Raynor Barry L, Lenke Lawrence G, Bridwell Keith H, Taylor Brett A, Padberg Anne M
Washington University Medical Center, Department of Orthopaedic Surgery, Barnes-Jewish Hospital Health Systems, St. Louis, MO 63110, USA.
Spine (Phila Pa 1976). 2007 Nov 15;32(24):2673-8. doi: 10.1097/BRS.0b013e31815a524f.
A retrospective analysis of 1078 spinal surgical procedures with lumbar pedicle screw placement at a single institution.
Based on previously established normative values, triggered electromyographic stimulation (TrgEMG) was re-examined to evaluate its efficacy in determining screw malposition.
Threshold values for confirmation of intraosseous placement of pedicle screws with EMG stimulation is controversial.
TrgEMG threshold values for 4857 pedicle screws placed from L2 to S1 from 1996 to 2005 were analyzed. An ascending method of constant current stimulation was applied to each pedicle screw to obtain a compound muscle action potential (CMAP) from lower extremity myotomes. Previously determined threshold value normative data from a published clinical series of 233 screws were as follows: 0 to 4 mA, high likelihood of pedicle wall breach; 4 to 8 mA, possible pedicle wall breach; >8 mA, no pedicle wall defect.
A total of 7.74% (376 of 4857) of all screws tested had threshold values <8.0 mA. A total of 19.1% (72 of 376) of these were <4.0 mA: 54% (39 of 72) were repositioned (26) or removed (13) while the remaining 33 screws were left in place following repalpation. A total of 80.9% (304 of 376) had thresholds between 4 and 8 mA: 17.4% (53) were repositioned (38) or removed (15). Nine screws had thresholds of <or=2.8 mA and were either repositioned or removed following confirmation of a medial wall breach. A total of 74.5% (280 of 376) of all screws with thresholds <8.0 mA were verified as correctly placed by repalpation/radiography and therefore left in place.
The probability of a medial breach pedicle screw detected by triggered EMG stimulation increases with decreasing triggered EMG thresholds: 0.31% for >8.0 mA, 17.4% for 4.0 to 8.0 mA, 54.2% for <4.0 mA, and 100% for <2.8 mA. At 2.8 mA, triggered EMG has a specificity of 100%, with sensitivity of 8.4%; at 4.0 mA, specificity of 99% and sensitivity of 36%; and at 8.0 mA, 94% specificity and 86% sensitivity. TrgEMG is an adjunct technique and should always be used in conjunction with palpation and radiography to optimize safe pedicle screw placement.
对某一机构进行的1078例腰椎椎弓根螺钉置入脊柱手术进行回顾性分析。
基于先前确立的标准值，重新审视触发式肌电图刺激（TrgEMG），以评估其在确定螺钉位置不当方面的有效性。
通过肌电图刺激确认椎弓根螺钉骨内置入的阈值存在争议。
分析了1996年至2005年期间从L2至S1置入的4857枚椎弓根螺钉的TrgEMG阈值。对每枚椎弓根螺钉采用恒流刺激递增法，以获取来自下肢肌节的复合肌肉动作电位（CMAP）。先前从一个包含233枚螺钉的已发表临床系列中确定的阈值标准数据如下：0至4毫安，椎弓根壁破裂可能性高；4至8毫安，可能存在椎弓根壁破裂；>8毫安，无椎弓根壁缺损。
所有测试螺钉中，共有7.74%（4857枚中的376枚）的阈值<8.0毫安。其中，共有19.1%（376枚中的72枚）<4.0毫安：54%（72枚中的39枚）被重新定位（26枚）或取出（13枚），其余33枚螺钉在重新触诊后留在原位。共有80.9%（376枚中的304枚）的阈值在4至8毫安之间：17.4%（53枚）被重新定位（38枚）或取出（15枚）。9枚螺钉的阈值≤2.8毫安，在确认内侧壁破裂后被重新定位或取出。所有阈值<8.0毫安的螺钉中，共有74.5%（376枚中的280枚）经触诊/影像学检查证实位置正确，因此留在原位。
触发式肌电图刺激检测到内侧椎弓根螺钉破裂的概率随触发式肌电图阈值降低而增加：>8.0毫安时为0.31%，4.0至8.0毫安时为17.4%，<4.0毫安时为54.2%，<2.8毫安时为100%。在2.8毫安时，触发式肌电图的特异性为100%，敏感性为8.4%；在4.0毫安时，特异性为99%，敏感性为36%；在8.0毫安时，特异性为94%，敏感性为86%。TrgEMG是一种辅助技术，应始终与触诊和影像学检查结合使用以优化椎弓根螺钉的安全置入。
