Analysis of the Hyalinization Reaction in Otosclerosis

Abstract

O tosclerosis is a disease of abnormal bone remodeling, which is unique in that it occurs only in the otic capsule of the human temporal bone. Large foci of otosclerosis may penetrate the endosteal layer of the cochlea, resulting in direct contact of otosclerotic bone with the softtissue structures of the inner ear. We have previously reported variable amounts of cochlear element degeneration with otosclerotic endosteal penetration, 1 and in that earlier study, the cochlear elements, including the hair cells, ganglion cells, and stria vascularis, were evaluated quantitatively. A reduction in the population of cochlear elements was not related to the extent and location of otosclerotic endosteal involvement, and a reduction in sensorineural thresholds was observed in some, but not all cases. These observations suggest that factors that limit the effect of otosclerotic endosteal involvement on the cochlear elements may be present. Reports on the association between endosteal involvement of the otic capsule with otosclerosis and sensorineural hearing loss have been summarized in a review of the literature. 1As early as 1899, Siebenmann 2 speculated that the diffusion of toxic substances from otosclerotic bone into the inner ear fluids resulted in hearing loss. Evidence now supports this concept. Hydrolytic enzymes produced by otosclerotic bone have been identified in perilymph and appear to be a factor leading to the degeneration of cochlear sensorineural elements and sensorineural hearing loss. 3,4 In addition, cytokines released by otosclerotic bone have been suggested as a potential source of spiral ligament dysfunction resulting in a loss of cochlear fluid and ion homeostasis. 5Histologic changes occurring in the cochlear soft tissues at the site of otosclerotic endosteal penetration have been descriptively referred to as a hyalinization reaction. [6][7][8] In hematoxylineosin stained temporal bone sections, the hyalinized tissue appears pink in color and is characterized by decreased cellularity IMPORTANCE Otosclerotic bone has been observed to penetrate the endosteal layer of the cochlea, resulting in direct contact with the soft-tissue structures of the inner ear. Sensorineural hearing loss has been observed in some, but not all, of these cases. The development of histologic changes occurring in the cochlear soft tissues at the site of otosclerotic endosteal penetration has been descriptively referred to as a hyalinization reaction. The role of the hyalinization reaction in the development of hearing loss is unknown.OBJECTIVE To evaluate the composition of these hyalinized soft tissues using immunostaining techniques. DESIGN, SETTING, AND PARTICIPANTSRetrospective review in a human temporal bone histopathology research laboratory of 3 specimens from patients with endosteal otosclerotic involvement.INTERVENTIONS Evaluation of human temporal bone pathology findings. MAIN OUTCOMES AND MEASURESHuman temporal bone sections with endosteal otosclerotic involvement were studied using immunostaining techniques to ide...

Immunohistochemical techniques for the human inner ear

“…Most of the human temporal bone banks have a collection of hematoxylin and eosin sections, from which there are remaining 9 out of 10 sections unstained that can be used for different types of staining, including IHC, histochemistry, molecular biology or proteomics (Jokay et al 1998; Kammen-Jolly et al 2001; Khetarpal 2000; Robertson et al 2001, 2006; Merchant et al 2008; Aarnisalo et al 2010; Markaryan et al 2008a, b, c, 2009a, b, c, 2010a, b, 2011; Maekawa et al 2010; Nelson and Hinojosa 2014). The tectorial membrane and Reissner’s membrane are generally well preserved, which often is not the case in paraffin-embedded or microdissected specimens.…”