目的 探讨人工耳蜗植入术前应用功能性磁共振(functional magnetic resonance imaging,fMRI)评价植入者听皮层功能的临床价值.方法 21例拟行人工耳蜗植入的重度、极重度感音神经性聋患儿(17例内耳结构正常,3例为大前庭水管综合征,1例为耳蜗神经发育不良)和7例听力正常儿童在镇静状态下行fMRI检查.受检者接受四种随机频率(500、1 000、2 000、4000 Hz)声刺激,采用组块式设计,每个组块的听觉刺激持续16 s,刺激间隔16 s,每类刺激重复2次,总扫描时间为4 min 28 s.患儿人工耳蜗植入后定期进行听力学随访,评估其听觉言语功能.结果 28例受检者在单耳及双耳接受声刺激后fMRI上出现大脑听皮层激活,表现为单纯颞横回激活、单纯丘脑激活以及颞横回和丘脑均激活.接受单耳刺激时,21例患儿中6例表现对侧优势,5例同侧优势,10例双侧均衡;7例听力正常儿童,3例对侧优势,2例同侧优势,2例双侧均衡.耳蜗植入患儿术前听皮层的激活强度与听力正常儿童无明显区别,差异无统计学意义(P＞0.05).21例人工耳蜗植入患儿术后听觉言语康复效果良好,大前庭水管综合征患儿与内耳结构正常患儿在听觉言语康复水平上未见明显差别.耳蜗神经发育不良患儿术前左耳给予声刺激后双侧颞横回激活,左耳植入耳蜗后开机对声音有反应,术后10个月行为测听平均阈值为55 dBHL.结论 fMRI是一种可行的听皮层功能评价方法,结合ABR和影像学检查,能够在人工耳蜗植入前较完整地评估整个听觉系统的功能.%Objective To investigate the functional evaluation of auditory cortex by functional magnetic resonance imaging (fMRI) before cochlear implantation (CI).Methods Twenty-one children with severe to profound sensorineural hearing loss(SNHL)(7 cases with normal inner ear structure,3 cases with large vestibular aqueduct syndrome,1 case with cochlear nerve hypoplasia) and 7 children with normal hearing were examined by fMRI under sedation.The subjects received acoustic stimuli at four random frequencies (500,1 000,2 000,4 000 Hz) during fMRI examination.Tones were interleaved with silence in a block-periodic fMRI design with 16-second on-off intervals.Each stimulus repeated twice and the total acquisition time was 4 minutes and 28 seconds.Results Activation was identified in the auditory cortex of the 28 subjects in response to monaural and binaural acoustic stimulation,which was shown in the transverse temporal gyrus (Heschl gyrus),the thalamus and both.Of the 21 patients with SNHL,contralateral dominance was shown in six cases,ipsilateral dominance in five cases and bilateral equilibrium in 10 cases when one ear was exposed to the stimuli.Of the seven children with normal hearing,contralateral dominance was shown in three cases,ipsilateral dominance in two cases and bilateral equilibrium in two cases.No significant difference of the activation intensity in auditory cortex was shown between children with SNHL and normal hearing(P ＞ 0.05).Good hearing recovery was obtained in the 21 patients after CI.No significant difference in the level of hearing and speech rehabilitation was shown between children with LVAS and with normal inner ear structure.Listening behavior response threshold was 55 dBHL in the case with cochlear nerve hypoplasia 10 months after CI.Conclusions fMRI would be a feasible means of evaluating the function of the auditory cortex,which can be used for assessing the function of the entire auditory system prior to CI combined with ABR and imaging.
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