Motor nerve biopsy in severe Guillain‐Barré syndrome

Abstract
We undertook a biopsy of a terminal branch of the musculocutaneous nerve in a man with severe Guillain‐Barré syndrome and very small distally evoked action potentials. The biopsy showed pronounced subperineurial edema, macrophage infiltration, and many axons that had been completely demyelinated, some associated with intratubal macrophages. The biopsy unequivocally indentified the pathological process as primary demyelination, not axonal degeneration, and was more informative than previous reports of sural nerve biopsies in patients with Guillain‐Barré syndrome.