Report of Consensus Panel 1 from the 12th International Workshop on the management of patients with IgM and Waldenstrom's Macroglobulinemia related neuropathy.

The IgM-related peripheral neuropathies (IgM-PN) are a group of chronic disorders characterized by the presence of monoclonal IgM that may be associated with one of several diseases affecting the peripheral nerves. In many cases, there is a monoclonal IgM associated with activity against neural targets, leading to progressive peripheral nerve demyelination. Neurological symptoms in this setting can also result from direct invasion of the peripheral or central nervous system by lymphoplasmacytic cells (neurolymphomatosis and Bing-Neel syndrome respectively) or via other mechanisms (for example AL amyloid deposition or cryoglobulinemic vasculitis). There is an expanding array of treatment options, but high-quality data are sparse. Diagnostic accuracy is important and needs collaboration between hematologists and neuromuscular specialists to determine the sequence and intensity of investigations. Appropriate causal attribution to the IgM disorder is essential to enable the correct therapeutic intervention. The aims of treatment intervention should be clear and realistic. Consistent and clinically meaningful measures are needed to capture treatment success. Despite therapeutic advances, many patients experience persistent disability, highlighting the need for further research.