Dennis G C, Dehkordi O, Millis R M, Cole A N, Brown D S, Paul O A
Department of Surgery, Howard University Hospital, Washington D.C. 20060, USA.
J Clin Neurophysiol. 1996 Jan;13(1):51-9. doi: 10.1097/00004691-199601000-00005.
We evaluated the intraoperative utility of monitoring median nerve somatosensory evoked potentials (SEPs) in 31 consecutively hospitalized neurosurgical patients (mean age 55.3 +/- 2.1 years) who underwent spinal cord decompression for cervical herniated disc, spondylosis, or tumor. Pre- and postoperative standard neurological examinations included evaluation of motor function, sensory responses, gait, tone, and reflexes. Evoked potentials were recorded from clavicular Erb's (N9) and contralateral cortical (N20) points. Intraoperatively, SEP measurements were obtained after the onset of anesthesia (baseline control) and were repeated throughout the operative procedures. N20 and N9-N20 conduction latencies were measured for each SEP recording; disappearance of the SEP waveform was interpreted as a nonquantifiable increase in latency. Follow-up neurological examinations were made immediately after and up to 6 months following surgery. Postoperatively, the 31 study subjects were assigned to one of two groups based on neurological evaluation: 27 group I subjects had either no change or improvement (good outcome) whereas four group II subjects had postoperative neurological deterioration (poor outcome). Intraoperative N9-N20 interpeak latency was found to increase during cervical decompression in six of 27 group I and in two of four group II subjects. Only two of the Group I subjects exhibited increases > 10% (14 and 19%, respectively). Intraoperative communication to the surgeon of a marked increase of N9-N20 latency during positioning for cervical traction clearly obviated a poor outcome in one group I subject; Upon removal of traction, latency decreased and significant changes in neurological function were not detected postoperatively. The SEP waveform disappeared in two of the group II and in none of the group I subjects. In the two group II subjects exhibiting increases of N9-N20 latencies, increments were > 20%. These findings indicate that in patients undergoing cervical spinal cord decompression, disappearance of SEPs or increases > 20% in the N9-N20 interpeak latency are suggestive of operative conditions that place patients at risk for poor neurological outcome.
我们评估了31例连续住院的神经外科患者（平均年龄55.3±2.1岁）术中监测正中神经体感诱发电位（SEP）的效用，这些患者因颈椎间盘突出症、颈椎病或肿瘤接受脊髓减压手术。术前和术后的标准神经学检查包括运动功能、感觉反应、步态、肌张力和反射的评估。诱发电位从锁骨上的埃尔布点（N9）和对侧皮质（N20）记录。术中，在麻醉开始后（基线对照）获得SEP测量值，并在整个手术过程中重复测量。每次SEP记录均测量N20和N9-N20传导潜伏期；SEP波形消失被解释为潜伏期不可量化的增加。术后立即及术后6个月内进行随访神经学检查。术后，根据神经学评估将31名研究对象分为两组：27名I组对象无变化或有改善（良好结果），而4名II组对象术后神经功能恶化（不良结果）。在I组的27名对象中有6名以及II组的4名对象中有2名在颈椎减压术中发现术中N9-N20峰间潜伏期增加。I组中只有2名对象的增加幅度>10%（分别为14%和19%）。在颈椎牵引定位过程中，术中向外科医生通报N9-N20潜伏期明显增加，显然避免了一名I组对象出现不良结果；去除牵引后，潜伏期缩短，术后未检测到神经功能有显著变化。II组中有2名对象的SEP波形消失，I组中无一例出现这种情况。在表现出N9-N20潜伏期增加的2名II组对象中，增加幅度>20%。这些发现表明，在接受颈椎脊髓减压手术的患者中，SEP消失或N9-N20峰间潜伏期增加>20%提示手术情况会使患者面临神经功能不良结果的风险。
