Oner Ali, Ely Claire G, Hermsmeyer Jeffrey T, Norvell Daniel C
Orthopedics and Traumatology Department, Mus State Hospital, Mus, Turkey.
Evid Based Spine Care J. 2012 Feb;3(1):35-43. doi: 10.1055/s-0031-1298599.
Systematic review.
To determine the effectiveness of using electromyography (EMG) during intraoperative pedicle screw placement in patients with thoracic deformity.
A systematic review of the English-language literature was undertaken for articles published between 1970 and July 2011. For our first question, we identified all articles that were designed to evaluate the diagnostic test characteristics (ie, measures of validity such as sensitivity, specificity, positive predictive value [PPV], negative predictive value [NPV]) of EMG for thoracic deformities in adolescent and adult patients. For our second question, we attempted to identify all articles that reported complication rates (pedicle wall breach or new neurological event) after pedicle screw placement in the same population comparing patients who did and did not undergo intraoperative EMG. Articles were excluded if they did not report or give raw data to calculate at least one of the four primary diagnostic test characteristics: sensitivity, specificity, PPV, or NPV for study question one. Articles were excluded if they did not have a "no EMG" control group for study question two. Other exclusions were reviews, editorials, case reports, non-English written studies, and animal studies. We rated the overall body of evidence with respect to each key question using a modified Grades of Recommendation Assessment, Development and Evaluation (GRADE) system for diagnostic and therapeutic studies.
The overall strength of evidence evaluating the diagnostic characteristics was low due to inconsistent findings between studies and uncertainty of the impact of false-negatives. The fairly low sensitivity may lead to a high-false negative rate. It is unclear what the impact of false-negatives would be since no neurological injuries were identified in the studies summarized. A higher specificity would suggest a fairly low false-positive rate; however, the rates could be as high as 30%. If sudden changes in treatment are required in the absence of any adverse event, this could be considered a limitation of such testing. The overall strength of evidence for evaluating the efficacy of EMG compared with no EMG was insufficient because of literature shortage on this topic.
The overall strength of evidence evaluating the diagnostic characteristics was low due to inconsistent findings between studies and uncertainty of the impact of false-negatives. Given the low sensitivity and potential high rate of false-negatives, pedicle wall breaches may occur, without EMG notification. These undetected breaches may lead to loose or weak screw position which may lead to neurovascular complications during or after a translation-rotation maneuver, especially in rigid deformities. The higher sensitivity would suggest a lower rate of false-positives. We recommend considering the use of intraoperative EMG-monitoring method to help identify potential complications based upon available technology, personal experiences and preferences; however, surgeons should keep in mind that false-positive results may lead to increased surgery time and increased blood loss. The surgeon should not depend solely on EMG since it can also render false-negatives.
系统评价。
确定在胸椎畸形患者术中椎弓根螺钉置入时使用肌电图（EMG）的有效性。
对1970年至2011年7月发表的英文文献进行系统评价。对于我们的第一个问题，我们检索了所有旨在评估EMG对青少年和成年患者胸椎畸形的诊断试验特征（即有效性指标，如敏感性、特异性、阳性预测值[PPV]、阴性预测值[NPV]）的文章。对于我们的第二个问题，我们试图检索所有报告了在同一人群中，比较接受和未接受术中EMG的患者在椎弓根螺钉置入后并发症发生率（椎弓根壁破裂或新发神经事件）的文章。如果文章未报告或未给出原始数据以计算四个主要诊断试验特征（敏感性、特异性、PPV或NPV）中的至少一个，则排除该文章用于研究问题一。如果文章没有用于研究问题二的“无EMG”对照组，则排除该文章。其他排除标准包括综述、社论、病例报告、非英文撰写的研究以及动物研究。我们使用针对诊断和治疗研究的改良推荐分级评估、发展和评价（GRADE）系统，对每个关键问题的总体证据进行评级。
由于研究结果不一致以及假阴性影响的不确定性，评估诊断特征的总体证据强度较低。相当低的敏感性可能导致高假阴性率。由于在总结的研究中未发现神经损伤，尚不清楚假阴性的影响会是什么。较高的特异性表明假阳性率相当低；然而，该比率可能高达30%。如果在没有任何不良事件的情况下需要突然改变治疗方案，这可能被视为这种检测的一个局限性。由于关于该主题的文献不足，评估EMG与不使用EMG相比疗效的总体证据强度不足。
由于研究结果不一致以及假阴性影响的不确定性，评估诊断特征的总体证据强度较低。鉴于敏感性低和潜在的高假阴性率，可能会发生椎弓根壁破裂而无EMG提示。这些未被检测到的破裂可能导致螺钉位置松动或不牢固，这可能在平移-旋转操作期间或之后导致神经血管并发症，尤其是在僵硬畸形中。较高的敏感性表明假阳性率较低。我们建议根据现有技术、个人经验和偏好考虑使用术中EMG监测方法，以帮助识别潜在并发症；然而，外科医生应牢记假阳性结果可能导致手术时间延长和失血增加。外科医生不应仅依赖EMG，因为它也可能出现假阴性结果。
