Acute Cerebral Ischemia-Infarction

KEY FACTS

TERMINOLOGY

• Interrupted blood flow to brain resulting in cerebral

ischemia/infarction with variable neurologic deficit

IMAGING

• Major artery (territorial) infarct

○ Generally wedge-shaped; both GM and WM involved

• Embolic infarcts

○ Often focal/small, at GM-WM interface

• NECT

○ Hyperdense vessel = clot (dense middle cerebral artery

sign)

○ Loss of GM-WM distinction in first 3 hours (50-70%)

– Insular-ribbon sign: GM-WM interface lost

– Disappearing basal ganglia sign

○ Calcified embolus

– Do not miss this (high risk of recurrent stroke)

• CTA: Excellent for major vessel occlusions

• pCT: CBF/CBV "mismatch" estimates penumbra

• MR

○ Parenchymal ± intraarterial FLAIR hyperintensity

○ ↑ intensity on DWI with corresponding ↓ on apparent

diffusion coefficient

○ ↓ cerebral blood flow (CBF), cerebral blood volume on

perfusion MR

TOP DIFFERENTIAL DIAGNOSES

• Normal vessel (MCA normally slightly hyperdense to brain)

• Nonvascular causes of hypodense brain (neoplasm,

cerebritis, etc.)

PATHOLOGY

• Severely ischemic core; CBF < (6-8 cm³)/(100 g/min)

• Peripheral penumbra; CBF between (10-20 cm³)/(100

g/min)

CLINICAL ISSUES

• 2nd most common cause of death worldwide

• Rx: IV thrombolysis (< 3 hours of onset), clot retrieval

(Left) Coronal graphic

illustrates left M1 occlusion.

Proximal occlusion ﬊ affects

the entire middle cerebral

artery (MCA) territory,

including the basal ganglia

(perfused by lenticulostriate

arteries ﬈). Acute ischemia is

often identified by subtle loss

of the gray-white interfaces

with blurring of the basal

ganglia and an insular-ribbon

sign on the initial CT. (Right)

NECT scan in a 46-year-old

man shows a very dense left

MCA ſt compared with the

normal minimally hyperdense

right MCA ﬇.

(Left) Coronal maximal

intensity projection view of

the CTA in the same patient

shows a proximal left MCA

occlusion ſt. Minimal filling of

the distal MCA branches ﬇ is

occurring via collaterals from

the anterior cerebral artery

and posterior cerebral artery.

(Right) Axial CT perfusion

shows decreased cerebral

blood flow in the left MCA

distribution ſt.

Trauma, and Stroke

Brain: Pathology-Based Diagnoses: Malformations,

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