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:
Cardioembolism
Large vessel artheroembolism
Occlusion at the primary site 2/2 atherosclerosis (ie ICA)
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.
Reference(s):
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.
Edited by Bassam Zahid, MD