Sturzenegger M, Newell D W, Aaslid R
Department of Neurological Surgery, University of Washington (Seattle), USA.
Stroke. 1996 Dec;27(12):2256-61. doi: 10.1161/01.str.27.12.2256.
We assessed the influence of different visual stimuli and the reproducibility and habituation of evoked flow responses using simultaneous two-channel transcranial Doppler monitoring and flow velocity averaging.
We measured stimulus-related percentage changes in posterior cerebral, basilar, and middle cerebral artery blood flow velocities in 14 normal volunteers using stimulus-triggered velocity averaging. With a two-channel transcranial Doppler system, simultaneous measurements in two arteries (both posterior cerebral arteries and the basilar and middle cerebral artery) were taken using multiple-array light-emitting diodes applying flash stimuli. Both posterior cerebral arteries were monitored to assess reproducibility and habituation of the evoked response with repetitive measurements under unchanged conditions and to analyze the influence of different features of the visual stimulus.
There was a distinctive increase in velocities resulting from visual stimuli in both posterior cerebral and the basilar arteries but not in the middle cerebral artery. The responses in both posterior cerebral arteries were larger than in the basilar artery (P = .0001). Brightness (P < .0001), as well as complexity (P < .0001), of the visual stimulus had a significant influence on the response amplitude. There was a trend toward a greater right-sided activation. Amplitudes of the evoked response were very stable during repetitive testing (coefficient of variation of the difference was 0.6). There was a trend toward habituation with monotonous (flash) but not with complex visual stimuli. A "zero" stimulus produced no responses.
The use of flow velocity averaging and two-channel simultaneous recording increases the sensitivity of transcranial Doppler monitoring to detect and correlate selective flow changes in the posterior cerebral arteries resulting from cerebral activation produced by visual stimulation.
我们使用双通道经颅多普勒监测和血流速度平均法，评估了不同视觉刺激的影响以及诱发血流反应的可重复性和适应性。
我们对14名正常志愿者进行刺激触发的速度平均测量，以测量大脑后动脉、基底动脉和大脑中动脉血流速度与刺激相关的百分比变化。使用双通道经颅多普勒系统，通过多阵列发光二极管施加闪光刺激，同时测量两条动脉（双侧大脑后动脉以及基底动脉和大脑中动脉）。监测双侧大脑后动脉，以评估在不变条件下重复测量时诱发反应的可重复性和适应性，并分析视觉刺激不同特征的影响。
视觉刺激导致大脑后动脉和基底动脉的血流速度显著增加，但大脑中动脉未出现这种情况。双侧大脑后动脉的反应大于基底动脉（P = 0.0001）。视觉刺激的亮度（P < 0.0001）以及复杂性（P < 0.0001）对反应幅度有显著影响。存在右侧激活更强的趋势。在重复测试期间，诱发反应的幅度非常稳定（差异的变异系数为0.6）。对于单调（闪光）视觉刺激存在适应性趋势，但对于复杂视觉刺激则不存在。“零”刺激未产生反应。
使用血流速度平均法和双通道同步记录可提高经颅多普勒监测的灵敏度，以检测和关联由视觉刺激引起的大脑激活所导致的大脑后动脉选择性血流变化。
