Use of somatosensory evoked potentials for preoperative assessment in patients with severe aneurysmal subarachnoid hemorrhage before surgical or interventional treatment: a prospective observational cohort study

Abstract

To explore the application value of short latency somatosensory evoked potentials (SLSEP) as a tool for preoperative assessment of surgical or interventional treatment in patients with severe aneurysmal subarachnoid hemorrhage (aSAH). A prospective observational cohort study was conducted. The patients with severe aSAH with a WFNS grade of IV or V admitted to intensive care unit (ICU) of Beijing Tiantan Hospital of Capital Medical University from November 2016 to April 2017 were enrolled. The patients received SLSEP monitoring within 12 hours after onset, and the monitoring results were classified according to the Judson scale. Meanwhile, the findings on cerebral CT scans at admission were evaluated by the modified Fisher classification. The follow-up was performed at 3 months after aSAH ictus based on the modified Rankin scale (mRS), and a mRS score 0-3 was defined as favorable outcome, 4-6 was defined as unfavorable outcome. For statistical evaluation, demographic, clinical, neuroimaging and SLSEP data were evaluated by univariate analysis to identify the risk factors associated with prognosis; afterwards, those factors were analyzed by multivariate Logistic regression; also the validity was assessed by calculating the respective sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV). A total of 41 patients with aSAH were selected, of which 7 were excluded because of the interference of the SLSEP monitoring results, 34 patients with aSAH were enrolled finally. Among them, 21 were classified in the unfavorable outcome group, while the rest (n = 13) were allocated into the favorable outcome group. No significant difference was found in gender, age, body mass index (BMI), time delay from ictus to treatment or the options for therapeutic methods between the two groups. The findings of univariate analysis, however, showed statistically differences in WFNS grade, the modified Fisher scale and Judson scale of SLSEP between the two groups. Yet, the further validity evaluation for these predictors demonstrated that the sensitivity, specificity, PPV and NPV of WFNS grade of V and modified Fisher scale of IV were all less than 85%, whereas the results for SLSEP Judson scale of III were much better (sensitivity: 90.5% vs. 71.4% and 71.4%, specificity: 84.6% vs. 69.2% and 76.9%, PPV: 90.5% vs. 79.0% and 83.3%). In the following multivariate Logistic analysis, only Judson scale of III was identified to be the independent risk factor for poor outcome [odds ratio (OR) = 45.73, 95% confidence interval (95%CI) = 4.25-499.31, P = 0.002], while the WFNS grade of V (OR = 1.14, 95%CI = 0.12-13.06, P = 0.912) and the modified Fisher scale of IV (OR = 7.22, 95%CI = 0.51-113.20, P = 0.160) were merely associated with poor outcomes without significant independence. In comparison with WFNS grade and the modified Fisher scale, SLSEP seems more accurate in the prediction of long-term outcome of severe aSAH prior to surgical or interventional treatment, and thus may be applied as an effective aid in preoperative assessment.