Acute Ischemic Stroke

Acute ischemic stroke (AIS) is brain infarction. A cerebral artery is occluded or critically hypoperfused, and the patient shows a sudden focal neurologic deficit. Penumbra is the at-risk tissue around the core infarct. Early reperfusion can save it. Once the core is dead, it cannot be recovered.

• Large-vessel occlusion (LVO): the internal carotid artery (ICA), the M1 segment of the middle cerebral artery or the basilar artery. It causes disabling deficits. It is the target for endovascular thrombectomy (EVT).
• Cardioembolism: the clot comes from the heart, as in atrial fibrillation, a recent myocardial infarction or another cardiac source. Onset is abrupt. Several territories are often involved.
• Large-artery atherosclerosis or small-vessel disease: the lesion is a stenosis or a lacunar infarct. The course is often stepwise or gradual.
• Clinical course: deficits can worsen in the first hours. Hemorrhagic transformation can follow reperfusion.

Typical Presentations

• Anterior LVO: arm weakness, aphasia, gaze deviation toward the lesion, neglect
• Posterior circulation: vertigo, diplopia, dysarthria, ataxia, reduced consciousness, bilateral or crossed signs
• Screen: FAST or BE-FAST, which adds balance and eye changes. A positive screen starts the stroke pathway.

Red Flags

• LKW within the treatment window (4.5 hr for standard IVT; up to 24 hr for selected EVT), or unknown onset or wake-up stroke
• Facial droop with arm or leg weakness, aphasia, gaze deviation or neglect
• NIHSS ≥6 with suspected anterior LVO; NIHSS ≥10 with suspected basilar occlusion
• BP ≥185/110 mm Hg before a lytic decision
• Reduced consciousness, vomiting or severe headache (possible hemorrhage)

Let the clock and the score make the call. Do not hold treatment for a full workup.

Know the scores. NIHSS (NIH Stroke Scale) runs 0–42. ASPECTS (Alberta Stroke Program Early CT Score) grades early ischemic change on CT from 0 to 10. For basilar occlusion, use PC-ASPECTS, the posterior-circulation version. LAMS (Los Angeles Motor Scale) and RACE (Rapid Arterial oCclusion Evaluation) are prehospital LVO screens. Use the cutoff in the local protocol.

• Hypoglycemia: glucose is low at the bedside. The deficits resolve after dextrose.
• Seizure with Todd paralysis: witnessed convulsion or postictal state
• Migraine with aura: gradually spreading visual symptoms, headache, no abrupt deficit
• Intracerebral hemorrhage: headache, vomiting or decreased consciousness. CT separates it from stroke, and it is a contraindication to lytic.
• Bell palsy: only the face is involved, forehead included. A central facial palsy spares the forehead.
• Functional or conversion disorder: the exam is inconsistent and does not match a vascular territory.
• Transient ischemic attack: the deficit has fully resolved. The patient still needs urgent imaging and a workup.

1. Record last known well and the time the deficit was seen; give the time to the crew and receiving center.
2. Stroke screen (FAST or BE-FAST) and start the stroke alert per local protocol.
3. Airway and breathing: protect the airway (side-lying if vomiting or reduced consciousness). Give oxygen when SpO2 is below 94%; do not give it routinely to patients at or above 94%.
4. Nothing by mouth until a swallow screen is passed, including oral medications.
5. Glucose: check by fingerstick and treat glucose below 60 mg/dL per protocol, then recheck.
6. Blood pressure: do not treat reflexively; BP targets are set by ALS and the stroke team, per protocol.
7. Transport: to the stroke center set by regional protocol, with short scene time.

Doses vary by protocol; follow local protocols and medical direction.

• IV access and labs (Paramedic/RN/CCT): draw glucose, platelets, PT/INR and aPTT without delaying transport.
• Hypoglycemia: IV dextrose per protocol for glucose below 60 mg/dL, then recheck; see Dextrose.
• BP before lytic (Paramedic/RN/CCT): if BP is ≥185/110 mm Hg, lower it with a titratable IV agent per protocol. Nicardipine starts at 5 mg/hr IV and increases by 2.5 mg/hr every 5 to 15 minutes to a maximum of 15 mg/hr. Labetalol and clevidipine are protocol alternatives with their own labeled dosing; see Nicardipine, Labetalol or Clevidipine.
• IV thrombolysis (eligible patients; ED or stroke team decision): tenecteplase 0.25 mg/kg IV single bolus over 5 seconds, maximum 25 mg. US label weight tiers: 15 mg under 60 kg, 17.5 mg at 60 to under 70 kg, 20 mg at 70 to under 80 kg, 22.5 mg at 80 to under 90 kg, 25 mg at 90 kg or more. See Tenecteplase and Fibrinolytics.
• Alteplase alternative: 0.9 mg/kg IV, maximum 90 mg; 10% as an initial bolus over 1 minute, the rest over 60 minutes.
• Antiplatelets: aspirin and any clopidogrel decision are set by the stroke team; see Aspirin and Clopidogrel.
• Cardiac monitor and 12-lead ECG (Paramedic/RN/CCT): identify atrial fibrillation and ischemia; see 12-lead ECG acquisition.
• Airway: advanced airway for airway protection or failure to protect, per protocol; avoid hyperventilation. See RSI.

• Imaging and eligibility: get noncontrast CT plus CTA (or MRI with MRA), and do not let it delay the lytic. The stroke team selects extended-window IVT (beyond 4.5 hr from LKW, or wake-up stroke) using perfusion or MRI DWI-FLAIR mismatch. The 2026 guideline class is not restated here.
• Standard IVT window: treat as fast as you can within 4.5 hr of LKW. Do not wait for extra imaging (COR 1).
• Before a lytic (commonly applied exclusions): drawn from the 2019 AHA/ASA guideline (Table 8) and the Activase and TNKase labels. The 2026 guideline revised its approach to thrombolysis contraindications, and its contraindication table was not verified for this page. Label items: current intracranial or subarachnoid hemorrhage; active internal bleeding; recent intracranial or intraspinal surgery or serious head trauma (within 2 months in the TNKase label, 3 months in the Activase label); intracranial conditions that raise bleeding risk; bleeding diathesis; current severe uncontrolled hypertension. Commonly applied guideline items: no hemorrhage on CT; glucose at least 50 mg/dL; platelets at least 100,000/mm³; INR 1.7 or less; no DOAC in the prior 48 hr; no heparin in the prior 48 hr with an elevated aPTT; no prior intracranial hemorrhage; no ischemic stroke or severe head trauma, and no intracranial or spinal surgery, in the prior 3 months; no GI or GU bleeding in the prior 21 days; no aortic arch dissection; no infective endocarditis. Do not delay IVT for labs unless coagulopathy is suspected. The stroke team makes the final decision under the current guideline and protocol.
• EVT, anterior circulation ≤6 hr: ICA or M1 occlusion, NIHSS ≥6, prestroke mRS 0–1. ASPECTS cutoff per the 2026 guideline and local protocol (the 2019 guideline used ASPECTS 6 or higher; large-core trials enrolled lower ASPECTS).
• EVT, 6–24 hr (selected patients): ICA or proximal MCA occlusion and last known well 6 to 24 hr, with a mismatch between deficit and infarct. DAWN (6–24 hr; prestroke mRS 0–1, NIHSS 10 or higher) used age-stratified clinical-core mismatch and enrolled patients both younger than 80 and 80 or older. DEFUSE 3 (6–16 hr; prestroke mRS 0–2) used perfusion-imaging mismatch (core under 70 mL; perfusion-to-infarct ratio 1.8 or more) without DAWN's age-specific core rule. The stroke team applies the trial criteria. The 2026 guideline class is not restated here.
• EVT, basilar occlusion ≤24 hr: baseline mRS 0–1 and NIHSS ≥10 are common selection criteria; confirm current criteria with the stroke team.
• BP after IVT: keep below 180/105 mm Hg for at least 24 hr (COR 1). Intensive lowering of SBP below 140 mm Hg after IVT in mild to moderate stroke gives no clear benefit.
• BP after successful EVT: avoid an SBP target below 140 mm Hg for the first 72 hr, absent another indication. The usual ceiling is below 180/105 mm Hg; confirm the 2026 value.
• Glucose: target 140–180 mg/dL in hospital. Intensive insulin to 80–130 mg/dL is not recommended to improve 3-month outcome.
• Minor stroke without IVT: short-course dual antiplatelet therapy (aspirin with clopidogrel) for 21 days, then single antiplatelet, for minor ischemic stroke with NIHSS 3 or less within 24 hr that is not cardioembolic (CHANCE and POINT trials). The stroke team decides whether to start it.
• Admission: stroke unit or neuro-ICU with serial neurologic checks, BP control and swallow screen.

• Destination: Suspected LVO goes to a thrombectomy-capable stroke center. Lytic-eligible patients go to a stroke-capable center when the thrombectomy center is not reachable, per regional protocol.
• Clocks: Write down LKW, lytic bolus time and door time. The door-to-needle goal is within 60 minutes of arrival.
• In transit (Paramedic/RN/CCT): Check BP and neuro status per protocol, especially after the lytic (BP below 180/105 mm Hg for 24 hr). Watch for bleeding, angioedema and sudden decline.
• If decline after lytic: A severe headache, vomiting, a new deficit or falling consciousness may signal symptomatic intracranial hemorrhage. Alteplase still infusing? Stop the infusion. A tenecteplase bolus cannot be stopped. Either way, get an urgent CT and notify the stroke team and receiving center. The stroke team directs treatment (coagulation labs, cryoprecipitate or antifibrinolytic, BP control).
• Angioedema after lytic: Lip, tongue or throat swelling needs early airway management per protocol. Tell the receiving team about any ACE-inhibitor use.
• Equipment: infusion pump for titrated BP agent, glucose meter, NIHSS sheet, suction and airway equipment, and the correct thrombolytic with the mg dose confirmed.
• Handoff: LKW, drug, mg, bolus time, BP trend, NIHSS on arrival, glucose, anticoagulant history, ACE-inhibitor use.

• Pediatrics: Alteplase and tenecteplase have not been established as safe and effective in children (Activase label). Stroke is often missed in children. Suspect it with sudden weakness, facial droop, speech change or a focal seizure with deficit. Transfer to a pediatric-capable stroke center per regional protocol for urgent neuroimaging. The 2026 guideline has a dedicated pediatric section. Its recommendations were not reviewed for this page. The pediatric stroke team makes the lytic and EVT decisions. See weight-based dosing for other drugs.
• Pregnancy: Published alteplase data in pregnancy are insufficient (Activase label). A life-threatening stroke is treated after the stroke team weighs risk against benefit. The FDA letter categories no longer apply. The 2026 guideline's pregnancy statements were not reviewed for this page.
• Older Adults: age is not an absolute exclusion from standard IVT or from EVT. DAWN enrolled patients both younger than 80 and 80 or older, under age-specific imaging criteria.
• Renal Impairment: do not delay contrast CTA to check creatinine.
• Anticoagulants: commonly applied exclusions (2019 AHA/ASA-derived; not restated from the 2026 guideline): a DOAC within 48 hr, and heparin with an elevated aPTT. Otherwise, eligibility depends on the agent, the last dose and the labs. The stroke team decides under current guidance.
• Obesity: thrombolytic dosing follows the label's weight tiers. Confirm the measured weight.

• Error: wrong time zero. Arrival time is the wrong clock. It misclassifies the windows. Use LKW.
• Error: lytic without a CT. Hemorrhage on CT is an absolute stop. Rule it out before the bolus.
• Error: tPA and TNK mix-up. Stroke tenecteplase is 0.25 mg/kg, maximum 25 mg. STEMI doses differ about twofold at each weight band. Write the drug, indication and mg on every order.
• Error: BP not controlled before lytic. Starting the lytic at ≥185/110 mm Hg. Treat the BP first, then bolus.
• Error: intensive BP lowering after EVT. Intensive SBP targets after successful EVT showed no benefit, and some showed harm. OPTIMAL-BP (below 140 mm Hg) and ENCHANTED2/MT (below 120 mm Hg) gave worse functional outcomes. BP-TARGET (100 to 129 mm Hg) was neutral. Avoid them unless another indication exists.
• Error: anchoring on mimics. Check glucose and LKW before accepting hypoglycemia or seizure as the cause.
• Error: bypassing the thrombectomy center. An LVO patient taken to a center without EVT loses the chance of thrombectomy. Ask medical direction early.