Acute relapsing sensory neuropathy associated with IgM antibody against B-series gangliosides containing a GalNAc beta 1-4(Gal3-2 alpha NeuAc8-2 alpha NeuAc)beta 1 configuration.

We report a patient with a relapsing form of the acute sensory neuropathy syndrome associated with IgM-kappa type monoclonal gammopathy of undetermined significance. He rapidly developed marked sensory ataxia without weakness following an upper respiratory tract infection at age 44. The symptoms reached their maximum in a few days, followed by subsequent gradual improvement over a few weeks. However, unsteady gait remained as a chronic deficit. Stepwise progression of his symptoms occurred over 15 years with 10 similar relapses. Sensory nerve conduction studies showed the absence of action potentials, and sural nerve biopsy revealed the marked loss of large myelinated fibers. The patient's serum had an extremely high titer of an IgM monoclonal antibody directed against gangliosides GD2, GD1b, GT1b, and GQ1b.