听神经病大脑听觉皮层功能区脑磁图初步观察

目的应用脑磁图探讨听神经病患者大脑听觉皮层功能区的病变情况。方法应用全头型306通道生物磁仪，对10例（20耳）听神经病患者和15例（30耳）正常对照组进行大脑听觉皮层诱发磁场的测试，观察了左右耳分别给予0．5、1、2、4、6、8kHz纯音刺激诱发的双侧大脑半球听觉皮层磁反应波M100，将其脑磁图的电生理资料与磁共振成像的解剖结构资料叠加，获得听神经病患者大脑听觉皮层的磁源性影像。结果15例正常对照组除16耳8kHz未诱发出M100外，其他各频率双耳均可诱发出M100，而听神经病患者在0．5、1、2、4、6kHz20耳（40侧）大脑听觉皮层磁反应波M100引出率分别为27．5％（11／40）、22．5％（9／40）、7．5％（3／40）、5％（2／40）、5％（2／40）；8kHz均未引出反应。与正常对照组相比较其潜伏期明显延长，波幅明显降低（P〈0．01）。在初级听皮层1kHz纯音刺激诱发的M100位置听神经病患者较正常对照组更靠大脑半球的外侧。结论听神经病是一种临床表现主要为听力学异常的，包括耳蜗后第Ⅷ颅神经耳蜗支和听觉传导通路直至大脑听觉皮层在内的听觉系统疾患。脑磁图可作为其是否适合配带助听器和电子耳蜗植入治疗的参考。

Preliminary study on the functional localization of auditory cortex in auditory pathyology patients using magnetoencepahalography

OBJECTIVE: To access the pathological changes of the functional localization of the primary auditory cortex in auditory neuropathy patients using magnetoencepahalography (MEG). METHODS: The M100 waves of cortical evoked magnetic fields (AEF) evoked by 0.5, 1, 2, 4, 6, 8 kHz pure tones were measured respectively in 10 auditory neuropathy patients (20 ears) and 15 healthy young subjects (30 ears) using a whole head 306 channel magnetoencephalogralography (MEG) system. The auditory cortex magnetic source imaging obtained by superimposing functional MEG data on structural magnetic resonance image (MRI). RESULTS: The M100 sources were obtained in all 15 healthy young subjects in all frequency except for 8 kHz in 16 ears. But in auditory neuropathy patients, the ratio of M100 from 0.5 to 6 kHz were 27.5% (11/40), 22.5% (9/40), 7.5% (3/40), 5% (2/40), 5% (2/40) respectively and no any waves in 8 kHz. The evoked ratio of M100 in low frequency was high and that decreased gradually with increasing of evoked pure tone frequency. The M100 latentencies and amplitudes were longer and lower in patient group than that in control group (P < 0.01). CONCLUSIONS: Auditory neuropathy is an audiology disease with pathological lesions from the VIII cranial nerve to auditory cortex. MEG might become an important reference in decision making for therapies.