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Hypotensive Cerebral Infarction

KEY FACTS

TERMINOLOGY

• Hypotensive cerebral infarction (HCI)

○ Infarction resulting from insufficient cerebral blood flow

(CBF) to meet metabolic demands (low-flow state)

○ 2 types of border zone or watershed infarcts

– Border zone between major arterial territories

□ Typically at cortex, gray matter (GM)-white matter

(WM) junctions

– Border zone between perforating arteries

□ Typically in deep WM

IMAGING

• Best imaging tool

○ MR with DWI/ADC ± MR perfusion

• Cortical border zone

○ Between major arterial territories

○ Typically at GM-WM matter junctions

○ Hypodensity between vascular territories

• WM matter border zone

○ Between perforating arteries

○ Typically in deep WM (centrum semiovale)

○ ≥ 3 lesions

○ Linear AP orientation → string of pearls appearance

○ If unilateral, look for stenosis of major vessel

• Imaging recommendations

○ MR + GRE, DWI, MRA (both cervical, intracranial)

○ ± pMR (may show ↓ CBF to affected areas)

○ NECT, pCT, CTA if MR not available

○ CTA/DSA > MRA for determining total vs. near occlusion

of internal carotid artery

TOP DIFFERENTIAL DIAGNOSES

• Acute embolic cerebral infarction(s)

• Arteriosclerosis ("small vessel disease")

• Posterior reversible encephalopathy (PRES)

• Vasculitis

• Pseudolaminar necrosis (other causes, e.g., Reye, lupus,

etc.)

(Left) T1WI show 2 watershed

(WS) zones. External WS zones

are depicted in turquoise.

Yellow lines indicate internal

(deep white matter)

watershed zones between

perforating arteries and major

territorial vessels. (Right) Axial

gross pathology shows classic

external (cortical) watershed

infarcts ſt from cerebral

hypoperfusion. The patient

survived several days, allowing

for petechial hemorrhagic

transformation to occur.

(Left) Axial FLAIR MR in a

patient with transient global

hypoperfusion secondary to a

hypotensive episode shows

multifocal hyperintensities

along the cortical WS zone ſt.

Changes are most severe at

the confluence of the anterior

cerebral, posterior cerebral,

and middle cerebral artery

cortical vascular territories

﬇. (Right) DWI in the same

patient shows corresponding

areas of restricted diffusion in

the cortical WS zones

bilaterally ſt, most severe at

the trivascular confluence ﬇.

The diagnosis was hypotensive

WS cerebral infarctions.

Trauma, and Stroke

Brain: Pathology-Based Diagnoses: Malformations,

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