Hearing in patients with congenital deformity of the inner ear

Human Cochleae With Three Turns: An Unreported Malformation

OBJECTIVE

The objective of this histologic study of archival temporal bone sections was to describe the morphology of human cochleae found with three turns, a previously unreported anomaly, found in three pairs of temporal bones.

METHODS

The authors conducted histopathologic processing and measurement of basilar membrane length. Basilar membrane length was compared with that found in six normal control bones.

RESULTS

Cochleae with three complete turns, rather than the usual two and a half turns, are described for the first time. All had longer than normal basilar membranes, with a mean length of 40.6 mm compared with a mean of 33.8 mm in the normal bones.

CONCLUSIONS

Human cochleae with three turns exist as an unreported anomaly. This is a new category of anomaly, not likely based on interruption of development.

Genetic deafness

Images

Variability in genetically induced age-related impairment of auditory brainstem response thresholds

In genetically induced hearing impairment or deafness, the recessive mode of inheritance is by far the most common, but it has seldom been feasible to document audiological aberrations. In this study, auditory brainstem response (ABR) thresholds were analysed in groups of 10 heterozygote jerker (je/+) mice each, at ages of 3, 6 and 9 months in the frequency range 2-31.5 kHz. The animals were thereafter regularly tested up to a final age of 12 months. Forty age-related CBA/CBA mice were used as controls. The individual ABR thresholds in 3-, 6-, 9- and 12-month-old CBA/CBA mice were very similar, as also were those in 3- and 6-month-old je/+ mice (mean values within the normal range). In contrast, at 9 months--and even more so at 12 months--all je/+ animals showed large individual variations, with ABR thresholds varying randomly from near-normal to profound impairment. The wide individual spread of ABR thresholds in old je/+ animals was interpreted as reflecting the expression of a random influence of recessive jerker vis-à-vis the wild type of gene.

Wildervanck's syndrome--unilateral Mondini dysplasia identified by computed tomography

We present a case of the Wildervanck (cervico-oculo-acoustic) syndrome exhibiting congenital deafness. Klippel-Feil anomaly and lateral rectus palsy with enophthalmos. Audiometry indicated a predominantly conductive loss which, because of masking difficulties, was assumed to be bilateral: an erroneous assumption supported by results of conventional petrous bone tomography which failed to demonstrate any abnormality of the inner ears. Computed tomography (CT), however, revealed a severe Mondini dysplasia of one ear, a condition which must be assumed to be associated with severe sensorineural hearing loss. Reconstructive middle ear surgery for the conductive loss on the other side was therefore contraindicated.

The Mondini defect in Turner's syndrome. A temporal bone report

The histopathology of the right temporal bone of a 47 year old deaf woman with Turner's Syndrome (gonadal dysgenesis) is described. The appearances are of the Mondini deformity, the cochlea consisting of a single basal turn with a bulbous apical dilatation. The organ of Corti was absent. The remainder of the bony labyrinth save for the cochlear aqueduct was normal. The patient's death was due to a cerebral astrocytoma. Previous reports concerning the co-existence of gonadal dysgenesis, congenital deafness and non-gonadal neoplasia are discussed.

Ear deformities associated with the Klippel-Feil syndrome

Congenital spinal fusion, constituting the Klippel-Feil anomaly, has long been known to be associated with severe deafness in many patients. Ten such cases are described, with audiometric and tomographic assessment of the ear lesions. Of the 20 ears examined, 12 showed evidence of severe hearing loss and of these, 11 had evidence of significant inner ear dysplasia on tomography. Middle and external ear abnormalities were also demonstrated. The significance of these findings and the relation to other syndromes is discussed.

The surgery of congenital deafness

This paper outlines the indications for surgery of congenital deafness in complete meatal aplasia, the methods of audiological and radiological assessment and an operative technique used in ten ears. It is felt that otologic surgery should be done before the pinna reconstruction as it is very important to try and introduce sound into these children at an early age. In addition, the position of the new auricle can be made more satisfactorily around an already established meatus. The value of tomography of the internal as well as the middle ear is stressed and the necessity for providing a stable and uninfected meatus emphasized with regard to the possible fitting of a hearing aid.