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Difficulty: Very hardInterpreting Imaging Results

A 3838-year-old female patient arrives at the acute care clinic reporting the abrupt onset of a headache that she describes as exploding in her head, reaching maximal intensity within seconds. The onset occurred two hours ago, shortly after she ingested a pseudoephedrine-based decongestant for a mild upper respiratory infection. She has a past medical history significant for major depressive disorder managed with fluoxetine.

Upon evaluation, her blood pressure is 186/104186/104 mm Hg and heart rate is 8484/min. Neurological examination demonstrates symmetric hyperreflexia in all four extremities, but no focal sensory or motor deficits, and no nuchal rigidity.

An initial unenhanced computed tomography (CT) scan of the head reveals no abnormalities. Subsequent lumbar puncture demonstrates crystal-clear fluid, opening pressure of 1616 cm H 2_2 O, 00 red blood cells/mm 3^3, 11 white blood cell/mm 3^3, and normal protein and glucose levels.

Because of persistent pain, advanced imaging is obtained. A CT angiogram of the head and neck reveals multifocal, diffuse segmental narrowing interspersed with dilated segments involving the bilateral middle and posterior cerebral arteries. A brain magnetic resonance imaging (MRI) scan shows bilaterally symmetric hyperintense areas on T2-weighted fluid-attenuated inversion recovery (FLAIR) sequences within the parieto-occipital subcortical white matter. No restricted diffusion is present.

Based on the interpretation of these imaging findings, which of the following is the most appropriate next step in the management of this patient?

  1. Administration of oral verapamilAnswer
  2. B
    Administration of high-dose intravenous methylprednisolone
  3. C
    Subcutaneous injection of sumatriptan
  4. D
    Conventional catheter cerebral angiography
  5. E
    Stereotactic brain biopsy

Answer

The most appropriate next step in management is the administration of oral verapamil.
The patient's clinical presentation of a thunderclap headache, especially triggered by a sympathomimetic (pseudoephedrine) and an SSRI (fluoxetine), combined with the classic imaging findings, is highly diagnostic of Reversible Cerebral Vasoconstriction Syndrome (RCVS) complicated by Posterior Reversible Encephalopathy Syndrome (PRES). The CT angiogram finding of multifocal segmental narrowing and dilatation ('string of beads' appearance) confirms severe cerebral vasoconstriction. The MRI showing symmetric parieto-occipital FLAIR hyperintensities without restricted diffusion represents vasogenic edema, which is the hallmark of PRES. The most appropriate next step in management is the administration of a calcium channel blocker, such as oral verapamil or nimodipine, which directly addresses the cerebral vasospasm and helps control the elevated blood pressure.

Step-by-Step Solution

1
Analyze the clinical presentation and initial workup.
The patient has a classic thunderclap headache triggered by sympathomimetics (pseudoephedrine) and SSRIs (fluoxetine). Normal non-contrast CT and normal lumbar puncture effectively rule out subarachnoid hemorrhage (SAH).
Ruling out SAH is the mandatory first step in any thunderclap headache evaluation.
2
Interpret the advanced neuroimaging findings.
CTA demonstrates a "string of beads" (segmental narrowing and dilatation) appearance in the cerebral arteries. MRI reveals symmetric parieto-occipital FLAIR hyperintensities without restricted diffusion.
Accurate imaging interpretation distinguishes the underlying pathology from ischemic stroke, venous thrombosis, or vasculitis.
3
Synthesize the imaging results into a unifying diagnosis.
The CTA findings are pathognomonic for Reversible Cerebral Vasoconstriction Syndrome (RCVS). The MRI findings indicate vasogenic edema, confirming concomitant Posterior Reversible Encephalopathy Syndrome (PRES).
PRES frequently complicates RCVS due to the severe fluctuations in cerebral vascular tone and elevated blood pressure.
4
Select the appropriate targeted intervention.
Administration of a calcium channel blocker, such as oral verapamil or nimodipine, is indicated.
Calcium channel blockers directly treat the intense arterial vasoconstriction characterizing RCVS and assist with blood pressure control for PRES.

Key Concept

Interpretation of advanced neuroimaging to diagnose Reversible Cerebral Vasoconstriction Syndrome (RCVS) and its common complication, Posterior Reversible Encephalopathy Syndrome (PRES), distinguishing it from primary CNS vasculitis.
Estimated Time:1m 30s
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Interpreting Imaging Results

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