What disturbance of gaze occurs as a result of compression of the superior colliculus?
Failure of up-gaze can result due to tectal compression, and this is known as Parinaud syndrome.
What are the other aberrant carotid-basilar communications?
1. Persistent trigeminal artery (most common); 2. Persistent otic (acoustic) artery (controversial, perhaps non-existent); 3. Persistent hypoglossal artery; 4. Persistent proatlantal artery.
Pineal cyst compresses the superior colliculus (orange arrow) and splays and displaces the internal cerebral veins (green arrows) superiorly.
MRA demonstrates an aberrant trigeminal artery (blue arrow) arising from the large right internal carotid artery (red arrow) and passing posteriorly in an upwardly convex loop to the terminal basilar artery (yellow arrow).