Nikolopoulos Thomas P, Kiprouli Katerina
Department of Otorhinolaryngology, Athens University, Ippokration Hospital, 114 Queen's Sophia Avenue, Athens 115-27, Greece.
Cochlear Implants Int. 2004 Sep;5 Suppl 1:56-63. doi: 10.1179/cim.2004.5.Supplement-1.56.
Expanding selection criteria and increasing numbers of cochlear implantations have revealed several challenging cases with regard to surgery and medical point of view. Cochlear implantation of congenitally deaf children with inner-ear malformations may involve difficulties in preoperative evaluation, surgical approach and postoperative follow-up. Cochlear nerve aplasia (as evidence of only one existing nerve in three dimensional magnetic resonance imaging) and hypoplastic cochleas are among the most difficult cases and sometimes children are considered unsuitable for cochlear implantation. However, there is always the possibility that hypoplastic cochleas may include ganglion cells and the only nerve in the internal auditory canal (facial nerve) may contain auditory fibres as well. A positive history of auditory experience and evidence of electrical auditory brainstem response or response to the promontory or round window electrical stimulation may imply that a functioning auditory system is in place. Malformations like common cavity deformity, isolated bilateral vestibular aqueduct enlargement and Mondini dysplasia are usually less challenging, although cerebrospinal fluid leak and postoperative meningitis may be a possibility. In cases of post-meningitic deaf patients, ossification (or obliteration) may be a serious problem even if computed tomography and MRI scan show a patent cochlea or minimal changes. Acoustic neuromas and neurofibromatosis type 2 are other challenging cases, as there is always the possibility that the sensorineural hearing loss is secondary to cochlear damage by interference of the tumour to cochlear blood supply. In conclusion, challenging cases are becoming more common as we are expanding selection criteria, and we should be prepared for alternative cochlear implant devices (straight electrode arrays, dual arrays, compressed arrays, etc.), increased rate of possible complications at, and following, surgery, and functional outcome that may vary considerably among implantees.
随着人工耳蜗植入的选择标准不断扩大以及植入数量的增加，从手术和医学角度来看，出现了几类具有挑战性的病例。为患有内耳畸形的先天性失聪儿童植入人工耳蜗可能在术前评估、手术方式及术后随访方面存在困难。耳蜗神经发育不全（如三维磁共振成像显示仅存在一条神经）和耳蜗发育不良是最具挑战性的病例，有时儿童被认为不适合进行人工耳蜗植入。然而，发育不良的耳蜗始终有可能包含神经节细胞，而内耳道中唯一的神经（面神经）也可能含有听觉纤维。有听觉经历的阳性病史以及电听觉脑干反应或对岬部或圆窗电刺激有反应的证据，可能意味着存在一个功能正常的听觉系统。像共同腔畸形、孤立性双侧前庭导水管扩大和Mondini发育异常等畸形通常挑战性较小，尽管可能会出现脑脊液漏和术后脑膜炎。对于脑膜炎后失聪患者，即使计算机断层扫描和磁共振成像扫描显示耳蜗通畅或仅有微小变化，骨化（或闭塞）也可能是一个严重问题。听神经瘤和2型神经纤维瘤病是其他具有挑战性的病例，因为感音神经性听力损失总是有可能继发于肿瘤干扰耳蜗血供对耳蜗造成的损伤。总之，随着我们扩大选择标准，具有挑战性的病例正变得越来越常见，我们应该为替代人工耳蜗装置（直电极阵列、双阵列、压缩阵列等）、手术中和手术后可能增加的并发症发生率以及植入者之间可能差异很大的功能结果做好准备。
