Toyoda K, Ibayashi S, Yamamoto T, Kuwabara Y, Fujishima M
Second Department of Internal Medicine, Faculty of Medicine, Kyushu University, Fukuoka, Japan.
J Neurol Neurosurg Psychiatry. 1998 Jun;64(6):777-84. doi: 10.1136/jnnp.64.6.777.
Magnetoencephalography (MEG) measures aspects of the function of the auditory cortex of the human brain with high spatial resolution. The objective was to determine whether MEG also accurately identifies the auditory cortex of the brain in patients with ischaemic stroke.
The auditory evoked magnetic field (AEF) was examined after stimuli of 1 kHz tone bursts in 24 stroke patients without apparent infarcts in the auditory cortex, and compared the topography of sources of 50 ms (P50m) and 100 ms latency deflections (N100m), the most prominent components of middle and long latency AEFs, with that of 12 normal subjects. Cerebral haemodynamics in and around the auditory cortex were evaluated using PET.
In nine of 24 stroke patients, the accurate magnetic sources of P50m or N100m were not identified. The distribution of P50m sources varied more widely than N100m. Eight of these nine patients had severe stenotic lesions in the carotid or middle cerebral arterial trunks. Patients with abnormal P50m responses had decreased supratemporal and hemispheric blood flow compared with patients with normal P50m responses.
These findings suggest that large vessel disease with disturbed cerebral haemodynamics in and near the auditory cortex tend to affect AEFs, especially the middle latency components. This is the first combined study of MEG and PET to show a significant correlation between AEF responses in stroke patients and their PET indices.
脑磁图（MEG）可在高空间分辨率下测量人类大脑听觉皮层的功能。目的是确定MEG是否也能准确识别缺血性中风患者的大脑听觉皮层。
对24例听觉皮层无明显梗死的中风患者进行1kHz短音刺激后检测听觉诱发磁场（AEF），并将50ms（P50m）和100ms潜伏期偏转（N100m）（中、长潜伏期AEF最显著的成分）的源地形图与12名正常受试者的进行比较。使用PET评估听觉皮层及其周围的脑血流动力学。
24例中风患者中有9例未识别出P50m或N100m的准确磁源。P50m源的分布比N100m变化更大。这9例患者中有8例在颈动脉或大脑中动脉主干有严重狭窄病变。与P50m反应正常的患者相比，P50m反应异常的患者颞上和半球血流量减少。
这些发现表明，听觉皮层及其附近脑血流动力学紊乱的大血管疾病往往会影响AEF，尤其是中潜伏期成分。这是第一项MEG与PET联合研究，显示中风患者的AEF反应与其PET指标之间存在显著相关性。
