Perilymphatic communication routes in guinea pig cochlea.
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Biomedical subjects
Publications and source records attributed to I Sando.
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A case of unilateral endolymphatic hydrops is presented in which several significant histopathological findings are observed in the affected inner ear and are absent in the opposite ear. Moderate endolymphatic hydrops is present in all cochlear turns on the involved side. Atrophic changes in the cochlear and vestibular end-organs, partial collapse and infolding of Reissner's and the saccular membranes, and collapse of the posterior canal membrane are also seen. There is also marked narrowing of the proximal rugose portion of the endolymphatic sac, associated with a flattened, epithelial lining, dense fibrotic connective tissue, brown pigment deposition, and poor vascularity in a relatively narrowed and straightened vestibular aqueduct. Fibrosis, loss of vascularity, and brown pigment deposition are also observed in the bony channels surrounding the vestibular aqueduct.
The histopathological study of two cases of sudden deafness is presented. The temporal bones showed cochleosaccular abnormality. The most striking pathological changes were collapse of the organ of Corti, atrophy of the tectorial membrane, atrophy of the stria vascularis, decrease in the number of the cochlear nerves, collapse of the saccular membrane and partial absence of the sensory epithelial layer in the saccular macula. These changes are quite similar in type to those occurring in labyrinthitis of known viral etiology and to those in previously reported cases of sudden deafness which were assumed to be of viral origin. This evidence suggests that a viral infection was the most probable etiology of sudden deafness in these ears. In addition, unusual findings of endolymphatic hydrops limited to the extreme basal end of the cochlear duct were found in Case 1. A patent cochlear aqueduct and circumscribed perilymphatic labyrinthine ossification in the superior seimicircular canal were also observed. With these histopathological findings, the possibility of viral infection via the meninges as well as via the hematogenous route into the inner ear is proposed.
Several significant histopathological findings were noted in a case of sudden hearing loss in a patient with chronic lymphocytic leukemia. The major pathological findings were leukemic hemorrhage into both perilymphatic and endolymphatic spaces in the cochlear and vestibular systems, endolymphatic hydrops in the cochlea and sacculus, and a relatively narrowed and straightened vestibular aqueduct and endolymphatic sac. Additional interesting findings include: loss of hair cells in the organ of Corti and vestibular end-organs; destruction of the stria vascularis (possibly the origin of the blood); fibrosis in the perilymphatic spaces in the cochlea and the vestibule, and in the endolymphatic space in the vestibule; and new bone formation in the perilymphatic spaces in the vestibule. The leukemic infiltrate observed in both the cochlea and the vestibule was not considered to be significant. Hemorrhage into the cochlea is thought to be the most reasonable cause of the sudden hearing loss in this case. Also discussed are fibrosis and osteogenesis as a late consequence of hemorrhage, and the coexistence of endolymphatic hydrops with an anomaly of the vestibular aqueduct and endolymphatic sac.
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The prevalence, location, and size of the crista neglecta in man were investigated by examining the histological sections of 223 human temporal bones (137 cases). The relationship between the crista neglecta and the singular nerve was also described. The crista neglecta was observed in 17 cases, ranging in age from 15-week fetal life to 76 years. This structure was located on the wall of the anterolateral quadrant of the posterior canal ampulla, close to the cribriform area of the singular nerve in the area between the utriculoampullar duct and the intermediate portion of the posterior canal crista. The average width, length, and height of the crista neglecta were described. The crista neglecta had a mound-like shape and contained nerve fibers, transitional epithelium, sensory hair cells, and a cupula. The nerve fibers from the crista neglecta were joined to a small branch of the singular nerve at the cribriform area in 5 of 17 crista neglecta cases, and to the main trunk of the singular nerve in the remaining 12 cases.