The so-called hypertensive emergency is a condition where blood pressure rises very quickly, reaching a very high level in a short period of time. At this time, it does not necessarily lead to hypertensive encephalopathy, which is a more dangerous condition. Hypertensive encephalopathy indicates that due to the rapid rise in blood pressure, the pressure in the brain's blood vessels becomes excessively high. This pressure causes cerebral edema. At this point, because the blood pressure is higher than the brain's perfusion pressure, the brain becomes swollen, which is extremely dangerous. If the swelling is severe, it may lead to brain herniation, which can be fatal. Therefore, relatively speaking, hypertensive encephalopathy is much more serious than a hypertensive emergency and represents a dangerous stage of progression within a hypertensive crisis. Thus, hypertensive encephalopathy is a very dangerous condition and is one of the most critical manifestations within a hypertensive emergency.