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Difficulty: MediumNeurosurgery

A resident is reviewing imaging studies and physical examination findings of patients with elevated intracranial pressure in the neurocritical care unit. Match each specific pattern of tissue displacement and associated clinical presentation with the correct brain herniation syndrome.

  • Medial aspect of the temporal lobe shifts over the tentorial edge, causing an ipsilateral fixed and dilated pupil along with contralateral hemiparesis.Uncal (lateral transtentorial) herniation
  • Cingulate gyrus is displaced horizontally beneath the falx cerebri, potentially causing contralateral lower extremity weakness due to arterial compression.Subfalcine (cingulate) herniation
  • Bilateral, symmetric downward movement of the diencephalon and midbrain, typically progressing from small reactive pupils to midposition fixed pupils and decorticate posturing.Central transtentorial herniation
  • Cerebellum moves superiorly through the tentorial notch, causing rapid midbrain compression, prominent obstructive hydrocephalus, and downward conjugate gaze.Upward cerebellar herniation

Answer

The presentations map directly to the respective anatomical boundaries breached: temporal lobe over tentorium is Uncal, cingulate beneath falx is Subfalcine, bilateral downward shift is Central, and upward cerebellar shift is Upward cerebellar herniation.
Correctly identifying herniation syndromes relies on mapping specific clinical deficits (like CN III palsy or ACA territory ischemia) to corresponding structural shifts within the rigid cranial vault. Each herniation pathway produces a highly stereotypic syndrome.

Step-by-Step Solution

1
Analyze the anatomical shift and cranial nerve/motor findings for the first description.
Temporal lobe shift with CN III palsy strongly indicates uncal herniation.
The uncus is the medial temporal lobe structure closest to the tentorial edge and the oculomotor nerve.
2
Evaluate the second description focusing on horizontal displacement beneath the falx.
Horizontal shift of the cingulate gyrus indicates subfalcine herniation, putting the ACA at risk.
The falx cerebri separates the cerebral hemispheres, and the cingulate gyrus is the most medial structure to herniate underneath it.
3
Assess the third description detailing bilateral, symmetric downward progression.
Symmetric diencephalon/midbrain downward shift points to central transtentorial herniation.
Unlike uncal herniation, central herniation lacks early focal lateralizing signs and presents with global rostrocaudal deterioration.
4
Examine the fourth description involving superior displacement and hydrocephalus.
Superior movement through the tentorial notch defines upward cerebellar herniation.
Mass effect in the posterior fossa pushes structures upwards against the tentorium, obstructing CSF flow at the aqueduct.

Key Concept

Brain herniation syndromes: anatomical pathways and distinct clinical manifestations.
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Topics

Neurosurgery

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