Department of Otolaryngology - Head & Neck Surgery, Harvard Medical School, Boston, MA, USA; Otopathology Laboratory, Massachusetts Eye and Ear, Boston, MA, USA; ExpORL, Department of Neurosciences, Katholieke Universiteit Leuven, Leuven, Belgium.
Otopathology Laboratory, Massachusetts Eye and Ear, Boston, MA, USA.
Hear Res. 2023 Feb;428:108681. doi: 10.1016/j.heares.2022.108681. Epub 2022 Dec 20.
Hearing preservation may be achieved initially in the majority of patients after cochlear implantation, however, a significant proportion of these patients experience delayed hearing loss months or years later. A prior histological report in a case of delayed hearing loss suggested a potential cochlear mechanical origin of this hearing loss due to tissue fibrosis, and older case series highlight the frequent findings of post-implantation fibrosis and neoosteogenesis though without a focus on the impact on residual hearing. Here we present the largest series (N = 20) of 3-dimensionally reconstructed cochleae based on digitally scanned histologic sections from patients who were implanted during their lifetime. All patients were implanted with multichannel electrodes via a cochleostomy or an extended round window insertion. A quantified analysis of intracochlear tissue formation was carried out via virtual re-sectioning orthogonal to the cochlear spiral. Intracochlear tissue formation was present in every case. On average 33% (SD 14%) of the total cochlear volume was occupied by new tissue formation, consisting of 26% (SD 12%) fibrous and 7% (SD 6%) bony tissue. The round window was completely covered by fibro-osseous tissue in 85% of cases and was associated with an obstruction of the cochlear aqueduct in 100%. The basal part of the basilar membrane was at least partially abutted by the electrode or new tissue formation in every case, while the apical region, corresponding with a characteristic frequency of < 500 Hz, appeared normal in 89%. This quantitative analysis shows that after cochlear implantation via extended round window or cochleostomy, intracochlear fibrosis and neoossification are present in all cases at anatomical locations that could impact normal inner ear mechanics.
在大多数接受耳蜗植入的患者中，听力保护最初可能得到实现，但其中相当一部分患者在数月或数年后会出现迟发性听力损失。先前有一例迟发性听力损失的病例报告提示，由于组织纤维化，这种听力损失可能存在耳蜗机械性原因，并且较旧的病例系列强调了植入后纤维化和新生骨形成的常见发现，尽管没有关注其对残余听力的影响。在这里，我们展示了基于在有生之年接受植入的患者的数字化扫描组织学切片的 20 例最大系列（N=20）的 3 维重建耳蜗。所有患者均通过耳蜗造口术或扩大圆窗插入术植入多通道电极。通过与耳蜗螺旋正交的虚拟切片对耳蜗内组织形成进行了定量分析。在每个病例中均存在耳蜗内组织形成。平均而言，新组织形成占据了总耳蜗体积的 33%（SD 14%），由 26%（SD 12%）纤维组织和 7%（SD 6%）骨组织组成。在 85%的病例中，圆窗完全被纤维-骨组织覆盖，并且在 100%的病例中与耳蜗导水管阻塞有关。基底膜的基底部分在每个病例中至少部分与电极或新组织形成相邻，而与特征频率<500 Hz 对应的顶端区域在 89%的情况下正常。这种定量分析表明，通过扩大圆窗或耳蜗造口术进行耳蜗植入后，在所有病例中，在内耳机械可能受到影响的解剖位置都存在耳蜗内纤维化和新生骨形成。
