{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,10]],"date-time":"2026-04-10T09:29:10Z","timestamp":1775813350894,"version":"3.50.1"},"reference-count":10,"publisher":"Scientific Scholar","content-domain":{"domain":["surgicalneurologyint.com"],"crossmark-restriction":true},"short-container-title":[],"abstract":"\n Background:<\/jats:title>\n \n De novo<\/jats:italic>\n aneurysm formation at the anastomosis site of a superficial temporal artery-middle cerebral artery (STA-MCA) bypass is a rare complication. We report a case of an anastomosis-site aneurysm appearing 3 years after STA\u2013MCA bypass surgery and treated with clipping.\n <\/jats:p>\n <\/jats:sec>\n \n Case Description:<\/jats:title>\n A man in his forties presented to a nearby hospital with left hemiparesis and dysarthria. Head magnetic resonance imaging and magnetic resonance angiography (MRI\/MRA) detected right hemispheric brain infarction due to the right M1 occlusion. After mechanical thrombectomy, the patient recovered without neurological deficits. The patient was admitted to our hospital for follow-up. During follow-up, the right M1 stenosis progressed and thrombosed, with a general decrease in blood flow in the right hemisphere observed on spectroscopy. The patient underwent an STA-MCA bypass 34 months after the first onset of brain infarction. Thirty-three months after the STA-MCA bypass surgery, follow-up MRA at the outpatient clinic showed an aneurysm at the anastomosis site. A retrospective checkup of the previous MRA revealed gradual enlargement of the aneurysm; therefore, surgical intervention was planned to prevent rupture. Intraoperatively, the aneurysm was identified on the STA side. The aneurysmal wall structure was preserved, and normal clipping was performed. The postoperative course was uneventful. There was no recurrence of the aneurysm at the 6 months follow visit to the outpatient clinic.<\/jats:p>\n <\/jats:sec>\n \n Conclusion:<\/jats:title>\n An anastomosis-site aneurysm is a rare complication of STA-MCA bypass. Distinguishing between a true aneurysm and a pseudoaneurysm preoperatively is challenging. A surgical plan that accommodates both types is necessary.<\/jats:p>\n <\/jats:sec>","DOI":"10.25259\/sni_1266_2025","type":"journal-article","created":{"date-parts":[[2026,4,10]],"date-time":"2026-04-10T08:30:43Z","timestamp":1775809843000},"page":"210","update-policy":"https:\/\/doi.org\/10.25259\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["A Case of\n de novo<\/i>\n aneurysm formation at the anastomosis site 3 years after superficial temporal artery\u2013middle cerebral artery bypass surgery"],"prefix":"10.25259","volume":"17","author":[{"given":"Tomiyuki","family":"Miyake","sequence":"first","affiliation":[{"name":"Department of Neurosurgery, Center of Neuroendoscopy, Japanese Red Cross Aichi Medical Center Nagoya Daini Hospital, Nagoya, Japan"},{"name":"Department of Neurosurgery, Nagoya University Graduate School of Medicine, Nagoya, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yusuke","family":"Sakamoto","sequence":"additional","affiliation":[{"name":"Department of Neurosurgery, Center of Neuroendoscopy, Japanese Red Cross Aichi Medical Center Nagoya Daini Hospital, Nagoya, Japan"},{"name":"Department of Neurosurgery, Aichi Medical University, Nagakute, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Tetsuya","family":"Nagatani","sequence":"additional","affiliation":[{"name":"Department of Neurosurgery, Center of Neuroendoscopy, Japanese Red Cross Aichi Medical Center Nagoya Daini Hospital, Nagoya, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Shinsuke","family":"Muraoka","sequence":"additional","affiliation":[{"name":"Department of Neurosurgery, Nagoya University Graduate School of Medicine, Nagoya, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ryuta","family":"Saito","sequence":"additional","affiliation":[{"name":"Department of Neurosurgery, Nagoya University Graduate School of Medicine, Nagoya, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"10894","published-online":{"date-parts":[[2026,4,10]]},"reference":[{"key":"10.25259\/SNI_1266_2025\/ref-1","doi-asserted-by":"crossref","first-page":"E905","DOI":"10.1227\/NEU.0b013e318260ffcf","article-title":"Ruptured de novo aneurysm arising at a site remote from the anastomosis 14 years after superficial temporal artery-middle cerebral artery bypass: A case report","volume":"71","author":"Aoki","year":"2012","journal-title":"Neurosurgery"},{"key":"10.25259\/SNI_1266_2025\/ref-2","first-page":"1406","article-title":"The impact of cerebrovascular steno-occlusive disease subtype on surgical and clinical outcomes after direct STA-MCA bypass surgery","volume":"142","author":"Golub","year":"2025","journal-title":"J Neurol Surg"},{"key":"10.25259\/SNI_1266_2025\/ref-3","doi-asserted-by":"crossref","first-page":"1012","DOI":"10.2176\/nmc.50.1012","article-title":"Intracerebral hemorrhage from a ruptured aneurysm at the site of anastomosis 27 years after superficial temporal artery-middle cerebral artery bypass","volume":"50","author":"Hokari","year":"2010","journal-title":"Neurol Med Chir (Tokyo)"},{"key":"10.25259\/SNI_1266_2025\/ref-4","doi-asserted-by":"crossref","first-page":"345","DOI":"10.1016\/j.wneu.2014.10.013","article-title":"Indications and results of direct cerebral revascularization in the modern era","volume":"83","author":"Kalani","year":"2015","journal-title":"World Neurosurg"},{"key":"10.25259\/SNI_1266_2025\/ref-5","doi-asserted-by":"crossref","first-page":"457","DOI":"10.1016\/j.clineuro.2012.05.044","article-title":"De novo ruptured aneurysm at the site of anastomosis after superficial temporal artery-middle cerebral artery anastomosis--case report and literature review","volume":"115","author":"Kawahara","year":"2013","journal-title":"Clin Neurol Neurosurg"},{"key":"10.25259\/SNI_1266_2025\/ref-6","doi-asserted-by":"crossref","first-page":"1051","DOI":"10.1097\/00006123-199605000-00041","article-title":"Subdural hemorrhage caused by de novo aneurysm complicating extracranialintracranial bypass surgery: Case report","volume":"38","author":"Kohno","year":"1996","journal-title":"Neurosurgery"},{"key":"10.25259\/SNI_1266_2025\/ref-7","doi-asserted-by":"crossref","first-page":"392","DOI":"10.3171\/jns.1980.52.3.0392","article-title":"Fatal subdural bleeding following superficial temporal-middle cerebral artery anastomosis. 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