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Difficulty: HardOrdering Imaging Studies

A 72-year-old man is brought to the emergency department by emergency medical services with sudden-onset severe right-sided hemiparesis, right facial droop, and expressive aphasia. His wife reports that he was in his usual state of health until 90 minutes ago when the symptoms abruptly started. His past medical history is significant for type 2 diabetes mellitus, hypertension, and chronic kidney disease stage 4 (baseline estimated glomerular filtration rate is 22 mL/min/1.73 m2). Vital signs are temperature 36.8°C, blood pressure 185/105 mmHg, heart rate 92/min, and respiratory rate 16/min. Point-of-care blood glucose is 128 mg/dL. An emergent non-contrast computed tomography (CT) of the head shows no evidence of intracranial hemorrhage or early ischemic changes. The stroke neurology team is evaluating the patient for both intravenous thrombolysis and endovascular thrombectomy. Assessment of the intracranial and extracranial vasculature is required to identify a potential large vessel occlusion. Which of the following is the most appropriate next step in the diagnostic imaging of this patient?

  1. Proceed immediately with CT angiography of the head and neckAnswer
  2. B
    Administer an intravenous bolus of isotonic fluids prior to CT angiography
  3. C
    Obtain magnetic resonance angiography of the head and neck without contrast
  4. D
    Perform duplex ultrasonography of the carotid arteries
  5. E
    Withhold further vascular imaging and proceed with management based on the non-contrast CT

Answer

Proceed immediately with CT angiography of the head and neck.
The correct action is to proceed immediately with CT angiography (CTA). In patients presenting with acute ischemic stroke who are potential candidates for mechanical thrombectomy, rapid identification of a large vessel occlusion (LVO) is critical. Current guidelines emphasize that 'time is brain' and strongly recommend performing non-invasive vascular imaging as quickly as possible. Although this patient has severe chronic kidney disease, the devastating neurological consequences of missing a treatable LVO far outweigh the risk of contrast-associated acute kidney injury. Therefore, CTA must not be delayed to wait for serum creatinine results, to administer prophylactic intravenous fluids, or to arrange for slower alternative imaging modalities.

Step-by-Step Solution

1
Identify the primary clinical presentation and time course.
The patient presents with acute focal neurological deficits highly suggestive of an acute ischemic stroke, well within the treatment window (90 minutes from onset) for both thrombolysis and mechanical thrombectomy.
Establishing the time last known well is required to determine eligibility for acute reperfusion therapies.
2
Recognize the required diagnostic workup for endovascular interventions.
Mechanical thrombectomy requires confirmation of a large vessel occlusion (LVO) using vascular imaging, typically CT angiography (CTA) of the head and neck.
Non-contrast head CT rules out hemorrhage but cannot visualize the occluded vascular anatomy necessary for thrombectomy planning.
3
Evaluate patient comorbidities against the urgency of the imaging test.
The patient has severe chronic kidney disease (CKD stage 4), which generally raises concerns for contrast-associated acute kidney injury. However, in this life-threatening, highly time-sensitive scenario ('time is brain'), the immediate benefit of identifying a treatable LVO far outweighs the renal risks.
Current AHA/ASA stroke guidelines state that emergent vascular imaging must not be delayed to wait for serum creatinine results or to administer prophylactic intravenous hydration.

Key Concept

In patients with suspected acute ischemic stroke who are candidates for mechanical thrombectomy, vascular imaging (e.g., CT angiography) should be performed immediately and must not be delayed for renal function testing or prophylactic hydration, regardless of underlying chronic kidney disease.
Estimated Time:1m 15s
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