Practice Trends in Intracranial Bypass Surgery in a 21-Year Experience

The aim of this study was to analyze practice trends in specific intracranial bypass types in a large, consecutive bypass experience.

This retrospective review of a prospectively maintained database included all intracranial bypasses performed by a single surgeon over 21 years. Bypass types were grouped into 7 categories and analyzed in seven 3-year time intervals: type 1 = extracranial-to-intracranial (EC-IC) bypass with scalp arteries as donors; type 2 = EC-IC bypass with interposition graft to cervical carotid arteries; type 3 = arterial reimplantation; type 4 = in situ bypass; type 5 = reanastomosis; type 6 = intracranial-to-intracranial bypass with interposition graft; and type 7 = combination bypass.

In total, 598 intracranial bypasses were performed including 359 type 1, 59 type 2, 24 type 3, 30 type 4, 37 type 5, 36 type 6, and 53 type 7. Although type 1 and type 3-7 bypasses increased, type 2 bypasses decrease in frequency. Aneurysms were the most common bypass indication (41.8%), followed by moyamoya disease (31.8%), and intracranial arterial stenosis or occlusion (24.9%). Endovascular treatment failure was observed in 10.8% of the aneurysm patients treated with a bypass procedure.

Intracranial bypass remains an essential technique for open vascular neurosurgeons. The classic low-flow EC-IC bypasses, intracranial-to-intracranial, and combination bypasses increased over time, whereas the high-flow EC-IC interpositional bypasses decreased over time. These trends reflect the increasing use of flow diverters as well as the need for surgical revascularization for complex aneurysms, and those that failed previous endovascular therapy.