What is the most likely diagnosis and best imaging test for a patient with intermittent loss of vision, headache, slurred speech, and pain around the affected eye, with a history of hypertension (high blood pressure)?

Hypertensive Encephalopathy: Diagnosis and Imaging

Based on the symptoms of intermittent vision loss, headache, slurred speech, and pain around the affected eye in a patient with hypertension, the most likely diagnosis is hypertensive encephalopathy, and the best imaging test is MRI with fluid-attenuated inversion recovery (FLAIR) sequences.

Clinical Presentation and Pathophysiology

Hypertensive encephalopathy occurs when markedly elevated blood pressure overwhelms cerebral autoregulation, leading to:

• Cerebral edema, particularly in posterior brain regions
• Microscopic hemorrhages and infarctions
• Development of posterior reversible encephalopathy syndrome (PRES) 1

The constellation of symptoms in this case strongly suggests hypertensive encephalopathy:

• Visual disturbances (intermittent vision loss) - a classic emergency symptom
• Headache - common in hypertensive crisis
• Slurred speech - neurological manifestation of cerebral edema
• Pain around the affected eye - may indicate retinal involvement

The history of hypertension is a critical risk factor, as hypertensive encephalopathy typically develops in patients with pre-existing hypertension, especially when blood pressure rises rapidly 1.

Diagnostic Approach

Immediate Assessment

• Measure blood pressure in both arms and lower limbs to detect pressure differences
• Perform fundoscopic examination to look for hypertensive retinopathy
• Assess neurological status for focal deficits

Laboratory Testing

• Complete blood count (hemoglobin, platelet count)
• Renal function (creatinine, sodium, potassium)
• LDH and haptoglobin to evaluate for thrombotic microangiopathy
• Urinalysis for proteinuria and hematuria 1

Imaging Studies

MRI with FLAIR sequences is the preferred imaging test because:

1. It can demonstrate the characteristic white matter lesions in posterior regions of the brain associated with hypertensive encephalopathy 1
2. It has superior sensitivity for detecting early cerebral edema compared to CT
3. It can differentiate hypertensive encephalopathy from other causes of neurological symptoms

While CT is useful to exclude intracranial hemorrhage, MRI provides more detailed information about the specific changes seen in hypertensive encephalopathy 1.

Differential Diagnosis

Several conditions should be considered:

• Transient ischemic attack (TIA): Can present with similar symptoms but typically doesn't include headache and eye pain 2, 3
• Ischemic stroke: Would typically have persistent rather than intermittent symptoms
• Thrombotic thrombocytopenic purpura (TTP): Would show more severe thrombocytopenia and schistocytes on blood smear 1
• Hemolytic uremic syndrome (HUS): Similar to TTP but with more prominent renal involvement

Management Considerations

If hypertensive encephalopathy is confirmed:

• Immediate hospitalization for continuous blood pressure monitoring
• Parenteral antihypertensive therapy (IV labetalol or nicardipine are first-line agents)
• Target blood pressure reduction of 20-25% over several hours
• Avoid excessive blood pressure reduction which could lead to cerebral hypoperfusion 4

Pitfalls to Avoid

1. Misdiagnosis as migraine or other primary headache disorders: The combination of hypertension with neurological symptoms should raise suspicion for hypertensive encephalopathy
2. Delayed imaging: Prompt neuroimaging is essential as hypertensive encephalopathy is reversible with timely treatment
3. Excessive blood pressure reduction: Too rapid lowering of blood pressure can lead to cerebral hypoperfusion and worsen neurological damage
4. Failure to evaluate for secondary causes of hypertension: Once stabilized, patients should be evaluated for underlying causes of severe hypertension 4

Without prompt treatment, hypertensive emergencies have extremely high mortality, with a 1-year death rate exceeding 79% 4. Early diagnosis with appropriate imaging and immediate treatment is crucial for improving outcomes.