Subcortical Injury


KEY FACTS

Terminology

  • Subcortical injury (SCI): Deep diffuse axonal injury lesions of brainstem, basal ganglia, thalamus, and regions around 3rd ventricle

  • Intraventricular hemorrhage (IVH): Hemorrhage within ventricular system

  • Choroid hemorrhage (CH): Hemorrhage localized to choroidal plexus

Imaging

  • SCI: FLAIR most sensitive → hyperintense foci

  • IVH: Hyperdense intraventricular blood; fluid-heme level common

  • CH: Localized hyperdense choroidal hemorrhage

Top Differential Diagnoses

  • SCI: Cavernous malformation, lacunar infarcts, small-vessel ischemia

  • IVH: None

  • CH: Normal calcification may mask small hemorrhages

Pathology

  • SCI: Most commonly induced by shear-strain forces that disrupt penetrating &/or choroidal vessels

  • IVH: Disruption of subependymal veins

  • CH: Traumatic shear forces damage to choroid tissue

Clinical Issues

  • SCI: Profound neurologic deficits

  • IVH: Obtundation, seizures

  • CH: Can lead to IVH

Diagnostic Checklist

  • Delayed development of deep lesions common

    • Initial scan may show only diffuse brain swelling

    • Focal lesions often appear 24-48 hours later

  • Remember: The deeper the lesion, the more severe the injury

Initial axial NECT in a 17-year-old girl involved in a high-speed MVA demonstrated only diffuse brain swelling (not shown). Because of persisting low GCS, repeat scan was obtained 24 hours later, showing a focal midbrain hemorrhage
.

More cephalad scan shows a punctate hemorrhage in the right fornix
and in the 3rd
and lateral ventricles
. The patient expired 1 week later. The presence of deep lesions and intraventricular hemorrhage indicate severe subcortical injury.

Axial NECT in a patient with subcortical injury shows a hyperdense choroidal hemorrhage within choroid plexus substance of both ventricles
. Note the subarachnoid hemorrhage
, corpus callosum diffuse axonal injury (DAI)
, left caudate hemorrhagic DAI
, and a ventriculostomy tube tip
.

Axial T2WI MR in the same patient shows hypointense hemorrhages distending the choroid plexi
. A left caudate hemorrhagic DAI
is again seen.

TERMINOLOGY

Abbreviations

  • Subcortical injury (SCI)

Definitions

  • Traumatic lesions of brainstem (BS), basal ganglia (BG), thalamus, and ventricles, composed of

    • Deep diffuse axonal injury (DAI)-type SCI lesions

    • Intraventricular hemorrhage (IVH)

    • Choroid hemorrhage (CH)

IMAGING

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