Paraproteinemic neuropathies

Autoantibodies in chronic inflammatory neuropathies: diagnostic and therapeutic implications

The chronic inflammatory neuropathies (CINs) are rare, very disabling autoimmune disorders that generally respond well to immune therapies such as intravenous immunoglobulin (IVIg). The most common forms of CIN are chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), multifocal motor neuropathy, and polyneuropathy associated with monoclonal gammopathy of unknown significance. The field of CIN has undergone a major advance with the identification of IgG4 autoantibodies directed against paranodal proteins in patients with CIDP. Although these autoantibodies are only found in a small subset of patients with CIDP, they can be used to guide therapeutic decision-making, as these patients have a poor response to IVIg. These observations provide proof of concept that identifying the target antigens in tissue-specific antibody-mediated autoimmune diseases is important, not only to understand their underlying pathogenic mechanisms, but also to correctly diagnose and treat affected patients. This state-of-the-art Review focuses on the role of autoantibodies against nodes of Ranvier in CIDP, a clinically relevant emerging field of research. The role of autoantibodies in other immune-mediated neuropathies, including other forms of CIN, primary autoimmune neuropathies, neoplasms, and systemic diseases that resemble CIN, are also discussed.

Paraproteinemic neuropathy: a practical review

The term paraproteinemic neuropathy describes a heterogeneous set of neuropathies characterized by the presence of homogeneous immunoglobulin in the serum. An abnormal clonal proliferation of B-lymphocytes or plasma cells, which may or may not occur in the context of a hematologic malignancy, produces the immunoglobulins in excess. If malignancy is identified, treatment should be targeted to the neoplasm. Most cases, however, occur as monoclonal gammopathy of undetermined significance. Few prospective, randomized, placebo-controlled trials are available to inform the management of paraproteinemic neuropathies. Clinical experience combined with data from smaller, uncontrolled studies provide a basis for recommendations, which depend on the specific clinical setting in which the paraprotein occurs. In this review, we provide a clinically practical approach to diagnosis and management of such patients.

Analyzing Relationship Between Monoclonal Gammopathy of Undetermined Significance (MGUS) with Different Types of Neuropathy: An Observational Study

To analyze multiple variables, including immunoglobulin subtypes in patients with monoclonal gammopathy of undetermined significance (MGUS) and different types of neuropathy. This was a retrospective, single center study done in a tertiary care hospital in the United States. The data was collected for years 2001-2011. Inclusion criteria were the presence of MGUS and neuropathy. Exclusion criteria were the presence of other factors such as diabetes, vitamin B12 deficiency, alcoholism etc. which can cause neuropathy. Patients with IgM MGUS were compared with patients having Non-IgM MGUS. A total of 281 patients were analyzed in this study. The average age at the time of diagnosis of MGUS and neuropathy was 68 years. The most common type of neuropathy was sensorimotor peripheral neuropathy (46 %). The most common location of neuropathy was the lower extremities (68 %). Among our patients, 52 % had their neuropathy symptoms for 1-5 years before presenting to the clinic. When IgM MGUS was compared with Non-IgM MGUS, a statistically significant difference was found in terms of race (White vs. Others, OR 4.43, 95 % CI 2.13, 9.19, p < 0.001) and survival status (OR 1.98, 95 % CI 1.01, 3.90, p = 0.046). Patients with MGUS are prone to develop different types of neuropathies. Caucasians are more likely to have IgM MGUS as compared to other races. IgM MGUS is generally related to worse outcomes as compared to Non-IgM MGUS. Medical therapies, including gabapentin and pregabalin are effective treatments and the response rate can be as high as 80-90 % with these medications.

Cellular targets and mechanistic strategies of remyelination-promoting IgMs as part of the naturally occurring autoantibody repertoire

Immunoglobulins with germline sequences occur in invertebrates and vertebrates and are named naturally occurring autoantibodies (NAbs). NAbs may target foreign antigens, self- or altered self-components and are part of the normal immunoglobulin repertoire. Accumulating evidence indicates that naturally occurring antibodies can act as systemic surveillance molecules, which tag, damaged or stressed cells, invading pathogens and toxic cellular debris for elimination by the immune system. In addition to acting as detecting molecules, certain types of NAbs actively signal in different cell types with a broad range of responses from induction of apoptosis in cancer cells to stimulation of remyelination in glial cells. This review emphasizes functions and characteristics of NAbs with focus on remyelination-promoting mouse and human antibodies. Human remyelination-promoting NAbs are potential therapeutics to combat a wide spectrum of disease processes including demyelinating diseases like multiple sclerosis. We will highlight the identified glycosphingolipid (SL) antigens of polyreactive remyelination-promoting antibodies and their proposed mechanism(s) of action. The nature of the identified antigens suggests a lipid raft-based mechanism for remyelination-promoting antibodies with SLs as most essential raft components. However, accumulating evidence also suggests involvement of other antigens in stimulation of remyelination, which will be discussed in the text.

Clinical assessment of the sensory ataxias; diagnostic algorithm with illustrative cases

Ataxia is a common neurological syndrome resulting from cerebellar, vestibular or sensory disorders. The recognition and characterisation of sensory ataxia remains a challenge. Cerebellar ataxia is the more common and easier to identify; sensory ataxia is often mistaken for cerebellar ataxia, leading to diagnostic errors and delays. A coherent aetiological work-up is only possible if clinicians initially recognise sensory ataxia. We discuss ways to separate sensory from cerebellar ataxia, the causes of sensory ataxia and the clinico-neurophysiological syndromes causing the sensory ataxia syndromes. We summarise a logical tiered approach as a diagnostic algorithm.