What is the likely diagnosis and appropriate management for an adult presenting with dizziness, headache, and markedly elevated blood pressure?

Hypertensive Emergency: Acute Hypertensive Encephalopathy

This patient is experiencing a hypertensive emergency—specifically acute hypertensive encephalopathy—requiring immediate ICU admission and intravenous nicardipine to reduce mean arterial pressure by 20-25% within the first hour. 1

Why This Is an Emergency, Not Just Elevated Blood Pressure

The triad of dizziness, headache, and markedly elevated blood pressure indicates acute target organ damage to the brain, which defines a hypertensive emergency rather than simple hypertensive urgency. 1, 2 The presence of neurological symptoms—not the absolute blood pressure number—is what makes this life-threatening. 1 Without treatment, hypertensive emergencies carry a 1-year mortality exceeding 79% and median survival of only 10.4 months. 1

The rate of blood pressure rise matters more than the absolute value; patients with chronic hypertension often tolerate higher pressures than previously normotensive individuals, so even "borderline" elevations with symptoms warrant emergency classification. 1, 2

Immediate Assessment for Target Organ Damage (Within Minutes)

Neurologic Red Flags

• Altered mental status, confusion, or memory problems—early signs of hypertensive encephalopathy that can rapidly progress to seizures and coma 1, 2
• Visual disturbances (blurred vision, vision loss, cortical blindness)—indicate retinal damage or posterior reversible encephalopathy syndrome 1, 2
• Focal deficits (unilateral weakness, facial drooping, difficulty speaking)—suggest acute stroke 1, 2
• Seizures or loss of consciousness—indicate severe encephalopathy with imminent permanent brain damage 1, 2

Cardiac Red Flags

• Chest pain—may indicate acute myocardial infarction, unstable angina, or aortic dissection 1, 2
• Shortness of breath (especially when lying flat)—suggests acute left ventricular failure or pulmonary edema 1, 2

Fundoscopic Examination

• Look for bilateral retinal hemorrhages, cotton-wool spots, or papilledema (grade III-IV retinopathy)—these define malignant hypertension 1
• A single subconjunctival hemorrhage is NOT target organ damage and does not constitute an emergency 1

First-Line Treatment: Nicardipine IV

Nicardipine is the preferred first-line agent for hypertensive encephalopathy because it preserves cerebral blood flow, does not increase intracranial pressure, and allows predictable titration. 1

Dosing

• Start 5 mg/hour IV infusion 1
• Titrate by 2.5 mg/hour every 15 minutes 1
• Maximum 15 mg/hour 1

Alternative: Labetalol

• 10-20 mg IV bolus over 1-2 minutes, repeat or double every 10 minutes (maximum cumulative 300 mg) 1
• OR continuous infusion 2-8 mg/min 1
• Contraindicated in reactive airway disease, COPD, heart block, bradycardia, or decompensated heart failure 1

Blood Pressure Target: Gradual Reduction

Reduce mean arterial pressure by 20-25% within the first hour, then if stable reduce to 160/100 mmHg over 2-6 hours, then cautiously normalize over 24-48 hours. 1

Critical Pitfall

Avoid systolic drops exceeding 70 mmHg—this can precipitate cerebral, renal, or coronary ischemia, particularly in patients with chronic hypertension who have altered cerebral autoregulation. 1 Patients with longstanding hypertension cannot tolerate acute normalization of blood pressure. 1

ICU Admission and Monitoring Requirements

• Class I recommendation for ICU admission with continuous arterial line blood pressure monitoring 1
• Serial neurological assessments for mental status changes, visual disturbances, or seizures 1
• Monitor heart rate for reflex tachycardia with nicardipine 1
• Laboratory tests: complete blood count (hemoglobin, platelets), creatinine, sodium, potassium, lactate dehydrogenase, haptoglobin, urinalysis for protein and sediment, troponins if chest pain present 1
• ECG to assess for cardiac involvement 1
• Consider brain imaging (CT or MRI with FLAIR) if encephalopathy suspected—MRI is superior for detecting posterior reversible encephalopathy syndrome 1

Medications to Avoid

• Immediate-release nifedipine—causes unpredictable precipitous blood pressure drops, stroke, and death 1, 3
• Hydralazine as first-line—unpredictable response and prolonged duration 1
• Sodium nitroprusside—reserve as last resort only due to cyanide toxicity risk; requires thiosulfate co-administration when infusion ≥4 µg/kg/min or exceeds 30 minutes 1

Post-Stabilization Management

Screen for Secondary Causes

20-40% of patients with malignant hypertension have identifiable secondary causes: 1

• Renal artery stenosis
• Pheochromocytoma
• Primary aldosteronism
• Renal parenchymal disease

Address Medication Non-Adherence

Medication non-adherence is the most common trigger for hypertensive emergencies. 1

Transition to Oral Therapy

After 24-48 hours of stabilization, transition to oral antihypertensive regimen combining a renin-angiotensin system blocker, calcium-channel blocker, and diuretic. 1 Target blood pressure <130/80 mmHg for most patients. 1

Follow-Up

Monthly follow-up until target blood pressure is achieved and organ damage regresses. 1 Patients who experienced a hypertensive emergency remain at significantly increased cardiovascular and renal risk. 1

If This Were Hypertensive Urgency Instead

If the patient had blood pressure >180/120 mmHg WITHOUT acute target organ damage (no headache, no dizziness, no neurological symptoms), this would be hypertensive urgency managed with: 1

• Oral antihypertensives (captopril 12.5-25 mg, extended-release nifedipine 30-60 mg, or labetalol 200-400 mg) 1
• Outpatient follow-up within 2-4 weeks 1
• Gradual blood pressure reduction over 24-48 hours—rapid lowering may cause cerebral, renal, or coronary ischemia 1
• No hospital admission required 1