Morphologic and metabolic studies in a case of oculo-cranio-somatic neuromuscular disease

Abstract

A case resembling the syndrome of "ophthalmoplegia plus" or "oculo-cranio-somatic neuromuscular disease" is reported. A biopsy of deltoid muscle showed that 23% of the fibers were "ragged-red fibers" and were all type 1. Study of their ultrastructure revealed clusters of abnormal skeletal muscle mitochondria in subsarcolemmal and intermyofibrillar spaces. A liver biopsy also revealed a considerable increase in the number and size of the mitochondria. In some instances the mitochondria contained osmiophilic rounded inclusions surrounded by myelin-like structures. Metabolic studies revealed an increase of blood lactate concentration after very light exercise, while the O2 consumption was increased within the expected range. It is concluded that: a) the association of ophthalmoplegia and ultrastructural alterations of the mitochondria in muscle fibers may represent a specific nosographic entity: b) mitochondrial abnormalities are not limited to the skeletal muscles and c) the dysmetabolic basis of such a clinico-pathological entity might lie in an alteration of the mechanism which regulates the mitochondrial oxidative phosphorylation.