Abstract
Histological characteristics of the blockage of the arterial supply to the inner ear and of viral endolymphatic labyrinthitis were studied in connection with the cause of sudden deafness.
In order to produce blockage in the radiating arterioles of the inner ear, plastic beads with a mean diameter of 25.7μm were injected into the vertebral artery of the cat and squirrel monkey. Celloidin sections of temporal bones from animals dissected from between 1 week to 1 year after injection showed various types of localized lesions in the inner ear. A decrease in the number of cells in the spiral ligament and limbus spiralis together with a disappearance of sensory cells and stria vascularis were evident in the damaged region. Proliferation of fibrous tissue and ossification were found in severely damaged tissues.
As an example of viral labyrinthitis, a pair of temporal bones from a 57 year old woman who had had a sudden profound bilateral hearing loss during the course of relapsing polychondritis was studied using both a light and a scanning electron microscope. Inner ear findings at 1 year after hearing impairment matched well with histological characteristics of viral endolabyrinthitis so far reported, namely, encapsulated and dislocated tectorial membrane and marked degeneration of the organ of Corti. Degeneration of sensory cells was also seen in the pars superior as well as the saccular macula of the vestibule.
From the findings quoted above the author concluded that blood circulatory disturbances could be histologically differentiated from viral labyrinthitis as a cause of sudden deafness. Accumulation of temporal bone histologies in cases of sudden deafness is of utmost importance for clarification of the specific cause of this defect.
