New approach for transcranial exposure of the internal maxillary artery: surgical anatomy and technique

Abstract

Objective To introduce a new approach through the middle cranial fossa for easy access and safe exposure of the Internal Maxillary Artery (IMA). Methods Ten specimens were prepared for surgical simulation. After pterional craniotomy and exposing the floor of middle fossa, a two-step drilling was performed. First, a triangular craniectomy was completed anterolateral to the foramen spinosum. By following the middle meningeal artery or deep temporal artery and dividing the lateral pterygoid muscle, the proximal part of IMA was located. Second, a bone slot was drilled in a posterior-to-anterior direction from the anterior aspect of the first craniectomy. Tracing the proximal part, the main trunk of IMA was obtained. The size of the two craniectomies, depth of IMA from the surface of middle fossa, and the length of exposed IMA were measured. Results The proposed two-step drilling technique allowed both the IMA's trunk andbranches of the trigeminal nerve to be manipulated safely. In six specimens, IMA ran medially to the pterygoid muscle and in the others ran laterally to it. The total craniectomy measured 27.8±4.2 mm in the anterior-posterior direction, and the posterior portion measured 13.3±1.5 mm in the lateral-medial direction. The depth from middle fossa to IMA (16.8±3.2 mm) was equal to the length of IMA exposed (17.6±3.3 mm). Conclusion This new approach provides an efficient and safe method to consistently locate and isolate a segment of IMA. Key words: Cranial fossa, middle; Internal maxillary artery; Dissection