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Background: The patency of cranial bypasses must be carefully evaluated during and after the microsurgical procedure. Although, several imaging techniques are used to evaluate the patency of bypasses, their findings are sometimes difficult to interpret., Purpose: The goal of this study was to assess the consistency of different diagnostic modalities for evaluating intracranial bypass patency., Patients and Method: This prospective study included 19 consecutive patients treated with EC-IC or IC-IC bypass for MoyaMoya disease (MMD) or complex/giant aneurysms between June 2016 and June 2018. In the early postoperative period (<7 days), all patients had transcranial Doppler (TCD), CT angiography (CTA) and MRA to demonstrate patency of anastomoses and to confirm exclusion of the aneurysm. When findings of anastomosis patency differed between these techniques, conventional angiography was performed., Results: All anastomoses were patent on indocyanine green videoangiography at the end of microsurgical procedure. The results of noninvasive postoperative exams were consistent to demonstrate the patency of anastomoses in 13 patients. In 4 patients, a discrepancy in patency of anastomoses arose between TCD, CTA and MRI in the early postoperative period. In 2 other patients, the interpretation of bypass patency remained inconclusive before the decision to occlude the aneurysm. In these 6 patients, a significant edema was noted in 2 cases, a postoperative subdural hematoma in 1 case, a low flow in the anastomosis in 1 case and vasospasm in 2 cases. The anastomosis was patent on the conventional angiography in five patients., Conclusion: Noninvasive imaging techniques provide useful data about the patency but their findings should be carefully interpreted due to local anatomical, physiological, and pathological factors. In case of discrepant findings, conventional angiography including supraselective catheterization of the donor vessel is suggested., (Copyright © 2020 Elsevier Masson SAS. All rights reserved.)

Objectives: To evaluate the effectiveness of superficial temporal artery-middle cerebral artery (STA-MCA) bypass in improving cerebrovascular reserve (CVR) in Moyamoya syndrome., Patients and Methods: This prospective study included 10 consecutive patients treated for Moyamoya syndrome by STA-MCA bypass in our institution between June 2016 and January 2018. Perfusion MRI, transcranial Doppler and 99m Tc-HMPAO SPECT with acetazolamide challenge were performed before and after treatment to evaluate perfusion and cerebrovascular reserve. STA-MCA bypass was indicated for patients with history of ischemic or hemorrhagic stroke and when CVR was diminished on both transcranial Doppler and 99m Tc-HMPAO SPECT with acetazolamide challenge or brain perfusion was deteriorated on MRI., Results: Bypass anastomosis was patent in all patients at end of surgery. One patient presented partial postoperative sensorimotor deficit related to an ischemic lesion in the frontal cortical area. One patient presented regressive chronic subdural hematoma without neurological deficit. Three months after treatment, CVR was significantly improved in 8 patients and unchanged in 2, probably related to low flow. Further follow-up found CVR deterioration in 1 patient, with anastomosis occlusion at 1 year., Conclusion: Our data suggest that improvement in cerebral perfusion and CVR depends on flow in the STA-MCA anastomosis in patients with Moyamoya syndrome. Systematic long-term follow-up of anastomosis flow, brain perfusion and CVR improves quantification of the benefit of STA-MCA anastomosis in terms of disease progression., (Copyright © 2019 Elsevier Masson SAS. All rights reserved.)