Giant cerebral dissecting aneurysm

Case contributed by Dr Naim Qaqish


3 months pregnant woman presenting through ER complaining of headache and dizziness upon initial evaluation meningitis was thought of.

Patient Data

Age: 25 years
Gender: Female

Brain and MRA

There is around 3 cm mixed signal intensity well defined lesion at the right temporal region with signal void depicting areas of T1 hyperintense signals closely related to the right middle cerebral artery bifurcation probably due to giant aneurysm for further investigation.

Local mass effect is seen without midline shift.

No significant surrounding edema.

No evidence of acute brain, brain stem or cerebellar infarcts.

Otherwise normal brain, brain stem and cerebellar signal.

Mucous retention cyst is seen in the left maxillary antrum.


There is around 3 cm giant aneurysm in the right temporal lobe supplied by enlarged right M2 segment with internal turbulent flow.

The right M1 segment appears slightly smaller than the opposite side with mild beading, probably due to spasm.

Dilated distal branch of the right middle cerebral artery lateral-superior to the mentioned aneurysm.

Normal intracranial internal carotid and vertebrobasilar arteries.

Patent both posterior communicating and anterior communicating arteries.

Annotated image


On first image (most left) sagital image, the arrow points towards the aneurysm continuous with the right M2 segment.

Middle image axial MIP the arrow points towards M2 segment.

The last image (most right) axial MIP show the size of the aneurysm.


CTA intracranial

There is evidence of a very peculiar aneurysmal dilatation of the M2 branch of the right middle cerebral artery which is measuring 2.6 x 2.2 cm and having like inverted comma shape.

The aneurysm itself it has no neck and it’s a continuation of M2 segment of the right middle cerebral artery which confirms the assumption of congenital ectasia.

There is no evidence of leakage from this aneurysmal dilatation with no evidence of any intracranial hemorrhage.

There is no evidence of any other associated arterial or anomalies in the intracranial or in the neck.

Case Discussion

Upon initial evaluation of the MRI images, hematoma and giant cavernoma were also thought of. As mentioned, the aneurysmal dilatation was seen continuous with the right M2 segment which is not typically seen in aneurysmal dilatation, and most likely representing congenital ectasia of that area which was developing with slow dilatation.

The patient was referred for further evaluation to interventional radiologist outside our institution and confirmed dissecting aneurysm of M1 segment extending to M4 segment of the right MCA.

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Case information

rID: 86725
Published: 17th Feb 2021
Last edited: 20th Feb 2021
Inclusion in quiz mode: Included
Institution: European Society of Radiology