Arne W. Scholtz

Juvenile nasopharyngeal angiofibroma : management and therapy

Objective To conduct a review of contemporary approaches on the diagnostic‐preoperative, operative, and postoperative methods in the management of juvenile nasopharyngeal angiofibroma (JNA).

Quantitative evaluation of cochlear neurons and computer-aided three-dimensional reconstruction of spiral ganglion cells in humans with a peripheral loss of nerve fibres

Quantitative data on human cochlear neuronal elements were collected from various regions in five patients with high-tone hearing loss due to presbycusis and in two patients with normal hearing. The number of nerve fibers was assessed in the spiral lamina and in the inner acoustic meatus together with counts of spiral ganglion cells. The results show that the number of neurons decreased peripherally, i.e., with increasing distance from the central nervous system in patients with high-tone hearing loss due to presbycusis. In two patients with normal hearing no significant difference in the number of neurons was found in the lamina spiralis as compared to the inner acoustic canal. Computer-aided 3-dimensional reconstruction of the human spiral ganglion displayed large bipolar neurons (type I cells), but also large ganglion cells with one missing axon. The results may indicate that a slow retrograde degeneration occurs from the periphery towards the spiral ganglion in presbycusis. Transmission electron microscopy analysis of freshly fixed human spiral ganglions displayed interneural connections. It is speculated whether a trophic supply from other neurons at the level of the spiral ganglion can prevent or delay further degeneration of the central axon.

Structural/audiometric correlations in a human inner ear with noise-induced hearing loss

A morphological analysis was performed on a human cochlea removed during skull base surgery. The patient experienced a noise-induced hearing loss following 30 years of mechanical exposure. The tissue was processed according to the block surface technique and the organ of Corti, osseous spiral lamina and spiral ganglion were analyzed at different levels. There was a circumscribed lesion approx. 10 mm from the round window extending to about 13 mm. At this site, the dominant pathological feature was the loss of outer hair cells that was comprehensive in the centermost area and partial in the peripheral region of the damage. The degradation of inner hair cells was less severe with signs of cell atrophy yet with limited loss. Outer pillar cells were often collapsed leading to deformation of the acoustic ridge. The Deiters cells were often present and physically interactive with remaining nerve fibers. In the reticular lamina, surgical manipulation and dissection resulted in tears which may be attributed to a reduction of intercellular strength between cells. In the damaged area, there was a 45% loss of myelinated nerve fibers measured at the osseous spiral lamina. Pathological changes could not be observed in the spiral ganglion with certainty although the type II cells innervating the outer hair cells were often difficult to discern.

Goldenhar's syndrome: congenital hearing deficit of conductive or sensorineural origin? Temporal bone histopathologic study.

Background Oculoauriculovertebral dysplasia (OAVD) (Goldenhars syndrome) is a congenital syndrome with ipsilateral deformity of the ear and face, epibulbar lipodermoids, coloboma, and vertebral anomalies. Goldenhars anomaly has often been associated with a degree of congenital hearing deficits, almost always of a conductive origin, but a sensorineural component is also suspected in some cases, evident through malformations of the inner ear. Patients and Methods Both temporal bones of a 10-day-old deceased patient with oculoauriculovertebral dysplasia were examined by light microscopy. Results The ear deformities included deformity of the auricle, atresia of the external auditory canal, and malformation of the tympanic cavity and ossicles. Abnormalities of the stria vascularis and the semicircular canals were also demonstrated. Further inner ear deformities were not identified in this case. Conclusion These histopathologic findings appear to confirm the conductive component of the congenital hearing deficit, but a sensorineural component could not be omitted. The ear alterations favor early developmental field defects. The causes of this condition are controversial. Recent results in genetic research pertaining to the MSX class genes permit better understanding of the variety, variability, and different degrees of severity of the anomalies described here.

Connexin 26 in human fetal development of the inner ear.

Specialized for intercellular communication, gap junctions have been theorized to provide a means (the epithelial and connective tissue gap junction systems) by which fluid and ions might be transported for maintenance of high levels of endolymphatic K+ [Kikuchi et al., 1994. Acta Otolaryngol. 114, 520-528] in the inner ear. A primary constituent of these gap junctions is connexin 26 (Cx26), a protein encoded by the gene GJB2 and found in both epithelial and connective tissue cells. It has been shown that a mutation in Cx26 accounts for 50% of patients with autosomal recessive nonsyndromic hearing loss. In the present study, we document the emergence and distribution features of Cx26 through various stages (weeks 11-31) of gestation in human, fetal cochleae. Comparative patterns of Cx26 distribution are also presented in the mature rat. The cochleae were fixed in 4% paraformaldehyde within 2 h post mortem. Immunohistochemical studies were performed using a rabbit polyclonal antibody raised against synthetic peptide and corresponding with amino acids 108-122. Specimens were mounted into paraffin sections. Results show that Cx26-like immunoreactivity is evident at a prenatal age of 11 weeks and maintains a high intensity of reactivity through 31 weeks of gestation. The appearance of this reactivity seemed to modulate in parallel with the onset of development and histological maturation as well as provide functional maintenance. In the human fetal cochlea, Cx26-like immunoreactivity distribution resembled adult patterns by fetal week 20. At the completion of morphological development by week 31, reactivity appeared to achieve an adult profile of distribution. Descriptions and discussion of Cx26 distribution patterns are presented in detail.

Selective aspects of human pathology in high-tone hearing loss of the aging inner ear

Accompanied with aging, the thresholds for high frequency sounds may elevate and result in a progressive hearing loss described as presbycusis. Based on correlations between audiometric measures of aged patients and histologic findings garnered from postmortem examinations, four types of presbycusis have been characterized: sensory-neural, neural, strial, and conductive [Schuknecht, H.F., Gacek, M.R., 1993. Ann. Otol. Rhinol. Laryngol. 102, 1--16]. Otopathologic changes to the inner ear as a direct function of age, however, remain controversial. The focus of this investigation involves the pathological impact on remaining sensory structures in patients having sensory--neural degeneration. The current study presents seven human temporal bones extracted from patients aged 53--67 years with high-tone hearing loss and with no known history of extraordinary environmental events involving head or noise trauma, acoustic overstimulation, or ototoxicity. In previously published findings of these specimens, all but one temporal bone failed to demonstrate a meaningful correlation between audiometric measurements and loss of functional hair cell populations with secondary retrograde degeneration of nerve fibers. Using the block surface method, electron microscopic micrographs demonstrate ultrastructural changes in the cuticular plate, stereocilia, pillar cells, stria vascularis, and the spiral ligament. In all pathological specimens, the greatest incidence of degeneration was seen at the cuticular plate. Conclusively, our findings present three implications in the aging human cochlea: firstly, audiometric measures that represent a high-tone hearing loss may take various forms with respect to ultrastructural patterns of degeneration and surviving structures; secondly, the incidence of lipofuscin and lysosome granules does not correlate with the degree of hearing loss and; thirdly, as shown only in guinea pigs [Anniko, M., 1988. Scanning Microsc. 2, 1035--1041], high-tone hearing loss can be associated with deformation of the cuticular plate.

Ultrastructural evaluation of calcitonin gene-related peptide immunoreactivity in the human cochlea and vestibular endorgans

Calcitonin gene‐related peptide (CGRP) is a neuropeptide widely distributed in the peripheral and central nervous system. Demonstrated in the efferent systems of the mammalian cochlea and vestibule, immunoreactive patterns of CGRP may vary by species. There is, however, no information in the literature investigating CGRP localization in the human cochlea. In the present study, the ultrastructural localization of CGRP immunoreactivity was evaluated in the human inner ear with immunoelectron microscopy. It was found that, in human cochlea, CGRP immunoreactivity was located in unmyelinated nerve fibres of the spiral lamina, inner spiral fibres beneath inner hair cells, tunnel spiral fibres, tunnel crossing fibres and outer radial fibres. In endorgans of human vestibule, CGRP immunoreactivity was located in vesiculated nerve fibres and bouton‐type nerve terminals which were seen to contact afferent nerve chalices surrounding type I sensory cells and afferent nerve fibres, or to form an en passant contact with afferent dendrites. CGRP immunoreactivity appeared to be confined to efferent systems in all cases. This study presents evidence that CGRP could serve a role in neurotransmission or neuroregulation in both cochlear and vestibular efferent systems of human.

Immunohistochemical investigation of enkephalins in the human inner ear

Enkephalins are generally considered as neuropeptides in the central and peripheral nervous system of mammals bound to three large precursor molecules. Several animal studies demonstrated the distribution of met- and leu-enkephalin-like immunoreactivities in neurons and terminals of the lateral olivocochlear system. The immunostainings in the medial system are more controversial. No data about the presence of different enkephalin sequences in the vestibular efferent terminals are known. In the present study, the ultrastructural localization and distribution of immunoreactivities for six different antibodies against met- and leu-enkephalins in the human cochlear and vestibular periphery were investigated. A modified method of pre-embedding immunoelectronmicroscopy was applied. Met- and leu-enkephalin-like immunoreactivities were observed in the efferent terminals of the human outer and inner hair cell region. Using different met- and leu-enkephalin antibodies, the distribution of immunoreactivities remained similar. In the five human vestibular endorgans, enkephalin-like immunostaining was absent.

Neurotransmission in the Human Labyrinth

Different neuroactive substances have been found in the efferent pathways of both the olivocochlear and vestibular systems. In the present study, the distribution and role of three neurotransmitters, choline acetyltransferase (ChAT), gamma aminobutyric acid (GABA), and enkephalin were investigated in the human labyrinth of 4 normal-hearing individuals. Immunohistochemical studies in human inner ear research, however, face a problem of procuring well-preserved specimens with maintained neurotransmitter antigenicity and morphology. Methods and findings are reported and discussed.

Cerebro-oculo-facio-skeletal syndrome as a human example for accelerated cochlear nerve degeneration.

Background Cerebro-oculo-facio-skeletal (COFS) syndrome is a rare autosomal-recessive disorder that includes microcephaly, severe mental retardation, and multiple congenital anomalies. Otologic findings are usually limited to descriptions of the auricles. Patient and Methods The authors report inner ear histopathologic findings of a deceased 13-year-old patient with COFS. A histologic study of the inner ear in COFS syndrome has not yet been described. This patient was documented as having a profound bilateral sensorineural hearing loss at the age of 2 years. Results Histologic evaluation revealed accelerated neural and neuronal degeneration at the cochlear and retrocochlear levels. Remaining myelinated nerve fibers, counted in the spiral lamina, had degenerated by up to 97% when compared with normal innervation densities. Afferent nerve fibers innervating inner hair cells were completely absent, whereas medial efferent fibers to outer hair cells were found. Vestibular nerve fibers were less affected. Conclusion The authors report inner ear findings that differ from animal models of primary cochlear neural degeneration and that resemble the pattern of hereditary cochlear nerve degeneration reported in Friedreichs ataxia.