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Moderate to severe hypertensive retinopathy and hypertensive encephalopathy in adults

Authors
William J Elliott, MD, PhD
Joseph Varon, MD, FACP, FCCP, FCCM, FRSM
Section Editors
George L Bakris, MD
Norman M Kaplan, MD
Deputy Editor
John P Forman, MD, MSc

DEFINITIONS AND TERMINOLOGY

Hypertensive emergencies are acute, life-threatening conditions resulting from markedly increased blood pressure (BP), generally ≥180/120 mmHg (table 1), characterized by acute, ongoing target-organ damage [1-4]. In addition to the hypertensive emergencies that are discussed in detail elsewhere (see "Evaluation and treatment of hypertensive emergencies in adults"), two less common clinical syndromes induced by acute, severe hypertension include:

Moderate to severe hypertensive retinopathy − Moderate to severe hypertensive retinopathy, corresponding to grades III and IV hypertensive retinopathy, is characterized by retinal hemorrhages, exudates, and papilledema (image 1) [5]. (See "Ocular effects of hypertension", section on 'Ocular diseases directly related to hypertension'.)

Severe hypertensive retinopathy was formerly called "malignant hypertension," a term that clinicians should avoid (although it is used for administrative purposes in the United States). Moderate hypertensive retinopathy was often referred to as "accelerated hypertension," but this term should likewise be avoided. Patients with moderate to severe hypertensive retinopathy frequently have acute hypertensive nephrosclerosis (formerly called "malignant nephrosclerosis"), although kidney biopsies are seldom performed.

Historically, papilledema was the hallmark of a more advanced condition (ie, "malignant hypertension") associated with a higher mortality (akin to having a malignancy). However, the advent of effective antihypertensive drug therapy has improved the prognosis and patients with moderate and severe hypertensive retinopathy have similar outcomes [6]. Thus, acute treatment of such patients is the same whether or not papilledema is present.

Hypertensive encephalopathy − Hypertensive encephalopathy refers to the presence of signs and/or symptoms of cerebral edema caused by severe and/or sudden rises in BP. It is primarily a diagnosis of exclusion after other causes of central nervous system dysfunction are ruled out, and it characteristically responds dramatically to acute lowering of the mean arterial pressure, sometimes by as little as 10 to 15 percent. (See "Evaluation and treatment of hypertensive emergencies in adults", section on 'Neurologic emergencies'.)

MECHANISMS OF VASCULAR INJURY

With mild to moderate elevations in blood pressure (BP), the initial response is arterial and arteriolar vasoconstriction. This autoregulatory process both maintains tissue perfusion at a relatively constant level and prevents the increase in pressure from being transmitted to the smaller, more distal vessels [7].

With increasingly severe hypertension, however, autoregulation eventually fails (figure 1) [7]. The ensuing rise in pressure in the arterioles and capillaries leads to acute damage to the vascular wall. Disruption of the vascular endothelium then allows plasma constituents (including fibrinoid material) to enter the vascular wall, thereby narrowing or obliterating the vascular lumen. Within the brain, the breakthrough vasodilation from failure of autoregulation leads to the development of cerebral edema and the clinical picture of hypertensive encephalopathy [7].

           

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Literature review current through: Nov 2016. | This topic last updated: Thu Jul 28 00:00:00 GMT 2016.
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