Serum hyperviscosity has been identified in a variety of pathological conditions, including macroglobulinemia (Waldenström), certain polyclonal gammopathies, and, rarely, multiple myeloma.1-9 The hyper-viscosity syndrome1-4 may lead to malaise, hemorrhagic diathesis, ocular disturbances, Ménière's syndrome, central nervous system dysfunction, or renal and cardiac abnormalities, depending upon the organs primarily affected. Plasmapheresis1,2,4,8,10-13 may be the only effective therapy. This report describes two patients with IgG-K multiple myeloma and severe hyperviscosity syndrome. Life-threatening manifestations of serum hyper-viscosity, hemorrhage in one patient, and bizarre neurological dysfunctions in the other responded to vigorous plasmapheresis.
—A 54-year-old Negro woman was admitted in January 1969 with a three-month history of low back pain, anemia, and a bone marrow determination compatible with multiple myeloma. There was mild arteriolar narrowing in the ocular fundi, tenderness over the lower thoracic and lumbar spine, pain on truncal movement, and generalized hyperactive reflexes. Findings of