Neurological Surgery No Shinkei Geka Volume 47, Issue 5 (May 2019)

A Rare Case of an Unruptured Aneurysm Arising from the Proximal End of the Fenestration of the Infracallosal Segment(A2)of the Anterior Cerebral Artery Genki CHIKAMATSU 1,2 , Takeshi HIU 2 , Eri SHIOZAKI 1,2 , Hikaru NAKAMURA 1,2 , Keisuke OZONO 2 , Kazuya HONDA 3 , Tomoya MORITSUKA 3 , Ichiro KAWAHARA 2 , Tomonori ONO 2 , Wataru HARAGUCHI 2 , Ryujiro USHIJIMA 2 , Keisuke TSUTSUMI 2 1Residency program, Department of Neurosurgery, National Hospital Organization Nagasaki Medical Center 2Department of Neurosurgery, National Hospital Organization Nagasaki Medical Center 3National Hospital Organization Nagasaki Medical Center Keyword: anterior cerebral artery fenestration , infracallosal segment , unruptured aneurysm , embryology , primitive plexiform anastomosis pp.565-572
Published Date 2019/5/10
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 We report an extremely rare case of a fenestration in the infracallosal(A2)segment of the right anterior cerebral artery(ACA)associated with an unruptured aneurysm at the proximal end of the fenestrated portion.

 A 70-year-old man was referred to our hospital for further examination and treatment of unruptured aneurysms at the A1/A2 junction of the right ACA and the distal end of the right vertebral artery that were incidentally detected on MR angiography. CT angiography and 3D-rotational angiography revealed a fenestration in the proximal A2 segment of the right ACA with a small(3.6×3.8mm)aneurysm arising from the proximal end of the fenestration. The dome of the aneurysm projected to the left anterior/inferior direction. He underwent aneurysm neck clipping surgery via the right pterional approach without complications, while the vertebral artery aneurysm was managed conservatively.

 An extensive review of the literature revealed that only a small number of cases of A2 fenestration have been reported to date. To our knowledge, this is the first report of an A2 fenestration associated with an aneurysm at the fenestrated segment.

 Embryologically, the A2 fenestration may represent a remnant of plexiform arterial channels that constitute the primitive ACA system including the primitive olfactory artery, median artery of the corpus callosum and anterior communicating plexus.

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Neurological Surgery 脳神経外科
47巻5号 (2019年5月)
電子版ISSN 1882-1251 印刷版ISSN 0301-2603 医学書院