Introduction: Antibodies directed against Myelin-Associated Glycoprotein (MAG) are found in some patients who have a demyelinating peripheral neuropathy which is predominantly sensory and follows a slowly progressive course. The disease often results in significant disability from sensory ataxia and weakness. Anti-MAG antibody is often associated with IgM paraprotein on protein electrophoresis. Nerve conduction studies reveal demyelination without conduction block with prolonged distal latencies. Nerve biopsy shows a characteristic widening of the myelin lamellae. Treatment options for this condition have been limited by poor efficacy, even though there is evidence of autoimmune causality. Response to steroids, cyclophosphamide, plasma exchange and intravenous immunoglobulin has been disappointing. Rituximab, however, has been shown to be beneficial in this condition.
Methods: We have reviewed the patients with neuropathy with anti-MAG antibody. The patient charts have been retrospectively reviewed and the nerve conduction study results provided.
Results: There were 7 patients, 5 males and 2 females. The mean age was 71.4 years. The clinical features were of sensory loss, maximal distally, and mild weakness. EMG/NCS revealed symmetric, length-dependent demyelinating neuropathy without conduction block. One patient developed melanoma after the onset of neuropathy. As therapy, we used PE, IVIG and Rituximab. Where Rituximab was used, the clinical course was stabilized or improved.
Discussion: This series confirms the male predominance and the typical distal demyelinating picture. Attempts at therapy led to stabilization of disease but no improvement. Rituximab therapy was safe. In one case, there is a suggestion of disease activity related to melanoma that warrants further investigation.