infratentorial. Supratentorial is above the tentorial membrane and infratentorial is below the tentorial membrane. If you will look at the screen you will see that the tentorial membrane basically separates the cerebrum and the cerebellum and brain stem. There are four types of supratentorial herniations. You can see them clearly in the picture on your screen. An uncal herniation occurs when a portion of the gyri of the cerebrum moves through the tentorial notch and compresses the third cranial nerve and the mesencephalon. Manifestations include decreased LOC, dilated ipsilateral pupil first, then the contralateral pupil, decorticate or decerebrate posturing, and Cheyne stokes respirations. A central herniation occurs when the diencephalon is forced down and through the tentorial notch. These individuals lose consciousness quickly, develop apnea, initially have small reactive pupils and later they dilate. Decorticate posturing or decerebrate posturing becomes evident. A cingulate gyrus herniation is characterized by the movement of the cingulate gyrus under the falx cerebri. Instead of moving down, it moves laterally. This herniation is labeled number 3 in the picture.
Transcalvarial herniation is characterized by brain tissue which moves through an opening in the skull. The opening may be a result of a skull fracture or a surgical opening. The main infratentorial herniation is the cerebellar tonsillar herniation, the most common type of brain herniation. It is characterized by the downward movement of the cerebellum through the foramen magnum. Clinical manifestations include a stiff neck, a decreased LOC, respiratory abnormalities, and pulse variations.
- Fall '15
- Intracranial pressure, Traumatic brain injury, cerebral blood flow, Brain herniation, Cerebral perfusion pressure