Kothbauer K F
Division of Neurosurgery, Department of surgery, Kantonsspital Luzern, 6000 Luzern 16, Switzerland.
Neurophysiol Clin. 2007 Dec;37(6):407-14. doi: 10.1016/j.neucli.2007.10.003. Epub 2007 Nov 9.
During resection of intramedullary spinal-cord tumors intraoperative neurophysiological monitoring has become a true surgical technology. Motor evoked potentials are the most important modality for this purpose. Its use requires neurophysiological expertise from the surgeon, and a monitoring team in place able to handle the necessary equipment. Motor potentials are evoked by transcranial electrical motor cortex stimulation. A "single stimulus technique" evokes D-waves recorded from the spinal cord. The "multipulse (or train) stimulation technique" evokes electromyographic responses in peripheral muscles. These are optimally recorded from the thenar, hypothenar, tibialis anterior, and flexor hallucis brevis muscles, which are known to have strong pyramidal innervation. D-wave monitoring looks primarily at the peak-to-peak amplitude. When monitoring muscle MEPs, the presence or absence of the response irrespective of stimulation intensity is the important parameter. Preparations for neurophysiological monitoring fit quite well into a neurosurgical operating room environment. Recording and interpretation of MEPs is fast and straightforward. Pre- and postoperative clinical motor findings correlate with intraoperative MEP results. Thus correct prediction of the clinical status at a given time during surgery is possible with a very high certainty. The sensitivity of muscle MEPs for postoperative motor deficits is nearly 100%, its specificity is about 90%. Thus MEP data indeed reflect the clinical "reality". Present and stable recordings document intact motor pathways and allow the surgeon to confidently proceed with a tumor resection. Loss of muscle MEPs and/or decrease of the D-wave amplitude constitutes a "window of warning". It reflects a pattern of MEP change indicating a reversible injury to the essential motor pathways. Using this information, the surgical strategy can be adapted before irreversible neurological damage is caused by the surgical manipulation. Such adaptation comprises simply waiting for the recordings to spontaneously improve again, irrigating with warm saline solution to wash out blocking potassium. Other measures include the elevation of mean arterial pressure to improve local perfusion. Even staged resection can be considered if intraoperative measures do not sufficiently improve the recordings.
在髓内脊髓肿瘤切除术中，术中神经生理监测已成为一项真正的外科技术。运动诱发电位是实现这一目的最重要的方式。其应用需要外科医生具备神经生理学专业知识，以及一个能够操作必要设备的监测团队。运动电位通过经颅电刺激运动皮层诱发。“单刺激技术”可诱发从脊髓记录到的D波。“多脉冲（或串刺激）技术”可诱发外周肌肉的肌电图反应。这些反应最好从鱼际肌、小鱼际肌、胫前肌和拇短屈肌记录，这些肌肉已知具有强大的锥体神经支配。D波监测主要关注峰峰值幅度。监测肌肉运动诱发电位时，无论刺激强度如何，反应的有无是重要参数。神经生理监测的准备工作与神经外科手术室环境非常契合。运动诱发电位的记录和解读快速且直接。术前和术后的临床运动检查结果与术中运动诱发电位结果相关。因此，在手术过程中的特定时间对临床状态进行非常准确的预测是可能的。肌肉运动诱发电位对术后运动功能缺损的敏感性接近100%，其特异性约为90%。因此，运动诱发电位数据确实反映了临床“实际情况”。当前稳定的记录表明运动通路完整，使外科医生能够自信地进行肿瘤切除。肌肉运动诱发电位的消失和/或D波幅度的降低构成一个“警告窗口”。它反映了运动诱发电位变化的模式，表明基本运动通路受到可逆性损伤。利用这些信息，可以在手术操作导致不可逆神经损伤之前调整手术策略。这种调整包括简单地等待记录再次自发改善，用温盐水冲洗以冲走阻滞的钾。其他措施包括提高平均动脉压以改善局部灌注。如果术中措施不能充分改善记录，甚至可以考虑分期切除。
