Abalkhail Tariq M, MacDonald David B, AlThubaiti Ibrahim, AlOtaibi Faisal A, Stigsby Bent, Mokeem Amal A, AlHamoud Iftetah A, Hassounah Maher I, Baz Salah M, AlSemari Abdulaziz, AlDhalaan Hesham M, Khan Sameena
Section of Neurophysiology, Department of Neurosciences, King Faisal Specialist Hospital & Research Center (KFSH), Saudi Arabia.
Section of Neurophysiology, Department of Neurosciences, King Faisal Specialist Hospital & Research Center (KFSH), Saudi Arabia.
Clin Neurophysiol. 2017 Nov;128(11):2300-2308. doi: 10.1016/j.clinph.2017.09.005. Epub 2017 Sep 28.
To determine optimal interstimulus interval (ISI) and pulse duration (D) for direct cortical stimulation (DCS) motor evoked potentials (MEPs) based on rheobase and chronaxie derived with two techniques.
In 20 patients under propofol/remifentanil anesthesia, 5-pulse DCS thenar MEP rheobase and chronaxie with 2, 3, 4 and 5ms ISI were measured by linear regression of five charge thresholds at 0.05, 0.1, 0.2, 0.5 and 1msD, and estimated from two charge thresholds at 0.1 and 1msD using simple arithmetic. Optimal parameters were defined by minimum threshold energy: the ISI with lowest rheobase×chronaxie, and D at its chronaxie. Near-optimal was defined as threshold energy <25% above minimum.
The optimal ISI was 3 or 4 (n=7 each), 2 (n=4), or 5ms (n=2), but only 4ms was always either optimal or near-optimal. The optimal D was ∼0.2 (n=12), ∼0.1 (n=7) or ∼0.3ms (n=1). Two-point estimates closely approximated five-point measurements.
Optimal ISI/D varies, with 4ms/0.2ms being most consistently optimal or near-optimal. Two-point estimation is sufficiently accurate.
The results endorse 4ms ISI and 0.2msD for general use. Two-point estimation could enable quick individual optimization.
基于用两种技术得出的基强度和时值，确定直接皮层刺激（DCS）运动诱发电位（MEP）的最佳刺激间隔（ISI）和脉冲持续时间（D）。
在20例接受丙泊酚/瑞芬太尼麻醉的患者中，通过对0.05、0.1、0.2、0.5和1ms D时的五个电荷阈值进行线性回归，测量5脉冲DCS拇指展肌MEP的基强度和时值，ISI分别为2、3、4和5ms，并使用简单算法根据0.1和1ms D时的两个电荷阈值进行估算。通过最小阈值能量定义最佳参数：基强度×时值最低时的ISI，以及其时值对应的D。接近最佳定义为阈值能量比最小值高<25%。
最佳ISI为3或4（各7例）、2（4例）或5ms（2例），但只有4ms始终为最佳或接近最佳。最佳D约为0.2（12例）、约0.1（7例）或约0.3ms（1例）。两点估计值与五点测量值非常接近。
最佳ISI/D各不相同，4ms/0.2ms最常为最佳或接近最佳。两点估计足够准确。
结果支持普遍使用4ms ISI和0.2ms D。两点估计可实现快速个体化优化。
