Side-to-Side Superficial Temporal Artery to Middle Cerebral Artery Bypass Technique: Application of Fourth Generation Bypass in a Case of Adult Moyamoya Disease

BACKGROUND Moyamoya disease (MMD) is a rare cause of cerebral hemorrhage and ischemia. Spontaneous development of collateral supply from the external carotid artery (ECA) may limit the use of donor arteries used in standard direct bypass techniques. OBJECTIVE To identify the technical feasibility of side-to-side (S-S) superficial temporal artery to middle cerebral artery (STA-MCA) bypass and demonstrate the application of fourth generational bypass techniques in the treatment of MMD. METHODS S-S bypass was performed in order to maintain distal outflow in the donor STA. Fourth generation bypass techniques, including atypical anastomosis construction and intraluminal suturing were utilized. RESULTS The novel S-S STA-MCA bypass was performed, with patent flow in both recipient MCA and endogenous ECA-ICA collaterals supplied by the distal STA. Technical nuances, including proper alignment of donor vessel, tension reduction, and S-S anastomosis construction with intraluminal suturing technique are essential for successful bypass. Unique flow properties of this bypass were identified, resulting in flow augmentation to the recipient territory compared to standard end-to-side (E-S) techniques. CONCLUSION Fourth generational bypass techniques can be successfully applied to MMD, allowing for novel bypass construction. S-S anastomosis can result in potentially beneficial flow properties compared to standard E-S constructions.