On MR angiography, the internal cerebral vein and the vein of Galen were observed to be dilated and an arteriovenous malformation (AVM) was noted originating from the interpeduncular cistern extending into the quadrigeminal cistern
and lateral ventricle, nourished by the posterior cerebral artery, draining into the internal cerebral vein and vein of Galen.
In a study by Galarza et al, the posterior fossa arachnoid cysts were located at the vermis-cisterna magna (n=4), the cerebellar hemispheres (n=2), the cerebellopontine angle (n=3) and the quadrigeminal cistern
Brain computed tomography (CT) and magnetic resonance imaging (MRI) showed right cystic lesion rising from the quadrigeminal cistern
on the left side and extending supratentorially, indenting the third ventricle causing obstructive hydrocephalus.
Identification of arachnoid cysts in the quadrigeminal cistern
Dilated arteries drain into a large midline venous pouch in the region of the quadrigeminal cistern
. It is a rare condition and is demonstrated in less than 1% of cerebral vascular malformations at any age and up to 30% of paediatric vascular malformations.