Sepideh Amin-Hanjani

BACKGROUND: Intraoperative flow measurement has proven utility in extracranial–intracranial bypass, particularly in assessing the adequacy of donors by measurement of cut flow. The nature of intracranial–intracranial (IC–IC) bypass precludes cut flow measurement, but quantitative intraoperative flow measurements may evaluate augment assessment of the bypass. OBJECTIVE: To retrospectively evaluate flow measurements performed in IC–IC bypass to determine the adequacy of the constructs in preserving flow. METHODS: With institutional review board approval, we performed a retrospective review of our bypass database from 2001 to 2021 for aneurysms treated with IC–IC bypass and with intraoperative flow measurements. Patients' preoperative characteristics, bypass indications, prebypass and postbypass intraoperative flow measurements, and patient outcomes were recorded. RESULTS: Of 346 bypasses, 21 cases using 22 IC–IC bypasses were included. The median age was 55 years; 13 of 21 cases were ruptured aneurysms. Aneurysms involved posterior inferior cerebellar artery (n = 7), middle cerebral artery (n = 6), distal anterior cerebral artery (n = 5), and anterior communicating artery (n = 3). Six bypasses were end-to-side (ETS), 10 were side-to-side (STS), and 6 were excisional with reanastomosis (end-to-end, ETE). Intraoperatively, 21 of the bypasses were patent; the postbypass/prebypass flow index averaged 1.15 (±0.32): ETE (n = 6) 1.22 ± 0.34 and ETS/STS bypasses (n = 15) 1.11 ± 0.32. All intraoperatively patent bypasses were patent on postoperative angiography. One occluded on delayed angiography without clinical sequelae. CONCLUSION: Despite advances in endovascular therapy, IC–IC bypass remains essential to the treatment of large and fusiform aneurysms. We demonstrate quantitatively that IC–IC donors provide adequate direct (ETE) and redistributed (STS ETS) flow to the recipient territory. Flow measurement provides valuable information regarding the patency and adequacy of IC–IC bypass for flow preservation.