Neuroanatomy Atlas in Clinical Context

CISTERNS AND SUBARACHNOID HEMORRHAGE 67

A

B

Subdural hemorrhage

Lamina terminalis cistern

Supraoptic recess

Sylvian cistern

Interpeduncular cistern

Crural cistern

Temporal horn

Blood on insular cortex

Ambient cistern

Midbrain Blood on tentorium cerebelli

Cerebellum

Quadrigeminal cistern

C

D

Third ventricle

Lamina terminalis cistern

Sylvian cistern

Blood on insula

Interpeduncular cistern

Crural cistern

Cerebello pontine cistern

Ambient cistern

Cerebellum

Rostral part of fourth ventricle

Blood on tentorium cerebelli

4-7 Blood in the subarachnoid space and cisterns ( subarachnoid hemorrhage ). In these CT examples, blood occupies the sub arachnoid space and cisterns, outlining these areas in various shades of white. Consequently, the shape of the cisterns is indicated by the config uration of the white area, the white area representing blood. Around the base of the brain ( A ), it is easy to identify the cisterns related to the midbrain, the supraoptic recess , which is devoid of blood, and blood extending laterally into the Sylvian cistern . In some cases ( B ), subdural hemorrhage may penetrate the arachnoid membrane and result in blood infiltrating between gyri, such as this example with blood on the cortex of the insula. In C , the blood is located around the mid brain ( crural and ambient cisterns ), extends into the Sylvian cistern , and into the cistern of the lamina terminalis . The sharp interface between the lamina terminalis cistern (containing blood) and the third ventricle (devoid of blood) represents the position of the lamina terminalis . In D , blood is located in cisterns around the pons but avoids the rostral part of the fourth ventricle. Also note the clearly enlarged temporal horn of

the lateral ventricle in D ; enlargement of this particular part of the ven tricle is indicative of increased pressure within the ventricular system. In fact, the presence of subarachnoid blood in the cisterns is in frank contrast to the stark and total lack of blood in the ventricles ( A – D ). Subarachnoid hemorrhage (SAH ) is always a serious medical event. In the case of SAH resulting from aneurysm rupture (about 75%–80% of all spontaneous cases), 10%–15% die prior to receiving medical attention and about 20% after hospital admission; about 30% have permanent disability; approximately 30% who survive may have mod erate to severe deficits, particularly depression and cognitive compro mise. Other comparable statistics indicate that about 45% to 50% die within the first 2–4 weeks and about 30% have moderate to severe deficits. More than one-third of patients who have aneurysms surgically clipped or endovascularly coiled have a poor functional outcome at 10 years. Compare these images with the locations of some of the com parable cisterns as seen in Figure 4-6. Images A–D are CT.

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