Functional and clinical morphology of Virchow-Robin spaces: from the discovery up to the newest theories

Abstract

Morphology of cerebrospinal fluid flow structures in CNS is an important and complex area of research and is associated with the problems of metabolites transport, including pathological ones in neurodegenerative pathology, e.g., Alzheimer's disease. Since Virchow and Robin first described the perivascular spaces in the 19th century, their role in the transport of cerebrospinal fluid and intracerebral metabolites has been established. On the grounds of the 20th century studies, a modern theory of intracerebral liquor transport of metabolites, the glymphatic system theory, has emerged, creating the basis for new areas of treatment of neurodegenerative diseases. The article presents an overview of the history of description and study of CNS perivascular transport pathways, terminology issues and clinical problems such as amyloid transport and its disruption as a mechanism of Alzheimer's disease and glaucoma. We present our own descriptive data on the morphology of the perivascular spaces (PVS) of the rat brain in normal and simulated glaucoma-like increases in intraocular pressure. Structures corresponding to perivascular spaces (PVS) in their original description are present in the rat brain along arteries and arterioles. They are represented by intervals between the medium and adventitia, in the adventitia, and between the adventitia and the inner pial fibrous layers. At the level of capillaries they are closed. In the venous link there are only paravenular spaces between the vascular wall and glial boundary membrane. Periarterial-like leptomeningeal structures and spaces are absent. In glaucoma-like experimental increase in intraocular pressure, the periarterial spaces respond with expansion, and in addition to them, intermyocyte spaces are formed in the medium On the basis of glymphatic theory we propose the possibility of regulation of intracerebral metabolic transport and hydrodynamic system”eye - optic nerve -brain” via vascular mechanisms of perivascular transport.