Autoimmune Neuropathies - Neuropathic Disease

Antibody testing is not part of accepted diagnostic criteria or management strategies for autoimmune neuropathies. In most cases, such as in Guillain-Barré syndrome (GBS), the initial diagnosis is based on clinical presentation and is established if cerebrospinal fluid (CSF) and electrodiagnostic studies (eg, nerve conduction studies) show abnormalities.  Antibody testing may help to clarify the diagnosis, but cannot be used as the sole diagnostic tool.

Some antibodies show statistically significant associations with specific neuropathic syndromes. For example, antimyelin-associated glycoprotein (anti-MAG) antibodies are often present in patients with predominant sensory symptoms, and anti-GM1 antibodies are present in patients with predominant motor symptoms. Refer to the Nonparaneoplastic Markers and Paraneoplastic Markers tables for more examples.

Most antibody titers do not correlate with the level of disease activity in autoimmune neuropathies.

Monoclonal gammopathy of undetermined significance (MGUS) has a prevalence of 3-4% among those older than 50 years, and the presence of an M protein does not automatically indicate a causal relationship to the neuropathy.  Additional investigation is required to differentiate monoclonal gammopathy-associated peripheral neuropathy from specific plasma cell disorders (eg, immunoglobulin light chain amyloidosis, POEMS [polyneuropathy, organomegaly, endocrinopathy, monoclonal protein, skin changes] syndrome) that are known to have a definite causal relationship. 

Frequent differential diagnoses include infections (eg, West Nile virus, enterovirus, and poliovirus), myasthenia gravis, and other autoimmune diseases (eg, rheumatoid arthritis, systemic lupus erythematosus, Sjögren syndrome, and mixed connective tissue disease).