[A case of chronic pure motor neuropathy associated with anti-GalNAc-GD1a-IgM antibody]

The patient was a 34-year-old male with chronic pure motor neuropathy with such acute onset as seen in Guillain-Barré syndrome. Neurological symptoms were gradually progressive for 4 weeks, and predominantly noted in the left side. Deep reflexes were normal and the distribution of muscle weakness was uneven. Plasma exchange reduced neurological symptoms. Four weeks later, right drop foot was relapsed. High dose intravenous immunoglobulin was effective. Serial electrophysiological studies indicated the asymmetric reduction of CMAP. Repeated assays of anti-GalNAc-GD1a IgM antibody were positive. This is the first report of chronic pure motor neuropathy as multiple mononeuritric type associated with anti-GalNAc-GD1a IgM antibody. This case adds to our knowledge better understanding of the pathogenetic role of anti-GalNAc-GD1a IgM antibody in inflammatory neuropathies.