Erfan Bashar
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Stroke Eligibility and Safety

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Educational scope notice: This is a study note for medical students, not medical advice, diagnosis, or treatment guidance. Clinical management should follow local protocols and current guidelines.

Reperfusion helps only the right patient, so a safety gate stands before every thrombolysis or thrombectomy decision. The gate has three questions: is this really stroke, is lysis forbidden, and does the patient fall inside a proven time window.

Rule out mimics first

Severe hypoglycemia can mimic a focal deficit, so glucose is checked and corrected before diagnosing stroke. Blood glucose below 2.7 mmol/L (50 mg/dL) or above 22 mmol/L (400 mg/dL) is a relative contraindication to intravenous thrombolysis. When high clinical suspicion for stroke justifies treatment and a mimic is diagnosed only later, the hemorrhagic risk stays low, with parenchymal hematoma around 1% in registry data.

Contraindications to thrombolysis

Intracranial hemorrhage on imaging is an absolute contraindication to intravenous alteplase. Platelet count below 100,000 per mm3 excludes treatment by both guidelines and drug labeling. Systolic pressure above 185 or diastolic above 110 mmHg excludes treatment unless controlled. An INR above 1.7, or direct thrombin or factor-Xa inhibitor effect without normal coagulation labs, also excludes it. Single or dual prior antiplatelet therapy does not exclude treatment.

For mild non-disabling deficits (NIH Stroke Scale 0–5), intravenous alteplase is not recommended. The trial behind this boundary showed no benefit within 3 hours for that severity band.

Thrombectomy and wake-up windows

For large anterior-circulation occlusion at 6 to 24 hours, selection rests on clinical-imaging mismatch as in the DAWN and DEFUSE-3 criteria. At the time of this review those were the only endorsed late-window selection criteria, and newer eligibility data will need a future update.

Wake-up or unknown-onset stroke with diffusion-FLAIR mismatch on MRI can benefit from alteplase within 4.5 hours of recognition. The mismatch marks tissue injured recently enough that lysis still helps.

Evidence anchors

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