"Threshold-level" multipulse transcranial electrical stimulation of motor cortex for intraoperative monitoring of spinal motor tracts: description of method and comparison to somatosensory evoked potential monitoring
"Threshold-level" multipulse transcranial electrical stimulation of motor cortex for intraoperative monitoring of spinal motor tracts: description of method and comparison to somatosensory evoked potential monitoring
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DOI：
10.3171/jns.1998.88.3.0457
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发表时间：
1998-03-01
影响因子：
4.1
通讯作者：
Green, BA
中科院分区：
文献类型：
--
作者：
Calancie, B;Harris, W;Green, BA
许多方法已被追求，以评估在麻醉患者的手术过程中的中枢运动通路的功能。目前，还没有标准出现，可能是因为迄今为止描述的每种方法都需要某种程度的妥协和/或缺乏敏感性。本研究的目的是开发和评价术中监测脊髓运动传导的方案，该方案：1）安全; 2）对运动通路敏感且特异; 3）提供即时反馈; 4）符合麻醉要求; 5）允许监测自发和/或神经根刺激诱发的肌电图; 6）需要很少或不需要手术团队参与;和7）除了常规用于体感诱发电位（SSEP）监测之外，需要有限的设备。使用多脉冲电刺激器设计的经颅应用，作者已经开发了一个协议，他们称之为“阈值水平”多脉冲经颅电刺激（TES）。研究了被认为是术后功能障碍高风险的患者。在麻醉诱导和患者定位后，但在切开前，获得SSEP的"基线"测量值以及从被监测的每块肌肉引起运动反应所需的最小（即阈值水平）TES电压。一个简短的，高频脉冲序列（三个脉冲; 2毫秒的脉冲间隔）被用于TES在所有情况下。在整个手术过程中的不同时间收集数据（SSEP的潜伏期和振幅; TES的阈值电压）。通过评估感觉和运动状态来判断术后神经功能状态，并与术中SSEP和TES结果进行比较，以确定每种电生理监测技术的敏感性和特异性。在入组的34例患者中，32例在麻醉诱导和定位后但在切开前检查时显示病变尾侧神经支配肌肉的TES诱发反应（即基线）。相比之下，34名患者中只有25名患者的基线SSEPs得到解决。在手术过程中，这25名患者中有12名患者的SSEP波形发生了显著变化，10名患者的TES阈值发生了变化。15例患者出现不同程度和持续时间的术后神经功能缺损。术中TES阈值的变化准确地预测了术后运动无力的每一个实例，没有错误，但未能预测术后感觉障碍的四个实例。术中SSEP监测在预测术后感觉状态方面并非100%准确，并且未能预测5例术后运动障碍。由于术中TES的发现，手术计划改变或其他影响6例患者（约15%的样本人群），可能限制了这些患者术后运动功能障碍的程度。这种术中监测脊髓运动传导的新方法似乎满足上述所有目标。虽然大多数脊柱手术（例如，简单的椎间盘手术）术后运动功能障碍的风险相对较低，但这种新的监测方法提供的几乎即时和准确的脊柱运动传导知识应有助于高风险手术，如肿瘤切除、血管异常矫正和严重畸形矫正。
Numerous methods have been pursued to evaluate function in central motor pathways during surgery in the anesthetized patient. At this time, no standard has emerged, possibly because each of the methods described to date requires some degree of compromise and/or lacks sensitivity.Object. The goal of this study was to develop and evaluate a protocol for intraoperative monitoring of spinal motor conduction that: 1) is safe; 2) is sensitive and specific to motor pathways; 3) provides immediate feedback; 4) is compatible with anesthesia requirements; 5) allows monitoring of spontaneous and/or nerve root stimulus-evoked electromyography; 6) requires little or no involvement of the surgical team; and 7) requires limited equipment beyond that routinely used for somatosensory evoked potential (SSEP) monitoring. Using a multipulse electrical stimulator designed for transcranial applications, the authors have developed a protocol that they term "threshold-level" multipulse transcranial electrical stimulation (TES).Methods. Patients considered at high risk for postoperative deficit were studied. After anesthesia had been induced and the patient positioned, but prior to incision, "baseline" measures of SSEPs were obtained as well as the minimum (that is, threshold-level) TES voltage needed to evoke a motor response from each of the muscles being monitored. A brief, high-frequency pulse train (three pulses; 2-msec interpulse interval) was used for TES in all cases. Data (latency and amplitude for SSEP; threshold voltage for TES) were collected at different times throughout the surgical procedure. Postoperative neurological status, as judged by evaluation of sensory and motor status, was compared with intraoperative SSEP and TES findings for determination of the sensitivity and specificity of each electrophysiological monitoring technique.Of the 34 patients enrolled, 32 demonstrated TES-evoked responses in muscles innervated at levels caudal to the lesion when examined after anesthesia induction and positioning but prior to incision (that is, baseline). In contrast, baseline SSEPs could be resolved in only 25 of the 34 patients. During surgery, significant changes in SSEP waveforms were noted in 12 of these 25 patients, and 10 patients demonstrated changes in TES thresholds. Fifteen patients experienced Varying degrees and durations of postoperative neurological deficit. Intraoperative changes in TES thresholds accurately predicted each instance of postoperative motor weakness without error, but failed to predict four instances of postoperative sensory deficit. Intraoperative SSEP monitoring was not 100% accurate in predicting post operative sensory status and failed to predict five instances of postoperative motor deficit. As a result of intraoperative TES findings, the surgical plan was altered or otherwise influenced in six patients (roughly 15% of the sample population), possibly limiting the extent of postoperative motor deficit experienced by these patients.Conclusions. This novel method for intraoperative monitoring of spinal motor conduction appears to meet all of the goals outlined above. Although the risk of postoperative motor deficit is relatively low for the majority of spine surgeries (for example, a simple disc), high-risk procedures, such as tumor resection, correction of vascular abnormalities, and correction of major deformities, should benefit from the virtually immediate and accurate knowledge of spinal motor conduction provided by this new monitoring approach.