IgG monoclonal paraproteinaemia and peripheral neuropathy

Neurosurgical Intervention for Nerve and Muscle Biopsies

(1) Background: Neurologic and musculoskeletal diseases represent a considerable portion of the underlying etiologies responsible for the widely prevalent symptoms of pain, weakness, numbness, and paresthesia. Because of the subjective and often nonspecific nature of these symptoms, different diagnostic modalities have been explored and utilized. (2) Methods: Literature review. (3) Results: Nerve and muscle biopsy remains the gold standard for diagnosing many of the responsible neurological and musculoskeletal conditions. However, the need for invasive tissue sampling is diminishing as more investigations explore alternative diagnostic modalities. Because of this, it is important to explore the current role of neurosurgical intervention for nerve and muscle biopsies and its current relevance in the diagnostic landscape of neurological and musculoskeletal disorders. With consideration of the role of nerve and muscle biopsy, it is also important to explore innovations and emerging techniques for conducting these procedures. This review explores the indications and emerging techniques for neurological intervention for nerve and muscle biopsies. (4) Conclusions: The role of neurosurgical intervention for nerve and muscle biopsy remains relevant in diagnosing many neurological and musculoskeletal disorders. Biopsy is especially relevant as a supportive point of evidence for diagnosis in atypical cases. Additionally, emerging techniques have been explored to guide diagnostics and biopsy, conduct less invasive biopsies, and reduce risks of worsening neurologic function and other symptoms secondary to biopsy.

Nerve biopsy: Current indications and decision tools

After initial investigation of patients presenting with symptoms suggestive of neuropathy, a clinical decision is made for a minority of patients to undergo further assessment with nerve biopsy. Many nerve biopsies do not demonstrate a definitive pathological diagnosis and there is considerable cost and morbidity associated with the procedure. This highlights the need for appropriate selection of patients, nerves and neuropathology techniques. Additionally, concomitant muscle and skin biopsies may improve the diagnostic yield in some cases. Several advances have been made in diagnostics in recent years, particularly in genomics. The indications for nerve biopsy have consequently changed over time. This review explores the current indications for nerve biopsies and some of the issues surrounding its use. Also included are comments on alternative diagnostic modalities that may help to supplant or reduce the use of nerve biopsy as a diagnostic test. These primarily include extraneural biopsy and neuroimaging techniques such as magnetic resonance neurography and nerve ultrasound. Finally, we propose an algorithm to assist in deciding when to perform nerve biopsies.

CNS demyelination in monoclonal gammopathy of undetermined significance (MGUS): possible cause of a dementia syndrome

In acquired peripheral demyelinating disease only few publications point out the possibility of simultaneous involvement of the CNS. We describe two patients with chronic polyneuropathy and monoclonal gammopathy of undetermined significance (MGUS) developing a progressive dementia syndrome with extensive cerebral white matter alterations.

Monoclonal Gammopathy-Associated Peripheral Neuropathy: Diagnosis and Management

Monoclonal gammopathies comprise a spectrum of clonal plasma cell disorders that include monoclonal gammopathy of undetermined significance, multiple myeloma, and Waldenström macroglobulinemia. In this review, we outline the epidemiology, etiology, classification, diagnosis, and treatment of monoclonal gammopathy-associated peripheral neuropathy. Monoclonal gammopathy of undetermined significance is relatively common in the general population, with a prevalence of 3% to 4% among individuals older than age 50 years. Therefore, the presence of M protein in a patient with neuropathy does not automatically indicate a causal relationship. Monoclonal gammopathy-associated peripheral neuropathy is often a difficult diagnosis with limited treatment options. Studies addressing the optimal approach to diagnosis and management of this entity are limited. In addition to a review of the literature, we present a diagnostic approach to patients with monoclonal gammopathy-associated peripheral neuropathy and discuss available data and options for treatment.

[A case of sensory ataxic axonal polyneuropathy with IgGλ monoclonal gammopathy successfully treated with intravenous immunoglobulin therapy]

We report the case of an 84-year-old man with sensory ataxic polyneuropathy and IgGλ monoclonal gammopathy of undetermined significance (MGUS), which was successfully treated with intravenous immunoglobulin (IVIG) therapy. He had developed progressive ataxic gait over the span of 2 years before he was admitted to our hospital. On admission, he was unable to walk without assistance because of severe sensory ataxia. He performed poorly on the finger-nose-finger and heel-knee tests, and his vibration and position sense in the feet was remarkably diminished. However, motor involvement was not remarkable. Serum immunoelectrophoresis revealed IgGλ monoclonal gammopathy, and MGUS was diagnosed. Nerve conduction studies revealed sensory-dominant axonal polyneuropathy. The patient was successfully treated with IVIG (400 mg/kg/day, for 5 days). He regained his capacity to walk independently after treatment, but his nerve conduction results remained unchanged. This sensory ataxia might be partially due to underlying cervical spondylotic myelopathy. To our knowledge, this is the first report in our country of the successful use of IVIG therapy to treat a patient with IgGλ monoclonal gammopathy and related sensory ataxic axonal polyneuropathy.

Ultrasound of the nerves - An appropriate addition to nerve conduction studies to differentiate paraproteinemic neuropathies

OBJECTIVE

To investigate the use of peripheral nerve ultrasound (PNUS) in addition to nerve conduction studies (NCS) in the diagnosis of paraproteinemic neuropathies (PN).

METHODS

PNUS/NCS of predefined peripheral nerves and the 5th/6th cervical roots were performed in patients with chronic inflammatory demyelinating polyneuropathy (CIDP) (+/-paraprotein), patients with anti-MAG neuropathy, and patients with neuropathy and multiple myeloma or monoclonal gammopathy of uncertain significance (MGUS) - summarized as M-protein associated neuropathies (MPAN) and compared to controls (+/-paraprotein).

RESULTS

39 patients and 27 age-matched controls were included. Nerve enlargement was most marked in patients with CIDP, while in anti-MAG neuropathies enlargement was significant in the legs. In MPAN, no nerve enlargement is found regularly. However, in two cases, the diagnostic steps were influenced by the finding of multiple enlarged nerves and finally immunotherapy response was successfully initiated. By the use of the ultrasound pattern sum score (UPSS), differentiation of PN can be simplified.

DISCUSSION

Due to the heterogeneous findings in NCS, correct diagnosis of PN, and straightforward therapeutic decisions often may be controversial. Particularly in cases of M-protein related neuropathy, the finding of multiple nerve enlargements facilitates the decision for therapeutic approaches or nerve biopsy. The UPSS enables the distinction of different PN from each other.

CONCLUSION

The use of an ultrasound quantification tool in addition to NCS facilitates a differentiation of PN.

Treatment for IgG and IgA paraproteinaemic neuropathy

BACKGROUND

Paraproteinaemic neuropathy refers to those neuropathies associated with a monoclonal gammopathy or paraprotein. The most common of these present with a chronic, predominantly sensory, symmetrical neuropathy, similar to chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) but with relatively more sensory involvement, both clinically and neurophysiologically. The optimal treatment for neuropathies associated with IgG and IgA monoclonal gammopathy of uncertain significance is not known. This is an update of a review first published in 2007.

OBJECTIVES

To assess the effects of any treatment for IgG or IgA paraproteinaemic peripheral neuropathy.

SEARCH METHODS

On 18 January 2014 we searched the Cochrane Neuromuscular Disease Group Trials Specialized Register, CENTRAL, MEDLINE and EMBASE. We also checked bibliographies for controlled trials of treatments for IgG or IgA paraproteinaemic peripheral neuropathy. We checked clinical trials registries for ongoing studies in November 2014.

SELECTION CRITERIA

We considered for inclusion randomised controlled trials (RCTs) and quasi-RCTs using any treatment for IgG or IgA paraproteinaemic peripheral neuropathy. We excluded people with IgM paraproteins. We excluded people where the monoclonal gammopathy was considered secondary to an underlying disorder. We included participants of any age with a diagnosis of monoclonal gammopathy of uncertain significance with a paraprotein of the IgG or IgA class and a neuropathy. Included participants were not required to fulfil specific electrophysiological diagnostic criteria.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methodology to select studies, extract data and analyse results. One trial author provided additional data and clarification.

MAIN RESULTS

We identified one RCT, with 18 participants, that fulfilled the predetermined inclusion criteria. The trial compared plasma exchange to sham plasma exchange in participants with IgG or IgA paraproteinaemic neuropathy over a three-week follow-up period. We identified four other studies but these were not RCTs or quasi-RCTs. The included RCT did not report our predefined primary outcome measure, change in disability six months after randomisation. The trial revealed a modest benefit of plasma exchange in the weakness component of the Neuropathy Disability Score (NDS, now the Neuropathy Impairment Score); the mean improvement with plasma exchange was 17 points (95% confidence interval (CI) 5.2 to 28.8 points) versus 1 point (95% CI -7.7 to 9.7 points) in the sham exchange group at three weeks' follow-up (mean difference (MD) 16.00; 95% CI 1.37 to 30.63, low quality evidence). There was no statistically significant difference in the overall NDS (MD 18.00; 95% CI -2.03 to 38.03, low quality evidence), vibration thresholds or neurophysiological indices. Adverse events were not reported. The trial was at low risk of bias overall, although limitations of trial size and duration reduce the quality of the evidence in support of its conclusions.

AUTHORS' CONCLUSIONS

The evidence from RCTs for the treatment of IgG or IgA paraproteinaemic neuropathy is currently inadequate. More RCTs of treatments are required. These should have adequate follow-up periods and contain larger numbers of participants, perhaps through multicentre collaboration, considering the relative infrequency of this condition. Observational or open trial data provide limited support for the use of treatments such as plasma exchange, cyclophosphamide combined with prednisolone, intravenous immunoglobulin, and corticosteroids. These interventions show potential therapeutic promise but the potential benefits must be weighed against adverse effects. Their optimal use and the long-term benefits need to be considered and validated with well-designed RCTs.

Paraproteinemic neuropathies

The term paraproteinemic neuropathy refers to a heterogeneous group of neuropathies, which share the common feature of a homogeneous immunoglobulin in the serum. The presence of a monoclonal gammopathy indicates an underlying clonal B-cell expansion, which may appear in the context of a lymphoproliferative disorder. If a neoplastic origin of the gammopathy is identified, the treatment should be targeted to the neoplasm. In most patients, however, the monoclonal gammopathy is not associated with malignant haematological disorders, and is defined as monoclonal gammopathy of undetermined significance.

Chronic inflammatory demyelinative polyneuropathy

Chronic inflammatory demyelinative polyneuropathy (CIDP) is an acquired polyneuropathy presumably of immunological origin. It is characterized by a progressive or a relapsing course with predominant motor deficit. The diagnosis rests on the association of non-length-dependent predominantly motor deficit following a progressive or a relapsing course associated with increased CSF protein content. The demonstration of asymmetrical demyelinating features on nerve conduction studies is needed for diagnosis. The outcome depends on the amplitude of axon loss associated with demyelination. CIDP must be differentiated from acquired demyelinative neuropathies associated with monoclonal gammopathies. CIDP responds well to treatment with corticosteroids, intravenous immunoglobulins, and plasma exchanges, at least initially.

Correlations of nerve conduction measures in axonal and demyelinating polyneuropathies

OBJECTIVE

In a considerable proportion of patients with polyneuropathy the electrophysiological distinction between primarily demyelinating or axonal pathology is not straightforward. This study aimed at determining whether the relation between the sensory nerve action potential (SNAP)/compound muscle action potential (CMAP) amplitude and conduction velocity (CV) or distal motor latency (DML) in demyelinating versus axonal polyneuropathy could be helpful in distinguishing these two pathophysiologies.

METHODS

The relation between amplitude reduction and conduction slowing was performed using regression analysis in nerve conduction studies from 53 axonal polyneuropathies and 45 demyelinating polyneuropathies. Sensory nerve conduction studies were performed using the near-nerve needle technique. Finally, needle EMG findings in 31 muscles in axonal and in 22 muscles in demyelinating polyneuropathies were compared.

RESULTS

A linear correlation between action potential amplitude and CV was seen in the majority of nerves in both axonal and demyelinating polyneuropathies. Further, an inverse linear correlation between CMAP amplitude and DML was found in most of the nerves in axonal polyneuropathies. The incidence and degree of abnormality, including decrease in action potential amplitude, was more pronounced in demyelinating than in axonal polyneuropathies, while there was no difference in EMG findings.

CONCLUSIONS

Amplitude reduction and conduction slowing were correlated in axonal as well as demyelinating polyneuropathies, and a significant reduction in SNAP and CMAP amplitudes was found in demyelinating as well as axonal polyneuropathies. The correlation in axonal polyneuropathies can be attributed to a concomitant or selective loss of large, fast conducting fibers, whereas the correlation in demyelinating polyneuropathies may be explained by temporal dispersion or secondary axonal degeneration.

SIGNIFICANCE

At present, relation between amplitude reduction and conduction slowing does not seem to be useful in revealing the primary pathophysiology of a polyneuropathy. Decrease in CV, increase in DML, increase in F-wave latency, conduction block and temporal dispersion should mainly be considered. Decrease in amplitude must be interpreted with caution.

Polyneuropathy associated with IgA paraproteinemia and amyloidosis: a case report and literature review

Paraproteinemia potentially causes peripheral neuropathy via an unknown underlying pathogenetic mechanism. We report a case of pathologically proven amyloid neuropathy with AL amyloidosis with an IgA kappa light chain, which was initially diagnosed as neuropathy associated with monoclonal gammopathy of undetermined significance. This case indicates that in cases of neuropathy with paraproteinemia, the other potential causes should be excluded by appropriate means, especially pathological evaluations.

Treatment for IgG and IgA paraproteinaemic neuropathy

BACKGROUND

Paraproteinaemic neuropathy refers to those neuropathies associated with a monoclonal gammopathy or paraprotein. Typically it presents with a chronic predominantly sensory, symmetrical neuropathy, similar to chronic inflammatory demyelinating polyradiculoneuropathy but with relatively more sensory involvement, both clinically and neurophysiologically. The optimal treatment for IgG and IgA monoclonal gammopathy of uncertain significance neuropathies is not known.

OBJECTIVES

The objective of this review is to examine the efficacy of any treatment for IgG or IgA paraproteinaemic peripheral neuropathy.

SEARCH STRATEGY

We performed searches of the Cochrane Neuromuscular Disease Group Trials register (May 2005), MEDLINE (from January 1966 to May 2005), EMBASE (from January 1980 to May 2005). We also checked bibliographies for controlled trials of treatments for IgG or IgA paraproteinaemic peripheral neuropathy.

SELECTION CRITERIA

We included randomised and quasi-randomised controlled trials using any treatment for IgG or IgA paraproteinaemic peripheral neuropathy. People with IgM paraproteins were excluded. We excluded participants where the monoclonal gammopathy was considered secondary to an underlying disorder. We included participants of any age with a diagnosis of monoclonal gammopathy of uncertain significance with a paraprotein of the IgG or IgA class and a neuropathy. Included participants were not required to fulfil specific electrophysiological diagnostic criteria.

DATA COLLECTION AND ANALYSIS

The full texts of potentially relevant studies were obtained and assessed and independent data extraction was performed by three authors. Additional data and clarification were received from one author.

MAIN RESULTS

We identified only one randomised controlled trial with 18 participants which fulfilled the predetermined inclusion criteria. Four other trials were identified but these were not randomised controlled trials. The included trial revealed a modest short-term benefit of plasma exchange in IgG or IgA paraproteinaemic neuropathy, over a short follow-up period, when compared to sham plasma exchange.

AUTHORS' CONCLUSIONS

The evidence from randomised controlled trials for the treatment of IgG or IgA paraproteinaemic neuropathy is currently inadequate. More randomised controlled trials of treatments are required. These should have adequate follow-up periods and contain larger numbers of participants, perhaps through multicentre collaboration, considering the relative infrequency of this condition. Observational or open trial data provide limited support for the use of treatments such as plasma exchange, cyclophosphamide combined with prednisolone, intravenous immunoglobulin and corticosteroids. These show potential therapeutic promise but the potential benefits must be weighed against adverse effects. Their optimal use and the long-term benefits need to be considered and validated with well-designed randomised controlled trials.

Chronic inflammatory demyelinating polyneuropathy

Chronic inflammatory demyelinative polyneuropathy (CIDP) is an acquired neuropathy, presumably of immunological origin. Its clinical presentation and course are extremely variable. CIDP is one of the few peripheral neuropathies amenable to treatment. Typical cases associate progressive or relapsing-remitting motor and sensory deficit with increased CSF protein content and electrophysiological features of demyelination. In other instances the neuropathy is predominantly or exclusively motor or sensory, CSF normal and electrophysiological studies fail to show evidence of demyelination. In such cases conventional diagnostic criteria are not filled yet the patient may respond to immunomodulatory treatments. In this paper we review the diagnostic pitfalls and clinical variants of CIDP to illustrate the problems that may arise. The different therapeutic options are reviewed. Axon loss associated with demyelination is the most important factor of disability and resistance to treatment.

Paraproteinemic neuropathies

The occurrence of a peripheral neuropathy (PN) in association with a monoclonal gammopathy is quite common and suggests that monoclonal proteins may play a pathogenetic role in peripheral nervous system damage. In fact, paraproteinemic PN constitute an heterogeneous group of disorders related to various pathogenetic factors, and the histopathologic features in peripheral nerve biopsies differ from one condition to another. In several well defined disorders, the responsibility of the monoclonal component in the development of the PN has been evidenced. This is the case for most of the PN associated with an IgM monoclonal gammopathy, either a monoclonal gammopathy of undetermined significance (MGUS) or Waldenstrom's macroglobulinemia. The responsibility of the monoclonal protein in the occurrence of amyloid neuropathy related to multiple myeloma is also recognized. However, most IgG or IgA MGUS, as well as the monoclonal component in POEMS syndrome, have an uncertain causal relationship with the neuropathy. PN associated with monoclonal cryoglobulin (type 1) are occasional and differ from those associated with mixed cryoglobulins (types 2 or 3).

Pathogenesis of chronic inflammatory demyelinating polyradiculoneuropathy

The acute lesions of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) consist of endoneurial foci of chemokine and chemokine receptor expression and T cell and macrophage activation. The myelin protein antigens, P2, P0, and PMP22, each induce experimental autoimmune neuritis in rodent models and might be autoantigens in CIDP. The strongest evidence incriminates P0, to which antibodies have been found in 20% of cases. Failure of regulatory T-cell mechanism is thought to underlie persistent or recurrent disease, differentiating CIDP from the acute inflammatory demyelinating polyradiculoneuropathy form of Guillain-Barré syndrome. Corticosteroids, intravenous immunoglobulin and plasma exchange each provide short term benefit but the possible long-term benefits of immunosuppressive drugs have yet to be confirmed in randomised, controlled trials.

Different types of chronic inflammatory demyelinating polyneuropathy have a different clinical course and response to treatment

Chronic inflammatory demyelinating polyneuropathy (CIDP) can occur in association with other systemic diseases such as diabetes mellitus (DM) and IgG or IgA monoclonal gammopathy of undetermined significance (MGUS). Whether CIDP that is idiopathic (I-CIDP) or associated with diabetes (CIDP-DM) or MGUS (CIDP-MGUS) differ in clinical presentation, laboratory features, response to treatment, and long-term outcome is unclear, as is the relationship between these coexisting diseases and CIDP. In order to clarify this issue, we began a prospective follow-up study. Thirty-one consecutive patients with untreated CIDP, fulfilling the most restrictive diagnostic criteria, were enrolled over 18 months. Among the patients, 16 were diabetic, 7 had a MGUS, and 8 had an idiopathic CIDP. All patients were treated with IVIg, and the responders were treated again if they relapsed. In all three groups, improvement occurred after treatment. At the end of the follow-up, there was no difference in clinical conditions between groups, but a significant difference existed in the number of relapses and of IVIg administrations. CIDP-DM is a more severe disease, but with a significantly better response to IVIg and fewer relapses, than the other types that we studied.

Polyneuropathy associated with IgG/IgA monoclonal gammopathy: a clinical and electrophysiological study of 15 cases

Peripheral neuropathy has been widely reported in patients with monoclonal gammopathy (MG), more frequently immunoglobulin M (IgM) or IgG than IgA. Nevertheless, it remains unclear whether this association has clinical or pathogenic relevance. In order to clarify the possible role of IgG/IgA MG in neuropathy, we studied the clinical and electrophysiological features of 15 consecutive patients with polyneuropathy and IgG/IgA-MG, and compared them to those of 40 patients with polyneuropathy associated with IgM-MG, previously reported. Nine middle-aged patients (60%) had a chronic progressive or relapsing demyelinating polyneuropathy (DP) that was clinically and electrophysiologically indistinguishable from classic chronic inflammatory demyelinating polyneuropathy (CIDP) and frequently responded to immunosuppressive treatments, both characteristics supporting a dysimmune process. Six older patients (40%) had a chronic axonal distal polyneuropathy similar to the so-called chronic cryptogenic sensory polyneuropathy: there was no clear relationship with the MG in these patients and the response to immunosuppressive treatments was poor. Several features allowed us to distinguish between polyneuropathies associated with IgG/IgA-MG (IgG/IgA-PN) considered together and polyneuropathies associated with IgM-MG (IgM-PN). In the first group, the proportion of patients with a predominantly sensory clinical picture (27%) was less than that in the second group (75%), and there were fewer changes in nerve conduction studies. In addition, we found that the nine patients with DP associated with IgG/IgA-MG (IgG/IgA-DP) differed from the 31 with DP associated with IgM-MG (IgM-DP): clinical and electrophysiological studies clearly showed that the demyelinating pattern was more heterogeneous in IgG/IgA-DP than in IgM-DP. The spectrum of polyneuropathies associated with IgG/IgA-MG is heterogeneous, including DP, which is similar to classic CIDP, and axonal polyneuropathy, in which the pathogenic role of the MG remains elusive. In addition, IgG/IgA-DP differ from IgM-DP on clinical and electrophysiological grounds, suggesting probable different physiopathological mechanisms.

Different clinical, electrophysiological and immunological features of CIDP associated with paraproteinaemia

Chronic inflammatory demyelinating polyneuropathy (CIDP) is frequently associated with monoclonal gammopathies of undetermined significance (MGUS), Waldenström disease and osteosclerotic myeloma. There are still controversies about the role of these paraproteinaemias in determining the clinical features and the response to treatment of CIDP. We review the clinical, electrophysiological and immunological features and the response to treatment of patients with CIDP associated with paraproteinaemias. The available literature suggest some conclusions: presence of antimyelin-associated glycoprotein (MAG) antibody (Ab) identifies patients with mainly sensory CIDP and low response to treatment; CIDP associated with IgM-paraproteinaemia without anti-MAG Ab probably are similar to CIDP not associated with paraproteinaemia as well as CIDP with IgG- or IgA-MGUS; however, some patients with IgA-MGUS can show features similar to CIDP with IgM paraproteinaemia and anti-MAG Ab. Low response to immunomodulating treatment in patients with mainly motor CIDP should prompt a careful research of an underlying osteosclerotic myeloma.

Systematic reviews of treatment for inflammatory demyelinating neuropathy

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

Clinical features, evaluation, and treatment of patients with polyneuropathy associated with monoclonal gammopathy of undetermined significance (MGUS)

A number of common disorders of the peripheral nervous system are closely linked to a monoclonal gammopathy. In a minority of patients, the neuropathy represents the sentinel feature of a malignant plasma cell dyscrasia, such as multiple myeloma or its osteosclerotic variant, Waldenstrom's disease, amyloidosis, cryoglobulinemia or lymphoma; the vast majority have so-called "monoclonal gammopathy of undetermined significance" (MGUS). Sensory symptoms predominate with paresthesias, numbness, imbalance, and gait ataxia. Electrodiagnostic studies show mixed demyelinating and axonal features and often may be indistinguishable from findings in chronic inflammatory demyelinating polyneuropathy. Some have a pure axonal polyneuropathy, and in these patients the relationship to the paraprotein is less certain. With limited success, correlations have been made between the immunoglobulin type (IgM, IgG, or IgA) and the clinical and electromyographic characteristics of the neuropathy. The treatment of MGUS neuropathies poses a considerable challenge. Patients with IgG/IgA-MGUS have improved with corticosteroids or intravenous immune globulin. Only the benefit of plasma exchange has been substantiated in a controlled trial. The IgM neuropathies tend to be more refractory but often improve with similar regimens, particularly if cytotoxic agents are added in doses sufficient to reduce the amount of the M-protein. In addition to plasma exchange, chlorambucil, and cyclophosphamide, interferon-alpha is a novel therapy that holds promise for patients with IgM neuropathies associated with anti-myelin associated antibodies.

Clinical features and anti-neural reactivity in neuropathy associated with IgG monoclonal gammopathy of undetermined significance

Neuropathy has been frequently reported in patients with IgG monoclonal gammopathy of undetermined significance (MGUS) but it is still unclear whether this association has clinical or pathogenetic relevance. In order to clarify the possible role of IgG MGUS in the neuropathy we correlated the clinical and electrophysiological features of the neuropathy with the duration and anti-neural activity of the M-protein in 17 patients with neuropathy and IgG MGUS. Ten patients (59%) had a chronic demyelinating neuropathy clinically indistinguishable from chronic inflammatory demyelinating polyneuropathy (CIDP) while 7 (41%) had a predominantly sensory axonal or mixed neuropathy. In 80% of patients in the CIDP-like and 28% in the sensory group the IgG M-protein became manifest several months to years after onset of the neuropathy. Antibodies to one or more neural antigens (including tubulin, a 35KD P0-like nerve myelin glycoprotein, GD1a, GM1 and chondrotin sulfate C) were found in 40% of patients with CIDP-like and 43% with sensory neuropathy but also in 37% patients with IgG MGUS without neuropathy. Neuropathy associated with IgG MGUS is probably less heterogeneous than previously considered suggesting that this association may not be merely casual. The evidence for primary pathogenetic role of IgG M-proteins in the neuropathy remains however elusive.

Human autoimmune neuropathies

Peripheral nerve diseases are among the most prevalent disorders of the nervous system. Because of the accessibility of the peripheral nervous system (PNS) to direct physiological and pathological study, neuropathies have traditionally played a unique role in developing our understanding of basic mechanism of nervous system injury and repair. At present they are providing new insight into the mechanisms of immune injury to the nervous system. A rapidly growing catalogue of PNS disorders are now suspected to be immune-mediated, and in the best understood of these disorders, the molecular and cellular targets of immune attack are known, and the pathophysiology follows directly from the specific immune injury. This review summarizes the immunologically relevant features of the PNS, then considers selected immune-mediated neuropathies, focusing on pathogenetic mechanisms. Finally, the PNS is providing a testing ground for new immunotherapies and approaches to protection and regeneration, including the use of trophic factors. The current status of treatment and implications for future approaches is reviewed.

Coagulation and vascular abnormalities in Crow-Fukase syndrome

Coagulation and vascular abnormalities were studied in 4 patients with Crow-Fukase syndrome (CFS or POEMS) to understand the pathophysiology. Fibrinogen, fibrinopeptide A, and thrombin-antithrombin complexes (TAT) increased in sera during active phase of CFS. In nerves of 2 untreated cases, the endothelium of small vessels was immunohistochemically stained with antithrombin III antibody, which indicates the existence of TAT. HLA-DR+ inflammatory cell infiltrate surrounded these vessels. Blood-nerve barrier opening was suggested by strong immunoglobulin staining in the endoneurium. More than 50% of endoneurial blood vessels had narrowed or closed lumina with thick basement membranes. Endothelial cell abnormality and chronic intravascular coagulation may play an important role in the pathogenesis of CFS, in addition to a still unknown demyelinating factor. Refractory cases responded to combined treatment of prednisolone, human leukocyte interferon, and antithrombin drug.

Generation and characterization of anti-sulfoglucuronosyl paragloboside monoclonal antibody NGR50 and its immunoreactivity with peripheral nerve

Sulfoglucuronosyl paragloboside (SGPG) is a member of the sulfated glucuronic acid-containing glycolipid (SGGL) family found primarily in peripheral nerves. These glycolipids contain the HNK-1 carbohydrate epitope and are recognized by monoclonal IgM from patients with chronic demyelinating neuropathy and paraproteinemia. Recent studies indicate that SGGLs may serve as ligands for selectins, amphoterin, and laminin, suggesting that these glycolipids may play an important role in cellular adhesion. To elucidate the biological function of these glycolipids, we produced a murine monoclonal antibody (mAb) and studied its antigenic specificity. Using an enzyme-linked immunosorbent assay (ELISA), we found that the mAb designated as NGR50 belonged to the IgG2a subclass, and that the minimal titer (2 SD above the mean optical density value of control) of this mAb was 1:640, with 20 ng of purified SGPG as the antigen. Thin-layer chromatography (TLC) immunoblotting revealed that this mAb reacted specifically with SGPG and sulfoglucuronosyl lactosaminyl paragloboside (SGLPG), which is a structural analogue of the former, but not with other glycolipids. Desulfated derivates of SGPG and SGLPG did not react with mAb NGR50. Western blot analysis showed crossreactivity with human myelin-associated glycoprotein (MAG), but not with rat MAG or rat glycoprotein P0. Unlike anti-HNK-1 monoclonal antibody, however, NGR50 reacted only weakly with several proteins in the 20-30-kD regions, including human P0, suggesting that mAb50 has a different fine specificity as an anti-HNK-1 antibody. Immunocytochemical study of rat sciatic nerve using mAb NGR50 revealed positive staining at the outer surface of the myelin sheath and Schwann cells, as well as in the intervening connective tissues. Faint staining was also visible at the axolemmal-myelin interface; however, compact myelin was not stained.

Link between peripheral neuropathy and monoclonal dysglobulinemia: a study of 66 cases

The association of peripheral neuropathy (PN) and monoclonal dysglobulinemia has often been reported, although a direct link between the two is not readily established. Linkage is generally based on consideration of the clinical, electrophysiological and immunological findings along with details of the course. We report here a study of 66 of our own cases which benefitted from immunological and immunopathological analyses of serum. In 62 of these cases, histological and immunopathological examinations of nerve biopsy specimens were realized. Such a discussion about a link between the dysglobulinemia and the peripheral neuropathy is of clinical interest as it provides information for decisions about the continuation of potentially neurotoxic chemotherapy. In this prospective study conducted on a case by case basis, the origin of the neuropathy, whether due to the chemotherapy, the dysimmune process, the presence of abnormal immunoglobulins in the nerve, amyloid deposits, infiltration of nerve parenchyme by abnormal cells, or a combination of one or more of these mechanisms, could be determined in most cases. We divided our population of 66 patients into 4 etiological groups: group 1: direct link (56.1%), group 2: indirect link (12.7%), group 3: no link (10.6%), group 4: doubtful link (21.2%). In group 1 we found a statistically significant association between the peripheral neuropathy and an IgM kappa MGUS.

Guillain-Barré syndrome and chronic inflammatory demyelinating polyneuropathy: immune mechanisms and update on current therapies

The relation between Guillain-Barré syndrome and chronic inflammatory demyelinating polyneuropathy is discussed. Most likely they represent parts of a continuum, arbitrarily separated by their time course. Within the concept of chronic inflammatory demyelinating polyneuropathy the presence of a monoclonal gammopathy of undetermined significance is discussed. The pathogenesis of inflammatory demyelinating polyneuropathies has not been elucidated yet, but involvement of the immune system has been firmly established. Preceding infections, especially with Campylobacter jejuni, and the analysis of antiganglioside antibodies lend new support to the hypothesis of molecular mimicry between epitopes on infectious agents and peripheral nerve constituents as one of the mechanisms in Guillain-Barré syndrome. In the future, a further classification of individual patients based on clinical, epidemiological, electrophysiological, pathological, microbiological, and immunological criteria may give a basis for more individualized treatment strategies. In Guillain-Barré syndrome the efficacy of high-dose intravenous immune globulin treatment was established after earlier positive findings with plasma exchange; immune globulins are easier to administer and may be superior. Even with these treatments it should be anticipated that one fourth of patients after immune globulin treatment and one third of patients after plasma exchange will show further deterioration in the first 2 weeks after onset of treatment. Despite this, just one treatment course usually is indicated in the individual patient, and no valid arguments were found to switch to the other treatment modality. In chronic inflammatory demyelinating polyneuropathy, prednisone, plasma exchange, and immune globulins are effective in a proportion of patients. The last two are equally effective. Patients may respond to one of these if a previous treatment failed, and here switching therapy may be effective due to the chronic course of the disease. Complexity and costs make plasma exchange the last choice. Whether prednisone or immune globulin is the first choice depends on the speed of recovery and the estimation of long-term loss of quality of life due to side effects of prednisone versus the costs of immune globulins. The mechanism of immune globulins in inflammatory polyneuropathies is discussed. There is evidence that idiotypic-antiidiotypic interaction may play a role, but several other mechanisms also may be involved.

Investigation of peripheral neuropathy

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