Electron microscopical study of a nerve biopsy from a case in the chronic state of “Subacute Myelo-Optico-Neuropathy”

N. suralis, taken from a patient in the chronic state of “Subacute Myelo-Optico-Neuropathy (SMON)” was examined by electron microscopy. The nerve showed a depletion of myelinated nerve fibres. Vacuoles or degenerated mitochondria were observed in the axis cylinders of myelinated and unmyelinated nerve fibres. Schwann cells were increased in number and many of them were atrophic. Onion-bulb formations were seen diffusely; regeneration of myelinated nerve fibres was sparse.