Intracystic hemorrhage of the middle fossa arachnoid cyst and subdural hematoma caused by ruptured middle cerebral artery aneurysm

Abstract

We report a case of a cerebral aneurysm arising from the bifurcation of the left middle cerebral artery that ruptured into a left middle cranial fossa arachnoid cyst, associated with acute subdural hematoma. We discuss the relationships of aneurysm, arachnoid cyst, and subdural hematoma.

fig 1.

A noncontrast CT shows a well-circumscribed and rounded high-attenuation area in the left Sylvian fissure without clearly defined mass effect. This image depicts a thin crescent of surrounding CSF.fig 2. A noncontrast CT scan obtained 4 years prior to the current admission shows an arachnoid cyst in the left middle cranial fossa, without coexistence of the above-shown hyperattenuating finding

fig 3.

MR imaging after CT study. A, MR imaging shows a marginally isointense and centrally hyperintense rounded lesion on T1-weighted images, surrounded by a clearly defined hypointense rim. B, T2-weighted images depict the CT hyperattenuating focus as a hypointense lesion surrounded by thin marginal hyperintensity, which presumably is the CSF of the subarachnoid space. C, Fluid attenuation inversion recovery (FLAIR) images help confirm the presence of CSF surrounding the hypointense rim. The marginal hyperintensity on T2-weighted imaging most likely represents CSF in light of the signal nulling, which is shown on the FLAIR sequence, as one would expect to see in an area of simple fluid. D, MR imaging depicts thin bilateral convexity subdural hematomas as hyperintense collections on the Tl-weighted image. A hypoplastic left Sylvian fissure also is noticed.

fig 4.

A lateral view of the left internal carotid angiogram shows an irregular anteriorly and laterally projecting aneurysm arising from the left middle cerebral artery bifurcation