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Difficulty: HardNeurosurgery

A neurosurgical team is evaluating several patients with elevated intracranial pressure and deteriorating neurologic status following severe traumatic brain injury. Match each specific brain herniation syndrome with its corresponding characteristic neuroimaging findings and clinical signs.

  • Uncal HerniationCT demonstrates obliteration of the ambient cistern; clinically manifests with an ipsilateral fixed, dilated pupil and potential contralateral hemiparesis.
  • Subfalcine HerniationCT reveals displacement of the cingulate gyrus across the midline; clinical presentation may include contralateral lower extremity weakness due to arterial compression.
  • Central HerniationCT shows diffuse downward displacement of the diencephalon and midbrain; clinically presents with early Cheyne-Stokes respirations and small, reactive pupils.
  • Tonsillar HerniationCT displays cerebellar structures descending through the foramen magnum; clinically characterized by Cushing triad and abrupt respiratory or cardiac arrest.

Answer

Uncal Herniation matches with ambient cistern obliteration and an ipsilateral blown pupil. Subfalcine Herniation matches with midline shift and potential leg weakness. Central Herniation matches with downward diencephalic shift and Cheyne-Stokes respirations. Tonsillar Herniation matches with foramen magnum descent and cardiorespiratory arrest.
Each herniation syndrome has specific anatomic and clinical correlates. The uncus compresses CN III (Uncal). The cingulate gyrus compresses the ACA under the falx (Subfalcine). The diencephalon causes central brainstem depression (Central). The cerebellar tonsils compress the medullary respiratory centers (Tonsillar).

Step-by-Step Solution

1
Analyze the clinical and radiologic signs for Uncal Herniation.
Identified by ambient cistern obliteration on CT, compression of the ipsilateral oculomotor nerve (CN III) causing a fixed, dilated pupil, and cerebral peduncle compression causing contralateral hemiparesis.
The medial temporal lobe (uncus) herniates downward over the tentorium cerebelli, pressing on adjacent midbrain structures.
2
Evaluate the presentation for Subfalcine Herniation.
Identified by the cingulate gyrus shifting under the falx cerebri on CT. It can compress the anterior cerebral artery (ACA), causing contralateral lower extremity weakness.
Increased unilateral supratentorial pressure pushes the medial aspect of the frontal lobe across the midline.
3
Identify the signs of Central Herniation.
Characterized by symmetric downward displacement of the diencephalon, leading to early Cheyne-Stokes respirations and small, reactive pupils due to initial diencephalic compromise.
Diffuse mass effect pushes the entire brainstem structure caudally through the tentorial notch.
4
Determine the features of Tonsillar Herniation.
Characterized by cerebellar tonsils descending through the foramen magnum on CT, leading to Cushing triad and fatal medullary compression (respiratory arrest).
Increased posterior fossa pressure or massive supratentorial pressure forces cerebellar structures into the rigid cervical canal.

Key Concept

Brain Herniation Syndromes
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Topics

Neurosurgery

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