Transcranial Doppler Combined With Quantitative Electroencephalography Brain Function Monitoring for Estimating the Prognosis of Patients With Posterior Circulation Cerebral Infarction

Abstract

Posterior circulation cerebral infarction (PCCI) can lead to deceased infratentorial cerebral blood flow (CBF) and metabolism. Neural activity is closely related to regional cerebral blood flow both spatially and temporally. Transcranial Doppler (TCD) combined with quantitative electroencephalography (QEEG) is a technique that evaluates neurovascular coupling and involves synergy between the metabolic and vascular systems. This study aimed to monitor brain function using TCD-QEEG and estimate the efficacy of TCD-QEEG for predicting the prognosis of patients with PCCI. We used a TCD-QEEG recording system to perform quantitative brain function monitoring; we recorded the related clinical variables simultaneously. The data were analyzed using a Cox proportional hazards regression model. Receiver-operating characteristic (ROC) curve analysis was used to evaluate the cut-off for the diastolic flow velocity (VD) and (delta + theta)/(alpha + beta) ratio (DTABR). The area under the ROC curve (AUROC) was calculated to assess the predictive validity of the study variables. Forty patients (aged 63.7 ± 9.9 years; 30 men) were assessed. Mortality at 90 days was 40%. The TCD indicators of VD [hazard ratio (HR) 0.168, confidence interval (CI) 0.047-0.597, p = 0.006] and QEEG indicators of DTABR (HR 12.527, CI 1.637-95.846, p = 0.015) were the independent predictors of the clinical outcomes. The AUROC after combination of VD and DTABR was 0.896 and showed better predictive accuracy than the Glasgow Coma Scale score (0.75), VD (0.76), and DTABR (0.781; all p < 0.05). TCD-QEEG provides a good understanding of the coupling mechanisms in the brain and can improve our ability to predict the prognosis of patients with PCCI.

Keywords: brain function monitoring; cerebral infarction; prognosis; quantitative electroencephalography; transcranial Doppler.

Figure 1

Representative patients. (A) QEEG for a non-survivor showing a significant increase in the slower delta frequency band and a significant decrease in the faster alpha frequency band. MF and spectral entropy decreased and DTABR and DAR (but not BSI) increased. TCD shows that the VD, VS, and VM decreased. (B) QEEG and TCD for a survivor showing similar changes that are not as significant as those seen in a. BSI did not increase either. (C) Normal QEEG and TCD in a healthy control patient. DTABR, (delta + theta)/(alpha + beta) ratio; DAR, delta/alpha ratio; BSI, brain symmetry index; MF, median frequency; VS, systolic flow velocity; VM, mean flow velocity; VD, diastolic flow velocity; PI, pulsatility index; TCD, transcranial Doppler; QEEG, quantitative electroencephalography.

Figure 2

Comparison of TCD and QEEG parameters between patients with PCCI and healthy controls. (A) Systolic flow velocity (VS), diastolic flow velocity (VD), mean flow velocity (VM); (B) pulsatility index (PI), brain symmetry index (BSI); (C) amplitude-integrated EEG (AEEG); (D) alpha variability (AV), spectral entropy, 95% spectral edge frequency (SEF95); (E) relative band power of delta, theta, beta; (F) median frequency (MF), peak frequency (PF); (G) envelope analysis (EA), relative band power of alpha, gross energy (GE); (H) delta ratio (DR), alpha/beta ratio (ABR); (I) delta/alpha ratio (DAR), (delta + theta)/(alpha + beta) ratio (DTABR). ^#P < 0.05 for non-survivors vs. survivors; *P < 0.05 for non-survivors vs. healthy controls; ⁺P < 0.05 for survivors vs. healthy controls.

Figure 3

Kaplan-Meier survival curves for the training cohort. (A) Kaplan-Meier survival curves for VD; (B) Kaplan-Meier survival curves for DTABR. Patients with a VD ≤ 14.5 had a higher risk of death than those with a VD > 14.5; the 90-day survival rate was lower in patients with a DTABR > 2 than in patients with a DTABR ≤ 2. VD, diastolic flow velocity; DTABR, (delta + theta)/(alpha + beta) ratio.

Figure 4

Comparison of ROC curves (AUROC) to predict the outcome between the four models in this cohort. Glasgow Coma Scale (GCS), AUROC 0.75 (0.588–0.873); diastolic flow velocity (VD), AUROC 0.76 (0.599–0.881); (delta + theta)/(alpha + beta) ratio (DTABR), AUROC 0.781 (0.622–0.896); transcranial Doppler (TCD) + quantitative EEG (QEEG), AUROC 0.896 (0.758–0.97). P < 0.05 for TCD (VD) + QEEG (DTABR) comparison with GCS, VD (independent predictor of TCD), and DTABR (independent predictor of QEEG).