Polyneuropathy attributes: a comparison between patients with anti-MAG and anti-sulfatide antibodies

Anti-sulfatide antibody-related Guillain-Barré syndrome presenting with overlapping syndromes or severe pyramidal tract damage: a case report and literature review

Introduction

Anti-sulfatide antibodies are key biomarkers for the diagnosis of Guillain-Barré syndrome (GBS). However, case reports on anti-sulfatide antibody-related GBS are rare, particularly for atypical cases.

Case description case 1

A 63 years-old man presented with limb numbness and diplopia persisting for 2 weeks, with marked deterioration over the previous 4 days. His medical history included cerebral infarction, diabetes, and coronary atherosclerotic cardiomyopathy. Physical examination revealed limited movement in his left eye and diminished sensation in his extremities. Initial treatments included antiplatelet agents, cholesterol-lowering drugs, hypoglycemic agents, and medications to improve cerebral circulation. Despite this, his condition worsened, resulting in bilateral facial paralysis, delirium, ataxia, and decreased lower limb muscle strength. Treatment with intravenous high-dose immunoglobulin and dexamethasone resulted in gradual improvement. A 1 month follow-up revealed significant neurological sequelae.

Case description case 2

A 53 years-old woman was admitted for adenomyosis and subsequently experienced sudden limb weakness, numbness, and pain that progressively worsened, presenting with diminished sensation and muscle strength in all limbs. High-dose intravenous immunoglobulin, vitamin B1, and mecobalamin were administered. At the 1 month follow-up, the patient still experienced limb numbness and difficulty walking. In both patients, albuminocytologic dissociation was found on cerebrospinal fluid (CSF) analysis, positive anti-sulfatide antibodies were detected in the CSF, and electromyography indicated peripheral nerve damage.

Conclusion

Anti-sulfatide antibody-related GBS can present with Miller-Fisher syndrome, brainstem encephalitis, or a combination of the two, along with severe pyramidal tract damage and residual neurological sequelae, thereby expanding the clinical profile of this GBS subtype. Anti-sulfatide antibodies are a crucial diagnostic biomarker. Further exploration of the pathophysiological mechanisms is necessary for precise treatment and improved prognosis.

Autoimmune peripheral neuropathies

Peripheral nervous system axons and myelin have unique potential protein, proteolipid, and ganglioside antigenic determinants. Despite the existence of a blood-nerve barrier, both humoral and cellular immunity can be directed against peripheral axons and myelin. Molecular mimicry may be triggered at the systemic level, as was best demonstrated in the case of bacterial oligosaccharides. The classification of immune neuropathy has been expanded to take into account specific syndromes that share unique clinical, electrophysiological, prognostic and serological features. Guillain-Barré syndrome encompasses a classical syndrome of acute demyelinating polyradiculoneuropathy and many variants: axonal motor and sensory, axonal motor, Miller-Fisher, autonomic, and sensory. Similarly, chronic immune neuropathy is composed of classic chronic inflammatory demyelinating polyradiculoneuropathy and variants characterized as multifocal (motor or sensorimotor), sensory, distal symmetric, and syndromes associated with monoclonal gammopathy. Among putative biomarkers, myelin associated glycoprotein and several anti-ganglioside autoantibodies have shown statistically significant associations with specific neuropathic syndromes. Currently, the strongest biomarker associations are those linking Miller-Fisher syndrome with anti-GQ1b, multifocal motor neuropathy with anti-GM1, and distal acquired symmetric neuropathy with anti-MAG antibodies. Many other autoantibody associations have been proposed, but presently lack sufficient specificity and sensitivity to qualify as biomarkers. This field of research has contributed to the antigenic characterization of motor and sensory functional systems, as well as helping to define immune neuropathic syndromes with widely different clinical presentation, prognosis and response to therapy. Serologic biomarkers are likely to become even more relevant with the advent of new targeted forms of immunotherapy, such as monoclonal antibodies.

Antibody testing in peripheral nerve disorders

The identification of autoantibodies associated with dysimmune neuropathies was a major contribution to the characterization of peripheral nerve disorders, the understanding of their pathophysiology, and the clinical diagnosis of neuropathies. Antibodies directed to GM1, GQ1b, and disyalilated gangliosides, and anti-MAG antibodies are very useful in the diagnosis of acute or chronic motor or sensory-motor neuropathies with or without monoclonal IgM. Anti-onconeural anti-Hu and anti-CV2/CRMP antibodies allow when they are detected the diagnosis of paraneoplastic neuropathies. This chapter focuses on the description of these antibodies as diagnostic markers and on their immunopathogenesis. We give a background overview on the origin of these antibodies, their detection, and review those studies, which clearly show that these antibodies are capable of binding to the target tissues in peripheral nerve and thereby can exert a variety of pathophysiological effects. The corresponding electrophysiological and histological changes observed both in human and animal models are exemplified in order to get a better understanding of the immune mechanisms of these antibody-mediated neuropathies.

Clinical, electrophysiological and immunological study of peripheral nerves in Egyptian patients with monoclonal gammopathies

Monoclonal antibodies are found in approximately 10% of patients with peripheral neuropathy (PN) of unknown etiology. Several autoantibodies, including anti-MAG (myelin-associated glycoprotein) antibodies, have been reported to induce neuropathy. It has been suggested that over 50% of patients with PN and IgM monoclonal gammopathy (MG) have anti-MAG IgM antibodies in their sera. This work aimed at studying the frequency and characteristics of PN in a group of Egyptian patients with MGs and to estimate the serum level of anti-MAG antibodies and its relationship to peripheral nerve dysfunction. Forty patients with MGs were enrolled in the study. Their mean age was 56.65 ± 8.55 years. There were 17 males and 23 females. Patients were subjected to complete general and neurological examination, laboratory investigations including serum LDH, β2 microglobulin, serum protein electrophoresis, urinary Bence-Jones protein, bone marrow aspiration and/or trephine biopsy, quantitative estimation of serum IgM and IgG by nephelometry, detection of anti-MAG antibodies by indirect immunofluorescence, radiological assessment and nerve conduction study of both upper and lower limbs. Clinical and electrophysiological evidences of PN were found in 32 (80%) out of the 40 patients with MG. Twenty-five patients (62.5%) had distal symmetrical polyneuropathy and seven (17.5%) had mononeuritis or mononeuritis multiplex. The majority of patients (65%) had sensory or predominantly sensorimotor polyneuropathy. The neuropathy was mainly demyelinating in 22 patients (55%) and axonal in the other 10 (25%) patients. Anti-MAG antibodies were positive in nine patients (22.5%) and six of them (66.6%) had PN. The latter was predominantly demyelinating motor neuropathy in 4 and axonal in the remaining 2. However, the relationship between the presence of anti-MAG antibodies and the development and type of PN was not statistically significant. Anti-MAG showed significant association with IgM level (P = 0.003**) and the MG subtypes: Waldenström's macroglobulinemia (WM) and monoclonal gammopathy of undetermined significance (MGUS) (P = 0.004**). The present study showed high frequency (>60%) of distal symmetrical polyneuropathy in Egyptian patients with MG. The neuropathy was predominantly sensory and demyelinating. Anti-MAG antibodies were detected only in 22.5% of the patients, especially those with WM and MGUS and were associated with more motor and demyelinating neuropathy. We recommend that patients with chronic polyneuropathies should be evaluated for underlying plasma cell dyscrasia.

Peripheral neuropathies in Waldenström's macroglobulinaemia

OBJECTIVE

We sought to determine the prevalence, clinical features, and laboratory characteristics of polyneuropathies in Waldenström's macroglobulinaemia (WM), a malignant bone marrow disorder with lymphocytes that produce monoclonal IgM.

METHODS

We prospectively studied 119 patients with WM and 58 controls. Medical history was taken, and neurological examinations, electrodiagnostic tests, and serum studies were performed by different examiners who were blinded to results except the diagnosis of WM.

RESULTS

Polyneuropathy symptoms, including discomfort and sensory loss in the legs, occurred more frequently (p<0.001) in patients with WM (47%) than in controls (9%). Patients with WM had 35% lower quantitative vibration scores, and more frequent pin loss (3.4 times) and gait disorders (5.5 times) than controls (all p<0.001). Patients with IgM binding to sulphatide (5% of WM) had sensory axon loss; those with IgM binding to myelin associated glycoprotein (MAG) (4% of WM) had sensorimotor axon loss and demyelination. Patients with WM with IgM binding to sulphatide (p<0.005) or MAG (p<0.001) had more severe sensory axon loss than other patients with WM. Demyelination occurred in 4% of patients with WM with no IgM binding to MAG. Age related reductions in vibration sense and sural SNAP amplitudes were similar ( approximately 30%) in WM and controls.

CONCLUSIONS

Peripheral nerve symptoms and signs occur more frequently in patients with WM than controls, involve sensory modalities, and are often associated with gait disorders. IgM binding to MAG or sulphatide is associated with a further increase in the frequency and severity of peripheral nerve involvement. Age related changes, similar to those in controls, add to the degree of reduced nerve function in patients with WM.

Clinical features and pathophysiological basis of sensory neuronopathies (ganglionopathies)

Sensory ganglionopathies have a frequent association with neoplastic disorders (paraneoplastic subacute sensory neuronopathy, or SSN) or dysimmune disorders (Sjögren's syndrome, SS; Miller Fisher syndrome; and Bickerstaff's brainstem encephalitis, BBE), with drugs, such as cisplatin or pyridoxine, and with inherited disorders with degeneration of dorsal root ganglion cells. Unsteady gait and pseudoathetoid movements of the hand are the distinctive signs encountered in these disorders. The chronic disorders are characterized by non-length-dependent abnormalities of sensory nerve action potentials (SNAPs) and differ from other sensory neuropathies in showing a global, rather than distal, decrease in SNAP amplitudes. This review focuses on recent advances in defining the mechanisms involved in sensory ganglionopathies. Specific topics include a summary of their clinical features, pathological findings, and immunopathology. In SSN, early diagnosis by the detection of anti-Hu antibodies and early treatment of the cancer gives the best chance of stabilizing the disorder. In SS sensory ganglionitis, response to treatment has been disappointing, but immunomodulating treatments are emerging. The immunological profile common to BBE and Fisher syndrome supports a common pathogenesis. In toxic sensory neuronopathy, no treatment is available. The differential diagnosis involves separating sensory ganglionopathies from other ataxic polyneuropathies, such as infectious neuropathies, sensory neuropathies with various autoantibodies, and the neuropathies seen in celiac disease.

Immunotherapy of idiopathic inflammatory neuropathies

Evaluation of peripheral neuropathy is a common reason for referral to a neurologist. Recent advances in immunology have identified an inflammatory component in many neuropathies and have led to treatment trials using agents that attenuate this response. This article reviews the clinical presentation and treatment of the most common subacute inflammatory neuropathies, Guillain-Barré syndrome (GBS) and Fisher syndrome, and describes the lack of response to corticosteroids and the efficacy of treatment with plasma exchange and intravenous immunoglobulin (IVIG). Chronic inflammatory demyelinating polyneuropathy, although sharing some clinical, electrodiagnostic, and pathologic similarities to GBS, improves after treatment with plasma exchange and IVIG and numerous immunomodulatory agents. Controlled trials in multifocal motor neuropathy have shown benefit after treatment with IVIG and cyclophosphamide. Also discussed is the treatment of less common inflammatory neuropathies whose pathophysiology involves monoclonal proteins or antibodies directed against myelin-associated glycoprotein or sulfatide. Little treatment data exist to direct the clinician to proper management of rare inflammatory neuropathies resulting from osteosclerotic myeloma; POEMS syndrome; vasculitis; Sjögren's syndrome; and neoplasia (paraneoplastic neuropathy).

Antibodies to myelin-associated glycoprotein accelerate preferential motor reinnervation

Predegeneration of nerve enhances its ability to support axon regeneration. Trophic factors are upregulated by reactive Schwann cells while potentially inhibitory molecules are removed. These experiments isolate the effects of one such inhibitory molecule, the myelin-associated glycoprotein (MAG), to determine its role in modifying regeneration after nerve repair. Suture of the mouse femoral nerve was followed by daily intraperitoneal injection of antibodies to MAG, antibodies to HNK-1, a specific muscle pathway marker, or no further treatment. Regeneration was assayed by double-labeling the femoral cutaneous and muscle branches with horseradish peroxidase and fluoro-gold after 4 weeks or 6 weeks of regeneration. Four weeks after nerve repair, selective reinnervation of the muscle branch by motoneurons, or preferential motor reinnervation (PMR), was not seen in either controls or L2-antibody-treated animals. In contrast, treatment with MAG antibodies resulted in dramatic PMR. By 6 weeks, the controls had achieved borderline specificity, substantial PMR developed in the L2 antibody group and the MAG group changed little. Blocking access to MAG in the distal nerve stump thus accelerated and enhanced PMR. Sensory regeneration was depressed by both antibody treatments at 4 weeks but recovered by 6 weeks. Antibody administration has a generalized effect on sensory regeneration that is unrelated to the behavior of motoneurons in the same nerve.

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.

Sensory neuropathy with monoclonal IgM binding to a trisulfated heparin disaccharide

We studied clinical and serological features of five patients with polyneuropathy and serum immunoglobulin M (IgM) binding to the trisulfated disaccharide IdoA2S-GlcNS-6S (TS-HDS), the most abundant disaccharide component of heparin oligosaccharides. The patients all had painful, predominantly sensory polyneuropathies. Sensory loss was distal and panmodal. Electrophysiological and pathological studies were consistent with axonal loss, especially of unmyelinated axons. Immunohistochemistry showed IgM and kappa light chains deposited around the rim of intermediate-sized veins in the perimysium and epineurium. Serum IgM binding to TS-HDS was selective, present in high titer (>12,000), and limited to kappa light chains. We conclude that TS-HDS is a newly identified target carbohydrate antigen of some IgM M-proteins. Monoclonal IgM binding to TS-HDS is associated with a painful, predominantly sensory, polyneuropathy syndrome with axonal loss and deposition of IgM in veins. The role of IgM binding to TS-HDS in the pathogenesis of the neuropathy remains to be determined.

Neuropathy and monoclonal gammopathy

The association of neuropathy with monoclonal gammopathy has been known for several years, even if the nosological position of these neuropathies is still debated. Similarly unsettled is the pathogenetic role and diagnostic relevance in clinical practice of the antineural antibodies frequently associated with monoclonal gammopathies of undetermined significance of IgM isotype, as well as the most effective therapy (if any) to be used in these patients. Over the past 12 months these issues have been addressed in several papers whose results will be critically reviewed here.