The study is to explore the molecular mechanisms underlying the occurrence of malignant cerebral edema (cerebral hernia) after large hemispheric infarction. Acute LHI (<=48h) patients that develop cerebral hernia or not within 5 days post-stroke onset, as well as the healthy controls will be studied. The participants will be followed for up to 6 months post stroke-onset, and their modified Rankin Scale (mRS) will be recorded. A mRS score of 0-4 is considered as a favorable outcome while a score of 5-6 as an unfavorable one.