Title : Impact of changes in intraoperative evoked potential monitoring on stroke rates in intracranial aneurysmal surgery
Objectives: To present the outcomes of 191 cases treated surgically for intracranial aneurysmal who underwent intraoperative SSEP and MEP monitoring and to analyze the sensitivity, specificity and predictive value of changes in predicting postoperative stroke. for intracranial aneurysmal who underwent intraoperative SSEP and MEP monitoring and to analyze the sensitivity, specificity and predictive value of changes in predicting postoperative stroke.
Methods: We retrospectively reviewed of data of 191 patients who underwent intracranial aneurysmal neck clipping and intraoperative MEP and SEP monitoring were carried out in all cases. Postoperatively, all patients underwent computed tomography(CT) or magnetic resonance imaging(MRI) within 72 hours. Sensitivity, specificity, positive predictive value(PPV), negative predictive value(NPV) of SSEP and MEP were calculated with a Fisher exact test.
Results: The patient population of 191 had a mean age of 58.6 years and consisted of 125 women (65.4%). The 22 (all anterior circulation) were ruptured aneurysm, and 169 (167 anterior, 2 posterior) were unruptured. Changes of SSEP occurred in 4 of 191 cases (20.9%): 2 of 4 (50%) were reversible. Changes of MEP occurred in 4 of 191 cases (20.9%): 1 of 4 (25%) were reversible. Postoperative CT or MRI findings were recorded as stroke in 5 patients. The sensitivity, specificity, PPV, NPV were 42.9%, 99.4%, 75%, 97.9% in only SEP change, 28.6%, 98.9%, 50%, 97.3% in only MEP change, 71.4%, 98.3%, 62.5%, 98.4% in SEP or MEP changes, respectively.
Conclusion: Detection of either MEP or SEP changes can provide higher sensitivity than single SEP, MEP monitoring for predicting postoperative stroke. Although specificity and NPV were very high because of large number of cases without SSEP changes and no postoperative stroke, this information is helpful during the intraoperative assessment of intracranial aneurysm.