Lawrence

Anyone can see the bright spot on diffusion—what sets you apart is if you can tell them why it’s there! Can you tell a stroke’s etiology from its appearance on MRI? Main stroke types: Artery to artery embolism —Vulnerable plaque ruptures & causes clot formation —Occludes the artery & distal blood flow —Makes a wedge shape Distal hypoperfusion: —At the border zones —Remember borderzones almost look like a fancy letter H for Hypoperfusion = two vertical lines (ant, internal watershed) that have curls at each end (ant & post external watersheds) Vasculitis —Inflammation ofvessel wall —Idiopathic, autoimmune, or infectious —Remember: Vascu-LIGHT-us = tons of little regions LIGHT up on DWI —Remember Vascu-LITE-us = usually in LITE vessels or small vessel territories Impingement on perforators: —Large vessel plaque covers opening of small perforator in its wall —Perforators affect the Ps = pons, putamen (lenticulostriate) Small vessel dz —Many different pathologies that cause occlusion of small, unnamed vessels —Remember: Small & subcortical both start w/—tend to be subcortical Cardioembolic —Emboli from heart stasis or vegetations —Remember: Emboli & everywhere both start w/E = emboli go everywhere So now you know how different etiologies have different distributions on MRI. Remember, catching a stroke on DWI isn’t the end of your job—it’s the beginning!

Can you get the diagnosis when it comes to carotid stenosis?   Having some confusion about the strokes you see w/ICA occlusion?   Why are there so many different patterns of infarcts w/ICA occlusion/stenosis?   There are 5 main infarct patterns—and they reflect the different types of disruption to flow you get w/carotid disease: artery to artery emboli, embolic shower, & hypoperfusion   Here’s what you see: 1.  Territorial infarction w/cortical or subcortical involvement --From artery-to-artery or distal embolism. --More than one occlusion indicates more proximal arterial dz   2.  Subcortical infarction --When ICA, MCA, & ACA perforating deep arteries are occluded --Can be from MCA occlusion w/good collaterals or emboli directly to deep perforating arteries   3. Combined territorial & smaller cortical and/or subcortical infarcts --From partial embolism fragmentation or emboli shower of various sizes   4. Multiple small infarcts in the distal territories of the MCA & ACA --If in more than one arterial territory, it’s suggestive of cardio-embolism --If single arterial territory, it’s from a parent artery steno-occlusive lesion   5. Watershed infarctions. Two types: --External border-zone (located between the cortical territories of ACA, MCA, & PCA) --Internal borderzone (between the deep & superficial networks of MCA & ACA) --Traditionally thought from low-flow, but emboli are often a cause --Hemodynamic mechanism may be more important in internal borderzone infarcts & embolism in external borderzone infarcts   Now you can draw the right conclusions with ICA occlusions!

Feeling stuck in the middle when it comes to middle cerebral artery infarcts? It may be only one vessel, but you can get many different infarct patterns & symptoms depending on where it’s occluded! Here’s what you NEED to know: FIVE MAIN INFARCT PATTERNS 1. Occlusion of the MCA stem or proximal M1 segment before the lenticulostriate origin --Involves deep & superficial territories --Weakness is usually severe. Face, arm, & leg are similarly affected --Remember: Whole MCA occlusion = Whole hemiparesis 2. Lenticulostriate artery (LSA) Infarcts --Involves deep territory --Hemiparesis, hemisensory, occasional aphasia & visual hallucinations --Remember: LSA stands for Limp (weakness), Sensory deficits, & occasional Aphasia 3. Distal M1 segment occlusion after the LSA origin --Involves whole superficial MCA territory --Sometimes weakness in face & arm > leg (brachiofacial hemiparesis) --Remember: Distal MCA occlusion can somewhat spare the DISTAL most extremity (leg) 4. Superior Division occlusion --Uncommon bc superior trunk is so short --Involves frontal & anterior parietal lobe, including pre- & post-central gyri --Prominent faciobrachial hemiparesis w/matching hemisensory --Rarely visual field defect --Remember: Superior is more = more pronounced motor deficits than inferior division 5. Inferior Division occlusion --Involves temporal gyri & superior/inferior parietal lobule --Facial brachial weakness is more mild than w/superior division --Common visual field defect (homonymous hemianopia or upper quadrantopia) --Remember: Inferior is less, so motor deficits are less pronounced --Remember: Inferior starts w/the letter “I” = “eye” so visual field deficits Hopefully now your reports won’t middling when it comes to middle cerebral artery infarcts!