Area Of Stria Vascularis Research Articles

Inner Ear Changes in Mucopolysaccharidosis Type I/Hurler Syndrome

Mucopolysaccharidosis type I/Hurler syndrome is an autosomal recessive disease caused by a deficiency of α-L-iduronidase activity. Recurrent middle ear infections and hearing loss are common complications in Hurler syndrome. Although sensorineural and conductive components occur, the mechanism of sensorineural hearing loss has not been determined. The purpose of this study is to evaluate the quantitative inner ear histopathology of the temporal bones of patients with Hurler syndrome. Eleven temporal bones from 6 patients with Hurler syndrome were examined. Age-matched healthy control samples consisted of 14 temporal bones from 7 cases. Temporal bones were serially sectioned in the horizontal plane and stained with hematoxylin and eosin. The number of spiral ganglion cells, loss of cochlear hair cells, area of stria vascularis, and cell density of spiral ligament were evaluated using light microscopy. There was no significant difference between Hurler syndrome and healthy controls in the number of spiral ganglion cells, area of stria vascularis, or cell density of spiral ligament. The number of cochlear hair cells in Hurler syndrome was significantly decreased compared with healthy controls. Auditory pathophysiology in the central nerve system in Hurler syndrome remains unknown; however, decreased cochlear hair cells may be one of the important factors for the sensorineural component of hearing loss.

Cochlear pathology in human temporal bones with otitis media

Conclusion: Middle and inner ear interactions in otitis media can lead to cochlear pathology. More severe pathological changes observed in the basal turn of the cochlea are consistent with prevalence of sensorineural hearing loss at higher frequencies in patients with otitis media. Methods: Of 614 temporal bones with otitis media, 47 with chronic and 35 with purulent otitis media were selected following strict exclusion of subjects with a history of acoustic trauma, head trauma, ototoxic drugs, and other diseases affecting the cochlear labyrinth. Temporal bones with labyrinthine inflammatory changes were further evaluated for loss of hair cells and other histopathologic changes compared to age-matched controls. Results: In all, 19% of temporal bones with chronic and 9% with purulent otitis media showed labyrinthine inflammatory changes. In chronic otitis media, inflammatory changes were: 56% localized purulent, 22% localized serous, 11% generalized seropurulent, and 11% generalized serous. Inflammatory changes in temporal bones with purulent otitis media included 67% localized purulent and 33% were generalized seropurulent. Pathological findings included: serofibrinous precipitates and inflammatory cells in scala tympani of basal turn and cochlear aqueduct, significant loss of outer and inner hair cells, and significant decrease in area of stria vascularis in the basal turn of the cochlea, as compared to controls.

Generalized Arteriosclerosis and Changes of the Cochlea in Young Adults

To disclose the histopathologic findings of the cochlea in young adults with generalized arteriosclerosis. It is well known that arteriosclerosis begins and progresses during childhood. Although the relationship between arteriosclerosis and auditory function in elderly people was examined in many reports, the histopathologic effect of arteriosclerosis on the cochlea in young adults has not been studied. This study involved quantitative analysis, including the number of spiral ganglion cells, the loss of cochlear outer hair cells, and the areas of stria vascularis and spiral ligament. It included 10 temporal bones from 6 subjects with generalized arteriosclerosis and 10 age-matched normal control temporal bones from 7 subjects. The mean number of spiral ganglion cells in the cochlea with generalized arteriosclerosis was significantly lower than that in normal controls in the basal turn. The mean loss of outer hair cells in the cochlea with generalized arteriosclerosis was significantly greater than that of normal controls in the basal and apical turns. The stria vascularis and spiral ligament were severely atrophic, with generalized arteriosclerosis in the basal turn. There was no significant difference in the thickness of the spiral modiolar artery between generalized arteriosclerosis and normal controls. Degeneration of the cochlea, especially in the basal turn, was already apparent in young adults with generalized arteriosclerosis.

S239 – Labyrinthine Changes in Otitis Media

Objectives Otitis media causes labyrinthine changes and subsequent sensorineural hearing loss. The aim of this histopathologic study was to evaluate the extension of inflammation to the inner ear and its effects. Methods Out of 614 temporal bones with otitis media, 47 (30 cases) with chronic and 35 (21 cases) with purulent were selected for histopathologic study. Subjects with a history of acoustic trauma, head trauma, ototoxic drugs and other otologic and systemic diseases affecting the inner ear were excluded. The pattern of labyrinthine inflammation was classified as localized purulent, localized serous, generalized seropurulent and generalized serous. Inner ear findings were compared to age-matched controls. Results 19% of temporal bones with chronic and 9% of temporal bones with purulent otitis media showed labyrinthine inflammatory changes. In chronic otitis media, inflammatory changes were: 56% localized purulent; 22% localized serous; 11% generalized seropurulent; and 11% generalized serous. Inflammatory changes in temporal bones with purulent otitis media included: 67% localized purulent; and 33% generalized seropurulent. Pathological findings included: serofibrinous precipitates and inflammatory cells in the scala tympani of basal turn and cochlear aqueduct; significant decrease in area of stria vascularis (p = 0.033); and loss of hair cells in the organs of Corti. No significant difference was found in area of spiral ligament area or number of fibrocytes in diseased and control bones. Conclusions Middle ear/inner ear interaction in otitis media can result in labyrinthine inflammation and cochlear damage. Early diagnosis and treatment of otitis media is important in preventing inner ear damage.

Inner ear pathology in the Palmerston North autoimmune strain mouse

The Palmerston North autoimmune strain mouse is a model for spontaneous systemic lupus erythematosus. Inner ear structure and function were examined during the onset and progression of systemic autoimmune disease to identify potentially correlated auditory system pathology. The onset of systemic disease occurred at 4 to 5 months of age and was characterized by elevated serum immune complexes, cryoglobulins, and antinuclear antibodies. Coincident with the onset of autoimmune disease was degeneration of the apical turn stria vascularis and outer hair cells. These cochlear changes progressed basal-ward. At 10 months of age, auditory brainstem response thresholds were elevated and the stria vascularis area was measurably smaller throughout the cochlea. Immunohistochemical staining showed immunoglobulin G deposits within the organ of Corti, the vas spirale of the basilar membrane, the scala tympani, and marrow cavities of the bony otic capsule. These results suggest that cochlear pathology may be immune mediated in this mouse, which would make the strain suitable for the study of the mechanisms relating inner ear abnormalities and autoimmune disease.

Autoimmune disease and cochlear pathology in the C3H/ lpr strain mouse

The C3H/ lpr autoimmune strain mouse is a model for spontaneous systemic lupus erythematosus. Inner ear structure and function were examined during systemic autoimmune disease progression to identify correlated auditory system pathology. Onset of the systemic disease occurred at 2–3 months of age and was characterized by elevated serum immune complexes, cryoglobulins, and antinuclear antibodies. Coincident with the onset of autoimmune disease was degeneration of the stria vascularis. Early edema of the stria occurred in the apex and progressed basalward with duration of the disease. By 10 months of age, stria vascularis area was smaller and auditory brainstem response thresholds were elevated. No degeneration of hair cells was seen at any age, suggesting that the stria vascularis may be the primary anatomic site of autoimmune auditory damage in this mouse model.