uncal herniation

uncal herniation

[ung′kəl]

Etymology: L, uncus, hook, hernia, rupture

a condition in which the medial part of the temporal lobe protrudes over the tentorial edge as a result of increased intracranial pressure. If uncorrected, the progressive disorder causes pressure on the brainstem after first impinging on the third cranial nerve. A dilated pupil on the side of the herniation is a diagnostic sign of the disorder.

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herniation

abnormal protrusion of an organ or other body structure through a defect or natural opening in a covering membrane, muscle or bone. See also hernia and individual anatomical sites for hernia.

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nucleus pulposus herniation

rupture or prolapse of the nucleus pulposus into the spinal canal, or against the spinal cord. See also intervertebral disk disease.

transtentorial herniation

downward displacement (caudal transtentorial herniation; uncal herniation) of the medial brain structures through the tentorial notch by a supratentorial mass, exerting pressure on the underlying structures, including the brainstem.

uncal herniation

transtentorial herniation.

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uncal herniation

Brain herniation, herniation syndrome, transtentorial herniation Neurology A condition in which the uncus–the anterior hooked end of the parahippocampal gyrus on the basomedial surface of the temporal lobe of the brain is displaced due to ↑ intracranial causing progressive brain and brainstem damage Etiology Cerebral edema due to head injury, space-occupying lesions–primary and metastatic brain tumors or other lesions within the skull, bacterial meningitis; UH compresses cranial nerve III, the midbrain, and the posterior cerebral artery, leading to coma and respiratory arrest. Cf Cerebellar herniation.