Hypertensive Encephalopathy 

  • Author: Ryan C Chang, MD; Chief Editor: Michael R Pinsky, MD, CM, FCCP, FCCM   more...
 
Updated: Apr 19, 2010
 

Background

Hypertension affects more than 60 million Americans. With adequate control, fewer than 1% of patients experience a hypertensive crisis. Hypertensive crisis is classified as hypertensive emergency or hypertensive urgency. Acute or ongoing vital target organ damage, such as damage to the brain, kidney, or heart, in the setting of severe hypertension is considered a hypertensive emergency. It requires a prompt reduction in blood pressure within minutes or hours. The absence of target organ damage in the presence of severe elevation of blood pressure with diastolic blood pressure frequently greater than 120 mm Hg is considered hypertensive urgency, and it requires reduction in blood pressure within 24-48 hours. A continuum exists between the clinical syndrome of hypertensive urgency and emergency; hence, their distinction may not always be clear and precise.[1]

In 1928, Oppenheimer and Fishberg introduced the term hypertensive encephalopathy to describe the encephalopathic findings associated with the accelerated malignant phase of hypertension. The terms accelerated and malignant were used to describe the retinal findings associated with hypertension. Accelerated hypertension is associated with group 3 Keith-Wagener-Barker retinopathy, which is characterized by retinal hemorrhages and exudates on funduscopic examination. Malignant hypertension is associated with group 4 Keith-Wagener-Barker retinopathy, which is characterized by the presence of papilledema, heralding the neurologic impairment from an elevated intracranial pressure.

Hypertensive encephalopathy describes the transient migratory neurologic symptoms associated with the malignant hypertensive state in hypertensive emergency. The clinical symptoms usually are reversible with prompt initiation of therapy. In the evaluation of an encephalopathic patient, exclude systemic disorders and various cerebrovascular events that may present with a similar constellation of clinical findings.

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Pathophysiology

The clinical manifestations of hypertensive encephalopathy are due to increased cerebral perfusion from the loss of blood-brain barrier integrity, resulting in exudation of fluid into the brain. In normotensive individuals, an increase in systemic blood pressure over a certain range (ie, 60-125 mm Hg) induces cerebral arteriolar vasoconstriction, thereby preserving a constant cerebral blood flow and an intact blood-brain barrier.

In chronically hypertensive individuals, the cerebral autoregulatory range gradually is shifted to higher pressures as an adaptation to chronic elevation of systemic blood pressure. This cerebral autoregulatory response is overwhelmed during a hypertensive emergency in which the acute rise in systemic blood pressure exceeds the individual's cerebral autoregulatory range, resulting in hydrostatic leakage across the capillaries within the central nervous system. With persistent elevation of the systemic blood pressure, arteriolar damage and necrosis occur. The progression of vascular pathology leads to generalized vasodilatation, cerebral edema, and papilledema, which clinically manifest as neurologic deficits and altered mentation in hypertensive encephalopathy.

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Epidemiology

Frequency

United States

Of the 60 million Americans with hypertension, fewer than 1% of patients develop a hypertensive emergency.

Mortality/Morbidity

The morbidity and mortality associated with hypertensive encephalopathy are related to the degree of target organ damage. Without treatment, the 6-month mortality rate for hypertensive emergencies is 50%, and the 1-year mortality rate approaches 90%.

Race

The frequency of hypertensive encephalopathy corresponds to the occurrence of hypertension in the general population. Hypertension is more prevalent in black people, exceeding the frequency in other ethnic minority groups. The incidence of hypertensive encephalopathy is lowest in white people.

Sex

Hypertension is more prevalent in men than in women.

Age

Hypertensive encephalopathy mostly occurs in middle-aged individuals who have a long-standing history of hypertension.

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Contributor Information and Disclosures
Author

Ryan C Chang, MD  Consulting Staff, Department of Internal Medicine, Divisions of Pulmonary and Critical Care, Kaiser Permanente San Francisco

Ryan C Chang, MD is a member of the following medical societies: American College of Chest Physicians and American Thoracic Society

Disclosure: Nothing to disclose.

Coauthor(s)

Irawan Susanto, MD  Director of Pulmonary Consultation and Procedures, Associate Professor, Department of Internal Medicine, Divisions of Pulmonary and Critical Care, University of California at Los Angeles School of Medicine

Irawan Susanto, MD is a member of the following medical societies: American College of Physicians-American Society of Internal Medicine

Disclosure: Nothing to disclose.

Specialty Editor Board

Oleh Wasyl Hnatiuk, MD  Program Director, National Capital Consortium, Pulmonary and Critical Care, Walter Reed Army Medical Center; Associate Professor, Department of Medicine, Uniformed Services University of Health Sciences

Oleh Wasyl Hnatiuk, MD is a member of the following medical societies: American College of Chest Physicians, American College of Physicians, and American Thoracic Society

Disclosure: Nothing to disclose.

Francisco Talavera, PharmD, PhD  Senior Pharmacy Editor, eMedicine

Disclosure: eMedicine Salary Employment

Timothy D Rice, MD  Associate Professor, Departments of Internal Medicine and Pediatrics and Adolescent Medicine, St Louis University School of Medicine

Timothy D Rice, MD is a member of the following medical societies: American Academy of Pediatrics and American College of Physicians

Disclosure: Nothing to disclose.

Chief Editor

Michael R Pinsky, MD, CM, FCCP, FCCM  Professor of Critical Care Medicine, Bioengineering, Cardiovascular Disease and Anesthesiology, Vice-Chair, Academic Affairs, University of Pittsburgh School of Medicine, University of Pittsburgh Medical Center

Michael R Pinsky, MD, CM, FCCP, FCCM is a member of the following medical societies: American College of Chest Physicians, American College of Critical Care Medicine, American Heart Association, American Thoracic Society, Association of University Anesthetists, European Society of Intensive Care Medicine, Shock Society, and Society of Critical Care Medicine

Disclosure: LiDCO Ltd Honoraria Consulting; iNTELOMED Intellectual property rights Board membership; Edwards Lifesciences Honoraria Consulting; Applied Physiology, Ltd Honoraria Consulting; Cheetah Medical Consulting fee Consulting

References
  1. Bales A. Hypertensive crisis. How to tell if it's an emergency or an urgency. Postgrad Med. May 1 1999;105(5):119-26, 130. [Medline].

  2. Amraoui F, van Montfrans GA, van den Born BJ. Value of retinal examination in hypertensive encephalopathy. J Hum Hypertens. Oct 29 2009;[Medline].

  3. Aggarwal M. Hypertensive crisis: hypertensive emergencies and urgencies. Cardiol Clin. 2006;24:135-46. [Medline].

  4. Biousse V, Newman NJ, Chang GY. Brainstem involvement in hypertensive encephalopathy: clinical and radiological findings. Neurology. Nov 9 2004;63(9):1759-60; author reply 1759-60. [Medline].

  5. Calhoun DA, Oparil S. Treatment of hypertensive crisis. N Engl J Med. Oct 25 1990;323(17):1177-83. [Medline].

  6. Frohlich E.D. Target organ involvement in hypertension: a realistic promise of prevention and reversal. Med Clin North Am. 2004;88:1-9. [Medline].

  7. Guidelines Subcommittee. 1999 World Health Organization-International Society of Hypertension Guidelines for the Management of Hypertension. Guidelines Subcommittee. J Hypertens. Feb 1999;17(2):151-83. [Medline].

  8. Healton EB, Brust JC, Feinfeld DA, Thomson GE. Hypertensive encephalopathy and the neurologic manifestations of malignant hypertension. Neurology. Feb 1982;32(2):127-32. [Medline].

  9. Immink RV, van den Born BJ, van Montfrans GA, Koopmans RP, Karemaker JM, van Lieshout JJ. Impaired cerebral autoregulation in patients with malignant hypertension. Circulation. Oct 12 2004;110(15):2241-5. [Medline].

  10. Lip GY, Beevers M, Beevers DG. Complications and survival of 315 patients with malignant-phase hypertension. J Hypertens. Aug 1995;13(8):915-24. [Medline].

  11. Loyke HF. The three phases of blood pressure in stroke. South Med J. Jun 1990;83(6):660-3. [Medline].

  12. Pancioli AM. Hypertension management in neurologic emergencies. Ann Emerg Med. Mar 2008;51(3 Suppl):S24-7. [Medline].

  13. Schilling S, Hartel C, Gehl HB, Sperner J. MRI findings in acute hypertensive encephalopathy. Eur J Neurol. May 2003;10(3):329-30. [Medline].

  14. Smith TM, Nokes SR. Posterior reversible encephalopathy syndrome: an overview. J Ark Med Soc. Dec 2003;100(6):200-2. [Medline].

  15. Strandgaard S, Olesen J, Skinhoj E, Lassen NA. Autoregulation of brain circulation in severe arterial hypertension. Br Med J. Mar 3 1973;1(5852):507-10. [Medline].

  16. Tsou TP, Yen ZS, Fang CC, et al. Hypertensive encephalopathy. J Emerg Med. Jul 2004;27(1):85-6. [Medline].

  17. Tzourio C, Dufouil C, Ducimetiere P, Alperovitch A. Cognitive decline in individuals with high blood pressure: a longitudinal study in the elderly. EVA Study Group. Epidemiology of Vascular Aging. Neurology. Dec 10 1999;53(9):1948-52. [Medline].

  18. Webster J, Petrie JC, Jeffers TA, Lovell HG. Accelerated hypertension--patterns of mortality and clinical factors affecting outcome in treated patients. Q J Med. Aug 1993;86(8):485-93. [Medline].

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