Hypertensive encephalopathy (HE) is general brain dysfunction due to significantly high blood pressure.
[4] This can occur in kidney failure, those who rapidly stop blood pressure medication, pheochromocytoma, and people on a monoamine oxidase inhibitor (MAOI) who eat foods with tyramine.
[citation needed] Symptoms of hypertensive encephalopathy typically start to occur 12–48 hours after a sudden and sustained increase in blood pressure.
Alterations in consciousness may follow several hours later, which include impaired judgement and memory, confusion, somnolence and stupor.
Several conditions may evoke blood pressure elevation: acute nephritis, eclampsia, crises in chronic essential hypertension, sudden withdrawal of antihypertensive treatment.
[citation needed] The impairment of cerebral blood flow that underlies hypertensive encephalopathy is still controversial.
According to the over-regulation conception, brain vessels spasm in response to acute hypertension, which results in cerebral ischemia and cytotoxic edema.
Since decreasing blood pressure is essential, anti-hypertensive medication is administered without awaiting the results of the laboratory tests.
[citation needed] The initial aim of treatment in hypertensive crises is to rapidly lower the diastolic pressure to about 100 to 105 mmHg (Incorrect - A decrease to 100mmHg from 180 would be almost a 40% decrease from baseline); 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.
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).
[18][19] 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.
)[citation needed]ref Several parenteral antihypertensive agents are most often used in the initial treatment of malignant hypertension.
[16][17] 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.