[Experimental studies of ischemia of the cochlea. Part 3: Pathophysiology]

Selective interruption of cochlear blood flow is possible without operative manipulations in the middle or inner ear. By fitting a magnet into the external auditory canal and injecting iron filings into the cephalic vein is it possible to obtain an impaired inner ear in otherwise healthy experimental animals that can be kept alive for any length of time. The hearing loss induced by the ischemia normally remains unchanged over a period of weeks. The highly vascularised areas of the cochlea, namely the spiral ligament, the vascular stria, the spiral prominence and the root cells in the external spiral sulcus, as well as the spiral limbus were all clearly degenerated, but to different degrees. Pronounced vacuolisation of cells, degeneration of tissue, reduction of cellular elements, stasis in large and small blood vessels and morphological disorganisation were observed. The organ of Corti showed no changes worthy of note. On revascularisation of the spiral ligament and the spiral limbus with resumption of function, the organ of Corti can return to normal activity again. Repeat blood flow disturbances can also lead to recurrent sudden hearing loss and intermittent loss of hearing.