Nadol J B
Department of Otolaryngology, Massachusetts Eye and Ear Infirmary, Boston 02114, USA.
Otolaryngol Head Neck Surg. 1997 Sep;117(3 Pt 1):220-8. doi: 10.1016/s0194-5998(97)70178-5.
Although the identity of all the variables that may influence speech recognition after cochlear implantation is unknown, the degree of preservation of spiral ganglion cells is generally considered to be of primary importance. A series of experiments in our laboratories, directed at quantification of surviving spiral ganglion cells in the profoundly deaf, evaluation of the predictive value of a variety of clinical parameters, and the evaluation of the consequences of implantation in the inner ear, is summarized. Histologic study of the inner ears of patients who were deafened during life demonstrated that the cause of deafness accounted for 57% of the variability of spiral ganglion cell counts. Spiral ganglion cell counts were highest in individuals deafened by aminoglycoside toxicity or sudden idiopathic deafness and lowest in those deafened by postnatal viral labyrinthitis, congenital or genetic deafness, or bacterial meningitis. Study of the determinants of degeneration of the spiral ganglion revealed that degeneration is most severe in the basal compared with the apical turn and more severe when both inner and outer hair cells are absent. Unlike the findings in some experimental animal studies, no survival advantage of type II ganglion cells could be identified. There was a strong negative correlation between the degree of bony occlusion of the cochlea and the normality of the spiral ganglion cell count. However, even in specimens in which there was severe bony occlusion, significant numbers of spiral ganglion cells survived. A strong positive correlation between the diameter of the cochlear, vestibular, and eighth cranial nerves with the total spiral ganglion cell count (p < 0.001) was found. This would suggest that modern imaging techniques may be used to predict residual spiral ganglion cell population in cochlear implant candidates. Trauma from implantation of the electrode array was studied in both cadaveric human temporal bone models and temporal bones from individuals who received implants during life. A characteristic pattern of damage to the lateral cochlear wall and basilar membrane was identified in the upper basal turn. New bone formation and perielectrode fibrosis was common after cochlear implantation. Despite this significant trauma and reaction, there is no firm evidence that further degeneration of the spiral ganglion can be predicted as a consequence.
尽管所有可能影响人工耳蜗植入后言语识别的变量尚不明确，但螺旋神经节细胞的保留程度通常被认为是至关重要的。本文总结了我们实验室进行的一系列实验，这些实验旨在量化极重度聋患者中存活的螺旋神经节细胞，评估各种临床参数的预测价值，以及评估内耳植入的后果。对生前致聋患者内耳的组织学研究表明，耳聋原因占螺旋神经节细胞计数变异性的57%。螺旋神经节细胞计数在因氨基糖苷类毒性或特发性突聋致聋的个体中最高，而在出生后病毒性迷路炎、先天性或遗传性耳聋或细菌性脑膜炎致聋的个体中最低。对螺旋神经节退变决定因素的研究表明，与顶转相比，基底转的退变最为严重，且当内、外毛细胞均缺失时退变更严重。与一些实验动物研究的结果不同，未发现II型神经节细胞有存活优势。耳蜗骨闭塞程度与螺旋神经节细胞计数的正常性之间存在很强的负相关。然而，即使在存在严重骨闭塞的标本中，仍有大量螺旋神经节细胞存活。发现耳蜗、前庭和第八对脑神经的直径与螺旋神经节细胞总数之间存在很强的正相关（p < 0.001）。这表明现代成像技术可用于预测人工耳蜗植入候选者中残余的螺旋神经节细胞数量。在尸体人类颞骨模型和生前接受植入的个体的颞骨中研究了电极阵列植入造成的创伤。在上基底转发现了耳蜗外侧壁和基底膜损伤的特征性模式。人工耳蜗植入后新骨形成和电极周围纤维化很常见。尽管有这种明显的创伤和反应，但没有确凿证据表明螺旋神经节会因此进一步退变。
