Transalar herniation

Last revised by Craig Hacking on 28 Apr 2020

Transalar (transsphenoidal) herniation describes herniation of brain matter in and around the middle cranial fossa across the greater sphenoid wing and can be ascending or descending. Compression of structures against the sphenoid bone results in symptoms.


Transalar herniation is not as common as the other types of brain herniation. It often occurs in combination with subfalcine and transtentorial herniation.

Descending transalar herniation

Descending transalar herniation occurs as a result of frontal lobe mass effect. There is posterior and inferior displacement of the posterior aspect of the frontal lobe orbital surface over the sphenoid wing. Small herniations involve only the orbital gyri, while larger herniations may include the gyrus rectus.

Posterior displacement of the frontal lobe can cause compression of the middle cerebral artery against the sphenoid ridge, resulting in MCA territory infarction

Ascending transalar herniation

Ascending transalar herniation is produced by middle cranial fossa or temporal lobe mass effect. There is displacement of the temporal lobe superiorly and anteriorly across the sphenoid ridge.

Superior displacement of the temporal lobe can compress the supraclinoid internal carotid artery against the anterior clinoid process and result in infarction of the anterior and middle cerebral artery territories.

See also

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