Hyperperfusion Syndromes: Insight into the Pathophysiology and Treatment of Hypertensive Encephalopathy

Abstract

ABSTRACTHypertensive encephalopathy is one of the manifestations of a hypertensive crisis. It is not the absolute value of the blood pressure that causes the encephalopathy, rather the presence of an abrupt rise in pressure. In terms of clinical and radiographic findings, there are many similarities among a group of entities, including hypertensive encephalopathy, eclampsia, and immunosuppressant neurotoxicity. Hyperperfusion syndromes may represent these clinical disease states that may share the same pathophysiology. Magnetic resonance imaging fluid attenuated inversion recovery sequences have recognized the prominent cortical involvement of the disease that had been previously missed on computed tomography. Studies have found cortical involvement in 94% of their patients, particularly in mild cases. Animal models demonstrate endothelial damage and enhanced pinocytosis in the cortex as reasons why edema may begin in that region of the brain. Patients diagnosed with hypertensive encephalopathy should be diagnosed and treated promptly in order to avoid further neurological complications. The mean arterial pressure should be lowered by 20% to 25% within the first hour of patient presentation, followed by further gradual reduction in blood pressure over the following 24 hours. Hypertensive emergency in acute ischemic stroke should be managed with more caution. According to the 2003 American Stroke Association treatment guidelines, for patients with ischemic stroke not eligible for thrombolytic therapy, target blood pressures are a diastolic blood pressure <120 mmHg and systolic blood pressure <220 mmHg. The systolic pressure must be <185 mmHg and diastolic pressure <110 mmHg at all times if eligible for thrombolytic therapy.