Measurement of brain edema by noninvasive cerebral electrical impedance in patients with massive hemispheric cerebral infarction.

BACKGROUND Malignant cerebral infarction often occurs in patients with massive cerebral infarction. Monitoring brain edema is therefore helpful to make correct clinical decisions. Our previous studies have confirmed that cerebral electrical impedance (CEI) can sensitively reflect the brain edema after stroke. METHODS The CEI was measured consecutively by a noninvasive brain edema monitor in 69 patients with massive hemispheric cerebral infarction (MHCI). The results of the CEI were converted into the perturbation index (PI). The characteristics of dynamic changes of the CEI after MHCI were analyzed. Receiver-operating characteristics analysis was used to calculate predictive values for PI and other known parameters including NIHSS score and infarct volume. RESULTS (1) The overall rate of positive CEI was 88.4% (61/69) in all patients with MHCI. (2) The PI on the infarct side increased significantly within 24 h after stroke onset and reached a peak level 3-5 days after stroke onset (p < 0.01). (3) Age, NIHSS score at admission, infarct volume, and the PI at 24 h after stroke onset were significantly different between the malignant and nonmalignant groups. The best predictor of a malignant MHCI was the PI at 24 h after stroke onset with a cut-off value of 10.02 (90.9% sensitivity, 87.2% specificity, 76.9% positive predictive value, 95.3% negative predictive value). CONCLUSIONS The noninvasive CEI can sensitively reflect the brain edema in patients with MHCI. Monitoring the CEI may help to predict malignant MHCI and guide treatment decisions.