Polyneuropathies associated with high titre antisulphatide antibodies: characteristics of patients with and without serum monoclonal proteins.

Objectives: Previous studies of small numbers of patients have shown that antisulphatide autoantibodies are associated with polyneuropathies having a prominent sensory component. However, clinical and electrodiagnostic features are variable. The range of clinical and electrodiagnostic findings in 19 patients with polyneuropathies and high titre (> 4500) serum IgM antisulphatide antibodies is described, together with testing for serum monoclonal (M) proteins.

Methods: About 20000 serum samples that were referred to the clinical laboratory from 1990 to the end of 1994 were screened by enzyme linked immunosorbent assay (ELISA) for specific high titre antisulphatide antibodies. The clinical and electrodiagnostic data in 23 patients with positive results were reviewed. IgM binding to peripheral nerve structures was also evaluated in these patients.

Results: Nineteen patients had predominantly distal, symmetric pansensory loss. Patients with IgM antisulphatide antibodies and no serum M protein usually had clinical syndromes that included: (1) neuropathic pain or dysaesthesiae, (2) no functionally significant weakness, and (3) an axonal neuropathy on electrodiagnostic testing. On immunocytochemical studies serum IgM from the patients without M proteins usually (nine of 10; 90%) bound to peripheral nerve axons, but never to myelin. Patients with antisulphatide antibodies and a serum M protein, usually IgM, were more likely than patients without a serum M protein, to have syndromes with: (1) no pain or dysaesthesiae, (2) motor abnormalities, and (3) a demyelinating polyneuropathy by electrodiagnostic criteria. In immunocytochemical studies serum IgM most often bound to either peripheral nerve myelin or endoneurial structures.

Conclusion: Patients with polyneuropathy and high titre serum IgM antisulphatide antibodies can be classified into subgroups according to the presence or absence of a serum M protein. Patients without an M protein are more likely to have pure sensory syndromes, pain, an axonal neuropathy, and serum IgM binding to axons. Patients with a serum M protein commonly had syndromes with prominent motor involvement, no pain, and a demyelinating neuropathy.