I. Clinical Presentation and Initial Triage

Early recognition of stroke symptoms and precise timing are essential for reperfusion eligibility—time is brain.

1.1 Time of Onset and Last Known Well (LKW)

• Define LKW as the last moment the patient was at baseline neurologic function.
• Reperfusion windows:
  • IV thrombolysis: ≤ 4.5 hours from LKW
  • Mechanical thrombectomy: ≤ 6 hours (standard) and up to 24 hours with favorable imaging
• Rapid history techniques:
  • Ask witnesses for exact or approximate times of symptom onset or when patient was last seen normal.
  • In unwitnessed or wake-up strokes, use DWI/FLAIR MRI mismatch if available.

1.2 Focal Neurologic Deficits

• Common presentations referable to vascular territories:
  • Motor deficit: sudden hemiparesis or facial droop
  • Sensory loss: contralateral numbness or tingling
  • Language dysfunction: expressive or receptive aphasia
  • Visual field cut: homonymous hemianopia
  • Neglect or inattention
• Perform a concise stroke exam, ideally using the NIH Stroke Scale (NIHSS).
• Correlate deficit pattern with likely vessel territory (e.g., MCA vs. PCA).

1.3 Stroke Mimics

• Common mimics and distinguishing features:
  • Hypoglycemia: check bedside glucose; mental status may fluctuate
  • Seizures/postictal paresis (Todd’s palsy): witness history of convulsion, EEG if needed
  • Migraine aura: gradual onset, positive visual phenomena, headache history
  • Functional disorders: non-anatomic findings, inconsistency on serial exam

II. Laboratory Evaluation

Targeted labs confirm diagnosis, exclude contraindications, and inform initial management without delaying reperfusion.

2.1 Serum Glucose

• Mandatory in all suspected AIS prior to thrombolysis.
• Hypoglycemia (< 60 mg/dL): correct before any stroke‐specific treatment.
• Mild hyperglycemia common; maintain 140–180 mg/dL range but do not delay reperfusion for elevated glucose.

2.2 Coagulation Profile

• INR > 1.7 or aPTT prolonged: contraindication to IV tPA.
• In patients without anticoagulant use, do not wait for routine coagulation results before starting tPA.

2.3 Comprehensive Chemistries

• CBC: exclude thrombocytopenia (platelets < 100,000/µL).
• Electrolytes and renal/hepatic panels: guide contrast imaging safety.
• Cardiac biomarkers and lipid panel: plan secondary prevention once acute phase is addressed.

III. Neuroimaging Modalities

Imaging rapidly excludes hemorrhage, identifies large vessel occlusion (LVO), and estimates salvageable tissue.

3.1 Non-Contrast CT (NCCT)

• First-line to exclude intracranial hemorrhage.
• Early ischemic signs (often subtle): loss of gray–white differentiation, sulcal effacement, hyperdense vessel sign.

3.2 CT Angiography (CTA)

• Detects LVO in cervical and intracranial arteries.
• Collateral circulation grading predicts infarct progression and expansion of therapeutic window.

3.3 CT Perfusion (CTP)

• Maps cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT).
• Estimates core infarct (low CBF/CBV) vs. penumbra (prolonged MTT).
• Useful in extended window (6–24 hours) but may delay treatment if overused early.

3.4 MRI DWI/FLAIR

• DWI: highest sensitivity for hyperacute ischemia within minutes.
• FLAIR: changes appear after ~ 4–6 hours; DWI-positive/FLAIR-negative suggests onset < 4.5 hours.
• Limited by availability, patient stability, and contraindications.

IV. Severity Scoring and Etiological Classification

Standardized scales quantify stroke severity and guide prognostication; etiologic classification informs secondary prevention.

4.1 NIH Stroke Scale (NIHSS)

• 11 items, score 0–42; higher score = more severe deficit.
• Guides urgency: NIHSS ≥ 6 often prompts CTA for possible thrombectomy.
• Serial NIHSS detects early deterioration (e.g., hemorrhagic transformation).

4.2 TOAST Classification

• Subtypes: large‐artery atherosclerosis; cardioembolism; small‐vessel occlusion; other determined; undetermined.
• Requires vascular imaging, cardiac evaluation, and labs for accurate subtype assignment.
• Directs secondary prevention (e.g., anticoagulation for cardioembolic stroke).

4.3 Additional Scales

• ASPECTS on NCCT (10-point MCA territory score): < 6 suggests large core infarct, poor thrombectomy candidate.
• Modified Rankin Scale (mRS): baseline and follow-up functional status for outcome assessment.

V. Integration into Management Pathway

Combine clinical, lab, and imaging data into a streamlined code-stroke algorithm to minimize delays.

5.1 Risk Stratification

• High NIHSS + LVO + small core (ASPECTS ≥ 6) = top priority for endovascular therapy.
• Lower NIHSS without LVO = consider IV thrombolysis alone.

5.2 Clinical Decision Algorithm

Telestroke and teleradiology can expedite expert interpretation in resource-limited centers.

5.3 Reassessment and Monitoring

• Repeat NIHSS every 15–30 minutes during and after reperfusion therapies.
• Immediate imaging if clinical worsening occurs.
• Continuous cardiac monitoring for arrhythmias (e.g., atrial fibrillation).

VI. Pearls, Pitfalls, and Controversies

Be aware of common exam traps and emerging debates that may impact decision-making.

6.1 Overestimation of Deficits

• Distinguish dysarthria from aphasia and neglect from hemianopia to avoid NIHSS misclassification.

6.2 Extended Time Windows

• DAWN and DEFUSE-3 criteria allow thrombectomy up to 24 hours in select patients with mismatch.
• Applicability in community settings remains under evaluation.

6.3 Imaging Modality Selection

• Routine use of CTP in early window (< 6 hours) may prolong door-to-treatment time without clear benefit.
• In unstable patients or those with contraindications to MRI, CT-based protocols suffice.