{"id":"f83713c3-a705-4bd9-91a7-f59c14e682ca","slug":"sni-17-462","title":"Ischemic complication in the anterior thalamoperforating artery territory following flow diverter stent placement for an internal carotid–posterior communicating artery aneurysm","authors":["Takumi Otake","Masahiro Nishihori","Shunsaku Goto","Issei Takeuchi","Takashi Izumi","Yusuke Sakamoto","Ryuta Saito"],"abstract":"Background: Flow diverter stents are widely used for internal carotid–posterior communicating artery (IC-PC) aneurysms, and covered branches such as the posterior communicating artery (PcomA) generally remain patent. Branches arising directly from the aneurysm dome, however, occupy a distinct anatomical position and may behave differently. Case Description: A woman in her 50s underwent Pipeline Flex with Shield Technology placement (5.0 × 16 mm) for a 9.2-mm wide-necked right IC-PC aneurysm. A thin branch arising directly from the aneurysm dome was preoperatively interpreted as a hypoplastic PcomA, with anticipated collateral support from an adequate ipsilateral P1 segment. Preoperative platelet function testing revealed clopidogrel non-response (adenosine diphosphate inhibition, 7.6%). On postoperative day 4, the patient developed left hemiparesis. Diffusion-weighted imaging demonstrated acute infarction in the right anterolateral thalamus, while digital subtraction angiography confirmed complete aneurysm thrombosis with disappearance of the branch and a fully patent stent. Vertebral artery angiography showed no retrograde filling of the PcomA. The hemiparesis resolved rapidly, but visuospatial and attentional-executive deficits persisted; the modified Rankin Scale score remained 2 at 18 months. Conclusion: When a hypoplastic PcomA arising from the aneurysm dome functions as a dominant terminal feeder of the anterior thalamoperforating artery, progressive intra-aneurysmal thrombosis after flow diversion may cause thalamic infarction—a risk incompletely addressed by antiplatelet optimization alone. An adequate P1 segment does not guarantee perfusion of such a dome-originating perforator. Preoperative functional assessment of collateral supply and branch-preserving alternatives merit consideration in this configuration.","thumbnailUrl":"https://sni-digital-videos.s3.amazonaws.com/articles/sni-17-462/figures/SNI-17-462-g001.jpg","publishDate":"2026-08-14T00:00:00.000Z","doi":"10.25259/SNI_831_2026","categories":["Neurovascular","Case Report"],"fullTextUrl":"https://surgicalneurologyint.com/api/articles/f83713c3-a705-4bd9-91a7-f59c14e682ca/pdf"}