Direct Graftless Internal Maxillary Artery–Middle Cerebral Artery Bypass via a Combined Sublabial Transmaxillary–Pterional Corridor: Cadaveric Study With 3-Dimensional Models

BACKGROUND AND OBJECTIVES: Bypass surgery has become one of the essential techniques in neurosurgery. The internal maxillary artery (IMAX) has emerged as an increasingly used donor vessel for large-caliber extracranial–intracranial bypass. However, the limited donor length reported in previously described techniques often necessitates the use of interposition grafts. This study describes a novel graftless direct IMAX–middle cerebral artery (MCA) bypass technique using a combined endoscopic sublabial transmaxillary and pterional approach. METHODS: Six silicone-injected, embalmed cadaveric heads were dissected in 3 stages: (1) endoscopic sublabial transmaxillary exposure of the IMAX, (2) microsurgical pterional exposure of the MCA divisions, and (3) graftless direct IMAX–MCA bypass. The diameter of the pterygopalatine segment of IMAX and the total available donor length were measured using digital calipers. The surgical corridor and vessel transposition were additionally demonstrated through anatomic modeling to support spatial orientation. RESULTS: The pterygopalatine segment of IMAX is defined via an endoscopic sublabial transmaxillary approach, transposed intracranially through a craniectomy performed superolateral to the foramen rotundum. Then direct graftless IMAX–MCA bypass was performed microscopically via pterional transsylvian approach. The mean diameter of the pterygopalatine segment of IMAX segment was 2.19 ± 0.34 mm (95% CI: 1.98-2.40 mm), and the total available donor length measured 5.40 ± 0.82 cm (95% CI: 4.88-5.91 cm). This length permitted tension-free transposition to the distal M1 without the need for interposition graft. CONCLUSION: This combined approach demonstrates the anatomic feasibility of a direct graftless large-caliber IMAX–MCA bypass by providing sufficient donor length.