Hypertensive Encephalopathy

Synonyms

Accelerated hypertension; Hypertensive crisis; Hypertensive emergency; Hypertensive urgency; Malignant hypertension

Definition

Hypertensive encephalopathy refers to an abrupt, sustained rise of blood pressure that exceeds the limits of cerebral autoregulation, causing leakage of fluid into perivascular tissue and resulting in cerebral edema and increased intracranial pressure.

Current Knowledge

Pathophysiology

In normotensive patients, a mean arterial pressure (MAP) above approximately 60 mm Hg triggers autoregulation. Autoregulation refers to the capacity to maintain cerebral blood flow by fluctuations in the vascular tone of the cerebral resistance arteries. Once MAP approaches 160 mm Hg, autoregulatory mechanisms are less able to sustain control over cerebral blood flow. Patients with chronic hypertension may develop encephalopathy at much higher MAP levels as cerebral autoregulatory range adapts to higher pressures over time. Once the autoregulatory capacity is exceeded,...