Basilar tip aneurysm

Case contributed by Bruno Di Muzio


Patient was presented at the ED with a slurred speech and mild right arm weakness.

Patient Data

Age: 65 years
Gender: Male

10 mm hypodense lesion anteriorly within the left frontal lobe periventricular white matter is compatible with prior small vessel infarction, with mild chronic small vessel ischemic change noted elsewhere (e.g. superior right frontal subcortical and periventricular white matter).

Demyelination is a much less likely differential in this demographic.

Small cavum septum pellucidum incidentally.

6 x 8 mm basilar tip aneurysm noted.


8.5 x 7.0 x 6.0 mm basilar tip aneurysm demonstrating a bilobed consideration. Both P1 segments may be incorporated into the base of the aneurysm. The neck of the aneurysm measures approximately 4.5 mm.

No further intracranial aneurysm or vascular malformation identified.

Annotated image

Arrow demonstrating the basilar tip aneurysm on non-enhanced brain images.  

Case Discussion

This case illustrates a saccular aneurysm at the very end of the basilar artery. A saccular aneurysm is a berry-like outpouching that tend to occur at arterial bifurcations, favoring the anterior circulation (~90%).

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