Endoscopic-Assisted Transorbital Approach for Microvascular Bypass to Deep Intracranial Targets Using the Maxillary Artery: An Anatomical Study

BACKGROUND AND OBJECTIVES: This anatomical study evaluates the feasibility of deep extracranial-to-intracranial microvascular bypass using the maxillary artery (MA) as a donor vessel accessed through an endoscopic transorbital approach. The aim was to assess potential donor–recipient configurations for revascularization of deep intracranial targets. METHODS: Four adult human cadaveric heads (8 sides) were dissected using a combined endoscopic–microscopic technique. The endoscopic transorbital approach was used to access the infratemporal fossa and expose the MA, while microsurgical techniques were employed for bypass anastomoses to intracranial recipient vessels. Bypass configurations included direct end-to-end MA-to-anterior temporal artery (ATA) and deep posterior temporal artery-to-ATA anastomoses, as well as interpositional bypasses using the superficial temporal artery (STA) to connect the MA to the supraclinoid internal carotid artery (SC-ICA) and second segment of the middle cerebral artery (M2). Feasibility, bypass quality, vessel diameters, graft length, and anatomical depth were assessed descriptively. RESULTS: Direct MA-to-ATA bypass was feasible in 3 of 8 sides and deep posterior temporal artery-to-ATA in 6 of 8. Interpositional MA-to-SC-ICA and MA-to-M2 bypasses using an STA graft were feasible in all 8 sides, as was end-to-end MA-to-STA anastomosis. The mean graft lengths were 30 mm for SC-ICA and 21 mm for M2 bypasses. Depth to target vessels ranged from 46 to 80 mm. Favorable donor–recipient diameter compatibility and short grafts supported anatomically efficient bypass geometry. Most bypasses were rated as good or intermediate quality. CONCLUSION: Deep extracranial-to-intracranial bypass using the MA through an endoscopic transorbital corridor is anatomically feasible and allows multiple donor–recipient configurations through a single minimally invasive route. Direct access to deep targets, accurate donor localization, and short graft constructs are facilitated. These findings establish an anatomical foundation for future clinical application of transorbital MA-based revascularization, particularly in patients requiring flow augmentation to deep-seated targets or with suboptimal cervical donor access.