Neurologists commonly evaluate patients with a monoclonal gammopathy and peripheral neuropathy. As both monoclonal gammopathy and peripheral neuropathy are common in the general population, their coexistence may, in some instances, be purely coincidental. However, monoclonal gammopathies or underlying lymphoplasmacytic disorders can affect the peripheral nervous system by various mechanisms. This article discusses how to approach patients with monoclonal gammopathy and peripheral neuropathy, highlighting clinical and laboratory clues that may aid in establishing a diagnosis in a timely manner.
From a hematologic standpoint, a monoclonal gammopathy may be of undetermined significance or can be associated with an underlying myeloma, lymphoplasmacytic lymphoma, or amyloidosis. Each of these conditions can cause peripheral neuropathy, with varying clinical and electrodiagnostic profiles. Treatment usually consists of treating the underlying hematologic disorder. IgM-associated peripheral neuropathy may not require treatment from a hematologic standpoint, and only anecdotal evidence exists for the use of immunotherapy in such patients. Therefore, treatment should be determined on a case-by-case basis.
Evaluating for an association between a monoclonal gammopathy and a peripheral neuropathy in a patient depends on the monoclonal gammopathy subtype and the clinical and electrodiagnostic characteristics of the peripheral neuropathy.