Hypertensive Encephalopathy

What happens in the brain

Normally, blood vessels in the brain constrict or widen to keep blood flow steady across a wide range of blood pressures, a process called autoregulation. When blood pressure rises too high, too fast, this system fails. Vessels are forced open, and fluid leaks into brain tissue, causing swelling (cerebral edema), especially in the back of the brain.

On MRI, this often appears as posterior reversible encephalopathy syndrome (PRES), which can also be triggered by eclampsia, kidney failure and some immunosuppressive and chemotherapy drugs.

Hypertensive encephalopathy is a type of hypertensive emergency: very high blood pressure with acute organ damage.

Causes and risk factors

• poorly controlled or untreated chronic hypertension
• stopping blood pressure medicines suddenly, especially clonidine or beta-blockers
• kidney disease, including acute glomerulonephritis
• preeclampsia and eclampsia
• stimulant drugs: cocaine, amphetamines, and some decongestants and diet pills
• hormonal causes: pheochromocytoma, Cushing syndrome, primary aldosteronism
• renal artery stenosis
• certain medicines: MAO inhibitors with tyramine-rich foods, some cancer drugs, immunosuppressants
• autonomic dysreflexia in people with high spinal cord injuries

People whose blood pressure is usually normal, such as children or pregnant women, can develop encephalopathy at lower absolute readings.

Symptoms

Symptoms usually develop over 24 to 48 hours:

• severe headache, often generalized
• confusion, restlessness or drowsiness, progressing to stupor or coma if untreated
• nausea and vomiting
• vision problems: blurring, loss of vision, seeing flashing lights, cortical blindness
• seizures
• less often, focal weakness or numbness

Associated signs of malignant hypertension may include eye findings (bleeding, swelling of the optic disc), kidney injury, chest pain or heart failure.

Diagnosis

Doctors aim to confirm the diagnosis quickly and rule out other emergencies such as stroke and brain bleeding:

• repeated blood pressure readings
• neurological examination
• eye examination for hypertensive retinopathy and papilledema
• brain imaging: CT to exclude bleeding, MRI to look for PRES
• blood and urine tests: kidney function, electrolytes, blood count, urine protein, toxicology screen, pregnancy test
• ECG and troponin to check the heart

The diagnosis is strongly supported when symptoms improve as blood pressure is lowered.

Treatment

Treatment happens in an intensive care unit with continuous blood pressure monitoring.

• IV blood pressure medicines such as nicardipine, clevidipine, labetalol or others, chosen based on the situation.
• Controlled lowering: blood pressure is reduced by no more than about 25% in the first hour, then gradually toward 160/100 over the next 2 to 6 hours, then toward normal over 24 to 48 hours. Lowering too fast can starve the brain of blood and cause a stroke.
• Seizure control with anti-seizure medicines if needed.
• Pregnancy: magnesium sulfate to prevent seizures, blood pressure control, and delivery of the baby in eclampsia.
• Treating the cause: stopping triggering drugs, treating kidney disease or pheochromocytoma.

After stabilization, the person transitions to oral blood pressure medicines, with close follow-up.

Outlook

With prompt treatment, symptoms usually resolve within days, and MRI changes often reverse within weeks. Delayed treatment can lead to stroke, brain bleeding, permanent brain damage or death. Long-term blood pressure control is essential to prevent recurrence and to protect the heart, kidneys and eyes.

Prevention

• take blood pressure medicines as prescribed and do not stop them suddenly
• monitor blood pressure at home if you have hypertension
• avoid stimulant drugs and check cold remedies with a pharmacist
• attend prenatal checks and know the warning signs of preeclampsia

Frequently asked questions

What is hypertensive encephalopathy?

It is brain swelling and dysfunction caused by a sudden, severe rise in blood pressure, usually 180/120 or higher. It causes headache, confusion, vision problems, vomiting and seizures and is a medical emergency.

What are the symptoms of hypertensive encephalopathy?

The main symptoms are severe headache, confusion or drowsiness, nausea and vomiting, blurred or lost vision, and seizures. Symptoms usually develop over a day or two and improve when blood pressure is lowered.

How is hypertensive encephalopathy treated?

It is treated in intensive care with IV medicines that lower blood pressure gradually and in a controlled way, usually by no more than 25% in the first hour. Seizures and underlying causes are treated at the same time.

Is hypertensive encephalopathy reversible?

Usually, yes. With prompt treatment, symptoms typically resolve within days and brain swelling settles. Without treatment, it can cause stroke, permanent brain damage or death.