Intracystic Hemorrhage of the Middle Fossa Arachnoid Cyst and Subdural Hematoma Caused by Ruptured Middle Cerebral Artery Aneurysm
Dong Huanga,
Toshi Abea,
Kazuyuki Kojimaa,
Norimitsu Tanakaa,
Mitsuo Watauabea,
Akio Ohkuraa,
Hiroshi Nishimuraa,
Naofumi Hayabuchia and
Alexander M. Norbasha
a Department of Radiology, Kurume University School of Medicine, Fukuoka, Japan (D.H., T.A., K.K., N.T., H.N., N.H.). Department of Neurosurgery, Koyanagi Memorial Hospital, Saga, Japan (M.W., A.O.), Interventional Neuroradiology, Massachusetts General Hospital, Harvard Medical School (A.M.N.)
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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
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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.
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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
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