Neurology · Topic 1 of 23

Acute Ischemic Stroke

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Neurology · cerebrovascular

Acute Ischemic Stroke

Time is brain: thrombolysis within 4.5 hours of last known well, thrombectomy for large-vessel occlusion within 6 hours (selected patients up to 24). BP under 185/110 first.

01 · Lytics windowThrombolysis within 4.5 h of last known well

02 · Before lyticsBP under 185/110, then under 180/105 for 24 h

03 · ThrombectomyLVO thrombectomy ≤ 6 h, selected patients to 24 h

Why it happens

Severe ischemia infarcts in 15–30 minutes; collateral-fed penumbra can be saved

Diagnosis: first minutes

Exclude bleeding and hypoglycemia, then look for a large-vessel occlusion

Windows run from last known well, not from discovery

Woke with deficits: last known well = bedtime

Noncontrast head CT (or MRI) to exclude hemorrhage

Fingerstick glucose: must be above 50 mg/dL before lytics

Suspected large-vessel occlusion: order CTA

Don't wait for CTA or perfusion imaging to give lytics don't delay

Never delay CTA to wait for a creatinine. A baseline ECG and troponin are recommended but must not delay thrombolysis or thrombectomy. Mimics: seizure with postictal (Todd) paralysis, hypoglycemia, hemiplegic migraine, CNS infection, functional disorders — thrombolysis given to a mimic carries about a 0.5% brain hemorrhage risk.

Red flags: hold thrombolysis

Classic exclusions — 2026 moved several to case-by-case with the stroke team

Any intracranial hemorrhage no lytics

Ischemic stroke or severe head trauma within 3 months no lytics

Intracranial or spinal surgery within 3 months no lytics

Active internal bleeding, or GI bleeding within 21 days no lytics

Platelets under 100,000/mcL or INR over 1.7 no lytics

DOAC dose within 48 h, unless anticoagulant tests are normal stroke team

Mild non-disabling deficit: DAPT, not lytics give DAPT

Summaries describe recent DOAC use as no longer an absolute bar under the 2026 guideline, but its exact DOAC wording could not be confirmed from an open source; the board-safe answer remains the 48-hour rule. A disabling deficit gets lytics regardless of NIHSS.

Treatment

Every minute to reperfusion costs brain

First moves, in order

Fix last known wellnot the time the patient was found

→

Noncontrast CT and fingerstick glucoseno hemorrhage; glucose above 50 mg/dL

→

Lower BP under 185/110before any thrombolytic

→

Give the thrombolytic within 4.5 hdisabling deficit; don't wait for CTA

→

CTA for large-vessel occlusionthrombectomy candidate up to 24 h

Thrombolysis≤ 4.5 h, disabling

Tenecteplase 0.25 mg/kg bolus (max 25 mg) Alteplase 0.9 mg/kg (max 90 mg)

Tenecteplase or alteplase — equally recommended (2026)

Alteplase: 10% bolus over 1 min, rest over 60 min

Thrombectomylarge-vessel occlusion

ICA or M1 occlusion, NIHSS ≥ 6, within 6 h

Selected patients 6–24 h, including ASPECTS 3–5

Bothlytics, then thrombectomy

Eligible for both: give lytics and proceed to thrombectomy

Never skip lytics for thrombectomy alone

Minor strokenon-disabling

Aspirin + clopidogrel × 21 days

Noncardioembolic, no lytics: DAPT 21 days, then one agent

2026: NIHSS 4–5 atherosclerotic too, start up to 72 h

Aspirinno lytics given

Aspirin 81–325 mg

Aspirin within 48 hours if no thrombolysis

After lytics: no antiplatelet or anticoagulant for 24 h

Extended windows and other drugs

Thrombolysis 4.5–9 h may be reasonableor within 9 h of the midpoint of sleep, with salvageable penumbra on automated perfusion imaging or DWI–FLAIR mismatch

Basilar occlusion: thrombectomy within 24 hstrongly recommended with NIHSS ≥ 10, prestroke mRS 0–1, PC-ASPECTS ≥ 6

AF-related stroke: early anticoagulation only in selected casesreasonable for carefully selected milder strokes; otherwise avoided for hemorrhagic transformation risk

No adjunctive antithrombotics with lytics or thrombectomyargatroban, eptifibatide, tirofiban show no benefit and are not recommended

Classic DAPT criteria (2021 secondary-prevention guideline): NIHSS ≤ 3 or high-risk TIA (ABCD2 ≥ 4), started within 24 hours.

Blood pressure targets

The target depends on whether the patient got reperfusion

Before lytics: lower BP to under 185/110 mmHg

After lytics: keep BP under 180/105 mmHg for 24 h

Don't target SBP under 140: no benefit, harm after thrombectomy not under 140

No reperfusion: treat only BP ≥ 220/120 mmHg

No reperfusion: lower BP about 15% over the first 24 h

The warning against intensive lowering (SBP under 140) is new in the 2026 guideline; the 185/110 and 180/105 thresholds are unchanged. Without reperfusion, another end-organ indication also justifies treating BP.

Supportive care

Glucose target 140–180 mg/dL; treat under 60

No intensive insulin to 80–130: more severe hypoglycemia no tight control

Oxygen only for hypoxia, to keep SpO₂ above 94%

Temperature over 38 °C: antipyretic and find the source

Swallow screen before any food, fluid or oral medication NPO until screened

Can't swallow safely: enteral nutrition within 7 days

Immobile: intermittent pneumatic compression; LMWH may be added

Oxygen: 2026 AHA/ASA, Class 2b. The 2018 BMJ panel would not start it at SpO₂ ≥ 93% and generally not at 90–92% (see Oxygen Therapy).

Complications: swelling

Large infarcts swell most at 48–72 hours

Malignant MCA edema with deterioration: decompressive craniectomy neurosurgery

Craniectomy saves lives; benefit less certain at age 60 or older

Swollen cerebellar infarct: suboccipital decompressive craniectomy neurosurgery

Cerebellar swelling: ventriculostomy alone risks upward herniation

IV thrombolysis or thrombectomy?

	IV thrombolysis	Endovascular thrombectomy
Who	Any eligible patient with a disabling deficit	Large-vessel occlusion (ICA, M1, basilar)
Standard window	≤ 4.5 h from last known well	≤ 6 h; selected patients 6–24 h
Extended window	4.5–9 h with perfusion or DWI–FLAIR mismatch	Basilar occlusion up to 24 h
Imaging before treatment	Noncontrast CT (no CTA needed)	CTA ± perfusion imaging
Severity	Disabling, regardless of NIHSS	NIHSS ≥ 6 (anterior), ≥ 10 (basilar)

Pearl

Last known well, not found down, starts the clock — and every minute to reperfusion costs brain.

Sources · 2026 Guideline for the Early Management of Acute Ischemic Stroke (AHA/ASA) · 2026 Guideline Update: Early Management of AIS (emDocs) · AHA/ASA AIS Guideline Spotlight (Guideline Central, 2026) · Guidelines for the Management of AIS Published (Practical Neurology, 2026) · Ischemic Stroke (Merck Manual Professional, 2026) · Blood pressure management in stroke: comparative guideline review (Hypertens Res 2026) · HelixTalk 196: the 2026 AIS guidelines · Cerebral and cerebellar infarction with swelling (AHA/ASA, 2014) · 2021 AHA/ASA Guideline for the Prevention of Stroke in Patients With Stroke and TIA · AHA/ASA Early Management of Acute Ischemic Stroke 2026, Guideline Central pocket guide (recommendation excerpt) · Siemieniuk RAC et al. Oxygen therapy for acutely ill medical patients: a clinical practice guideline. BMJ 2018;363:k4169 · Follow your institution's protocols.