Head Trauma

Question 1

Uncal (tentorial) herniation

Answer 1

Occurs w/ mass lesions of the middle cranial fossa. Uncus herniated down into the posterior fossa b/w the rostral brainstem and the tentorium cerebelli. Typically, CN3 is entrapped, resulting in a unilateral dilated pupil. As herniation progresses, hemiparesis and alteration of consciousness can occur, with eventual brainstme signs and changes in resp. patterns. In later stages, death is imminent.

Question 2

Cingulate herniation

Answer 2

Occurs when there is a mass lesion, usually in the frontal lobes, causing displacement of the cingulate gyrus across the falx cerebri in the frontal midlign. No specific signs of herniation, but frequently seen on CT.

Question 3

Central (transtentorial) herniation

Answer 3

Occurs when a large supratentorial mass causes downward displacement of the diencephalon and midbrian through the tentorial opening. Findings include altered consciousness, bilaterela small reactive puils, and decorticate posturing followed by decerebrate posturing. Cheynes-stokes respirations common, imply bilateral cerebral dysfunction, not specific.

Question 4

Tonsillar herniation

Answer 4

occurs when a posterior fossa mass causes herniation of th ecerebllar tonsils through the foramen magnum. Compresses the medulla, resulting in eventual respiratory arrest. Usually quickly fatal.