The function and structure of the cerebrospinal fluid outflow system

This review traces the development of our understanding of the anatomy and physiological properties of the two systems responsible for the drainage of cerebrospinal fluid (CSF) into the systemic circulation. The roles of the cranial and spinal arachnoid villi (AV) and the lymphatic outflow systems are evaluated as to the dominance of one over the other in various species and degree of animal maturation. The functional capabilities of the total CSF drainage system are presented, with evidence that the duality of the system is supported by the changes in fluid outflow dynamics in human and sub-human primates in hydrocephalus. The review also reconciles the relative importance and alterations of each of the outflow systems in a variety of clinical pathological conditions

Formation of cerebrospinal fluid

✓ After a brief summary of current views on the origin of cerebrospinal fluid (CSF) and the processes underlying its elaboration, the author discusses studies of isolated choroid plexus in extracorporeal perfusion systems and flux chambers. The results suggest that transependymal water flow is secondary to the electrically silent pumping of sodium. The author presents evidence in support of the standing gradient hypothesis as the structural basis of CSF secretion.</jats:p