PMC5590341_01
(a) An original image of gadolinium-enhanced MR angiography. A dumbbell-shaped aneurysm is intruding into the entorhinal sulcus from the right internal carotid artery. (b) A T2-weighted horizontal MRI image. A high signal intensity area suggesting edema around the aneurysm is shown in the medial temporal lobe. (c)The right internal carotid artery angiography shows an aneurysm with a narrow neck at the posterior communicating artery bifurcation. (d) A coronal section image of gadolinium-enhanced T2-weighted CISS MRI. The tip of the aneurysm reaches the vicinity of the amygdala nuclei
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F1
On magnetic resonance angiography (MRA) of the head, we noted a dumbbell-shaped aneurysm, 10 mm in diameter, appeared to have extended from the right internal carotid artery to pierce the medial temporal lobe cortex [Figure 1a]. T1-weighted MRI revealed an area of high signal intensity in the distal dome of the aneurysm, suggesting thrombosis. The surrounding brain showed high signal intensity on the T2-weighted image [Figure 1b]. Cerebral angiography revealed that the principal site of the aneurysm was the posterior communicating artery (P-com) bifurcation, and contrast medium retention was observed in the distal dome [Figure 1c]. Post-contrast constructive interference in the steady state (CISS) imaging revealed that the aneurysm dome intruded into the entorhinal sulcus and reached the amygdala [Figure 1d].
(a) Clear spikes were evoked in several electrodes of intraoperative cortical EEG. (b) The exposed aneurysm intruded into the right medial temporal lobe cortex, where brownish discoloration (arrow) occurred (*right oculomotor nerve). (c) After detachment of the posterior communicating artery and its perforators, neck clipping was performed, followed by corticotomy of the brownish discolored area of the medial temporal lobe cortex. With these procedures, the thrombosed distal dome (*) was exposed. (d) After resection of the aneurysmal dome, the right medial temporal lobe cortex was removed until normally colored white matter was exposed. (e) No obvious spikes were detected on the intraoperative cortical EEG after removal of the medial temporal lobe cortex
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F2
As a result, clear spike discharges were detected from some electrodes [Figure 2a]. The aneurysm intruded into the medial temporal lobe cortex, which was slightly discolored to a brownish tone [Figure 2b]. Thereafter, the discolored medial temporal lobe cortex was incised and resected, and thrombosis of the distal dome was confirmed [Figure 2c]. Thereafter, the medial temporal lobe cortex was resected by aspiration until normally colored white matter was exposed, and the posterior cerebral artery was visually identified at the bottom [Figure 2d]. In the EEG, although slow waves appeared in part, no obvious spikes were detected, and the operation was completed [Figure 2e].
(a) The resected aneurysm wall was a pseudoaneurysm without an arterial wall structure. (b) The medial temporal lobe resected at the same time showed degenerated neurons and edematous tissue accompanied by gliosis. There was no clear hemosiderin deposition. (c) Postoperative 3D-CT angiography confirmed the complete disappearance of the aneurysm and presented a favorable image of the posterior communicating artery
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F3
The resected aneurysm wall was a pseudoaneurysm without an arterial wall structure; the internal elastic lamina was composed of thin fibrous tissue with a mild inflammatory response [Figure 3a]. There were no changes suggestive of an old hemorrhage [Figure 3b]. Postoperative 3D-CT angiography confirmed the disappearance of the aneurysm and the patency of the P-com [Figure 3c].