Jäntti V, Sonkajärvi E, Mustola S, Rytky S, Kiiski P, Suominen K
Department of Clinical Neurophysiology, Oulu University Hospital, Finland.
Electroencephalogr Clin Neurophysiol. 1998 Apr;108(3):320-4. doi: 10.1016/s0168-5597(98)00005-7.
Cortical evoked responses to median nerve stimulation were recorded from 21 subjects during sevoflurane anaesthesia at the level of burst suppression in EEG. The N20/P22 wave had the typical form of a negative wave postcentrally, and positive precentrally. The amplitude exceeded 4 microV in all patients, making it easily visible without averaging on the low-amplitude suppression. These results show that two kinds of somatosensory evoked potential can be studied without averaging during EEG suppression in deep anaesthesia. One is the localised N20/P22 wave, which is seen regularly during suppression after stimuli with intervals exceeding 1 s. The other is the burst, involving the whole cortex, which is not evoked by every stimulus. We suggest that somatosensory evoked potentials can be monitored during sevoflurane-induced EEG suppression, and often can be evaluated reliably from a couple of single sweeps with stimulation interval exceeding 1 s. The enhancement of early cortical components of SEP, their adaptation to repeated stimuli, and the disappearance of later polysynaptic components during EEG suppression, give new possibilities to study the generators of SEP and the different effects of anaesthetics.
在七氟醚麻醉期间，当脑电图处于爆发抑制水平时，对21名受试者进行了正中神经刺激的皮质诱发反应记录。N20/P22波具有典型的中央后负波和中央前正波形式。所有患者的波幅均超过4微伏，因此在低幅抑制时无需平均即可轻松观察到。这些结果表明，在深度麻醉的脑电图抑制期间，无需平均即可研究两种体感诱发电位。一种是局部的N20/P22波，在间隔超过1秒的刺激后的抑制期间经常可见。另一种是涉及整个皮质的爆发，并非每次刺激都能诱发。我们建议，在七氟醚诱导的脑电图抑制期间可以监测体感诱发电位，并且通常可以通过几次刺激间隔超过1秒的单次扫描可靠地进行评估。体感诱发电位早期皮质成分的增强、它们对重复刺激的适应性以及在脑电图抑制期间后期多突触成分的消失，为研究体感诱发电位的发生器和麻醉剂的不同作用提供了新的可能性。
