[Axonal motor neuropathy associated with anti-SGPG antibody]

We report a case of axonal motor neuropathy associated with anti-sulfated glucuronic paragloboside (SGPG) antibody which has not been reported yet. A 49-year-old man was admitted with asymmetrical patchy weakness which started in his upper extremities. The deep tendon reflexes were absent in the upper extremities, but normal in the lower extremities. There was a slight decrease in the vibratory sensation in the distal portions of the lower extremities. The general laboratory tests including the protein level of the cerebrospinal fluid revealed no abnormalities. Motor conduction studies showed the low amplitudes of CMAP and no demonstrable conduction block in the limbs. Sensory conduction studies showed no abnormalities except for slightly decreased amplitude of SNAP in the limbs. Electromyography showed active denervation in the upper extremities. Serial electrophysiological studies suggested that the predominant process was axonal degeneration of the motor nerves. Thin-layer chromatography with immunostaining showed that his serum IgM reacted with SGPG. Treatment with cyclophosphamide and corticosteroids was unsuccessful. In this case, this anti-SGPG antibody may be involved in the pathogenesis of chronic axonal degeneration of the motor nerves.