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Case Reports
. 2021 Jun 21;1(25):CASE21240.
doi: 10.3171/CASE21240.

Selection of approach and bypass for fetal-type posterior cerebral artery aneurysm: illustrative cases

Yoshichika Kikuta  1 , Koji Yamaguchi  1 , Tatsuya Ishikawa  1 , Takayuki Funatsu  1 , Yoshikazu Okada  1 , Takakazu Kawamata  1
Affiliations
Case Reports

Selection of approach and bypass for fetal-type posterior cerebral artery aneurysm: illustrative cases

Yoshichika Kikuta et al. J Neurosurg Case Lessons. .

Abstract

Background: Unlike in aneurysms of the adult-type posterior cerebral artery (PCA), in aneurysms of the fetal-type PCA, parent artery occlusion (PAO) results in vascular insufficiency and major ischemic strokes. Preservation or reconstruction of fetal-type PCAs is necessary to prevent these complications. Furthermore, it is necessary to select an appropriate bypass method and approach for revascularization of the PCA.

Observations: The authors report 2 cases of aneurysms of fetal-type PCAs that were successfully treated with PAO with revascularization. A 38-year-old man with a large unruptured right PCA aneurysm at the postcommunicating (P2) segment underwent trapping with superficial temporal artery-PCA bypass via the anterior temporal and subtemporal approaches. In addition, a 45-year-old woman with a left PCA aneurysm at the quadrigeminal (P3)-cortical (P4) segments resulting in subarachnoid hemorrhage underwent proximal clipping of the P3 segment via the occipital interhemispheric approach with an occipital artery-PCA bypass. Although she had perforator infarction, major ischemic stroke was prevented, and aneurysm occlusion was accomplished in both cases.

Lessons: Aneurysms of fetal-type PCAs pose a risk of ischemia due to PAO. The combined use of bypass and revascularization should be considered to prevent major ischemic stroke after occlusion of the fetal-type PCA. However, perforator infarction is a concern.

Keywords: ICG = indocyanine green; 3D-CTA = three-dimensional computed tomography angiography; ATA = anterior temporal approach; DSA = digital subtraction angiography; MRI = magnetic resonance imaging; OA = occipital artery; P1 segment = precommunicating segment; P2 segment = postcommunicating segment; P3 segment = quadrigeminal segment; P4 segment = cortical segment; PAO = parent artery occlusion; PCA = posterior cerebral artery; SCA = superior cerebellar artery; STA = superficial temporal artery; approach; bypass; fetal-type posterior cerebral artery; parent artery occlusion; posterior cerebral artery aneurysm.

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Conflict of interest statement

Disclosures The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.

Figures

FIG. 1.
FIG. 1.
Case 1. A: Preoperative 3D-CTA showing a large fusiform aneurysm in the right PCA (P1–P2 segments). B: T2-weighted MRI showing the aneurysm near the peduncle of the midbrain. C: PCA (arrow) proximal to the aneurysm (asterisk) identified via the ATA. D: The PCA (arrow) distal to the aneurysm (asterisk) identified via the subtemporal approach. E: Clipping of the PCA distal (white arrow) to the aneurysm (asterisk) after STA-PCA bypass (black arrows). F: Postoperative 3D-CTA shows disappearance of the aneurysm and good bypass patency.
FIG. 2.
FIG. 2.
Preoperative and intraoperative findings of case 2. A: Computed tomography showing a thrombosed aneurysm and unclear subarachnoid hemorrhage on the left side. B: Left internal carotid angiogram showing a large thrombosed aneurysm in the P3–P4 segments of the PCA. C: The P3 segment of the PCA (asterisk) proximal to the aneurysm identified via the occipital interhemispheric approach. D: The branches of the OA (black and white arrows) anastomosed to the calcarine artery (white asterisk) and the parietooccipital artery (black asterisk). E: ICG angiography showing good patency of bypass (white and black arrows). The white asterisk shows the calcarine artery, and the black asterisk shows the parietooccipital artery. F: Clip (arrow) applied to the proximal side of the aneurysm (asterisk).
FIG. 3.
FIG. 3.
Postoperative examination of case 2. A: Postoperative left internal carotid angiogram showing absence of aneurysm at the clipped portion (arrow). High signal intensity in the occipital lobe is caused by retraction. B : Postoperative left external carotid angiogram showing the PCA (white arrows) visualized from the bypass to the posterior side of the clipped portion (black arrow). C: Postoperative diffusion-weighted imaging showing perforator infarction involving the left thalamus (arrow). High signal intensity in the occipital lobe is caused by retraction.
FIG. 4.
FIG. 4.
Approach to each segment of the PCA and bypass options for each approach. P2A = anterior postcommunicating segment; P2B = posterior postcommunicating segment.
See this image and copyright information in PMC

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