The initial aim of treatment in<unk>  crises is to rapidly lower the diastolic pressure to about 100 to 105 mmHg; this goal should be achieved within two to six hours, with the maximum initial fall in BP not exceeding 25 percent of the presenting value. This level of BP control will allow gradual healing of the necrotizing vascular lesions. More aggressive hypotensive therapy is both unnecessary and may reduce the blood pressure below the autoregulatory range, possibly leading to ischemic events (such as stroke or coronary disease). Once the BP is controlled, the person should be switched to medication by mouth, with the diastolic pressure being gradually reduced to 85 to 90 mmHg over two to three months. The initial reduction to a diastolic pressure of approximately 100 mmHg is often associated with a modest worsening of renal function; this change, however, is typically transient as the vascular disease tends to resolve and renal perfusion improves over one to three months. Antihypertensive therapy should not be withheld in this setting unless there has been an excessive reduction in BP. A change in medication, however, is indicated if the decline in renal function is temporally related to therapy with an angiotensin (ACE) converting enzyme inhibitor or angiotensin II receptor blocker, which can interfere with renal autoregulation and produce acute kidney failure in patients with bilateral renal artery stenosis. (See "Renal effects of ACE inhibitors in hypertension".)ref Several parenteral antihypertensive agents are most often used in the initial treatment of malignant hypertension. * Nitroprusside – an arteriolar and venous dilator, given as an intravenous infusion. Nitroprusside acts within seconds and has a duration of action of only two to five minutes. Thus, hypotension can be easily reversed by temporarily discontinuing the infusion, providing an advantage over the drugs listed below. However, the potential for cyanide toxicity limits the prolonged use of nitroprusside, particularly in patients with chronic kidney disease. * Nicardipine – an arteriolar dilator, given as an intravenous infusion. * Clevidipine – a short-acting dihydropyridine calcium channel blocker. It reduces blood pressure without affecting cardiac filling pressures or causing reflex tachycardia. * Labetalol – an alpha- and beta-adrenergic blocker, given as an intravenous bolus or infusion. Bolus followed by infusion. * Fenoldopam – a peripheral dopamine-1 receptor agonist, given as an intravenous infusion. * Oral agents — A slower onset of action and an inability to control the degree of BP reduction has limited the use of oral antihypertensive agents in the therapy of<unk>  crises. They may, however, be useful when there is no rapid access to the parenteral medications described above. Both sublingual nifedipine and sublingual captopril can substantially lower the BP within 10 to 30 minutes in many patients. A more rapid response is seen when liquid nifedipine is swallowed. The major risk with oral agents is ischemic symptoms (e.g., angina pectoris, myocardial infarction, or stroke) due to an excessive and uncontrolled hypotensive response. Thus, their use should generally be avoided in the treatment of<unk>  crises if more controllable drugs are available.
Hypertensive encephalopathy
Hydrocephalus
Hypertensive leukoencephalopathy
Cocaine intoxication
Posterior reversible encephalopathy syndrome
Stroke
Idiopathic intracranial hypertension
Uremia