基于动物模型的大脑皮质中央沟定位与运动诱发电位的初步研究

摘要

Objective To preliminarily explore the method of the central sulcus localization (CLS) and motor evoked potential (MEP) during operation in dogs. Methods Five healthy adult beagle dogs were chosen. Somatosensory evoked potentials (SSEP) of the cerebral cortex were recorded by a subcortical strip electrode through unilateral stimulation of the forelimb median nerve and the CLS was made. The electrode was placed in the cortex of both cerebral hemispheres and subcortical strip electrode was placed in the left abductor pollicis brevis. Single-phase anode, single-phase cathode and bipolar electrode with constant current stimulation were applied respectively, the waveform of MEP was recorded, and latency was compared. The single-phase anode electrode with constant voltage stimulation was applied, the different pulse number (5 and 7), pulse width (0.075 and 0.050 ms) and stimulation frequency (150, 250, 350 Hz) were adjusted, and the change in the latency of MEP was observed. Results The phase reversal of SSEP occurred in the cerebral cortex. The average peak latencies of the initial main positive and negative waves were 15.4±2.1 ms and 16.3±2.0 ms respectively. There was no difference in latency between two waves (P>0.05). The average latencies of MEP induced by single-phase anode, single-phase cathode and bipolar stimulation were 31.7±1.8, 29.0±3.9 and 40.0 ±1.6 ms, and the threshold stimulation intensity was 5.0, 5.5, 6.0 mA respectively. The average latencies of MEP with pulse number of 7 was less than those with pulse number of 5 (P<0.05). The average latencies of MEP with pulse width of 0.075 ms was less than those with pulse width of 0.050 ms (P<0.05). The average latencies of MEP with stimulation frequency of 350 Hz was less than those with stimulation frequency of 150 Hz (P<0.05). Conclusions SSEP can be used to locate the boundary line between the sensory and motor areas in two sides of the central sulcus through the stimulation of the forelimb median nerve in dogs. The pulse number, pulse width and stimulation frequency can affect the latency of MEP.%目的：初步探讨犬术中大脑皮质中央沟定位(central sulcus localization，CSL)及运动诱发电位(motor evoked potential，MEP)的方法。方法选取健康比格犬5只，皮下针状电极刺激前肢正中神经，记录大脑皮质的躯体感觉诱发电位(somatosensary evoked potentials，SSEP)，从而定位中央沟。皮质电极置于左右大脑半球皮质，皮下针状电极置于左侧拇短展肌(left abductor pollicis brevis，LAPB)，分别采用单相阳极、单相阴极及双极恒流刺激，记录LAPB的MEP波形并比较潜伏期。采用单相阳极恒压刺激，观察不同刺激脉冲数(5、7个/串)、脉宽(0.075、0.050 ms)及刺激频率(150、250、350 Hz)下MEP潜伏期变化。结果 SSEP在大脑皮质发生相位翻转，第1个正相主波和负相主波的平均潜伏期分别为(15.4依2.1)、(16.3依2.0)ms，二者之间无统计学差异(P＞0.05)。单相阳极、单相阴极及双极刺激诱发MEP的平均潜伏期分别为(31.7依1.8)、(29.0依3.9)、(40.0依1.6)ms，阈刺激强度分别为5.0、5.5、6.0 mA。刺激脉冲数为7个/串时MEP平均潜伏期小于5个/串(P＜0.05)，脉宽为0.075 ms时MEP平均潜伏期小于0.050 ms(P＜0.05)，刺激频率为350 Hz时MEP平均潜伏期小于频率150 Hz(P＜0.05)。结论刺激犬正中神经成功诱发SSEP，可区分中央沟两侧感觉区和运动区。刺激脉冲、脉宽、刺激频率均可影响MEP潜伏期。