Hydrocephalus including lateral and third ventricles

1-This means obstruction at the level of duct of sylvius.

Incomplete canalization of the aqueduct of sylvius

Congenitally obstructed aqueduct

Ballooned third ventricle with normal sized or attenuated fourth ventricle.

2-It results in dilatation of both lateral ventricles and the third one with normal sized or attenuated fourth ventricle.

3-In this type of hydrocephalus, the third ventricle appears to be ballooned.

4-Causes:

-Congenital aqueductal stenosis which is the most common cause in children and is due to x-linked recessive disorder.

-Inflammatory due to encephalitis.

-Tumors such as brain stem glioma and pineal body tumors.

Axial T2 image shows the hyperintense mass lesion causing marked expansion of pons more clearly and the flow void in basilar artery. Notice the mass effect on the fourth ventricle that is distorted and displaced posteriorly.

Axial postcontrast CT image shows non-enhancing diffuse mass causing expansion of the pons and engulfing the basilar artery.

Sagittal post gad T1 image showing the cranio-caudal extent of mass lesion with involvement of entire brainstem.

Sagittal T1-weighted MR image demonstrating obstructive hydrocephalus caused by a tectal glioma.