Neuroanatomy Atlas in Clinical Context

72 CHAPTER 4 / MENINGES, CISTERNS, VENTRICLES, AND RELATED HEMORRHAGES

A

B

Anterior horn of lateral ventricle

Anterior horn

Third ventricle

Atrium of lateral ventricle

Posterior horn of lateral ventricle

C

Temporal horn of lateral ventricle

Basilar pons

Tegmentum of pons

Fourth ventricle

Cerebellum

D

Pons – medulla junction

Fourth ventricle

Lateral recess of fourth ventricle

Cerebellum

4-12 Examples of hemorrhage occupying portions of the ventric ular system ( intraventricular hemorrhage ). In these CT images, blood appears white within the ventricles. Consequently, the shape of the ventricular system is outlined by the white area (these are sometimes called casts ) and the specific portion of the ventricular system is correspondingly identified. Note blood in the anterior horn, atrium, and posterior horn of the lateral ventricles ( A , B ) and blood clearly outlining the shape of the third ventricle ( B ). Blood also clearly outlines central portions of the fourth ventricle ( C ) and caudal portions of the fourth ventricle ( D ), including an extension of blood into the left lateral recess of the fourth ventricle ( D ). In addition to these images, Figure 4-13C on the facing page shows blood in the most inferior portions of the third ventricle.

The presence of blood within the ventricular system occurs in about 25% of cases with ruptured aneurysm. The most common aneurysm sites, and point at which blood may enter the ventricular system upon rupture, are as follows: the distal posterior inferior cerebellar artery, through the roof of the fourth ventricle or foramen of Luschka (fourth ventricle); the basilar tip, through the floor of the third ventricle (third ventricle); at the junction of the anterior communicating and anterior cerebral arteries, through the lamina terminalis (third ventricle); or from this same location into the anterior horn of the lateral ventricle. Blood may also be found within the ventricles following traumatic brain injury , bleeding from or rupture of an arteriovenous malformation ( AVM ) in certain locations, and bleeding from tumors, especially those located in the brain parenchyma or in the ventricular system. Copyright © Wolters Kluwer, Inc. Unauthorized reproduction of the content is prohibited. 2024