High-resolution agarose gel electrophoresis, combined with immunofivation electrophoresis, was used to detect and identify immunoglobulins in the cerebrospinal fluid of six patients with paraproteinemic polyneuropathy. In four patients with serum IgMK monoclonal protein, we found a discrete band in the Cerebrospinal fluid identified also as IgMK; one patient with serum IgGK had an IgGK cerebrospinal fluid band, and one patient with serum IgAK had an IgAK monoclonal band in the cerebrospinal fluid. The permeability of the blood-cerebrospinal fluid barrier was increased 3 to 10 times in all these patients. The findings indicate that in patients with paraproteinemic polyneuropathy, the increased permeability of the blood-cerebrospinal fluid barrier results in influx of serum proteins into the cerebrospinal fluid, including high-molecular-weight IgM. Because monoclonal IgM, unlike monoclonal IgG and IgA, is not found in the cerebrospinal fluid of neurologically intact patients, its presence in the cerebrospinal fluid of patients with paraproteinemias should lead the physician to suspect neurological involvement and can be of diagnostic value.
Dalakas MC, Papadopoulos NM: Paraproteins in the spinal fluid of patients with paraproteinemic polyneuropathies. Ann Neurol 15.590-593, 1984 The association of peripheral neuropathy with paraproteinemias is well recognized El-4, 9, 11, 14-16, 18, 271, but the role of paraprotein in the pathogenesis of neuropathy remains uncertain. Although in some patients paraproteins have antibody-binding activity to peripheral nerve components [I, 3, 11, 15, 18}, they can also be immunoreactive with central nervous system (CNS) tissue { 151, including multiple central and peripheral myelin proteins 1181, without causing CNS disease. In addition, paraproteinemias can be associated with other neurological illnesses, some of which exclusively affect the CNS, including at least 15 reported cases of amyotrophic lateral sclerosis [9, 10, 201 and several cases of Parkinson's disease, multiple sclerosis, dementia, cervical spondylosis, myasthenia gravis, and cerebellar ataxia E9, 13, 261, suggesting that there is a