Historical evolution of extracranial-intracranial bypass: a single-center 45-year experience

The technique for extracranial-intracranial (EC-IC) bypass was introduced in 1976. Over the subsequent 45 years, indications and surgical techniques have significantly evolved. This study aims to analyze the trends in patient demographics, bypass techniques, and clinical indications for bypass surgeries performed at our institution from 1976 to 2020. We conducted a retrospective review of patient records, using digital medical records available from 2001 and manually reviewing paper records for cases prior to that year. A comprehensive analysis was performed on surgical procedure descriptions and indications for bypass surgery. A total of 374 patients underwent EC-IC bypass surgery from 1976 to 2020. The frequency of surgeries increased until 1985, followed by a marked decline in 1986. From 1996 onward, the average number of bypass surgeries performed annually was 4 until 2010, and this number increased to 7 from 2011 to 2020. Indications and detailed techniques were recorded in 284 cases. Between 1976 and 2000, occlusive cerebrovascular disease (OCVD) was the predominant indication for bypass surgery (69.2%); however, in the last two decades, the primary indication shifted to flow preservation for complex aneurysms (74.8%). Prior to 2011, the primary focus was on internal carotid artery (ICA) aneurysms, while in the last decade, middle cerebral artery (MCA) aneurysms have gained prominence. High-flow (HF) graft-mediated bypasses were mainly utilized for the management of complex aneurysms; notably, there has been a decline in HF bypass requirements, with only 10% of flow preservation surgeries needing this technique in the past decade. Our study underscores the significant evolution of cerebral bypass surgery over the past 45 years, with flow preservation for complex aneurysms currently being the leading indication for EC-IC bypass. The superficial temporal artery to middle cerebral artery (STA-MCA) bypass remains the most frequently performed technique. Moreover, the use of HF EC-IC bypass has declined in the last decade, reflecting the emergence of alternative methods for flow preservation.