What are the diagnostic criteria and initial treatment for non-hemorrhagic (ischemic) stroke?

Diagnostic Criteria and Initial Treatment for Non-Hemorrhagic (Ischemic) Stroke

The diagnosis of non-hemorrhagic (ischemic) stroke requires rapid neuroimaging with CT or MRI to distinguish it from hemorrhagic stroke, followed by immediate initiation of appropriate reperfusion therapy for eligible patients within established time windows. 1

Diagnostic Criteria

Clinical Presentation

• Sudden onset of focal neurological deficits, including unilateral weakness (face, arm, and/or leg), speech disturbance, sensory loss, visual disturbances, or ataxia 1, 2
• Time of symptom onset must be clearly established (defined as when the patient was last known to be at their baseline or symptom-free) 2
• Severity assessment using the National Institutes of Health Stroke Scale (NIHSS) 1, 2

Essential Imaging

• Non-contrast CT scan of the brain is the primary diagnostic test to rule out hemorrhage 1
• CT should be interpreted by a physician skilled in assessing for early signs of infarction, including:
  • Hyperdense middle cerebral artery sign (indicating thrombus)
  • Loss of gray-white differentiation in the cortical ribbon or lentiform nucleus
  • Sulcal effacement 1
• MRI with diffusion-weighted imaging (DWI) is more sensitive for detecting acute and small infarctions, especially in the posterior fossa, but should not delay treatment 1

Vascular Imaging

• CT angiography (CTA) from aortic arch to vertex is recommended at the time of initial brain CT to assess both extracranial and intracranial circulation 1
• Alternative vascular imaging options include MR angiography or carotid ultrasound (for extracranial vessels), based on availability and patient characteristics 1

Laboratory Investigations

• Essential laboratory tests include:
  • Complete blood count
  • Electrolytes
  • Coagulation studies (INR, aPTT)
  • Renal function (creatinine, eGFR)
  • Blood glucose
  • Troponin 1, 2

Cardiac Assessment

• 12-lead ECG to assess cardiac rhythm and identify atrial fibrillation or evidence of structural heart disease 1
• ECG monitoring for at least 24 hours as part of initial stroke workup to detect paroxysmal atrial fibrillation 1

Initial Treatment

Thrombolytic Therapy

• Intravenous recombinant tissue plasminogen activator (rtPA) at 0.9 mg/kg (maximum 90 mg) is recommended for eligible patients 1, 2
• Time windows for IV rtPA:
  • Within 3 hours of symptom onset for all eligible patients 1
  • Extended window of 3-4.5 hours for patients meeting additional criteria 1

Eligibility Criteria for IV rtPA (0-3 hours)

• Diagnosis of ischemic stroke causing measurable neurologic deficit
• Onset of symptoms <3 hours before beginning treatment
• Age ≥18 years 1

Additional Exclusion Criteria for Extended Window (3-4.5 hours)

• Age >80 years
• Severe stroke (NIHSS >25)
• Taking oral anticoagulants regardless of INR
• History of both diabetes and prior ischemic stroke 1

Contraindications to IV rtPA

• Head trauma or prior stroke in previous 3 months
• Symptoms suggesting subarachnoid hemorrhage
• Arterial puncture at noncompressible site in previous 7 days
• History of previous intracranial hemorrhage
• Elevated blood pressure (systolic >185 mmHg or diastolic >110 mmHg)
• Evidence of active bleeding
• Acute bleeding diathesis (platelet count <100,000/mm³, heparin within 48 hours with elevated aPTT, INR >1.7)
• Blood glucose <50 mg/dL
• CT showing multilobar infarction (hypodensity >1/3 cerebral hemisphere) 1

Blood Pressure Management

• For patients eligible for thrombolytic therapy: maintain BP <185/110 mmHg before treatment 1, 2
• For patients not receiving thrombolytic therapy: consider lowering BP only if systolic >220 mmHg or diastolic >120 mmHg 1
• A reasonable target is to lower blood pressure by 15% to 25% within the first day 1

Early Management Considerations

• Swallowing assessment before oral intake to prevent aspiration 2
• Temperature monitoring every 4 hours for the first 48 hours, with temperature-reducing measures if temperature exceeds 37.5°C 2
• Treatment of seizures if they occur, but prophylactic anticonvulsants are not recommended 2
• Early mobilization and adequate hydration to prevent venous thromboembolism 2

Common Pitfalls and Caveats

• Clinical features alone cannot reliably distinguish ischemic from hemorrhagic stroke - neuroimaging is essential 3, 4
• Stroke mimics include seizures, conversion disorder, migraine headache, and hypoglycemia - check blood glucose immediately 4, 5
• The presence of early infarct signs on CT (even if they involve greater than one third of the middle cerebral artery territory) in patients with stroke onset <3 hours does not preclude treatment with IV rtPA 1
• For patients with cerebellar symptoms, the HINTS examination (head-impulse, nystagmus, test of skew) is more sensitive for cerebellar stroke than early MRI 4
• Patients with wake-up stroke or unknown time of onset may still be eligible for treatment based on advanced imaging criteria 6, 4