bacteria that colonize the body. Because of this natural infection, antibodies recognizing a variety of bacterial glycans are found in sera of adult humans and animals. The immune response to glycans is restricted by self-tolerance, and no antibodies to self-glycans should exist in normal subjects. However, antibodies recognizing structures closely related to self-glycans do exist, and can lead to production of harmful anti-self antibodies. Normal human sera contain low-affinity anti-GM1 IgM-antibodies. Similar antibodies with higher affinity or different isotype are found in some neuropathy patients. Two hypotheses have been developed to explain the origin of disease-associated anti-GM1 antibodies. According to the "molecular mimicry" hypothesis, similarity between GM1 and Campylobacter jejuni lipopolysaccharide carrying a GM1-like glycan is the cause of Guillain-Barré syndrome associated with anti-GM1 IgG-antibodies. According to the "binding site drift" hypothesis, IgM-antibodies associated with disease originate through changes in the binding site of normally occurring anti-GM1 antibodies. We now present an "integrated" hypothesis, combining the "mimicry" and "drift" concepts, which satisfactorily explains most of the published data on anti-GM1 antibodies.

Acute sensory ataxic neuropathy with antibodies to GD1b and GQ1b gangliosides and prompt recovery

Three patients developed acute pure sensory ataxic neuropathy. Two of the three patients had a recent Campylobacter jejuni infection. Patient 1 had monospecific IgG anti-GD1b. Patients 2 and 3 had cross-reactive IgG anti-GQ1b and anti-GD1b and patient 2 also had IgG anti-GT1a. Motor nerve conduction studies were completely normal. Sensory conductions showed reduced amplitude or absent sensory nerve action potentials with normal or slightly slowed conduction velocities. In patient 2, serial electrophysiological studies showed reappearance and improvement of sensory nerve potential amplitudes in 4 weeks. All patients recovered completely in 2 months and sensory potential amplitudes normalized in 3-5 months. Our findings: (1) confirm the existence of a pure acute sensory ataxic neuropathy with cross-reactive IgG anti-GQ1b and anti-GD1b as a variant of Guillain-Barré syndrome; (2) expand the clinical presentation of Guillain-Barré syndrome after C. jejuni infection and suggest that molecular mimicry is at the basis of acute sensory ataxic neuropathy; and (3) indicate that, in acute sensory ataxic neuropathy with prompt recovery, the site of the lesion is not in the primary sensory neurons and the pathophysiological mechanism may be functional in nature.

Anti-GQ1b antibody does not affect neuromuscular transmission in human limb muscle

Anti-ganglioside GQ1b antibody induces neuromuscular blocking on mouse phrenic nerve-diaphragm preparations. Several reports suggest that patients with this antibody show abnormal neuromuscular transmission in the facial or limb muscles, but limb muscle weakness is unusual in Miller Fisher syndrome that is often associated with anti-GQ1b antibody. To determine whether anti-GQ1b sera affect neuromuscular transmission in human limb muscles, axonal-stimulating single fiber electromyography was performed in the forearm muscle of seven patients with anti-GQ1b antibody. All showed normal jitter and no blocking. Anti-GQ1b antibody does not affect neuromuscular transmission in human limb muscles. The different findings in mouse and human may be explained by the extent of expression of GQ1b on the motor nerve terminals in the muscle examined.

A Haemophilus influenzae strain associated with Fisher syndrome expresses a novel disialylated ganglioside mimic

The non-typeable Haemophilus influenzae strain DH1 was isolated from a 25 year old male patient with Fisher syndrome, a postinfectious autoimmune condition characterized by the presence of anti-GQ1b IgG antibodies that target and initiate damage to peripheral nerves. DH1 was found to display an alphaNeuAc(2-8)alphaNeuAc(2-3)betaGal branch bound to the tetraheptosyl backbone core of its lipooligosaccharide (LOS). The novel sialylation pattern was found to be dependent on the activity of a bifunctional sialyltransferase, Lic3B, which catalyzes the addition of both the terminal and subterminal sialic acid residues. Patient serum IgGs bind to DH1 LOS, and the reactivity is significantly influenced by the presence of sialylated glycoforms. The display by DH1, of a surface glycan that mimics the terminal trisaccharide portion of disialosyl-containing gangliosides, provides strong evidence for its involvement in the development of Fisher syndrome.

Treatment for Fisher syndrome, Bickerstaff's brainstem encephalitis and related disorders

BACKGROUND

Fisher syndrome is one of the regional variants of Guillain-Barré syndrome, characterised by impairment of eye movements (ophthalmoplegia), incoordination (ataxia) and loss of tendon reflexes (areflexia). It can occur in more limited forms, and may overlap with Guillain-Barré syndrome. A further variant is associated with upper motor neuron signs and disturbance of consciousness (Bickerstaff's brainstem encephalitis). All of these variants are associated with anti-GQ1b IgG antibodies. Intravenous immunoglobulin (IVIg) and plasma exchange are often used as treatments in this patient group. This review was undertaken to systematically assess any available randomised controlled data on acute immunomodulatory therapies in Fisher Syndrome or its variants.

OBJECTIVES

To provide the best available evidence from randomised controlled trials on the role of acute immunomodulatory therapy in the treatment of Fisher Syndrome and related disorders.

SEARCH STRATEGY

We searched the Cochrane Neuromuscular Disease Trials register (March 2004), MEDLINE (from January 1966 to November 2004), EMBASE (from January 1980 to November 2004), CINAHL (from January 1982 to November 2004) and LILACS (from January 1982 to November 2004) for randomised controlled trials, quasi-randomised trials, historically controlled studies and trials with concurrent controls. We adapted this strategy to search MEDLINE from 1966 and EMBASE from 1980 for comparative cohort studies, case-control studies and case series.

SELECTION CRITERIA

All randomised and quasi-randomised controlled clinical trials (in which allocation was not random but was intended to be unbiased, e.g. alternate allocation, and non-randomised controlled studies were to have been selected. Since no such clinical trials were discovered, all retrospective case series containing five or more patients were assessed and summarised in the discussion section.

DATA COLLECTION AND ANALYSIS

All studies of Fisher Syndrome and its clinical variants were scrutinised for data on patients treated with any form of acute immunotherapy. Information on the outcome was then collated and summarised.

MAIN RESULTS

We found no randomised or non-randomised prospective controlled trials of immunotherapy in Fisher Syndrome or related disorders. We summarised the results of retrospective series containing five or more patients in the discussion section.

AUTHORS' CONCLUSIONS

There are no randomised controlled trials of immunomodulatory therapy in Fisher Syndrome or related disorders on which to base practice.

Recognition Characteristics of Monoclonal Antibodies That Are Cross-Reactive with Gangliosides and Lipooligosaccharide fromCampylobacter jejuniStrains Associated with Guillain-Barré and Fisher Syndromes†

The enteropathogen Campylobacter jejuni has the ability to synthesize glycan structures that are similar to mammalian gangliosides within the core component of its lipooligosaccharide (LOS). Exposure to ganglioside mimics in some individuals results in the production of autoantibodies that deleteriously attack nerve surface gangliosides, precipitating the onset of Guillain-Barré and Fisher syndromes (GBS and FS). We have characterized the interaction of four monoclonal antibodies (mAbs), established by sensitization of mice with LOS isolated from GBS- and FS-associated C. jejuni strains, with chemoenzymatically synthesized gangliooligosaccharides. Surface plasmon resonance (SPR) measurements demonstrate that three of the mAbs interact specifically with derivatives corresponding to their targeted gangliosides, with dissociation constants ranging from 10 to 20 microM. Antibody binding to the gangliooligosaccharides was probed by saturation transfer difference (STD) NMR spectroscopy. STD signals, resulting from antibody/oligosaccharide interaction, were observed for each of the four mAbs. In two cases, differential saturation transfer rates to oligosaccharide resonances enabled detailed epitope mapping. The binding of GD1a-S-Phe with GB1 is characterized by close association of the immunoglobulin with sites that are distributed over several residues of the oligosaccharide. This contrasts sharply with the profile observed for the binding of both GD3-S-Phe and GT1a-S-Phe with FS1. The close antigenic contacts in these ganglioside derivatives are confined to the N-acetylmannosaminyl portion of the terminal N-acetylneuraminic acid (NeuAc) residue of the disialosyl moiety. Our characterization of FS1 provides insight, at an atomic level, into how a single antigenic determinant presented by the LOS of C. jejuni can give rise to antibodies with binding promiscuity to [alphaNeuAc-(2-8)-alphaNeuAc]-bound epitopes and demonstrates why sera from FS patients have antibodies that are often reactive with more than one disialylated ganglioside.

Ganglioside mimicry and peripheral nerve disease

Four criteria must be satisfied to conclude that a given microorganism causes Guillain-Barré (GBS) or Fisher (FS) syndrome associated with anti-ganglioside antibodies: (1) an epidemiological association between the infecting microbe and GBS or FS; (2) isolation in the acute progressive phase of illness of that microorganism from GBS or FS patients with associated anti-ganglioside IgG antibodies; (3) identification of a microbial ganglioside mimic; and (4) a GBS or FS with associated anti-ganglioside antibodies model produced by sensitization with the microbe itself or its component, as well as with ganglioside. Campylobacter jejuni is a definitive causative microorganism of acute motor axonal neuropathy and may cause FS and related conditions. Haemophilus influenzae and Mycoplasma pneumoniae are possible causative microorganisms of acute motor axonal neuropathy or FS. Acute and chronic inflammatory demyelinating polyneuropathies may be produced by mechanisms other than ganglioside mimicry.

Bickerstaff brainstem encephalitis associated with Mycoplasma pneumoniae infection

Bickerstaff brainstem encephalitis is a clinical syndrome of ophthalmoplegia, cerebellar ataxia, and central nervous system signs and is associated with the presence of anti-GQ1b antibodies. There is a clinical continuum between Bickerstaff brainstem encephalitis and Miller Fisher syndrome. We describe the case of an 11-year-old boy with encephalopathy, external ophthalmoplegia, brainstem signs, and ataxia with raised titers of anti-GQ1b antibodies. He presented following a respiratory illness and had laboratory evidence of recent infection with Mycoplasma pneumoniae. M pneumoniae infection has been associated with both Bickerstaff brainstem encephalitis and Miller Fisher syndrome. This is only the second case in the literature of Bickerstaff brainstem encephalitis with raised titers of anti-GQ1b antibodies described in association with M pneumoniae infection. The patient responded to intravenous immunoglobulin administration.

Molecular mimicry: sensitization of Lewis rats with Campylobacter jejuni lipopolysaccharides induces formation of antibody toward GD3 ganglioside

Recently we have reported cases of demyelinating inflammatory neuropathy showing elevated titers of anti-GD3 antibodies, which occurs rarely in Guillain-Barré syndrome. To examine the correlation between the anti-GD3 antibody titer and Campylobacter jejuni infection, we sensitized female Lewis rats with lipopolysaccharides (LPSs) from serotype HS19 of C. jejuni and examined changes in nerve conduction velocity and nerve conduction block (P/D ratio). After 16 weeks of sensitization, animals revealed decreases of nerve conduction velocity and conduction block (P/D ratio) and high titer of anti-GD3 antibodies. These anti-GD3 antibodies also blocked transmission in neuromuscular junctions of spinal cord-muscle cells cocultures. The GD3 epitope was verified to be located on the Schwann cell surface and nodes of Ranvier in rat sciatic nerve. To determine the target epitope for GD3 antibodies in causing nerve dysfunction, the LPS fraction containing the GD3 epitope was purified from the total LPS by using an anti-GD3 monoclonal antibody-immobilized affinity column. Subsequently, chemical analysis of the oligosaccharide portion was performed and confirmed the presence of a GD3-like epitope as having the following tetrasaccharide structure: NeuAcalpha2-8NeuAc2-3Galbeta1-4Hep. Our data thus support the possibility of a contribution of GD3 mimicry as a potential pathogenic mechanism of peripheral nerve dysfunction.

A case of overlapping Bickerstaff's brainstem encephalitis and Guillain-Barré syndrome

OBJECTIVE

There is no report on Bickerstaff's brainstem encephalitis (BBE) patients in China. We here report the first case of BBE in China.

METHODS

Clinical features, results of electromyography, electroencephalography (EEG), magnetic resonance imaging (MRI) and cerebrospinal fluid (CSF) examination were studied to clarify the characteristics of this syndrome.

RESULTS

A 44-year-old man presented himself at our inpatient department with somnolence and dizziness as his initial symptoms. He developed multiple cranial nerves paralysis especially internal and external ophthalmoplegia, ataxia and tetraparesis within 1 week. His condition rapidly deteriorated, and he experienced coma. Electromyography showed indications of peripheral nerve dysfunction, electroencephalography revealed loss of basic rhythm, MRI demonstrated high-intensity abnormalities on T(2)-weighted images of medulla oblongata, and CSF albuminocytological dissociation was defined abnormally as high protein. Ten months later, he almost completely recovered.

CONCLUSION

BBE, fisher syndrome (FS) and Guillain-Barré syndrome (GBS) are similar clinically; BBE and FS were proposed to be the variant of GBS.

Recent developments in Miller Fisher syndrome and related disorders

PURPOSE OF REVIEW

Miller Fisher syndrome is a localized variant of Guillain-Barré syndrome, characterized by ophthalmoplegia, areflexia and ataxia. Bickerstaff's brainstem encephalitis is a related syndrome in which upper motor neurone features accompany the classic triad. Anti-GQ1b antibodies are uniquely found in both conditions and are believed to be pathogenic.

RECENT FINDINGS

Infectious illnesses usually precede Miller Fisher syndrome. The clearest associations have been described with Haemophilus influenzae and Campylobacter jejuni infection. Raised cerebrospinal fluid protein is seen in 60% of patients, but clinical features and anti-GQ1b antibody testing are diagnostically more informative. Experimental studies demonstrating complement-dependent neuromuscular block may be relevant to the clinical pathophysiology of Miller Fisher syndrome. Recent neurophysiological studies suggest abnormal neuromuscular transmission occurs in some cases of Miller Fisher syndrome and Guillain-Barré syndrome. Recent mouse models have demonstrated that presynaptic neuronal membranes and perisynaptic Schwann cells are targets for anti-GQ1b antibody attack. The elimination of antiganglioside antibodies from the circulation through specific immunoadsorption therapy has the potential to ameliorate the course of Miller Fisher syndrome. This condition is typically a benign, self-limiting illness. Both plasmapheresis and intravenous immunoglobulin may be employed as treatment, especially in cases of Bickerstaff's brainstem encephalitis or those with overlapping Guillain-Barré syndrome.

SUMMARY

Anti-GQ1b antibody testing has allowed clinicians to develop a greater understanding of the spectrum of Miller Fisher syndromes and to refine clinical diagnoses in patients with unusual presentations. Experimental studies strongly suggest anti-GQ1b antibodies are pathogenic, which in principle should direct treatments towards antibody neutralization or elimination.

Anti-disialosyl antibodies mediate selective neuronal or Schwann cell injury at mouse neuromuscular junctions

The human paralytic neuropathy, Miller Fisher syndrome (MFS) is associated with autoantibodies specific for disialosyl epitopes on gangliosides GQ1b, GT1a, and GD3. Since these gangliosides are enriched in synaptic membranes, anti-ganglioside antibodies may target neuromuscular junctions (NMJs), thereby contributing to disease symptoms. We have shown previously that at murine NMJs, anti-disialosyl antibodies induce an alpha-latrotoxin-like effect, electrophysiologically characterized by transient massive increase of spontaneous neurotransmitter release followed by block of evoked release, resulting in paralysis of the muscle preparation. Morphologically, motor nerve terminal damage, as well as perisynaptic Schwann cell (pSC) death is observed. The relative contributions of neuronal and pSC injury to the paralytic effect and subsequent repair are unknown. In this study, we have examined the ability of subsets of anti-disialosyl antibodies to discriminate between the neuronal and glial elements of the NMJ and thereby induce either neuronal injury or pSC death. Most antibodies reactive with GD3 induced pSC death, whereas antibody reactivity with GT1a correlated with the extent of nerve terminal injury. Motor nerve terminal injury resulted in massive uncontrolled exocytosis with paralysis. However, pSC ablation induced no acute (within 1 h) electrophysiological or morphological changes to the underlying nerve terminal. These data suggest that at mammalian NMJs, acute pSC injury or ablation has no major deleterious influence on synapse function. Our studies provide evidence for highly selective targeting of mammalian NMJ membranes, based on ganglioside composition, that can be exploited for examining axonal-glial interactions both in disease states and in normal NMJ homeostasis.

Characterisation of the immunoglobulin variable region gene usage encoding the murine anti-ganglioside antibody repertoire

Neuropathogenic murine antibodies reactive with terminal disialylgalactose epitopes are innate and preferentially encoded by the VH7183.3b gene. Here we have studied antibodies reactive with internal galactose-linked disialosyl epitopes and the terminal trisaccharide of GT1b. Antibodies were of moderate affinity and unmutated. Anti-GD1b antibodies were often encoded by the VH10.2b heavy and gj38c light chain genes. Anti-GT1b antibodies with broader glycan binding patterns were encoded by VHQ52 and VHJ558 family genes. These data indicate that the discrete specificities of ganglioside-binding antibodies are dictated by particular patterns of V gene usage residing within the innate B cell repertoire.

Delayed motor and sensory neuropathy in a patient with brainstem encephalitis

Bickerstaff's brainstem encephalitis (BBE), Miller Fisher syndrome (MFS) and Guillain-Barré syndrome (GBS) are thought to be closely related and to form a continuous spectrum. However, chronic polyneuropathy in BBE has not been reported. We report the temporal profile of anti-ganglioside antibody titer in a case of BBE-like brainstem encephalitis complicated with chronic polyneuropathy. A 71-year-old Japanese woman presented with drowsiness and cerebellar ataxia in addition to mild weakness in distal limb muscles. Anti-GalNAc-GD1a IgG and anti-GalNAc-GM1b IgG antibodies were positive in her serum. Brain magnetic resonance imaging revealed high-intensity signals in the midbrain, pons, and middle cerebellar peduncles on T2-weighted images. Central nervous system manifestations improved after immunomodulating therapy that included prednisolone, plasmapheresis and intravenous immunoglobulin. Nevertheless, the distal muscle weakness was exacerbated when the anti-GalNAc-GD1a IgG titer was elevated. Nerve conduction study indicated motor and sensory neuropathy which was developed motor dominant axonal damage. These findings suggest that anti-ganglioside antibodies, including anti-GalNAc-GD1a IgG, may be involved in a common autoimmune mechanism in BBE-like brainstem encephalitis and chronic motor dominant axonal neuropathy. However, the fact that the latter manifestation exacerbated after the improvement of former one possibly indicates different thresholds of neurologic symptoms mediated by anti-ganglioside antibodies in the present patient.

Innate murine B cells produce anti-disialosyl antibodies reactive with Campylobacter jejuni LPS and gangliosides that are polyreactive and encoded by a restricted set of unmutated V genes

In Guillain-Barré syndrome following Campylobacter enteritis, anti-lipopolysaccharide antibodies cross-react with neural gangliosides, thereby precipitating autoimmune neuropathy. We examined the properties of 15 murine anti-LPS/ganglioside mAbs specific for NeuAc(alpha2-8)NeuAc-Gal disialosyl epitopes. Many mAbs displayed features of an innate B cell origin including polyreactivity (13/15), hybridoma CD5 mRNA expression (5/15), predominance of IgM (9/15) or IgG3 (3/6) isotype, low affinity, and utilisation of unmutated VH and VL VDJ rearrangements. Antibody specificity resided in highly selective V gene usage, with 6/15 mAbs being encoded by the VH7183.3b gene. These data indicate that neuropathogenic antiganglioside autoantibodies can arise from the natural autoantibody repertoire.

Recurrent Miller–Fisher syndrome

A case of recurrent Miller-Fisher syndrome is presented and features of this very rare condition are discussed.

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.

Clinical deterioration in Bickerstaff's brainstem encephalitis caused by overlapping Guillain-Barré syndrome

A 37-year-old man developed an acute encephalitic condition after respiratory infection. His condition rapidly deteriorated, and he experienced ophthalmoplegia, tetraplegia, loss of brainstem reflexes and deep tendon reflexes, and deep coma. Electrophysiological evaluations indicated involvement of the peripheral nerve as well as the brainstem. Follow-up studies found acute progression of peripheral nerve damage. Serum anti-GQ1b IgG antibody was present. The initial condition was diagnosed as Bickerstaff's brainstem encephalitis, and subsequent overlapping of Guillain-Barré syndrome probably was responsible for the clinical deterioration. When unusual worsening is observed in clinically suspected encephalitis, neurologists must take into account the possibility of associated Guillain-Barré syndrome and related disorders.

Dissociation between titer of anti-ganglioside antibody and severity of symptoms in a case of Guillain-Barré syndrome with treatment-related fluctuation

Since plasma exchange (PE) and intravenous immunoglobulin (i.v.Ig) have been widely used in treatment for Guillain-Barré syndrome (GBS), early relapse and treatment-related fluctuation have been a potential problem, but little is known about the mechanism of relapse and fluctuation. We describe a patient who had GBS with treatment-related fluctuation. A 37-year-old Japanese man exhibited acute distal-dominant weakness in upper limbs after upper respiratory infection. His cranial nerve system was normal and muscle weakness was limited to upper limbs. Anti-GT1a IgG was strongly positive and anti-GQ1b IgG was also detected in his serum. Muscle weakness responded well to double-filtration plasmapheresis (DFPP) followed by i.v.Ig, but relapsed 45 days after the initial treatment. Although repeated treatments were effective, the patient showed additional minor deterioration twice. Motor nerve conduction velocities (MCVs) corresponded to the muscle weakness, but elevated level of cerebrospinal fluid (CSF) protein remained and anti-ganglioside antibody titers steadily decreased throughout the clinical course. These findings indicate that the clinical fluctuation was not due to changes in the production of anti-ganglioside antibodies but presumably to the transient beneficial effects of DFPP/i.v.Ig and the outlasting inflammatory response in peripheral nerves.

Anti-GT1a IgG in Guillain-Barré syndrome

OBJECTIVE

To investigate the presence of serum anti-GT1a IgG in Guillain-Barré syndrome (GBS) and its relation to clinical manifestations.

BACKGROUND

Several patients with GBS and bulbar palsy have been reported to have serum anti-GT1a IgG. Most, however, also have anti-GQ1b IgG. A previous study failed to detect GT1a in human cranial nerves, but GQ1b was abundant in human ocular motor nerves. Whether anti-GT1a IgG itself determines the clinical manifestations is not yet clear.

METHODS

The association of clinical manifestations with the presence of anti-GT1a IgG and with its cross reactivity was investigated. An immunochemical study was performed to determine whether GT1a is present in human cranial nerves.

RESULTS

Anti-GT1a and anti-GQ1b IgG were positive in 10% and 9% respectively of 220 consecutive patients with GBS. Patients with anti-GT1a IgG often had cranial nerve palsy (ophthalmoparesis, 57%; facial palsy, 57%; bulbar palsy, 70%), and 39% needed artificial ventilation. These features were also seen in patients with anti-GQ1b IgG. There was no significant difference between the two groups with respect to the frequency of clinical findings. An enzyme-linked immunosorbent assay showed that anti-GT1a IgG cross reacted with GQ1b in 75% of the patients, GD1a in 30%, GM1 in 20%, and GD1b in 20%. All five patients who carried anti-GT1a IgG that did not cross react with GQ1b had bulbar palsy, neck weakness, absence of sensory disturbance, and positive Campylobacter jejuni serology. Thin-layer chromatography with immunostaining showed that GT1a is present in human oculomotor and lower cranial nerves.

CONCLUSIONS

These findings provide further evidence that anti-GT1a IgG itself can determine clinical manifestations. The distinctive clinical features of patients with anti-GT1a IgG without anti-GQ1b activity distinguish a specific subgroup within GBS.

Clinical, electrophysiological, and serological overlap between Miller Fisher syndrome and acute sensory ataxic neuropathy

We report a patient with severe sensory ataxia, areflexia, and ophthalmoplegia with preservation of limb muscle strength. Electrophysiological examinations revealed peripheral sensory nerve involvement. A serological examination showed the elevation of IgG antibodies to various b-series gangliosides as well as GT1a. These indicated that this case is an overlap between acute sensory ataxic neuropathy and Miller Fisher syndrome. Autoantibody is implicated as potential pathogenic agents in some cases of acute sensory ataxic neuropathy.

Detection and prevalence of alpha-latrotoxin-like effects of serum from patients with Guillain-Barré syndrome

Anti-GQ1b antibodies are associated with the Miller Fisher syndrome (MFS), a variant of the Guillain-Barré syndrome (GBS). In the ex vivo mouse diaphragm, anti-GQ1b-positive MFS serum induces muscle fiber twitching, a temporary dramatic increase of spontaneous quantal acetylcholine release, and transmission blockade at neuromuscular junctions (NMJs). These effects resemble those of alpha-latrotoxin (alpha-LTx) and are induced by antibody-mediated activation of complement. We developed an assay for detection of the alpha-LTx-like effect, using muscle fiber twitching as indicator. We tested 89 serum samples from GBS, MFS, and control subjects, and studied correlations with clinical signs, anti-ganglioside antibodies, micro-electrode physiology, and complement deposition at NMJs. Twitching was observed with 76% of the MFS and 10% of the GBS samples. It was associated with ophthalmoplegia and anti-GQ1b antibodies in patients, and with increased spontaneous acetylcholine release and C3c-deposition at mouse NMJs. This study strongly suggests that antibodies to GQ1b (with cross-reactivity to related gangliosides) are responsible for the alpha-LTx-like activity. The twitching assay is an efficient test for detection of this effect, and allows for screening of large numbers of samples and modifying drugs.

Fine specificities of anti-LM1 IgG antibodies in Guillain-Barré syndrome

We investigated the prevalence of anti-LM1 IgG antibody and its fine specificity in Guillain-Barré syndrome (GBS). Anti-LM1 IgG and IgM antibodies from sera of 47 patients with GBS--19 with acute inflammatory demyelinating polyneuropathy (AIDP), 27 with acute motor axonal neuropathy (AMAN), and 1 with acute motor-sensory axonal neuropathy (AMSAN)--were tested. Anti-LM1 IgG antibody was detected in only one patient with AIDP, whereas it was present in seven with AMAN and in one with AMSAN. Sera from the eight IgG anti-LM1-positive patients with AMAN/AMSAN also had IgG activity against the gangliosides GM1, GM1b, GD1a, GalNAc-GD1a, GD1b, or GQ1b. Anti-LM1 IgG antibodies from the AMAN/AMSAN patients cross-reacted with other gangliosides, whereas IgG antibody from the AIDP patient was monospecific against LM1. Anti-LM1 IgG antibody therefore, cannot be a marker of AIDP. In addition, whether monospecific anti-LM1 IgG antibody is associated with AIDP remains to be concluded. Larger studies are needed to verify whether monospecific anti-LM1 IgG antibody could be a marker of AIDP.

Progress in Guillain-Barré syndrome

This editorial review summarizes and critically analyses reports published in the preceding 18 months on the pathogenesis of Guillain-Barré syndrome, with particular emphasis on the role of ganglioside antibodies, antecedent infections, and the concept of molecular mimicry. It concludes with an appraisal of currently available and proposed therapies.