PARAPROTEINEMIC POLYNEUROPATHIES

A paraproteinemia is found in about 10% of patients with chronic polyn europathies. Monoclonal immunoglobulin M (IgM) with kappa light chain without associated B-cell disease are prevalent [monoclonal gammopathy of undetermined significance (MGUS)]. Anti-myelin-associated glycopro tein (anti-MAG) antibodies have been identified in about half the pati ents with IgM paraproteinemic neuropathy. The clinical picture is in m ost cases indistinguishable from chronic demyelinating inflammatory ne uropathy (CIDP) with symmetrical sensory symptoms in the beginning and motor deficits in the later course. CSF protein is normal or moderate ly elevated. Serum and urine immunoelectrophoresis and immunofixation are the crucial laboratory tests to establish the diagnosis of parapro teinemia. Nerve conduction studies, electromyography and histology rev eal a demyelinating neuropathy with varying degrees of axonal degenera tion. Corticosteroids, plasma exchange and high-dose i.v. immunoglobul in G are the recommended standard therapy. In patients with malignant gammopathies, a combined therapy with corticosteroids, antineoplastic chemotherapy and radiotherapy may be necessary. In most cases, neuropa thic symptoms gradually improve with therapy but residual deficits may persist.