PMC9062942_01
(a) Fluid-attenuated inversion recovery image demonstrates hemorrhage in the right ambient cistern (red arrow head). (b) T2 star-weighted MR image demonstrates hemorrhage in the right ambient cistern (red arrow head). (c) Axial CT image demonstrates hemorrhage in the right ambient cistern (red arrow head). (d) CT angiography shows a dissecting cerebral aneurysm at the right distal SCA (red arrow head).
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F1
A SAH was suspected because low signal intensity on the right ambient cistern on T2 star-weighted images and high signal intensity on fluid-attenuated inversion recovery images were observed [Figures 1a and b]. In addition, small saccular aneurysms were also found in the periphery of the right posterior inferior cerebellar artery (PICA), which were diagnosed as unruptured cerebral aneurysms based on the distribution of hemorrhage [Figures 1c and d].
(a) Digital subtraction angiography examination of the vertebral artery angiogram shows a dissecting cerebral aneurysm at the right distal SCA (red arrow head), (b) which are occluded with n-butyl-2-cyanoacrylate (red arrow head).
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F2
Embolization of the aneurysm from the main trunk of the SCA was performed using n-butyl cyanoacrylate since it was difficult to guide the catheter to the aneurysm site [Figure 2].
(a) Axial CT image demonstrates hemorrhage in the right ambient cistern and fourth ventricle 10 weeks after the patient was transferred. (b-d) CT angiography showing a new aneurysm at the right distal PICA (red arrow head) and a disappearance of the peripheral aneurysm (red arrow).
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F3
Other aneurysms also showed changes in a short period (e.g., the disappearance of the peripheral aneurysm) [Figure 3].
Intraoperative findings show an aneurysm in the fourth ventricle in addition to the right distal PICA aneurysm (blue arrow). Both were trapped and removed. A thrombotic unruptured aneurysm on the right cerebellar hemisphere (blue arrow head) that was not visualized by 3D-CT was also removed.
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F4
Bilateral occipital subcranial craniotomy was performed in the prone position, the right PICA was traced to the periphery, and the aneurysm in the fourth ventricle was trapped and removed with the telovelotonsillar segment [Figure 4].
In the ruptured aneurysm, the internal elastic lamina is segmentally torn. (a) Histopathological examination. (b) Elastica van Gieson. Even in an unruptured aneurysm, the internal elastic plate is segmentally missing. (c) Histopathological examination. (d) Elastica van Gieson. (e) Masson trichrome.
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F5
On the other hand, no calcification of the blood vessel wall or infiltration of inflammatory cells was observed, and the patient was pathologically diagnosed with SAM [Figure 5].