The Lateral Triangle of the Middle Fossa: Surgical Anatomy and a Novel Technique for Transcranial Exposure of the Internal Maxillary Artery

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BACKGROUND: The challenge of locating and isolating the internal maxillary artery (IMA) hinders its potential use as an arterial donor for extracranial-to-intracranial bypass surgery. OBJECTIVE: To introduce a new approach through the middle cranial fossa for easy access and safe exposure of the IMA. METHODS: Ten specimens were prepared for surgical simulation. After the pterional craniotomy, a 2-step drilling technique was performed (lateral triangle). First, a triangular craniectomy was completed anterolateral to the foramen spinosum. By following the middle meningeal 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. By tracing of the proximal part, the main trunk of the IMA was obtained. The size of the 2 craniectomies, the depth of IMA from the surface of the middle fossa, and the length of exposed IMA were measured. RESULTS: Drilling within the lateral triangle allowed safe exposure of both the trunk and the branches of the mandibular nerve of the IMA. 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 the middle fossa to the IMA (16.8 ± 3.2 mm, mean ± SD) was equal to the length of IMA exposed (17.6 ± 3.3 mm, mean ± SD; P > .05). CONCLUSION: This new approach provides an efficient and safe method to consistently find and isolate a segment of the IMA suitable for extracranial-to-intracranial bypass.

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Operative neurosurgery (Hagerstown, Md.)







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