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Lacunar Infarction


KEY FACTS

Terminology

  • Small, deep cerebral infarcts located in basal ganglia and thalamus, pons, or cerebral white matter (WM), ≤ 15 mm

Imaging

  • Commonly deep gray nuclei, especially putamen, thalamus, caudate nuclei; internal capsule, pons

    • Other locations include deep and periventricular WM

  • Range in size from microscopic to 15 mm

  • Because of small size, most acute lacunar infarcts are not seen on CTs

  • Acute: T2/FLAIR increased signal

  • Chronic: FLAIR central low signal with increased peripheral signal (gliosis)

  • DWI: Restricted diffusion (hyperintense) if acute/subacute

    • May show small lesions otherwise undetectable

  • Prominent perivascular spaces are main imaging differential diagnosis

Pathology

  • Embolic, atheromatous, or thrombotic lesions in long, single-penetrating-end arterioles supplying deep cerebral gray matter

  • Size of lacunar infarct depends on level of occlusion and anatomy of affected vessel

Clinical Issues

  • Many different presentations, depending on size, location, number

  • Most lacunar infarctions are clinically “silent,” often subtle neurological deficits that may go unnoticed by patient and physician

  • Typical risk factors for cerebrovascular disease: Hypertension, diabetes, smoking history, obesity, hypercholesterolemia, etc.

  • Lacunar infarcts account for up to 25% of all strokes

  • Lacunar stroke is most common stroke subtype associated with vascular dementia

Axial graphic illustrates numerous bilateral lacunar infarcts within the thalami
and basal ganglia
, the most common locations. Also shown are prominent perivascular (Virchow-Robin) spaces
, a common normal variant.

Axial FLAIR MR shows multiple chronic lacunar infarcts in the periventricular white matter
with central hypointense encephalomalacia and mild peripheral hyperintense gliosis in a patient with chronic hypertension. Note the hyperintensity
related to chronic small vessel ischemia.

Axial DWI MR shows focal diffusion hyperintensity
related to an acute lacunar infarct in the pons, a common location for lacunar infarcts. Risk factors for lacunar infarcts include hypertension, diabetes, smoking history, obesity, and hypercholesterolemia.

Axial FLAIR MR shows a chronic lacunar infarct in the right thalamus
with central encephalomalacia and mild peripheral gliosis. The surrounding gliosis and typical location can help differentiate a chronic lacunar infarct from a perivascular space.

TERMINOLOGY

Synonyms

  • Lacunar infarction (LI), lacunar stroke

  • “Lacunes”

Definitions

  • Small, deep cerebral infarcts typically located in basal ganglia (BG) and thalamus, pons, or cerebral white matter (WM), ≤ 15 mm in size

  • From Latin word “lacuna,” meaning hole

    • Used to describe small focus of encephalomalacia

  • “L'état lacunaire” or “lacunar state” = multifocal BG lacunar infarcts with surrounding gliosis

IMAGING

General Features

  • Best diagnostic clue

    • Small, well-circumscribed areas of parenchymal abnormality (encephalomalacia) in BG, thalamus, WM

  • Location

    • Commonly deep gray nuclei, especially putamen, thalamus, caudate nuclei; internal capsule, pons

    • Can be in other locations

      • –

        Cerebral WM in patients > 65 years

      • –

        Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) characteristically has subcortical lacunar infarcts

  • Size

    • Commonly 3 mm to 15 mm

    • Majority < 8 mm

  • Morphology

    • Typically round or ovoid

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