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Intracranial Herniation Syndromes


KEY FACTS

Terminology

  • Brain displaced from 1 compartment into another

Imaging

  • Subfalcine herniation

    • Cingulate gyrus displaced under falx

    • Lateral ventricle compressed/displaced across midline

    • Contralateral ventricle dilated

  • Unilateral descending transtentorial herniation (DTH)

    • Temporal lobe displaced medially into incisura

    • Encroaches on, then effaces suprasellar cistern

  • Bilateral DTH (“central herniation”)

    • Both temporal lobes herniated into tentorial hiatus

    • Diencephalon crushed against skull base

    • Suprasellar cistern, cerebrospinal fluid spaces obliterated

    • Midbrain/pons displaced inferiorly

  • Ascending transtentorial herniation

    • Cerebellum displaced up through incisura

    • Quadrigeminal cistern, tectum flattened

  • Tonsillar herniation

    • Tonsils impacted into foramen magnum

    • Cisterna magna obliterated

  • Transalar herniation

    • Ascending (middle fossa mass) or descending (frontal mass)

    • Brain, middle cranial artery herniated up/over sphenoid

  • Transdural/transcranial herniation

    • Brain extruded through dural/skull defect

Top Differential Diagnoses

  • Intracranial hypotension

Clinical Issues

  • Uncal herniation: Ipsilateral pupil-involving CN3 palsy, contralateral hemiparesis

  • Progressive bilateral (“central”) herniation: Decorticate → decerebrate → death

Diagnostic Checklist

  • DWI, T2* for ischemic, hemorrhagic complications

Axial gross pathology section through the ventricles in a patient who died of multiple traumatic injuries shows findings of severe subfalcine herniation. Ventricles are displaced across the midline, and the cingulate gyrus
is herniated under the falx. Left PCA infarct
occurred secondary to descending transtentorial herniation.

(Courtesy R. Hewlett, MD.)

Axial NECT in severe trauma shows subfalcine herniation
with severely compressed left
and slightly dilated right lateral ventricle
.

Submentovertex gross pathology shows unilateral descending transtentorial herniation. Undersurface of herniated temporal lobe shows “grooving”
from impaction against the tentorium. Note the 3rd nerve compression
and midbrain displacement.

(Courtesy R. Hewlett, MD.)

Axial T2WI shows mixed-age subdural hematomas
causing typical uncal herniation. The herniating uncus
, hippocampus
compress, displace the midbrain against the opposite edge of the tentorium
.

TERMINOLOGY

Abbreviations

  • Subfalcine herniation (SFH)

  • Descending transtentorial herniation (DTH)

Definitions

  • Herniation of brain from 1 compartment (normally separated by calvarial &/or dural boundaries) to another

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