Anatomy of the Human Osseous Spiral Lamina and Cochlear Partition Bridge: Relevance for Cochlear Partition Motion.

The classic view of cochlear partition (CP) motion, generalized to be for all mammals, was derived from basal-turn measurements in laboratory animals. Recently, we reported motion of the human CP in the cochlear base that differs substantially from the classic view. We described a human soft tissue "bridge" (non-existent in the classic view) between the osseous spiral lamina (OSL) and basilar membrane (BM), and showed how OSL and bridge move in response to sound.

Foreign Body Response to Silicone in Cochlear Implant Electrodes in the Human.

Hypothesis: Silicone as part of a cochlear implant electrode may be responsible for a foreign body response in the human.

Background: Clinical evidence of a foreign body response to a cochlear implant has been reported. In a previous study, particulate material found within the fibrous sheath and within macrophages surrounding a cochlear implant has been identified as being consistent with platinum.

Histopathology of the Human Inner Ear in the p.L114P COCH Mutation (DFNA9).

The histopathology of the inner ear in a patient with hearing loss caused by the p.L114P COCH mutation and its correlation with the clinical phenotype are presented. To date, 23 COCH mutations causative of DFNA9 autosomal dominant sensorineural hearing loss and vestibular disorder have been reported, and the histopathology of the human inner ear has been described in 4 of these.

Cochlear neuropathy in human presbycusis: Confocal analysis of hidden hearing loss in post-mortem tissue.

Recent animal work has suggested that cochlear synapses are more vulnerable than hair cells in both noise-induced and age-related hearing loss. This synaptopathy is invisible in conventional histopathological analysis, because cochlear nerve cell bodies in the spiral ganglion survive for years, and synaptic analysis requires special immunostaining or serial-section electron microscopy. Here, we show that the same quadruple-immunostaining protocols that allow synaptic counts, hair cell counts, neuronal counts and differentiation of afferent and efferent fibers in mouse can be applied to human temporal bones, when harvested within 9 h post-mortem and prepared as dissected whole mounts of the sensory epithelium and osseous spiral lamina.

Cellular immunologic responses to cochlear implantation in the human.

A cochlear implant array consists of biomaterials, including metal and polymeric in type which are biocompatible, but not necessarily bio-inert. Histologic evidence of a foreign body reaction has been described in temporal bones in patients who in life had undergone cochlear implantation. In the current study, the cellular immune response was characterized using immunohistochemical stains for B-cell lymphocytes (CD20), T-cell lymphocytes (CD3), and macrophages (CD68).

Correlation between histologic and radiographic reconstruction of intracochlear electrode position in human temporal bones.

In our laboratory, human temporal bone specimens from patients who in life have undergone cochlear implantation are routinely processed with the implant in situ, embedded in Araldite, sectioned at 20 µm and serially photographed during cutting, stained with toluidine blue and mounted on glass slides. From the images, two-dimensional and three-dimensional reconstructions can be made and a very accurate implant insertion depth can be calculated from the three-dimensional reconstructions. However, this method precludes subsequent special stains and further molecular investigations of the tissue including proteomics and immunostaining, which is now possible with celloidin-embedded tissue.

Techniques of celloidin removal from temporal bone sections.

Objectives: We sought to determine whether the technique of celloidin removal influences the results of immunostaining in celloidin-embedded cochleae.

Methods: We compared four protocols of celloidin removal, including those using clove oil, acetone, ether-alcohol, and methanol saturated with sodium hydroxide. By optimally fixing our tissue (perfused mice), and keeping constant the fixative type (formalin plus acetic acid), fixation time (25 hours), and decalcification time (ethylenediaminetetraacetic acid for 7 days), we determined whether the technique of celloidin removal influenced the immunostaining results.

Foreign body or hypersensitivity granuloma of the inner ear after cochlear implantation: one possible cause of a soft failure?

Hypothesis: A tissue response in the form of foreign body or a hypersensitivity reaction to cochlear implantation is common and may be one possible cause of a soft failure of cochlear implantation.

Background: After a successful cochlear implantation, delayed failure may occur. The causes of a "soft" failure, that is, one in which device malfunction cannot be proven, are unknown.

Effects of fixative and embedding medium on morphology and immunostaining of the cochlea.

The localization of proteins by immunostaining is a powerful method to investigate otologic disorders. However, the use of fixatives and embedding media (necessary for the preservation of morphology) can obscure antigens, making it difficult to perform immunoassays. We performed a systematic investigation of the effects of fixative and embedding medium on morphology and immunostaining of the mouse cochlea.

Histopathology of the peripheral vestibular system after cochlear implantation in the human.

Objectives: The objective of this study was to describe the histology of the peripheral vestibular system in temporal bones from patients who in life had undergone cochlear implantation and to correlate the findings with previous reports of vestibular dysfunction after cochlear implantation. This is the first quantitative report of the impact of implantation on the vestibular neuronal end organ. METHODSThere were 19 temporal bones available for histologic study.

Is word recognition correlated with the number of surviving spiral ganglion cells and electrode insertion depth in human subjects with cochlear implants?

Objectives/hypothesis: Speech perception scores using cochlear implants have ranged widely in all published series. The underlying determinants of success in word recognition are incompletely defined. Although it has been assumed that residual spiral ganglion cell population in the deaf ear may play a critical role, published data from temporal bone specimens from patients have not supported this hypothesis.

Temporal bone histopathology in alport syndrome.

Objective: To determine the histopathologic abnormalities within the cochlea in Alport syndrome.

Background: Alport syndrome, which manifests as hereditary nephritis and sensorineural hearing loss (SNHL), is caused by mutations in genes that code for the proportional, variant3, proportional, variant4, and proportional, variant5 chains of type IV collagen. The proportional, variant3, proportional, variant4, and proportional, variant5 chains of type IV collagen are present in the basement membrane of the organ of Corti.

Morphometric changes in the cochlear nucleus in patients who had undergone cochlear implantation for bilateral profound deafness.

We have investigated the morphometric changes in the cochlear nucleus of patients who had undergone cochlear implantation following profound deafness. The brain stems of 11 adult patients who had undergone implantation and four non-implanted control cases with varying degrees of hearing loss were studied. The volumes of the ventral cochlear nucleus (VCN) and dorsal cochlear nucleus (DCN), and the maximal cross-sectional area and densities of cell bodies in the anterior ventral cochlear nucleus (AVCN) were measured bilaterally by light microscopy assisted by the Neurolucida 2000 image analysis system.

Reciprocal innervation of outer hair cells in a human infant.

Reciprocal synapses are characterized by the presence of both afferent and efferent types of synaptic specializations between two cells. They have been described at the neural poles of outer hair cells (OHCs) in humans with advanced age and two monkey species. Our objective was to study the innervation of the OHCs and determine if reciprocal synapses were present in a young (8-month-old infant) human subject.

Axodendritic and dendrodendritic synapses within outer spiral bundles in a human.

Axodendritic and dendrodendritic synapses have been described at the level of the outer spiral bundle (OSB) (Nadol, J.B., Jr.