Giant axonal neuropathy. Endocrinological and histological studies.

A case of giant axonal neuropathy (GAN) in a boy of 4 years and 6 months, is reported. Nerve conduction velocity (NCV), EEG and CT scan indicated both peripheral and central nervous system involvement. Intestinal absorption tests did not reveal vitamin B12 malabsorption; the endocrine situation was found to be substantially normal. The clinical picture was not modified by 18 months cyanocobalamine administration followed by 2 months therapy with prednisone. Electron microscopic (EM) examination revealed longitudinal and opposing grooves (pili canaliculi) in the hair and bundles of neuro-filaments in the myelinated and unmyelinated nerve fibre axons in sural nerve. EM of conjunctiva and skin revealed masses of intermediate-sized filaments within mast cells, fibroblasts, melanocytes, endothelial and Schwann cells. These findings confirm the hypothesis that GAN is a generalised abnormality of cytoplasmic microfilament formation, probably linked to an unknown disorder of protein metabolism.