In a 60‑year‑old prediabetic with uncontrolled hypertension (BP 160/90 mm Hg) who has had intermittent fever for two days and recent memory lapses, what is the most likely diagnosis and how should it be evaluated and managed?

Hypertensive Emergency with Encephalopathy

This 60-year-old prediabetic patient with intermittent fever and new memory lapses presenting with BP 160/90 mmHg requires immediate emergency department transfer for evaluation of hypertensive encephalopathy—a true hypertensive emergency that demands ICU admission and IV antihypertensive therapy, regardless of whether the current BP reading appears "controlled." 1

Critical Initial Assessment

The combination of memory lapses (altered cognition) with intermittent fever in the setting of hypertension raises immediate concern for hypertensive encephalopathy, which occurs in 10-15% of patients with malignant hypertension and is characterized by neurological symptoms including altered mental status, lethargy, and cognitive impairment 2. Importantly, BP may fluctuate in hypertensive emergencies, and a "normal" reading on presentation does not exclude the diagnosis—the history of cognitive changes suggests prior severe elevations 1.

Why This is an Emergency, Not Urgency

• The presence of acute target organ damage (neurologic impairment) defines a hypertensive emergency, not the absolute BP number 1, 3
• Memory lapses represent acute cognitive dysfunction, which is a form of neurologic target organ damage requiring immediate intervention 1, 2
• Up to one-third of patients with hypertensive encephalopathy may lack advanced retinopathy, so diagnosis relies primarily on neurological symptoms 2, 3
• Hypertensive encephalopathy can progress to seizures, coma, and irreversible brain injury without immediate treatment 2

Immediate Diagnostic Workup

Neurological Assessment

• Perform rapid neurological examination assessing mental status, orientation, visual changes (including cortical blindness), focal deficits, and signs of impending seizure activity 1, 2
• MRI with FLAIR imaging is superior to CT for detecting posterior reversible encephalopathy syndrome (PRES), showing white matter lesions in posterior brain regions that are fully reversible with timely treatment 1, 2

Laboratory Evaluation

• Complete blood count (hemoglobin, platelets) to assess for microangiopathic hemolytic anemia 1
• Comprehensive metabolic panel including creatinine, sodium, potassium to evaluate renal function and electrolyte abnormalities 1
• Lactate dehydrogenase (LDH) and haptoglobin to detect hemolysis in hypertensive thrombotic microangiopathy 1
• Urinalysis for protein and urine sediment examination to identify renal damage 1
• Glucose measurement is critical given prediabetes and the fact that marked hyperglycemia can cause acute cognitive impairment and memory deficits 4, 5

Fundoscopic Examination

• Look for bilateral retinal hemorrhages, cotton wool spots, or papilledema (Grade III-IV retinopathy) indicating malignant hypertension 1, 3
• However, absence of retinopathy does not exclude hypertensive encephalopathy 2, 3

Differential Diagnosis Considerations

Hyperglycemic Encephalopathy

• Acute severe hyperglycemia can cause selective neurocognitive deficits, particularly in working and declarative memory, and may be responsible for memory complaints in prediabetic patients 4
• Stressful events (including hypertensive crisis) frequently aggravate glycemic control and may precipitate marked hyperglycemia with altered consciousness 1
• Check fingerstick glucose immediately and obtain HbA1c 5

Infectious Encephalitis

• The intermittent fever for 2 days preceding cognitive symptoms raises concern for infectious encephalitis (viral, bacterial, or fungal) 5
• Obtain blood cultures, consider lumbar puncture if no contraindications after neuroimaging 5
• However, fever can also occur with hypertensive encephalopathy due to hypothalamic dysfunction 2

Cerebrovascular Accident

• Acute ischemic or hemorrhagic stroke must be excluded with urgent neuroimaging 1
• However, the subacute onset over 2 days with intermittent symptoms is more consistent with encephalopathy than acute stroke 2

Immediate Management Algorithm

Step 1: Emergency Department Transfer

• Immediate ER referral is mandatory for BP >180/120 mmHg with evidence of acute target organ damage (cognitive impairment) 1
• Even though current BP is 160/90, the history of memory lapses indicates prior severe elevations requiring emergency evaluation 1
• Patients with acute target organ damage require immediate ER transfer and ICU admission 1

Step 2: ICU Admission with Continuous Monitoring

• ICU admission is a Class I recommendation (Level B-NR) for hypertensive emergencies 1
• Continuous arterial line BP monitoring is essential 1
• Serial neurological assessments every 1-2 hours initially 1

Step 3: First-Line IV Antihypertensive Therapy

Nicardipine is the preferred first-line agent for hypertensive encephalopathy because it maintains cerebral blood flow, does not increase intracranial pressure, and allows predictable titration 1, 3:

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

Labetalol is an acceptable alternative 1, 3:

• 10-20 mg IV bolus over 1-2 minutes
• Repeat or double every 10 minutes
• Maximum cumulative dose 300 mg
• Or continuous infusion 2-8 mg/min 1

Step 4: Blood Pressure Targets

For hypertensive encephalopathy, reduce mean arterial pressure by 20-25% immediately within the first hour 1, 2, 3:

• Then reduce to 160/100 mmHg over 2-6 hours if stable
• Cautiously normalize over 24-48 hours 1
• Avoid excessive acute drops >70 mmHg systolic, as this precipitates cerebral, renal, or coronary ischemia, particularly in patients with chronic hypertension who have altered cerebral autoregulation 1, 3

Management of Concurrent Hyperglycemia

• If marked hyperglycemia is present (glucose >300 mg/dL), temporary insulin therapy may be required even if previously managed with diet alone 1
• Ensure adequate fluid intake, as infection or dehydration is more likely to necessitate hospitalization in prediabetic patients 1
• Any condition with marked hyperglycemia accompanied by vomiting or alteration in consciousness requires immediate interaction with the diabetes care team 1

Critical Pitfalls to Avoid

• Do not dismiss the "normal" BP reading of 160/90 on presentation—patients with hypertensive emergencies may have fluctuating BP, and the history of memory lapses suggests prior severe elevations 1
• Do not delay emergency transfer while attempting outpatient oral antihypertensive management—the presence of cognitive impairment defines this as an emergency 1, 3
• Do not use immediate-release nifedipine, as it causes unpredictable precipitous BP drops and reflex tachycardia 1
• Do not normalize BP acutely—patients with chronic hypertension have altered cerebral autoregulation and cannot tolerate acute normalization 1, 3
• Do not overlook infectious causes—the 2-day fever history mandates infectious workup including blood cultures and consideration of lumbar puncture 5

Post-Stabilization Management

Screen for Secondary Hypertension

• 20-40% of patients with malignant hypertension have identifiable secondary causes including renal artery stenosis, pheochromocytoma, primary aldosteronism, and renal parenchymal disease 1, 3
• Screening should be performed after stabilization 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 thiazide/thiazide-like diuretic 5
• Target BP <130/80 mmHg for most patients with diabetes/prediabetes 5

Cognitive and Glycemic Management

• Simplify diabetes treatment regimens as much as possible in the presence of cognitive impairment to minimize hypoglycemia risk 5
• Arrange frequent follow-up (at least monthly) until target BP is achieved and cognitive function is reassessed 1
• Address medication non-adherence, the most common trigger for hypertensive emergencies 1

Long-Term Neuroprotection

• Effective antihypertensive therapy strongly reduces the risk of developing significant white matter changes that could lead to further cognitive decline 2
• The optimal BP range to prevent cognitive decline in older individuals is 135-150 mmHg systolic and 70-79 mmHg diastolic 2
• However, given prediabetes and prior hypertensive emergency, this patient requires more aggressive BP control (<130/80 mmHg) 5