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Zorluk: ZorOrdering Imaging Studies

Emergency medical responders bring a 71-year-old female to the resuscitation bay after her daughter found her unable to speak or move her right side this morning at 07:00. The patient and her daughter watched television together until 23:00 last night, at which point the patient went to bed in her usual state of health. Vital signs include a blood pressure of 172/95 mm Hg and a heart rate of 94/min that is irregularly irregular. Neurologic examination reveals global aphasia, a right-sided facial droop, and 1/5 strength in the right upper and lower extremities. Her National Institutes of Health Stroke Scale (NIHSS) score is 18. An initial non-contrast computed tomography of the head reveals a hyperdense left middle cerebral artery sign and subtle loss of gray-white matter differentiation in the left insular ribbon, with no evidence of intracranial hemorrhage. Which of the following is the most appropriate next step in imaging for this patient?

  1. Computed tomography angiography and perfusion imaging of the brainCevap
  2. B
    Magnetic resonance imaging of the brain with gadolinium enhancement
  3. C
    Carotid duplex ultrasonography
  4. D
    Conventional digital subtraction angiography
  5. E
    Repeat non-contrast computed tomography of the head in 24 hours

Cevap

Computed tomography angiography and perfusion imaging of the brain
The patient presents with a 'wake-up' stroke and an initial non-contrast CT head demonstrating early ischemic changes without hemorrhage, alongside a hyperdense artery sign indicative of a large vessel occlusion (LVO). Because her last known well time was 8 hours prior, she falls outside the standard 4.5-hour window for intravenous thrombolysis but within the up to 24-hour window for mechanical thrombectomy. Landmark trials (e.g., DAWN and DEFUSE 3) established that patients in the 6- to 24-hour window must undergo advanced neurovascular imaging. Computed tomography angiography (CTA) is required to confirm the presence of a proximal LVO, while computed tomography perfusion (CTP) is needed to identify a clinical-core or perfusion-core mismatch. This mismatch represents the ischemic penumbra—brain tissue that is hypoperfused but not yet irreversibly infarcted—which is the target of endovascular reperfusion.

Adım Adım Çözüm

1
Determine the time elapsed since the patient was last known to be in her normal state of health.
The patient was last seen normal at 23:00 and found with deficits at 07:00, creating an 8-hour gap and placing her in the extended time window (beyond the 4.5-hour limit for intravenous thrombolysis).
Establishing the precise stroke time window dictates the availability and type of acute reperfusion therapies.
2
Assess the clinical severity and findings on the initial non-contrast CT.
The patient has a severe stroke (NIHSS 18) with a hyperdense middle cerebral artery sign, strongly suggesting a proximal large vessel occlusion (LVO) in the anterior circulation.
Patients with LVOs are the primary candidates for mechanical thrombectomy.
3
Select the appropriate imaging to evaluate eligibility for mechanical thrombectomy in the 6-24 hour window.
Guidelines require advanced imaging, such as CT angiography and CT perfusion (or MRI equivalent), to identify salvageable brain tissue (ischemic penumbra) relative to the irreversibly damaged tissue (infarct core).
Intervention is only beneficial if there is a significant mismatch indicating that brain tissue can still be saved by restoring blood flow.

Anahtar Kavram

In patients presenting with an acute ischemic stroke in the extended time window (6 to 24 hours), CT angiography and CT perfusion imaging are indicated to identify a target large vessel occlusion and assess for salvageable ischemic penumbra prior to mechanical thrombectomy.

Alternatif Yöntem

An alternative imaging pathway for extended-window stroke evaluation is Magnetic Resonance Imaging (MRI) of the brain without contrast, specifically looking for a mismatch between the Diffusion-Weighted Imaging (DWI) sequence (which shows the irreversible infarct core) and the Fluid-Attenuated Inversion Recovery (FLAIR) sequence or MR Perfusion. If a lesion is visible on DWI but not on FLAIR, it suggests the stroke is less than 4.5 hours old, potentially allowing for IV thrombolysis even in a wake-up stroke.
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