Non-aneurysmal perimesencephalic subarachnoid hemorrhage

Case contributed by Kamil Bekalarek
Diagnosis certain


Headache for four days, subarachnoid hemorrhage suspected.

Patient Data

Age: 60 years
Gender: Male

A small amount of subarachnoid hemorrhage in the basal cisterns located mainly anterior to the midbrain.

CTA of the cerebral arteries


Subsequently obtained brain CTA excluded clinically suspected basilar artery aneurysm as a source of hemorrhage.

Case Discussion

Although in the case of perimesencephalic subarachnoid hemorrhage (PMSAH), CTA is a recommended further imaging investigation for the exclusion of vertebrobasilar artery aneurysm, the vast majority of PMSAH are non-aneurysmal in origin. It's worth to keep that in mind to avoid unnecessary DSA investigation in negative CTA scan as in this case.

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