Acute subarachnoid hemorrhage and accessory anterior cerebral artery

Case contributed by Dr Madeleine Scicchitano


Sudden onset thunderclap headache.

Patient Data

Age: 50 years
Gender: Female

Acute subarachnoid hemorrhage is seen within the bilateral Sylvian fissures, temporal lobes, peri-mesencephalic cisterns, suprasellar cistern and interhemispheric fissure. 

The temporal horns of the lateral ventricles are prominent which is suggestive of early hydrocephalus

CT angiography demonstrates variant anatomy of the anterior circulation with an accessory ACA that arises from and courses parallel to the right ACA. 

In addition, there is aneurysmal dilatation at the origin of the accessory artery in the region of the right A1/proximal A2 measuring 2.5 mm in diameter, thought to be the culprit of the acute subarachnoid hemorrhage.

The left ACA is seen separately with no anterior communicating artery between the two systems. 

No other focal aneurysmal disease. 

The MIP images from the cerebral CT angiography better demonstrate the accessory ACA on the right. In addition, it is noted that the accessory right ACA supplies branches to the left superior frontal lobe. 

Only a 1 mm aneurysm at the right A1/A2 segment was identified and the patient did not have any intervention. 

Case Discussion

The patient presented with the classic history for acute subarachnoid hemorrhage (thunderclap headache) which was subsequently confirmed on unenhanced CT of the brain. The patient was GCS 14 which classifies the case as a Grade 2 SAH using the WFNS grading system. 

The patient went on to have an urgent CT angiography of the carotids and circle of Willis which demonstrates variant anatomy of the anterior circulation as well as aneurysm as described. 

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Case information

rID: 69231
Published: 3rd Jul 2019
Last edited: 5th Sep 2019
Inclusion in quiz mode: Included

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