# Ischaemic Stroke > Ischaemic stroke for NEET-PG Medicine: CT diagnosis, thrombolysis window and contraindications, thrombectomy, blood pressure care and secondary prevention. - Canonical URL: https://prepelephant.com/topics/neet-pg/medicine/ischaemic-stroke - Exam / course: NEET-PG · Subject: Medicine - Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team - First published: 2026-10-02 - Last updated: 2026-10-02 - How to cite: "Ischaemic Stroke", PrepElephant, https://prepelephant.com/topics/neet-pg/medicine/ischaemic-stroke ## Direct answer Ischaemic stroke — sudden focal neurological deficit from vascular occlusion — accounts for the large majority of all strokes. Immediate non-contrast CT of the head excludes haemorrhage and opens the reperfusion pathway: intravenous thrombolysis with alteplase 0.9 mg per kg (maximum 90 mg, 10 per cent as bolus) within 4.5 hours of onset, and mechanical thrombectomy for anterior-circulation large-vessel occlusion up to 6 hours, extended to 24 hours in selected patients with imaging mismatch. Aspirin within 24 to 48 hours, stroke-unit care, and early secondary prevention complete the management. ## What you must remember - Recognition: sudden face-arm weakness, speech disturbance or visual and cerebellar deficits; check glucose first to exclude mimics — hypoglycaemia, seizure with Todd's paresis, migraine, functional weakness. - Non-contrast CT is the first investigation in every acute stroke; it excludes haemorrhage and may show early ischaemic signs such as a hyperdense vessel or lost grey-white differentiation. - IV thrombolysis: alteplase 0.9 mg per kg, maximum 90 mg, 10 per cent bolus then infusion over one hour, within 4.5 hours; tenecteplase as a single bolus is an accepted alternative. - Contraindications: intracranial haemorrhage, recent intracranial surgery or head trauma, active bleeding, platelets below 100,000, INR above 1.7, a direct oral anticoagulant within 48 hours, and blood pressure above 185/110 mmHg that cannot be lowered. - Thrombectomy: for internal carotid or proximal middle cerebral artery occlusion within 6 hours; up to 24 hours in selected patients with favourable perfusion mismatch. - Blood pressure: do not lower unless above 220/120 mmHg (without reperfusion) or above 185/110 mmHg before thrombolysis — maintain permissive hypertension for penumbral perfusion. - General care and prevention: swallow assessment before oral intake, euglycaemia, normothermia, DVT prophylaxis, early rehabilitation, decompressive hemicraniectomy for malignant MCA infarction; then high-intensity statin, antiplatelet therapy (short-term dual for minor stroke or high-risk TIA), timed anticoagulation for atrial fibrillation, and risk factor control. ## A thrombolysis decision, minute by minute A 64-year-old develops right hemiparesis and aphasia at 9:15 am; she reaches the emergency department at 10:40 am, last-seen-well certain. Glucose first — 130 mg/dL, excluding hypoglycaemia — then non-contrast CT immediately, because the haemorrhage question is settled only by imaging and thrombolysing a haemorrhagic stroke is the catastrophic error. The CT shows no blood and a subtle hyperdense left middle cerebral artery. Time from onset: 85 minutes, inside the 4.5-hour window. Run the contraindication list: no recent intracranial surgery or head trauma, no active bleeding, platelets above 100,000, no anticoagulants, and blood pressure — 198/104 — needs labetalol below 185/110 before the needle. Alteplase 0.9 mg per kg, maximum 90 mg, 10 per cent as bolus and the rest over one hour (tenecteplase as a single bolus is an accepted alternative); aspirin waits 24 hours, then starts within the 24-to-48-hour rule. Had CT angiography shown a proximal middle cerebral artery or internal carotid occlusion, thrombectomy enters — within 6 hours standard, to 24 hours with perfusion mismatch — and neither therapy excuses stroke-unit care: swallow assessment before oral intake, euglycaemia, normothermia, DVT prophylaxis, early rehabilitation, decompressive hemicraniectomy for malignant MCA infarction. After the acute phase, the aetiological work-up decides prevention: ## Where students slip Two blood pressure thresholds get interchanged: 185/110 belongs to the thrombolysis candidate, 220/120 to the patient managed without reperfusion — and "treat the hypertension urgently" is the reflex the permissive-hypertension principle overrides, because pressure perfuses the penumbra. The dose arithmetic is the second error: 10 per cent bolus of 0.9 mg per kg with a 90 mg ceiling. TIA complacency is the third: resolving symptoms still carry early stroke risk demanding urgent work-up. Territory questions pair the deficit with the vessel and then the prevention — cardioembolic atrial fibrillation above all. ## Frequently asked questions ### What is the time window and dose for IV thrombolysis? Within 4.5 hours of onset, alteplase 0.9 mg per kg up to 90 mg — 10 per cent as a bolus, the remainder over one hour. ### Why must a non-contrast CT precede thrombolysis? To exclude intracranial haemorrhage and large established infarction, both absolute contraindications; CT is the fastest discriminator between ischaemic and haemorrhagic stroke. ### When is mechanical thrombectomy indicated? For anterior-circulation large-vessel occlusion within 6 hours, and up to 24 hours in selected patients when perfusion imaging shows salvageable brain. ### How is blood pressure managed in acute ischaemic stroke? Permissive hypertension is the rule; treat only above 220/120 mmHg without reperfusion, or above 185/110 mmHg before and during thrombolysis. ### When is aspirin started? Within 24 to 48 hours, but withheld for at least 24 hours after thrombolysis; a brief dual antiplatelet course follows minor stroke or high-risk TIA. ### Which patients need anticoagulation rather than antiplatelets? Those with cardioembolic sources — chiefly atrial fibrillation, mechanical valves or intracardiac thrombus — with timing individualised to infarct size.