Subarachnoid hemorrhage and mycotic aneurysm

Case contributed by Prof Peter Mitchell


D7 post cardiac surgery, sudden collapse and facial weakness. INR 3.0. Bleed?

Patient Data

Age: 66 years
Gender: Female

CT and CTA brain

CT brain (non-contrast)

Non-contrast axial images through the brain have been obtained.

There is extensive infra and supratentorial subarachnoid hemorrhage demonstrated centered at the suprasellar cistern and extending into the premedullary cistern, cerebellopontine cistern, into bilateral Sylvian fissures, along the floor of the middle cranial fossa and falx cerebri anteriorly.

There is also widespread sulci hemorrhage seen in bilateral frontal, anterior temporal and parietal as well as right anterior occipital lobe. Confluent areas of right posterior frontal and parietal hemorrhage appear predominantly parenchymal, measure up to 2.2 x 1.3 cm in the axial plane and demonstrate surrounding vasogenic edema. Associated mass effect further results in effacement of the right lateral ventricle and 5mm left sided midline shift.

A 2 x 1.5 cm area of ill-defined hypodensity is shown in the right frontal ACA/MCA watershed territory and appears most suspicious for an area of established infarction.

No intraventricular blood. No midline shift. No focal mass identified.

CTA COW (aortic arch to vertex)


Volume acquisition from the vertex to the aortic arch has been obtained with dynamic administration of intravenous contrast and reviewed in multiple planes.


There is adequate opacification of the first and second segment of the right vertebral artery. No opacification is seen in the distal aspect of the third segment and in the fourth segment for a length of approx 4cm. Opacification of the distal aspect of the right V4 for a length of approx 11mm just before its confluence with the left vertebral artery is thought secondary to backfilling. The right sided PICA is not identified.

The appearance of the left vertebral artery is normal. Focal calcification is evident of bilateral V4 segments.

Left V4 focal stenosis of moderate severity.

Peripheral right MCA dilatation suspicious for mycotic aneurysm.


Extensive subarachnoid hemorrhage as described above. Small amount of intraventricular blood. Rule out mycotic aneurysm with DSA

DSA (angiography)

Slow to fill and empty, small distal MCA aneurysm.

DSA (angiography)

Post clipping DSA

Post surgical clipping DSA to confirm exclusion of the aneurysm.

Case Discussion

Although INR 3.0, other causes of IPH and SAH need to be considered.  Review of history indicated the thoracic surgery was performed on background of bacterial endocarditis.  CTA source images (not shown) did reveal the aneurysm immediately deep to the cranial vault, at an unusual site for typical aneurysms, and with artefact from skull vault potentially leading to missed diagnosis.

The DSA shows an aneurysm at an atypical site - on these images alone a mycotic (infective) aneurysm would be proposed without additional history.  Once the additional history was known, the diagnosis is confirmed.

In this case the very distal location, tortuous cervical ICA access led to the consensus decision to manage with surgical clipping.  Once thought a relative contraindication to endovascular treatment, infective aneurysms have now been treated with coil embolization.

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Case information

rID: 34439
Published: 23rd Feb 2015
Last edited: 29th Apr 2020
Inclusion in quiz mode: Included

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