HYPERTENSIVE encephalopathy is a syndrome consisting of a sudden elevation of arterial blood pressure usually preceded by severe headache and followed by convulsions, coma, or a variety of transitory cerebral phenomena. The syndrome may complicate any type of hypertension, acute glomerulonephritis, toxemia of pregnancy, or essential or malignant hypertension.
From the hemodynamic standpoint, encephalopathy is associated with an increase in arterial blood pressure, diminished cerebral blood flow, and cerebral arteriolar constriction. The constancy of increased blood pressure and the frequency of a sharp rise in arterial blood pressure preceding the attack, suggests that the hypertension (or the phenomena that are concerned in its production) are causally related to the cerebral syndrome.
The sudden waxing and waning, the variability and the transitory nature of the cerebral phenomena seen in all types of hypertensive encephalopathy suggest a rapid decrease in cerebral blood flow caused by a sudden increase in cerebral vasoconstriction. The