Subacute Cerebral Infarction

KEY FACTS

TERMINOLOGY

• Subacute infarction ~ 2-14 days following initial ischemic

event

IMAGING

• Best diagnostic clue: Gyral edema and enhancement within

basal ganglia and cortex

• Typically wedge-shaped abnormality involving gray and

white matter within vascular distribution

• Hemorrhagic transformation of initially ischemic infarction

occurs in 20-25% of middle cerebral artery occlusions,

usually by 48-72 h

• "2-2-2" rule = enhancement begins at 2 days, peaks at 2

weeks, disappears by 2 months

• MRS: ↑ lactate, ↓ NAA within infarcted tissue

• DWI:  ↑ diffusion restriction, ↓ ADC initially, reversing as it

proceeds into/through subacute stage

• "Fogging" effect = normal T2WI with striking enhancement

on T1WI C+ 1-2 weeks following ictus

TOP DIFFERENTIAL DIAGNOSES

• Neoplasm

• Venous infarction

• Encephalitis/cerebritis

CLINICAL ISSUES

• Acute-onset focal neurologic deficit

• Elderly patient with typical risk factors: Hypertension,

diabetes, smoking history, obesity, hypercholesterolemia

• 1st month after infarction, mortality predominantly from

neurologic complications; 1:4 die of recurrent stroke event

• Acute anticoagulation after 1st infarction reduces mortality

DIAGNOSTIC CHECKLIST

• Enhancement is key to defining subacute stage of cerebral

infarction

• Subacute ischemia often mimics neoplasm

○ Recommend short-term follow-up to ensure expected

course of evolution

(Left) Axial CT obtained 48 h

after initial onset of weakness

and speech difficulties shows

the classic appearance of an

early subacute cerebral

infarct. Note the wedgeshaped, low-density area ſt

involving both the gray and

white matter in the left middle

cerebral artery distribution.

(Right) Axial FLAIR MR in a 58-

year-old man 1 week after

onset of visual changes shows

classic imaging of a subacute

infarct with hyperintensity in

the cortex and subcortical WM

of the occipital lobe ﬇ in a

posterior cerebral artery (PCA)

distribution.

(Left) Axial DWI in the same

patient shows hyperintensity

within the left PCA

distribution. The

hyperintensity represents a

combination of true diffusion

restriction and T2 shine

through. (Right) Axial T1 C+

MR in the same patient shows

gyriform enhancement along

the cortex of the occipital lobe

﬇. This enhancement may be

seen as early as 2 days and

may last up to 2 months after

the patient's initial ischemic

event. Without clinical history,

imaging may mimic a tumor,

venous infarct, or cerebritis.

Brain: Pathology-Based Diagnoses: Malformations,

Trauma, and Stroke

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