MRI下蜗神经未见显示人工耳蜗植入患者影像学特点及术后效果分析

The imaging characteristics and prognosis of patients with cochlear implants whose cochlear nerves are not shown on MRI

目的了解MRI下内听道内蜗神经未见显示的人工耳蜗植入患者的颞骨CT及内耳MRI影像学特点,观察其术后听觉及言语康复效果,探讨影像学测量指标与术后效果之间的相关性。方法收集2014年5月至2018年10月在山东省耳鼻喉医院行人工耳蜗植入的蜗神经发育不良患儿共88例,排除伴有耳蜗发育畸形的患儿,仅保留耳蜗结构正常且MRI下内听道内蜗神经未见显示的蜗神经发育不良患者,共64例,其中双侧植入4例,共68耳。患儿植入时年龄范围1~6岁,平均2.8岁。人工耳蜗为澳大利亚Cochlear公司产品(型号包括24RECA和512)。所有患者术前均行内耳MRI和颞骨CT扫描,影像学评估指标包括颞骨CT下蜗神经管宽度、内听道宽度,内耳MRI下桥小脑角处位听神经直径、面神经直径以及面神经与位听神经的直径比。分别于术后12、24和36个月时进行听觉言语功能评估,包括听觉行为分级问卷(Categories of Auditory Performance,CAP)和语言可懂度分级评估问卷(Speech Intelligibility Rating,SIR)及助听听阈测试。采用SPSS 13.0软件对术后助听听阈、CAP、SIR结果与影像学结果进行相关性分析。结果64例蜗神经未见显示患者中,有CT资料的56耳显示颞骨CT中蜗神经管宽度为(0.72±0.30)mm(均数±标准差,下同),内听道宽度为(4.07±1.10)mm;有MRI资料的66耳显示内耳MRI桥小脑角处位听神经的直径为(1.58±0.27)mm,面神经的直径为(1.57±0.27)mm,面神经与位听神经的直径比为(1.02±0.23)。术后12、24及36个月时平均助听听阈分别为(46.8±2.5)dB HL、(40.7±0.8)dB HL和(36.8±1.5)dB HL,即术后助听听阈随植入时间的延长而不断降低。术前和术后12、24及36个月时CAP得分分别为(1.0±1.0)分、(3.8±1.4)分、(4.5±1.4)分和(5.1±0.7)分,即术后听觉功能不断提高。术前和术后12、24及36个月时SIR得分分别为(1.1±0.3)分、(1.9±0.9)分、(2.5±0.9)分和(2.9±0.6)分,即术后语言清晰度缓慢提升。术后24个月时的助听听阈与颞骨CT的内听道宽度呈负相关(r=-0.349,P=0.037),术后36个月时的助听听阈与内耳MRI桥小脑角处面听比呈正相关(r=0.740,P=0.001)。结论MRI下内听道内蜗神经未见显示的蜗神经发育不良患儿可以从人工耳蜗植入中获益,术后的听觉及言语功能较术前均有明显进步,且随开机时间的延长不断提高。患者颞骨CT内听道宽度及内耳MRI桥小脑角处面神经与位听神经直径的比值可能与术后远期助听听阈有一定相关性。

Objective To analyze the temporal bone CT and inner ear magnetic resonance imaging characteristics of cochlear implant patients with no cochlear nerve display in the inner auditory canal under MRI.To retrospectively analyze the long-term hearing and speech rehabilitation effects of such patients after cochlear implant.And to analyze the correlation between the results of imaging examinations and the postoperative effects of cochlear implant patients with this type of cochlear nerve deficiency.Methods A total of 88 children with cochlear nerve deficiency,who underwent cochlear implantation in Shandong Provincial ENT Hospital from May 2014 to October 2018,were enrolled.Patients with cochlear malformations were excluded,only the patients with cochlear nerve deficiency whose cochlear structure was normal and no cochlear nerve displayed in inner auditory canal under MRI were enrolled.There were 64 patients,including 4 bilaterally implanted,68 ears in total,with an average age of(2.8±1.7)years(range 1-6 years)at the time of implantation.The implanted product was Cochlear,including 24RECA and 512 models.All patients underwent inner ear magnetic resonance imaging and temporal bone CT scan before operation.Auditory speech function assessments were performed at 12 months,24 months,and 36 months after surgery,including categories of auditory performance(CAP),speech intelligibility rating(SIR)and hearing aid threshold test.The imaging evaluation content included the width of the cochlear nerve canal of temporal bone CT,the width of the internal auditory canal,the width of the auditory nerve at the cerebellopontine angle of the inner ear MRI,and the ratio of the facial nerve to the width of the auditory nerve at the cerebellopontine angle.The correlations between the results of postoperative hearing aid hearing threshold,CAP,SIR and imaging results were analyzed.Results Among the 64 cases of cochlear nerve not shown under MRI,56 ears with CT data showed that the width of the cochlear nerve canal in temporal bone CT was(0.72±0.30)mm(mean±standard deviation,the same below),and the width of the internal auditory canal was(4.07±1.10)mm;66 ears with MRI data showed that the diameter of the auditory nerve at the cerebellopontine angle of the inner ear MRI was(1.58±0.27)mm,the diameter of the facial nerve was(1.57±0.27)mm,and the ratio of the diameter of the facial nerve to the auditory nerve was(1.02±0.23).The average hearing thresholds at 12,24,and 36 months after surgery were(46.8±2.5)dB HL,(40.7±0.8)dB HL,and(36.8±1.5)dB HL,respectively.The preoperative and postoperative CAP scores at 12,24 and 36 months were(1.0±1.0),(3.8±1.4),(4.5±1.4)and(5.1±0.7)points,respectively.The preoperative and postoperative SIR scores at 12,24,and 36 months were(1.1±0.3),(1.9±0.9),(2.5±0.9),and(2.9±0.6)points,respectively.The hearing threshold at 24 months after surgery was negatively correlated with the width of the internal auditory canal of temporal bone CT(r=-0.349,P=0.037),and the hearing threshold at 36 months after surgery was positively correlated with the ratio of the diameter of the facial nerve to the auditory nerve at the cerebellopontine angle of the inner ear MRI(r=0.740,P=0.001).Conclusions Children with cochlear implants whose cochlear nerves are not shown on MRI can benefit from cochlear implantation,and their speech and auditory functions can improve significantly after surgery.The width of the internal auditory canal in the temporal bone CT and the ratio of the diameter of the facial nerve to the auditory nerve at the cerebellopontine angle of the inner ear MRI may be related to the long-term hearing threshold after surgery.