ABSTRACT
Objective To explore the advantage of motor evoked potentials (MEPs) monitoring for postoperativemotor deficit evaluation under threshold-level electrical stimulation using cranial peg-screw electrode (CPSE) during cerebral aneurysm keyhole approach microsurgery. Methods A total of 31 patients who underwent anterior circulation aneurysm microsurgery through keyhole approach were selected in this study. MEPs monitoring of the operation side was conducted with threshold-level electrical stimulation using CPSE, and that of the non-operation side was conducted with transcranial electric stimulation using the same stimulation threshold. The change of minimum voltage required for MEPs monitoring was observed and recorded. The intraoperative MEPs monitoring results and postoperative neurological functions were analyzed by prospective observational study. Results MEPs of the operation side was successfully induced in 28 cases. No complications related to MEPs monitoring were observed. Intraoperative MEPs abnormalities were monitored in3 cases, and2 of them had postoperative transient hemiplegia, showing a sensitivity of 100% (2/2). No motor dysfunction was observed in the other 26 cases who were not presented with intraoperative MEPs abnormalities in 25 cases, showing a specificity of 96. 30% (26/27). Conclusion MEPs monitoring with threshold-level electrical stimulation using CPSE is a feasible and reliable method and t has satisfactory sensitivity and specificity for predicting motor dysfunction induced by cerebral ischemia, indicating that this method can be an alternative for routine MEPs monitoring with conventional transcranial electrical stimulation in cerebral aneurysm microsurgery.
ABSTRACT
<p><b>BACKGROUND</b>Neurophysiologic monitoring during surgery is to prevent permanent neurological injury resulting from surgical manipulation. To improve the accuracy and sensitivity of intraoperative neuromonitoring, combined monitoring of transcranial electrical stimulation motor evoked potentials (TES-MEPs), somatosensory evoked potentials (SSEPs) and brainstem auditory evoked potentials (BAEPs) was attempted in microsurgery for lesions adjacent to the brainstem and intracranial aneurysms.</p><p><b>METHODS</b>Monitoring of combined TES-MEPs with SSEPs was attempted in 68 consecutive patients with lesions adjacent to the brainstem as well as intracranial aneurysms. Among them, 31 patients (31 operations, 28 of posterior cranial fossa tumors, 3 of posterior circulation aneurysms) were also subjected to monitoring of BAEPs. The correlation of monitoring results and clinical outcome was studied prospectively.</p><p><b>RESULTS</b>Combined monitoring of evoked potentials (EPs) was done in 64 (94.1%) of the 68 patients. MEPs monitoring was impossible for 4 patients (5.9%). No complication was observed during the combined monitoring in all the patients. In 45 (66.2%) of the 68 patients, EPs were stable, and they were neurologically intact. Motor dysfunction was detected by MEPs in 8 patients, SSEPs in 5, and BAEPs in 4, respectively.</p><p><b>CONCLUSIONS</b>A close relationship exists between postoperative motor function and the results of TES-MEPs monitoring. TES-MEPs are superior to SSEPs and BAEPs in detecting motor dysfunction, but combined EPs serve as a safe, effective and invasive method for intraoperative monitoring of the function of the motor nervous system. Monitoring of combined EPs during microsurgery for lesions adjacent to the brainstem and intracranial aneurysms may detect potentially hazardous maneuvers and improve the safety of subsequent procedures.</p>