Bridging the gap between chronic cerebrospinal venous insufficiency and Ménière disease

Ménière disease (MD) is a chronic illness of the inner ear that affects a substantial number of patients every year worldwide. Because of a dearth of well-controlled studies, the medical and surgical management of MD remains quite empirical. The main reason is that it is very difficult to investigate patients affected with Certain MD due to the post-mortem criterion necessary for this diagnostic grade. Although endolymphatic hydrops (EH) is the worldwideaccepted mechanism of MD, the causes that induce it are still not clear. In fact MD has been correlated mostly to a wide and different disturbances ranging from trauma to sleep disorders. It is nowadays sufficiently demonstrated that chronic cerebrospinal venous insufficiency (CCSVI) is very frequent in MD. Even if CCSVI may potentially induce EH through a pure hydraulic mechanism CCSVI, per se does not explain how the various disorders correlated with MD may interact with CCSVI and provoke EH. The aim of this review is an attempt to approach MD into the context of the more recent findings about the global brain waste clearance system, to which inner ear is anatomically and functionally connected, in order to build a reasonable model of MD pathogenesis. The major part of the diseases correlated to MD may act on the inner ear disturbing the glymphatic (GS) and/or brain lymphatic system (BLS) activity. The venous system interplays with GS and BLS. In this model CCSVI is considered more than a direct cause of MD rather the anatomical predisposition to develop the disease. In this model EH, and then MD, is the consequence of a failure of the compensation of the congenital venous abnormalities, anatomical compensation as collateral pathways and/or functional compensation as GS and BLS. In this model the major part of the disturbances correlated to MD and the various treatment proposed find their appropriate placement.