Ultrastructural study of a muscle biopsy from a patient with subacute myelo-optic neuropathy.

A man, aged 46, who had been taking Clioquinol in high doses for a long period, developed a characteristic neurological syndrome of subacute myelo-optic neuropathy rather abruptly. Electron microscopical examination of the muscle biopsy, obtained five months after the onset of the disease, revealed severe degenerative changes of the presynaptic nerve endings and some unique paracrystalline inclusions in the sole plate region. The latter may represent the morphological expression of the toxic agent which is held responsible for the subacute myelo-optic neuropathy.