Vascular mechanisms in Meniere's disease. Theoretical considerations

Unimpeded venous drainage of the vestibular organs via the paravestibular canaliculus (PVC) vein is crucial to inner ear fluid mechanisms. With increased venous pressure, insufficient drainage may result in endolymphatic hydrops, unless collateral veins develop. Different mechanisms cause venous insufficiency in different cases of Meniere's. One suggested mechanism is alteration of the intermediate endolymphatic sac (IES) microcirculation with decreased regulation of blood held within subepithelial capillaries of the sac. Increased blood may thus drain into the veins, with increased venous pressure and inadequate vestibular drainage. Altered microcirculation may be morphological as in fibrosis or shortening of the IES, or physiological where the microcirculation receives abnormal stimuli or reacts abnormally to normal stimuli. Venous insufficiency may result from PVC vein anomalies. Variations in venous pattern whereby vestibular organs preponderantly drain through the PVC vein may predispose to Meniere's disease.