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The Best in FOAM Education

  • Samita Heslin, MD, MPH, MBA, MA

Identifying Large Vessel Occlusions in the ED

A 77 y/o F presents with new-onset global aphasia, dysarthria, R hemiplegia, R sided neglect, and R homonymous hemianopsia without R hemi-sensory defect. Her last known normal was 2 hours ago.

CTA/CTP showed sub-occlusive thrombus/embolus in the left middle cerebral artery with good distal flow. The blood volume map was normal; the mean transit time showed a large area of severely delayed blood flow.

After the patient received TPA, she was able to speak (but not fluently). She was following simple commands. Her R arm and leg strength had improved from 0/5 to 3/5.

The patient then went for a mechanical thrombectomy. Afterward, the patient’s language was intact without dysarthria and her R arm and leg strength had improved to 5/5.

Take Away #1

What is a large vessel occlusion (LVO)?

Acute blockage of the proximal vessels of the Circle of Willis (i.e. internal carotid artery, proximal posterior/anterior/middle cerebral artery, vertebral artery, or basilar artery)

Why is it important to identify an LVO?

46% of acute ischemic strokes are LVOs and they have 2x the morbidity and mortality of small vessel occlusions.

What’s the pathophysiology of an LVO?

There are a few different mechanisms that can cause LVOs:

  1. Cardioembolism

  2. Large vessel artheroembolism

  3. Occlusion at the primary site 2/2 atherosclerosis (ie ICA)

  4. Cryptogenic causes.

Take Away #2

Patient’s with LVOs will exhibit cortical signs. If your patient has one or more of the following cortical signs, consider an LVO (and consider calling neurosurgery immediately):

  • aphasia

  • neglect/hemiattention

  • homonymous hemianopsia

  • double simultaneous extinction

  • gaze deviation/preference

  • agraphithesia (inability to recognize writing on the skin purely by touch)

Take Away #3

Dense Vessel Signs on non-contrast CT: These are a focal increase in density of MCA/PCA/vertebral artery/basilar artery due to thromboembolic material in lumen.

CT Perfusion:

Irreversible Infarction: Matched area of decreased Cerebral Blood Volume (CBV) and increased Mean Transit Time (MTT)

Penumbra/Salvageable Tissue: Mis-matched area with normal normal and increased MTT

Take Away #4

Call Neurosurgery immediately for LVOs!

DAWN Trial (Nogueira et al., NEJM 2018):

Showed that 6-24 hrs after acute stroke, patients who had a mismatch between infarct and clinical deficit who received endovascular thrombectomy and standard care had better 90-day outcomes than those that just received standard care.

Los Angeles Motor Scale (Noorian et al., Stroke 2018):

A validated 3-item (facial droop, arm drift, and grip strength) pre-hospital screening tool for LVOs.


Samita Heslin, MD, MPH, MBA, MA is a current second year resident at Stony Brook Emergency Medicine. She can be found on Twitter @SamitaHeslin.


  • Lui, Y. W., et al. "Evaluation of CT perfusion in the setting of cerebral ischemia: patterns and pitfalls." American Journal of Neuroradiology 31.9 (2010): 1552-1563.

  • Nogueira, Raul G., et al. "Thrombectomy 6 to 24 hours after stroke with a mismatch between deficit and infarct." New England Journal of Medicine 378.1 (2018): 11-21.

  • Noorian, Ali Reza, et al. "Los Angeles Motor Scale to identify large vessel occlusion: prehospital validation and comparison with other screens." Stroke 49.3 (2018): 565-572.

  • Rennert, Robert C., et al. "Epidemiology, Natural History, and Clinical Presentation of Large Vessel Ischemic Stroke." Neurosurgery 85.suppl_1 (2019): S4-S8.

  • Vitt, Jeffrey R., Michael Trillanes, and Jesse Claude Hemphill. "Management of Blood Pressure During and After Recanalization Therapy for Acute Ischemic Stroke." Frontiers in neurology 10 (2019): 138.

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