any structural anomaly in the stratified, secretory epithelium which lines the upper part of the cochlear spiral ligament and maintains potassium ion homeostasis in the endolymph; stria vascularis normally consists of marginal, intermediate, and basal cells: basal and marginal cell tight junctions preclude paracellular diffusion into and out of the intrastrial space while basal and intermediate cells secrete into this space potassium ions derived from fibrocytes through gap junctions