Vascular occlusion in the endolymphatic sac in Meniere's disease.
In 2 patients with severe Meniere's disease (MD), there was histologic evidence of occlusion of the vein of the vestibular aqueduct (VVA). This finding coincided with total or partial occlusion of numerous small vessels around the endolymphatic sac (ES), flattening of epithelium, extensive perisaccular fibrosis, and signs of new bone formation. Ultrastructural analysis of the occluding material showed foci with dense connective tissue, calcification, lipid deposits, and layers of basement membrane, sometimes concentrically arranged. The exact nature of the occluding material was unknown. In another 2 MD patients, the VVA was not visualized, and the ES vessels showed no signs of occlusion. Seven controls with acoustic schwannoma or meningioma had normal vasculature. The presence of vascular impairment in the ES in MD patients indicated that altered hemodynamics may contribute to the pathogenesis of endolymphatic hydrops and MD.