Hypertensive encephalopathy manifests initially with a slow onset of nausea, vomiting and headaches and non-specific neurologic symptoms such as confusion and restlessness. These symptoms can progress into seizures and coma without treatment.
The physical exam is critical in establishing the diagnosis, particularly the neurologic and ophthalmoscopic exams. Hypertensive encephalopathy is generally implied by grade IV retinal abnormalities that include exudates, hemorrhage, cotton-wool spots and papilledema. The presence of papilledema does not imply decreased survival likelihood relative to a combination of hemorrhage and exudates alone, even though it is commonly considered a manifestation of severe encephalopathy  .
Neurologic deficits becoming evident in physically exam are generally limited to non-localizing signs such as weakness, nystagmus and altered mental status that can range from confusion to coma. It is also important to conduct a vascular exam to detect any abnormality in blood perfusion.
The cardiovascular, renal and pulmonary systems may also be affected and physicians should look for specific signs for their involvement such as elevated neck veins, murmurs, S3 sound, rales, wheezes and peripheral edema that could be indicative of acute renal failure.
Hypertensive encephalopathy can ultimately result in severe neurologic damage, possibly leading to coma and death.
Workup in cases of hypertensive encephalopathy is directed at excluding other causes for the presenting symptoms and assessing damage to different organs in the body. Adequate history and physical exam remain the cornerstones of diagnosis and cannot be substituted by laboratory tests or radiologic imaging.
In general, a complete blood count needs to be obtained to look for microangiopathic hemolytic anemia. Kidney damage is assessed with urinalysis and measurements of blood urea nitrogen and creatinine. Hypertensive nephropathy usually manifests with the presence of hematuria and casts on urinalysis and elevated creatinine and blood urea nitrogen. Cardiac enzyme serum levels are also required to rule out myocardial ischemia.
Imaging tests with radiography, computed tomography (CT) and magnetic resonance imaging (MRI) along with electrocardiograms (ECG) can be useful. CT helps in detecting hemorrhages, strokes and intracranial masses. A chest-Xray can identify other complications of the disease such as aspiration due to altered mental status, pulmonary edema or aortic dissection. An ECG is important in the diagnosis of cardiac ischemia and, finally, MRI may demonstrate edema of the white matter in parieto-occiptal areas of the brain, a phenomenon known as the "reversible posterior leukoencephalopathy syndrome".
Treatment of hypertensive encephalopathy aims to lower diastolic blood pressure within 2 to 6 hours to a range corresponding to 100 - 110 mmHg, while making sure the initial decline is less than 25% of the presenting value. Patients with hypertensive encephalopathy generally have a mean arterial pressure that is higher than in normal individuals, as autoregulation shifts to a more elevated range of blood pressures to maintain adequate blood cerebral perfusion. For this reason, diastolic blood pressure needs to be slowly reduced, so as not to compromise cerebral blood flow and induce further damage. A gradual decline in diastolic blood pressure will allow a progressive healing of vascular lesions.
Patients should be admitted to the intensive care unit (ICU), in order to closely monitor blood pressure, end organ function and overall condition. ICU admission also permits a more accurate titration of pharmacologic agents and aids in avoiding potential complications. If the patient's condition keeps on deteriorating despite adequate control of blood pressure, the physician should attempt to exclude other causes of the patient's symptoms before further proceeding .
The choice of pharmacologic agent has important clinical consequences. The favored medications include nicardipine, labetalol and esmolol. Nicardipine is a dihydropyridine calcium channel blocker and is characterized by its ability to promote cerebral and cardiac vasodilation as well as its specificity for the cardiovascular system . Labetalol, on the other hand, decreases diastolic blood pressure without impinging on cerebral blood flow. Nonetheless, because it is a non-selective beta blocker, it is generally not administered in patients with cardiogenic shock or asthma. It is best to avoid agents that exert side effects on the central nervous system, such as clonidine, reserpine and methyldopa. Nitroglycerin may be used for elevated blood pressure in the context of myocardial ischemia but can reduce blood pressure too rapidly in patients with hypertensive encephalopathy. In addition, its venodilatory effects may result in severe complications in hypovolemic patients. Other agents that should not be used include nitroprusside sodium and hydralazine. Both of these medications increase intracranial pressure by shunting blood into the brain. Hydralazine can also cause reflex tachycardia and should not be used in patients who have coronary artery disease (CAD). Finally, it is important to avoid diuretics as patients with hypertensive encephalopathy are generally volume depleted and can actually benefit from increased hydration .
Patients who experienced malignant hypertension may still suffer from damage to the heart, kidneys and brain despite adequate and effective treatment with anti-hypertensive medication. One retrospective study evaluated renal outcomes in 169 patients diagnosed with malignant hypertension, and found that creatinine levels were elevated in 57% of patients after a mean follow up of 53 months, and even after effective treatment with antihypertensive medication .
Without treatment, 10 to 20% of patients are expected to survive . Nonetheless, current therapy has significantly improved outcomes with more than 70% surviving to 5 years. Some studies suggest that the 40 to 52 months survival rate is close to 90%   .
Hypertensive encephalopathy is most commonly caused by a sudden elevation of blood pressure in a patient already diagnosed with chronic hypertension. In addition, there are a number of conditions that can cause a similar clinical situation and they include kidney disease (renal parenchymal disease, renovascular hypertension, acute glomerulonephritis), clonidine withdrawal, drugs that stimulate the sympathetic nervous system (cocaine, amphetamines, lysergic acid diethylamide and phenycyclidine), eclempsia, collagen vascular disease, vasculitis, a combination of tricyclic antidepressants or monamine oxidase inhibitors with ingestion of tyramine rich food, autonomic hyperactivity and adrenal and kidney tumors (for example, renin-secreting tumors and pheochromocytoma).
Hypertensive encephalopathy generally develops in patients with chronic hypertension, so that the prevalence and incidence of the disease correlate strongly with those of hypertension. Hypertension is more common among middle-aged men and tends to target African Americans more than Caucasians. The morbidity and mortality of hypertensive emergency is associated with the severity of organ damage. Less than 1% of patients with hypertension develop hypertensive emergencies. In the absence of adequate treatment, 6-month mortality of hypertensive emergencies is 50% and 1 year mortality is 90%.
Two major theories have been established to explain the pathogenesis of hypertensive encephalopathy . The first theory proposes that acute hypertension results in cerebral vasospasm, with subsequent vascular thrombosis and hypoperfusion. Ultimately, this leads to cerebral ischemia and cellular edema. The second theory postulates that a sudden increase in blood pressure impairs the autoregulatory mechanisms in the brain, leading to fluid extravasation and swelling of the brain tissue  . Normally, mild to moderate increases in blood pressure result in vasoconstriction and serve to maintain a constant blood flow, thus preventing the transmission of the high pressure to small blood vessels . Nonetheless, when sudden blood pressure elevation occurs, autoregulation fails and the vascular wall in arterioles and capillaries becomes damaged. Components of the plasma such as fibrinoid material penetrate the wall of the vessel and obliterate its lumen. This ultimately translates into vasodilation and the extravasation of fluid in the brain, resulting in cerebral edema.
Prevention is directed at limiting risk factors for developing chronic hypertension. Patients are advised to consume moderate amounts of sodium and alcohol, to exercise regularly and to avoid smoking. Patients who were diagnosed with hypertensive encephalopathy should be discharged on the medications used to lower their blood pressure during hospitalization. It is important to recommend medication adherence and follow up at regular intervals to monitor treatment response.
Hypertensive encephalopathy describes the rapid development of neurologic symptoms linked to increased intracranial pressure, following an acute episode of elevated blood pressure. It most commonly develops in patients already diagnosed with chronic hypertension and usually presents with non-localizing neurologic symptoms such as headaches, seizures, visual disturbances and altered mental status .
Treatment of the condition consists of a gradual lowering of diastolic blood pressure into a range of 100 - 110 mmHg. It is important not to decrease blood pressure too quickly, as this may compromise cerebral blood flow and lead to further brain damage. The most common pharmacologic agents used are nicardipine, labetalol and esmolol. With prompt and adequate treatment, prognosis is favorable with around 70% 5 year survival rate.
Hypertensive encephalopathy is an emergent condition caused by a sudden increase in blood pressure in patients already suffering from chronic hypertension. Without adequate treatment, it can lead to severe damage to the brain as well as to other organs, especially the kidneys and the heart. Two major theories have been proposed to explain the pathophysiological mechanisms underlying hypertensive encephalopathy. The first theory suggests that a sudden increase in blood pressure leads to contraction of the blood vessels in the brain (vasospasm) and to the formation of blood clots within the major vessels (thrombosis), disrupting in the process blood flow to the brain and causing cell death due to oxygen deprivation. Ultimately this may result in permanent brain damage. The second theory postulates that a sudden increase in blood pressure impairs the normal regulatory mechanisms of the brain that maintain a constant blood flow despite changes in the blood pressure. In normal individuals, an increase in blood pressure leads to constriction of blood vessels and prevents high pressure transmission into capillaries and other smaller vessels. When this mechanism is impaired, the high pressure in the very thin vessels in the brain leads to damage of the vessel walls and subsequent fluid escape (extravasation) into brain tissue. This process causes swelling of the brain tissue and damage to brain cells.
Patients with hypertensive encephalopathy generally present with nausea, vomiting, headaches, confusion and ultimately progress into coma and death without prompt and adequate treatment. The physical exam the physician conducts is extremely important in establishing the diagnosis. The doctor may use an ophthalmoscope to look into the eye and visualize the retina. Abnormalities on this exam may detect increased pressure inside the skull, a hallmark of the disease. It will also be important to rule out other causes of the patient's presenting signs. The doctor may request blood tests to check any signs of damage to other organs, especially the heart and the kidneys. Radiologic exams of the brain and the chest can also be useful to exclude a stroke, an intracranial mass or to check for the presence of fluids in the lungs. The latter can result from damage to the kidneys, which is also associated with sudden increases in blood pressure.
Treatment is targeted at a gradual lowering of the blood pressure. It is important not to decrease the blood pressure too quickly, so as not to compromise blood perfusion into the brain. Patients may also be admitted to the inpatient care unit (ICU), where their blood pressure can be closely monitored and the exact doses of the antihypertensive used are titrated.
Hypertensive encephalopathy used to have a very bad prognosis before recent innovations advanced treatment options. Currently, 70% of patients survive for up to 5 years with adequate treatment, with some studies suggesting that 5 year survival can reach 90%.
Hypertensive encephalopathy can be best prevented by controlling blood pressure and avoiding the development of chronic hypertension. Patients are advised to ingest sodium and alcohol in moderate amounts, to exercise regularly and to avoid smoking. They should also adhere to their medication schedule and follow up regularly with their physician to monitor any potential complications. Patients who experience an episode of hypertensive encephalopathy are generally discharged on the same medication used to reduce their blood pressure during their stay in the hospital.