正常人及单侧突发感音神经性耳聋患者的功能MRI研究

Functional MRI in normal subjects and sudden unilateral sensorineural hearing loss patients

目的研究正常人及单侧突发感音神经性耳聋患者调幅音刺激任务时听觉皮层的激活。方法对25名健康受试者及30例突发感音神经性耳聋患者分别进行正弦调幅音任务下的EPI序列的fMRI数据采集，实验刺激声音分别为0．5、2、4 kHz纯音经8Hz调幅。功能MRI的检查时间为突聋后12d内。调幅音刺激强度为96 dB SPL，双耳同时呈现。采用事件相关Sparse设计采集数据以减少扫描噪音，利用SPM2软件进行数据分析。结果大部分正常听力者及耳聋患者主要表现为初级听觉皮层激活，正常听力者以左侧半球优势（11／16），突发感音神经性耳聋患者表现为患耳侧听觉皮层优势（16／22）。正常受试者及单侧突发感音神经性耳聋患者双侧初级听觉皮层的激活体积和强度均随刺激频率的增高而降低。结论两组人群听觉皮层激活偏侧性的改变表明在单侧突发感音神经性耳聋初期，听觉皮层发生了适应性的改变。

Objective Brain activities in responses to amplitude modulation （AM） was evaluated using functional MRI （fMRI） in subjects with sudden unilateral sensorineural hearing loss （SSNHL） and those with normal hearing （NH）. Methods Totally 25 subjects with normal hearing and 30 with SSNI-IL were examined with fMRI in response to AM tones of 500, 2000 and 4000 Hz respectively with the modulation frequency at 8 Hz. The fMRI was examined within 12 days after the onset of SSNHL. The AM signals were presented at 96 dB SPL binaurally. An event-related design was combined with a sparse clustered volume acquisitioning paradigm in data collection in the attempt to reduce the influence of acoustic scanner noise. SPM2 software was used for offline data analyzing. Results Brain activation in fMRI image was found mainly in the primary auditory cortex （PAC） in both subjects with NH and SSNHL. NH subjects showed a clear lateralization to left cerebral hemisphere（11/16） and SSNHL patients showed a lateralization ipsilateral to the impaired ear（16/22）. The activation voxel and intensity shown in BOLD were found to be decreased with increasing signal frequency in both groups. Conclusion The difference in the lateralization between the two groups suggests that an adaptive process occurs shortly after the onset of SSNHL.