Considerations About a Possible Role Played by Connective Tissue Proliferation and Vascular Disturbances in the Pathogenesis of Progressive Muscular Dystrophy

Abstract

The connective tissue increase within the muscle seen in progressive muscular dystrophy (PMD) is surely not an "apparent" finding and is probably not a mere ''replacement fibrosis'' and that many considerations speak in favor of a noxa involving both the muscle fibers (causing degeneration) and the endomysial and perimysial connective tissue (stimulating their proliferation). It is suggested that the marked thickening of the pericellular reticulum sheath and the proliferation of the endomysium and perimysium, resulting in an alteration of the intercellular substance and in a derangement of the capillary network, cannot be considered to be without effects on muscle fiber nutrition. Several direct and indirect proofs of the presence in PMD of a vascular disturbance (disorder of the micro-circulation) which is ischemic in nature were collected. Hypotheses about the reasons for the early involvement of the proximal muscles in PMD, the cause of the deterioration resulting from the bed-rest in patients suffering from the Duchenne type PMD, possible explanations for the resemblance between the histopathological picture of PMD and that of subacute polymyositis and mechanism explaining the enlargement and atrophy of muscle fibers and central migration of the nuclei, were proposed. The possibility that ischemia and connective tissue proliferation play a major role in the pathogenesis of PMD was discussed.