Endoscopic Anatomy of the Maxillary Strut: A Cadaveric Study

Background: Over the last two decades, the traditional boundaries of endoscopic transnasal surgery have been expanded to access lesions of the anterior skull base. Recent advancements in endoscopic transnasal approaches to the skull base raise the possibility of extending these approaches further. In this cadaveric study, we evaluate the feasibility and extent of exposure of the “maxillary strut” through an endoscopic transnasal approach. The “maxillary strut” is a term that is found sporadically in the neurosurgery and otolaryngology literature to describe the fragment of bone located between the superior orbital fissure and the foramen rotundum. The removal of the maxillary strut theoretically allows access to the middle cranial fossa.

Methods: Endoscopic dissection was performed in two frozen cadaver heads and two formalin fixed cadaver heads (eight sides). An endoscopic, transnasal approach was used to remove the posterior nasal septum. The maxillary nerve was then identified in the pterygopalatine fossa and traced back toward the cavernous sinus. The contents of the superior orbital fissure were also identified. The maxillary strut was then identified and removed.

Results: With the endoscopic transnasal approach, we could visualize the maxillary strut after identifying the maxillary nerve and tracing it back along the foramen rotundum. With careful dissection, the carotid artery and the contents of the superior orbital fissure were identified. With further dissection, the maxillary strut was then removed to gain access to the contents of the middle cranial fossa.

Conclusion: In this cadaveric study, using an endoscopic transnasal approach permitted exposure of the maxillary nerve in the foramen rotundum and the contents of the superior orbital fissure. The maxillary strut was then identified and removed. The anatomy presented will assist experienced endoscopic skull base surgeons in the biopsy or removal of lesions involving the anterior aspect of the middle cranial fossa. This technique could potentially offer the advantage of avoiding a craniotomy and brain retraction and hasten postoperative recovery.