Differential diagnosis of chronic dysimmune demyelinating polyneuropathies with and without anti-MAG antibodies

The distinction between chronic demyelinating polyneuropathies associated with IgM paraproteinemia and anti-myelin-associated glycoprotein (MAG) antibodies (MAG-PN) and chronic inflammatory demyelinating polyneuropathies (CIDPs) relies on the anti-MAG antibodies assay. The aim of the study was to identify clinical and electrophysiological features suggesting a diagnosis of MAG-PN. Fourteen patients with MAG-PN and 35 with COP were included, and a discriminant analysis was performed to identify the clinical and electrophysiological features suggestive of MAG-PN. Pure sensory clinical phenotype, low median and ulnar terminal latency index, and absence of M responses in the lower limbs were significantly associated with the diagnosis of MAG-PN, and indicate a moderate to large increase in probability of this diagnosis in patients with chronic dysimmune demyelinating polyneuropathies.