EPIDEMIC NEUROPATHY IN CUBA - MORPHOLOGICAL CHARACTERIZATION OF PERIPHERAL-NERVE LESIONS IN SURAL NERVE BIOPSIES

More than 50 000 patients were affected in Cuba during an epidemic out break of peripheral neuropathy from January 1992 until September 1993. The disease presented as either a retrobulbar optic neuropathy, a pre dominantly sensory peripheral neuropathy, a dorsolateral myeloneuropat hy, or as mixed forms. The morphological findings in sural nerve biops ies from 34 patients with various forms of the disease are presented h ere. Frozen, paraffin and semi-thin sections were prepared for light a nd electron microscopy, immunohistochemistry and morphometric analysis . Every case presented morphological alterations ranging from mild axo nal dystrophy (9 cases, or 27%) to moderate and severe atonal damage ( 25 cases, or 73%). In 6 cases (18%), axonal damage was accompanied by perineural fibrosis and vascular abnormalities. Axonal regeneration wa s noted in 8 cases (23%) and remyelination in 9 (26%). Morphometric an alysis showed a predominant loss of myelinated fibers in 92% of the pa tients. Quantification of myelinated fiber loss in 11 patients reveale d a remarkable decrease in large caliber fibers. Scarce mononuclear ce lls were observed in 17 cases. No virus-like elements were seen. The m orphological features found in this study indicate that, regardless of the clinical presentation, peripheral nerve lesions of the epidemic n europathy in Cuba correspond to an axonal neuropathy. These lesions ar e compatible with nutritional, toxic, or metabolic etiologies. An infl ammatory etiology would be unusual with these lesions.