What is the management approach for acute Cerebrovascular Accident (CVA) typing?

Management of Acute Cerebrovascular Accident (CVA) Typing

The immediate priority in acute CVA management is rapid neuroimaging with non-contrast CT to differentiate hemorrhagic from ischemic stroke, as this single determination dictates all subsequent treatment decisions and must be completed within 45 minutes of emergency department arrival. 1

Initial Diagnostic Approach

Emergency Neuroimaging Protocol

• Non-contrast CT (NCCT) is the gold standard initial imaging modality for acute stroke typing because it rapidly excludes intracranial hemorrhage (absolute contraindication to thrombolysis), is widely available, time-efficient, and provides the necessary information for emergency management decisions 1

• The brain imaging study must be interpreted within 45 minutes of patient arrival by a physician with expertise in reading CT and MRI studies of the brain parenchyma 1

• MRI with gradient echo sequences is equally sensitive to CT for detecting acute hemorrhage and more sensitive for prior hemorrhage, but time constraints, availability, and patient tolerance often preclude its use in the emergency setting 1

Critical Questions Answered by Imaging

The neuroimaging evaluation must answer three essential questions to guide treatment 1:

1. Is there evidence of intracranial hemorrhage? This determines eligibility for thrombolytic therapy
2. Is there a vessel occlusion, and where is it located? This guides decisions about endovascular therapy
3. What is the extent of established infarction? This assesses the risk/benefit ratio of treatment

Hemorrhagic vs. Ischemic Stroke Differentiation

Hemorrhagic Stroke Identification

• Acute hemorrhage appears as hyperdense (bright) foci on NCCT, and absence of such foci virtually excludes intracranial hemorrhage 1

• CT angiography (CTA) and contrast-enhanced CT may identify patients at high risk of hematoma expansion based on contrast extravasation within the hematoma 1

• The high rate of early neurologic deterioration in hemorrhagic stroke relates to active bleeding that may proceed for hours after symptom onset 1

Ischemic Stroke Identification

• Intravenous fibrinolytic therapy is recommended even in the presence of early ischemic changes on CT (other than frank hypodensity), regardless of their extent 1

• Frank hypodensity involving more than one-third of the middle cerebral artery (MCA) territory increases hemorrhage risk with fibrinolysis and is a contraindication to intravenous rtPA 1

• A noninvasive intracranial vascular study (CTA or MRA) is strongly recommended during initial imaging if intra-arterial fibrinolysis or mechanical thrombectomy is contemplated, but should not delay intravenous rtPA if indicated 1

Advanced Imaging for Large Vessel Occlusion

Vascular Imaging Requirements

• Visualizing a vessel occlusion confirms the diagnosis of acute ischemic stroke, and its location guides treatment decisions 1

• Large vessel occlusions (intracranial carotid artery and M1 occlusions) are less likely to recanalize with alteplase alone and should be considered for endovascular therapy 1

• Time-consuming imaging methods and overly selective treatment selection criteria should be avoided because every 30-minute delay in recanalization decreases the chance of good functional outcome by 8-14% 1

Perfusion Imaging Considerations

• CT perfusion and MRI perfusion/diffusion imaging may be considered for selecting patients for acute reperfusion therapy beyond standard time windows 1

• These techniques provide additional information about infarct core and penumbra that may improve diagnosis, mechanism assessment, and severity determination, allowing more informed clinical decision-making 1

• However, methods for processing perfusion data vary, and the most biologically salient perfusion parameters and thresholds for acute decision-making have not been fully defined 1

Critical Pitfalls to Avoid

Common Diagnostic Errors

• Do not rely on clinical characteristics alone to differentiate hemorrhagic from ischemic stroke - vomiting, severe headache, systolic blood pressure >220 mmHg, coma, and symptom progression all suggest hemorrhage but are not specific 1

• A negative plain CT or MRI does not rule out cerebral venous thrombosis; a venographic study (CTV or MRV) must be performed if clinical suspicion remains 1

• Flow gaps are commonly seen on time-of-flight MRV images and asymmetrical lateral sinuses occur in 49% of normal patients, which can lead to false-positive interpretations 1

• Diffusion-weighted MRI has potential pitfalls in evaluating small hyperacute posterior fossa strokes and venous infarcts 2

Time-Critical Considerations

• Document the precise time of symptom onset (or time last known normal), as this determines eligibility for reperfusion therapies 3

• Up to 24% of patients with acute retinal artery occlusion have concurrent cerebrovascular accident on diffusion-weighted MRI, emphasizing the need for urgent neuroimaging in ocular stroke presentations 1

• Silent brain infarction is present in 19% of central retinal artery occlusion and 25% of branch retinal artery occlusion patients, warranting prompt referral to a stroke center 1

Organizational Requirements

• Every emergency department must be prepared to treat patients with acute stroke or have a plan for rapid transfer to a tertiary care center with neurology, neuroradiology, neurosurgery, and critical care facilities 1

• Advance notice by emergency medical services to the emergency department significantly shortens time to CT scanning 1

• Critical pathways for acute stroke management allow for more efficient, standardized, and integrated care of critically ill patients 1