Entrapment in anti myelin-associated glycoprotein neuropathy

Entrapment partly participates in the longitudinal progression of neuropathy with anti-MAG antibodies

Neuropathy with anti-myelin-associated glycoprotein (MAG) antibodies commonly demonstrates distal-dominant prolongation of nerve conduction. However, recent electrophysiological studies have shown that distal motor demyelination is not always a distinct feature. We aimed to elucidate whether the longitudinal progression of nerve impairment occurs in a distal-dominant manner. Seven patients with neuropathy with anti-MAG antibodies were enrolled. Sequential nerve conduction studies revealed nerve conduction reduction only at the wrist segment in the median nerve of the patients, but not in the ulnar nerve. Median nerve entrapment at the wrist may play a role in longitudinal disease progression in neuropathy with anti-MAG antibodies.

Value of Antibody Determinations in Chronic Dysimmune Neuropathies

Chronic dysimmune neuropathies encompass a group of neuropathies that share immune-mediated pathomechanism. Chronic dysimmune antibody-related neuropathies include anti-MAG neuropathy, multifocal motor neuropathy, and neuropathies related to immune attack against paranodal antigens. Such neuropathies exhibit distinguishing pathomechanism, clinical and response to therapy features with respect to chronic inflammatory demyelinating polyradiculoneuropathy and its variants, which represent the most frequent form of chronic dysimmune neuropathy. This narrative review provides an overview of pathomechanism; clinical, electrophysiological, and biochemical features; and treatment response of the antibody-mediated neuropathies, aiming to establish when and why to look for antibodies in chronic dysimmune neuropathies.

Polyneuropathy Associated with IgM Monoclonal Gammopathy; Advances in Genetics and Treatment, Focusing on Anti-MAG Antibodies

With increasing age, the chances of developing either MGUS or polyneuropathy increase as well. In some cases, there is a causative relationship between the IgM M-protein and polyneuropathy. In approximately half of these cases, IgM targets the myelin-associated glycoprotein (MAG). This results in chronic polyneuropathy with slowly progressive, predominantly sensory neurological deficits and distally demyelinating features in nerve conduction studies. Despite the disease being chronic and developing slowly, it can cause considerable impairment. We reviewed English medical publications between 1980 and May 2022 on IgM gammopathy-associated polyneuropathy, with special attention to studies addressing the pathophysiology or treatment of anti-MAG polyneuropathy. Treatment options have been limited to a temporizing effect of intravenous immunoglobulins in some patients and a more sustained effect of rituximab but in only 30 to 55 percent of patients. An increase in our knowledge concerning genetic mutations, particularly the MYD88L265P mutation, led to the development of novel targeted treatment options such as BTK inhibitors. Similarly, due to the increasing knowledge of the pathophysiology of anti-MAG polyneuropathy, new treatment options are emerging. Since anti-MAG polyneuropathy is a rare disease with diverse symptomatology, large trials with good outcome measures are a challenge.

Neuropathy associated with immunoglobulin M monoclonal gammopathy: A combined sonographic and nerve conduction study

Introduction

We assessed the specific sonographic pattern of structural nerve abnormalities in immunoglobulin M (IgM) neuropathy and disease controls.

Methods

We enrolled 106 incident patients—32 patients with IgM neuropathy, 42 treatment‐naive patients with chronic inflammatory demyelinating polyneuropathy, and 32 patients with axonal neuropathies. All patients underwent standardized ancillary testing in addition to standardized sonography of the brachial plexus and the large arm and leg nerves bilaterally.

Results

We found widespread nerve enlargement in IgM neuropathy and chronic inflammatory demyelinating polyneuropathy (CIDP), with specific enlargement of brachial plexus and proximal segments of median nerve but not in axonal disease controls (P < .001). Sonographic nerve hypertrophy in IgM neuropathy was not associated with nerve conduction, clinical, or laboratory characteristics.

Discussion

Immunoglobulin M neuropathy is characterized by widespread nerve enlargement indistinguishable from CIDP. Our data provide evidence to confirm that the disease process is not confined to the more distal parts of nerves in either classical demyelinating or axonal variants of neuropathy with associated IgM.

Entrapment syndrome of multiple nerves in graft-versus-host disease

INTRODUCTION

Peripheral nerve entrapment syndromes are associated with hereditary neuropathy with liability to pressure palsies and a variety of rheumatic and endocrinological diseases.

METHODS

We report a patient with entrapment syndromes of multiple nerves associated with chronic graft-versus-host-disease (GVHD) after allogeneic hematopoietic stem cell transplantation. Nerve ultrasound, histology, and ultrastructural changes were assessed.

RESULTS

The 51-year-old man had developed severe deep dermal sclerosis due to chronic GVHD with a progressive polyneuropathy and entrapment syndromes of multiple nerves. Pre-stenotic enlargement was shown by nerve ultrasound. Histology demonstrated fibrosis of the epineurium with scarce infiltration of macrophages. Electron microscopy demonstrated alterations of the myelin sheaths and marked depletion of normal-sized myelinated nerve fibers.

CONCLUSIONS

In addition to polyneuropathy, chronic GVHD can be associated with peripheral nerve entrapment syndromes and should be added to the differential diagnosis of compressive neuropathies.

Update on neuropathies associated with monoclonal gammopathy of undetermined significance (2008-2010)

Studies on paraproteinemic neuropathies have appeared in the last 2 years improving the diagnosis of these neuropathies, clarifying their pathogenesis, and informing practice by randomized clinical trial publications. Two recent randomized controlled trials with rituximab failed to provide evidence of efficacy in primary outcome measures, despite the fact that anti-myelin-associated glycoprotein (MAG) antibodies were reduced in most treated patients. This discrepancy, besides inducing the search for more effective therapy for this neuropathy, indicates that some aspects on the pathogenesis of this neuropathy probably need further clarification.