One, 2, and 4 months after surgical obliteration of the endolymphatic sac, the sequence of degenerative changes in the organ of Corti of the guinea pig was studied. The block surface technique with interference differential (Nomarski) microscopy was used for this investigation to study the morphological changes in the organ of Corti. The hair cell loss was calculated and mapped in cytocochleograms. One month postoperatively a minimal loss of only outer hair cells was observed in the apical cochlear turn. At 2 months a progression of outer hair cell loss was seen, which proceeded in the 4-month group. At 4 months the inner hair cells showed a slight tendency to degenerate, again beginning in the most apical part of the cochlea.

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Studies on progressive hereditary perceptive deafness in a family of 335 members. I. Genetical and general audiological results.

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Adolescent↗

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Studies on progressive hereditary perceptive deafness in a family of 335 members. II. Characteristic pattern of hearing deterioration.

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Animals↗

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Treatment of Bell's Palsy. An analysis of the available studies.

In this paper the basic requirements for a clinical therapeutic trial in Bell's palsy are discussed. The available therapeutic studies are analysed in view of these requirements. The following conclusions seem justified: (1) Galvanic stimulation has not been proved to lead to a better recovery. (2) There is no evidence that decompression of the mastoid part of the facial nerve in the second or third week has a positive effect. Whether surgery at an earlier stage or decompression of the complete intratemporal part of the nerve is effective, has not yet been studied. (3) There is no convincing proof that prednisone administration up to a daily dose of 60-80 mg during the first days has any effect.

Adrenocorticotropic Hormone↗

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A follow-up study in a family with dominant progressive inner ear deafness.

A family with dominant progressive inner ear deafness beginning in the high tones has been examined in 1962, 1968 and 1978. The audiometric data of 86 affected members (376 audiograms) were studied by 1) determination of averages, 2) principal component and factor analysis, and 3) curve fitting procedures. The hearing appeared to deteriorate in six characteristic phases with a separate deterioration for the high and the low frequencies. The hearing loss was equal for the R and L ear; in females low tone loss was greater than in males; in branch II the hearing loss proceeded more rapidly than in other branches. No abnormal excretion of organic acids in the urine could be established.

Adolescent↗

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Ultrastructure of the stria vascularis and Reissner's membrane in experimental hydrops.

A time-sequence study was made of the early ultrastructural changes of the stria vascularis and Reissner's membrane in the guinea pig after obliteration of the endolymphatic sac and duct. Pathological alterations of both the stria vascularis and Reissner's membrane were found to start in the apex of the cochlea. The morphological changes of the stria vascularis were characterized by an increase of vesicles in the marginal cells and by intercellular edema, followed by vacuolization and atrophy of marginal and intermediate cells. In Reissner's membrane extensive gaps in the mesothelial cell layer were observed together with intracellular pathology of the epithelial cells. The significance of these ultrastructural changes in the stria vascularis and Reissner's membrane with regard to the pathophysiology of the endolymphatic hydrops is discussed.

Animals↗

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An improved fixation method for guinea pig cochlear tissues.

The influence of different fixation methods and of various primary fixatives on the ultrastructural preservation of guinea pig cochlear tissues was investigated. No differences in fixation quality were observed between cochleas fixed by intravascular perfusion and cochleas fixed by intralabyrinthine perfusion. Tri-aldehyde primary fixation resulted, in contrast to other formulae investigated, in an excellent, uniform preservation of all cochlear tissues without obvious fixation artefacts. The influence of OSO4/K4Ru(CN)6- and OSO4/K4Fe(CN)6 postfixation was also tested. Cochlear tissues postfixed with OSO4/K4Ru(CN)6 or OSO4/K4Fe(CN)6 exhibited more cellular detail (e.g., membrane- and glycogen contrast) as compared to tissues postfixed with OSO4 alone. Tri-aldehyde primary fixation followed by OSO4/K4Ru(CN)6- or OSO4/K4Fe(CN)6 postfixation therefore is recommended as a multipurpose procedure for optimal preservation of labyrinthine tissues.

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Electrocochleographic changes in relation to cochlear histopathology in experimental endolymphatic hydrops.

The relation between electrocochleographic and histological changes in experimental endolymphatic hydrops was studied 1, 2, 4, or 8 months after obliteration of the endolymphatic sac. An increase in the compound Action Potential (AP) threshold was found 2, 4, and 8 months after obliteration. This increase was strongly correlated with loss of outer hair cells, nerve fibres and spiral ganglion cells. An enhanced negative Summating Potential (SP) and an enhanced SP-AP ratio were found mainly in animals with an endolymphatic hydrops without further cochlear pathology. A normal or decreased SP and SP-AP ratio was regularly recorded in animals with both an endolymphatic hydrops and a variety of other histopathological changes in the inner ear. An increased second peak (N2) in the AP waveform was recorded from 63% (15/24) of the hydropic ears, equally divided over the four groups. There was no obvious correlation between the increased N2 and other electrophysiological or histological findings.

Action Potentials↗

PubMedDate not supplied

Ultrastructure of the organ of Corti in experimental hydrops.

The early ultrastructural changes of the organ of Corti in the guinea pig after obliteration of the endolymphatic sac and duct were examined in a time-sequence study. Initial loss of outer hair cells was followed by inner hair cell degeneration, both starting at the apical part of the cochlea. Morphological changes of the sensory cells were found to start at the endolymphatic surface and were characterized by a variety of sterociliary pathologies, distortion of the cuticular plate and a less prominent contrast-staining of glycocalyx. Further degeneration was marked by pathological changes of intracellular organelles and the afferent and efferent nerve endings. Details of the ultrastructural changes in the organ of Corti are discussed with regard to the pathophysiology of experimental hydrops.

Animals↗

PubMedDate not supplied

Densitometry of the cochlear capsule and correlation between bone density loss and bone conduction hearing loss in otosclerosis.

Radiodensity of the bony cochlear capsule was investigated by CT-scanning in 134 ears with otosclerosis and 35 normal control ears. A technique of densitometry of the cochlea was developed comprising the measurement of maximum and minimum density together with mapping of the cochlea and measurement of the density at six predefined points in the cochlear capsule. Bone density in the normal cochlea showed very little interindividual variation. In the otosclerosis patients, minimum density was decreased in 58% of the ears, indicating the presence of a focus. At visual examination, foci were only detectable when density loss exceeded 200 Hounsfield. A positive correlation was found between bone density loss and bone conduction hearing loss with a maximum at 2,000 Hz and the medioventral point of the cochlear wall. The method appears to be useful for the follow-up during fluoride treatment, as is demonstrated by a case report.

Cochlea↗