Cellular voids in the pathogenesis of otosclerosis

Abstract

Background

Otosclerosis is a common ear disease that causes fixation of the stapes and conductive hearing impairment. However, the pathogenesis of otosclerosis is still unknown. Otosclerosis could be associated with the unique bony environment found in the otic capsule. Normal bone remodelling is almost completely absent around the inner ear after birth allowing degenerative changes and dead osteocytes to accumulate. High levels of inner ear anti resorptive osteoprotegerin (OPG) is most likely responsible for this capsular configuration. Studies have demonstrated how osteocyte lifespan variation creates occasional clusters of dead osteocytes, so-called cellular voids, at otosclerotic predilection sites in the human otic capsule. These cellular voids have been suggested as possible starting points of otosclerosis.

Aim

To describe the cellular viability in otosclerotic lesions and compare it to that of cellular voids.

Materials and Methods

The study was based on unbiased stereological quantifications in undecalcified human temporal bones with otosclerosis.

Results

Osteocyte viability was found to vary within the otosclerotic lesions. Furthermore, the results presented here illustrate that inactive otosclerotic lesions consist of mainly dead interstitial bone, much like cellular voids.

Conclusions and significance

Focal degeneration in the otic capsule may play an important role in the pathogenesis of otosclerosis.

Chinese Abstract

背景：耳硬化症是一种常见的耳部疾病, 会导致镫骨固定和传导听觉受损。 然而, 耳硬化症的发病机制仍然未知。 耳硬化症可能是与耳囊中的独特骨环境有关。 正常的骨重建于出生后在内耳周围几乎完全消失, 导致退行性变化和死骨细胞堆积。 大量的内耳抗再吸收骨保护素 (OPG) 最有可能是这种囊状结构的原因。 研究表明了骨细胞寿命的变化是如何在耳囊中耳硬化症的易发部位, 即所谓的细胞空隙, 偶尔产生死骨细胞群。 这些细胞空隙已被看作可能的耳硬化症起始点。

目的：描述耳硬化性病变中的细胞活力, 并将其与细胞空隙的细胞活力进行比较。

材料和方法：该研究基于对患有耳硬化症的未脱钙颞骨进行的无偏体视学量化。

结果：发现骨细胞活力在耳硬化病灶内是不一致的。 此外, 这里展示的结果说明非活动性耳硬化病灶主要由死间质骨组成, 很像细胞空隙。

结论和意义：耳囊的局灶性退行性变化可能在耳硬化症的发病机制上起重要作用。

Keywords:

• Otosclerosis
• cellular voids
• bone remodelling
• undecalcified histology

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This research was supported by a donation from Iris Lundholm Iversen for research in otosclerosis, Grant number non existing.