Kearse L A, Brown E N, McPeck K
Department of Anesthesia, Massachusetts General Hospital, Boston 02114.
Stroke. 1992 Apr;23(4):498-505. doi: 10.1161/01.str.23.4.498.
The relation between electroencephalographic pattern changes and cerebral ischemia during carotid endarterectomy under general anesthesia is well established. Pattern changes seen on somatosensory evoked potentials under the same conditions are reported to be more sensitive indicators of cerebral ischemia. We estimated the sensitivity and specificity of somatosensory evoked potentials relative to electroencephalography for detecting cerebral ischemia during carotid endarterectomy under general anesthesia.
We simultaneously monitored electroencephalographs and somatosensory evoked potentials in 53 carotid endarterectomies performed on 51 patients under general anesthesia, and we determined the extent to which somatosensory evoked potentials detected cerebral ischemia defined by electroencephalographic pattern changes at the time of carotid cross-clamp.
Twenty-three of the 53 cases studied had electroencephalographic evidence of ischemia following carotid cross-clamp. Ten of these 23 cases had an increased somatosensory evoked potential latency of 0.1 msec or greater (sensitivity 0.43). One of these 23 patients had a decrease in somatosensory evoked potential amplitude of 50% or greater (sensitivity 0.04). Of the 30 subjects who had no electroencephalographic evidence of ischemia, 13 had either no change or a decrease in somatosensory evoked potential latency (specificity 0.45). None of these 30 cases had a significant decrease in somatosensory evoked potential amplitude (specificity 1.0). If somatosensory evoked potential latencies were a sensitive method for detecting cerebral ischemia (true sensitivity of 0.95 or higher), the probability of only 10 subjects having somatosensory evoked potential latency increases would be less than 0.001. Therefore, our observed sensitivity cannot be attributed to chance.
We conclude that measuring somatosensory evoked potentials is not a sensitive method for detecting cerebral ischemia during carotid endarterectomy.
全身麻醉下颈动脉内膜切除术期间脑电图模式变化与脑缺血之间的关系已得到充分证实。据报道，在相同条件下体感诱发电位出现的模式变化是脑缺血更敏感的指标。我们评估了在全身麻醉下颈动脉内膜切除术期间，体感诱发电位相对于脑电图检测脑缺血的敏感性和特异性。
我们在51例接受全身麻醉的患者所进行的53例颈动脉内膜切除术中同时监测脑电图和体感诱发电位，并确定在颈动脉交叉钳夹时，体感诱发电位检测由脑电图模式变化所定义的脑缺血的程度。
在研究的53例病例中，有23例在颈动脉交叉钳夹后有脑电图缺血证据。这23例中的10例体感诱发电位潜伏期增加0.1毫秒或更多（敏感性0.43）。这23例患者中有1例体感诱发电位波幅下降50%或更多（敏感性0.04）。在30例无脑电图缺血证据的受试者中，13例体感诱发电位潜伏期无变化或下降（特异性0.45）。这30例中无一例体感诱发电位波幅有显著下降（特异性1.0）。如果体感诱发电位潜伏期是检测脑缺血的敏感方法（真敏感性为0.95或更高），那么只有10例受试者体感诱发电位潜伏期增加的概率将小于0.001。因此，我们观察到的敏感性不能归因于偶然。
我们得出结论，测量体感诱发电位不是检测颈动脉内膜切除术期间脑缺血敏感的方法。
