Internal Maxillary Artery to Anterior Circulation Bypass with Local Interposition Grafts Using a Minimally Invasive Approach: Surgical Anatomy and Technical Feasibility

BACKGROUND: The internal maxillary artery (IMA) is a reliable donor for extracranial-intracranial high-flow bypasses. However, previously described landmarks and techniques to harvest the IMA are complex and confusing and require extensive bone drilling, carrying significant neurovascular risk. The objective of our study was to describe a minimally invasive technique for exposing the IMA and to assess the feasibility of using the IMA as a donor for anterior-circulation recipient vessels using 2 different local interposition vessels. METHODS: Via a minimally invasive technique, the IMA was harvested in 10 cadaveric specimens and a pterional craniotomy was performed. Two interposition grafts-the superficial temporal artery (STA) and middle temporal artery-were evaluated individually. Transsylvian exposure of the second segment of middle cerebral artery (M2), the supraclinoid internal carotid artery, and the proximal postcommunicating anterior cerebral artery segment was completed. Relevant vessel calibers and graft lengths were measured for each bypass model. RESULTS: The mean caliber of the IMA was 2.7 +/- 0.5 mm. Of all 3 recipients, the shortest graft length was seen in the IMA-STA-M2 bypass, measuring 42.0 +/- 8.4 mm. There was a good caliber match between the M2 (2.4 +/- 0.4 mm) and STA (2.3 +/- 0.4 mm) at the anastomotic site. The harvested middle temporal artery was sufficient in length in only 30% cases, with a mean distal caliber of 2.0 +/- 0.7 mm. CONCLUSIONS: This study confirmed the technical feasibility of IMA as a donor for an extracranial-intracranial bypass to the second segment of the anterior cerebral artery, M2, and the supraclinoid internal carotid artery. However, IMASTA-M2 was observed to be the most suitable bypass model.