Combining Transcranial Doppler and EEG Data to Predict Delayed Cerebral Ischemia After Subarachnoid Hemorrhage

Background and Objectives: Delayed cerebral ischemia (DCI) is the leading complication of subarachnoid hemorrhage (SAH). Because DCI was traditionally thought to be caused by large vessel vasospasm, transcranial Doppler ultrasounds (TCDs) have been the standard of care. Continuous EEG has emerged as a promising complementary monitoring modality and predicts increased DCI risk. Our objective was to determine whether combining EEG and TCD data improves prediction of DCI after SAH. We hypothesize that integrating these diagnostic modalities improves DCI prediction. Methods: We retrospectively assessed patients with moderate-severe SAH (2011-2015, Fisher=3-4 or Hunt-Hess=4-5) who had both prospective TCD and EEG acquisition during hospitalization. Middle cerebral artery (MCA) peak systolic velocities (PSV) and the presence or absence of epileptiform abnormalities (EA), defined as seizures, epileptiform discharges, and rhythmic/periodic activity, were recorded daily. Logistic regressions were used to identify significant covariates of EA and TCD to predict DCI. Group-Based Trajectory Modeling (GBTM) was used to account for changes over time by identifying distinct group trajectories of MCA PSV and EA associated with DCI risk. Results: We assessed 107 patients, and DCI developed in 56 (51.9%). Univariate predictors of DCI are presence of high-MCA velocity (PSV≥200cm/s, Se=27%, Sp=89%) and EA (Se=66%, Sp=62%) both on or before day 3. Two univariate GBTM trajectories of EA predicted DCI (Se=64%, Sp=62.75%). Logistic regression and GBTM models using both TCD and EEG monitoring performed better. The best logistic regression and GBTM models used both TCD and EEG data, Hunt-Hess score at admission, and aneurysm treatment as predictors of DCI (Logistic Regression: Se=90%, Sp=70%; GBTM: Se=89%, Sp=67%). Discussion: EEG and TCD biomarkers combined provide the best prediction of DCI. The conjunction of clinical variables with the timing of EA and high-MCA velocities improved model performance. These results suggest that TCD and cEEG are promising complementary monitoring modalities for DCI prediction. Our model has potential to serve as a decision support tool in SAH management. Classification of Evidence: This study provides Class II evidence that combined TCD and EEG monitoring can identify delayed cerebral ischemia after subarachnoid hemorrhage.