Abstract SNACC-28

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Systematic review of motor evoked potentials monitoring with transcranial and direct motor cortex stimulation in patients undergoing intracranial aneurysm surgery

Yoshimura K, Ida M, Tanaka Y, Hayashi H, Kawaguti M
Nara Medical University, Kashihara, Nara, Japan

Background: In intracranial aneurysm surgery, postoperative motor deficits can be caused by blood flow insufficiency. In order to prevent postoperative motor deficits after intracranial aneurysm surgery, monitoring of motor evoked potential (MEP) has been widely applied. Although the monitoring of MEP during intracranial aneurysm surgery has become feasible, its reliability remained undetermined. In fact, false positive and false negative results occasionally developed associated with intraoperative MEP monitoring. Furthermore, two types of stimulating technique for MEP including transcranial stimulation (Tc-MEP) and direct motor cortex stimulation (D-MEP) can be applied. It is unknown which technique is preferable to the other. In this study, we conducted a systematic review of literatures regarding intraoperative MEP monitoring during intracranial aneurysm surgery and evaluated the the reliability of MEP monitoring using Tc-MEP and/or D-MEP.
Methods: We searched the electronic databases of MEDLINE, EMBASE, Cochrane Central, CINAHL and the Japanese Central Review of Medicine (covering January 1998 to October 2013) for articles that reported on MEP monitoring in patients scheduled for intracranial aneurysm clipping and that included clinical outcome such as postoperative motor function. The data extraction from studies was carried out independently by two researchers based on a data checklist which contained basic data, method of MEP, results of MEP monitoring and postoperative motor function. Studies were excluded in case of case report, case study with a number of examined population enrolled at less than 10 cases and review articles without personal data. We divided stimulation technique to Tc-MEP or D-MEP and evaluated the relationship between the results of MEP monitoring and postoperative motor function.
Results: Online search identified 229 publications. Seventeen studies were included in this literature review. There are 10 studies for Tc-MEP and 10 for D-MEP. Tc-MEP monitoring was performed in 633 patients and was feasible 627 patients (success rate 99.1%). Table 1 showed the relationship between the intraoperative changes in Tc-MEP and postoperative motor function. The sensitivity and specificity of Tc-MEP were 28.1% and 99.2% respectively. False positive and negative rates were 0.8% and 71.9% with an accuracy of 95.5%. D-MEP monitoring was performed in 753 patients and was feasible 723 patients (success rate 96.0%). Table 2 showed the relationship between the intraoperative changes of D-MEP and postoperative motor function. The sensitivity and specificity of D-MEP were 31.4% and 98.4% respectively. False positive and negative rates were 1.6% and 68.6% with an accuracy of 95.2%.
Conclusions: Reliability of intraoperative MEP monitoring with Tc-MEP and D-MEP was comparable in patients undergoing intracranial aneurysm surgery. However, further improvement would be required to reduce the false negative rates.

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