What is the likely diagnosis for a patient with severe hypertension, headaches, visual disturbances, and hyperintense signals in the parietal occipital lobes on MRI, with normal magnetic resonance angiography and magnetic resonance venography?

Posterior Reversible Encephalopathy Syndrome (PRES)

The likely diagnosis is posterior reversible encephalopathy syndrome (PRES), based on the combination of severe hypertension (195/120 mmHg), acute neurological symptoms (headache, visual disturbances), and characteristic MRI findings of hyperintense T2/FLAIR signals in the parietal-occipital lobes with normal vascular imaging. 1, 2

Diagnostic Confirmation

The clinical presentation and imaging findings are pathognomonic for PRES:

• MRI findings are diagnostic: Hyperintense T2/FLAIR signals in the parietal-occipital regions represent vasogenic edema, which is the hallmark of PRES 1, 2, 3
• Normal MRA/MRV excludes vascular pathology: The normal magnetic resonance angiography and venography effectively rule out cerebral venous thrombosis and arterial occlusion 4, 2
• Clinical syndrome matches perfectly: The triad of severe hypertension, visual disturbances (inability to see/count fingers), and headache with altered mental status are classic PRES manifestations 1, 2, 5

Why Other Diagnoses Are Excluded

Cavernous sinus thrombosis is ruled out by:

• Absence of periorbital swelling, redness, or ophthalmoplegia 4
• Normal MRV showing no venous thrombosis 4
• Wrong clinical pattern (cavernous sinus thrombosis presents with orbital signs, cranial nerve palsies) 4

Cerebral venous thrombosis is excluded by:

• Normal MRV demonstrating patent venous sinuses 4
• Absence of focal parenchymal hemorrhagic venous infarction pattern 4

Pseudotumor cerebri is unlikely because:

• No papilledema was identified on examination 4
• Acute presentation over days rather than chronic progressive course 4
• MRI shows parenchymal edema rather than empty sella, optic nerve sheath dilatation, or flattened posterior globes 4

Estrogen-associated migraine is excluded by:

• Severity requiring ICU admission with blood pressure 195/120 1
• Profound visual loss (unable to count fingers) far exceeds typical migraine aura 1
• MRI shows vasogenic edema, not normal or migraine-associated findings 1

Pathophysiology Supporting the Diagnosis

PRES develops when markedly elevated blood pressure exceeds cerebral autoregulation capacity, particularly affecting posterior brain regions, leading to cerebral edema 2, 6. The rate of blood pressure increase is more critical than the absolute value, though values commonly exceed 200/120 mmHg 1. This patient's blood pressure of 195/120 with inadequate outpatient control (single agent amlodipine despite obesity and hypertension) created the perfect substrate for breakthrough edema 1, 2.

Risk Factors Present in This Patient

• Obesity (BMI 38): Significantly increases PRES risk through multiple mechanisms including endothelial dysfunction 2
• Inadequate hypertension control: Single-agent therapy in a high-risk patient 2
• Acute severe hypertension: Blood pressure 195/120 exceeding autoregulatory capacity 1, 2

Immediate Management Required

Blood pressure reduction strategy (already initiated with clevidipine):

• Reduce mean arterial pressure by 20-25% within the first hour 1, 2
• Target 160/100 mmHg within 2-6 hours if stable 1, 2
• Cautiously normalize over 24-48 hours 1, 2

Critical management principles:

• ICU admission with continuous arterial blood pressure monitoring is mandatory 1, 2
• Nicardipine (5-15 mg/hr IV) or labetalol (0.25-0.5 mg/kg bolus, then 2-4 mg/min infusion) are optimal first-line agents 2
• Avoid excessive acute drops exceeding 70 mmHg systolic, as chronic hypertension alters cerebral autoregulation 2
• Continuous neurological monitoring for seizures, which occur frequently in PRES 2, 3, 5

Prognosis and Reversibility

The white matter lesions are fully reversible with timely recognition and appropriate blood pressure management 2, 3. Most patients recover completely when treatment is initiated promptly 3, 5, 7. However, inadequate therapeutic support or treatment delay may result in permanent neurological deficits or progression to infarction 5, 6.

Common Pitfalls to Avoid

• Do not delay treatment waiting for additional confirmatory testing—the clinical and radiographic picture is sufficient 1, 2
• Do not normalize blood pressure too rapidly—patients with chronic hypertension cannot tolerate acute normalization due to altered autoregulation 2
• Do not dismiss this as "just hypertension"—PRES represents acute hypertension-mediated organ damage requiring emergency intervention 1
• Do not assume complete reversibility is guaranteed—while typical, some patients develop permanent sequelae if treatment is delayed 3, 5