2026 Proffered Presentations
S227: THE TRANSZYGOMATIC TRANSMANDIBULAR APPROACH TO ANTERIOR AND MIDDLE INFRATEMPORAL FOSSA: A STEP-BY-STEP CADAVERIC DISSECTION AND ILLUSTRATIVE CASE
Elena Rosellini, MD1; Maria Pia Tropeano, MD, PhD1; Cezar Kabbach Calaça Prigenzi, MD2; Gean Franco Gerbino, MD3; Aysu Iyigun Kabakci, MD4; Sergio Augusto Barbosa De Farias, MD5; Gabriel Vargas Rosales, MD6; Federico Pessina, MD, PhD1; Joao Paulo Almeida, MD, PhD4; 1Humanitas University, IRCCS Humanitas Research Hospital, Milan, Italy; 2Mandaqui Hospital, São Paulo, Brazil; 3Hospital Posadas, Buenos Aires, Argentina; 4Department of Neurosurgery, Neuroscience Institute, Indiana University, Indianapolis, IN, US; 5State University of Campinas, Campinas, São Paulo, Brazil; 6Department of Neurosurgery, Universidad Military Nueva Granada,Hospital Militar Central, Colombia
Objective: The preauricular transzygomatic transmandibular approach is a useful tool in skull base neurosurgery to approach tumors that extend into the infratemporal fossa and pterygoid fossa through a middle fossa corridor. The aim of this anatomical study is to present a detailed step-by-step cadaveric dissection of this surgical approach that allows access to anterior and middle infratemporal fossa (ITF) regions and to present a surgical case in which this approach was applied.
Material and methods: Five formalin flushed, silicon injected, alcohol preserved (70%) cadaveric head specimen were dissected under microscopic magnification. Every step of the approach and critical neuroanatomy structures were photographed and documented in a stepwise fashion. Moreover, we presented a case of a spheno-orbital extra-axial lesion, extending to ITF, where the transzygomatic transmandibular approach was used to target the lesion.
Results: A sickle shaped incision was made beginning 5 mm below the inferior border of the root of the zygomatic arch. A zygomatic osteotomy between the lateral orbit and the root of the zygoma and a low positioned fronto-temporal craniotomy were performed. The dura propria was dissected from the maxillary nerve (V2), the madibular nerve (V3), and the gasserian ganglion. After middle fossa peeling and skeletonization of foramen ovale and rotundum, the corridor between the second and third trigeminal branches was exposed and drilled.
During the stepwise cadaveric dissections all neurovascular structures of the ITF and their relationships were accurately photographed. Access to the glenoid fossa can be further obtained with additional mandibular condyle distraction and vertical ramus osteotomy.
In the cadaveric specimen the temporomandibular joint was removed by cutting the condylar process of the mandible to better show the middle ITF anatomy.
Clinical Case: The patient presented with left trigeminal neuralgia, visual impairment, partial third nerve palsy, left exophthalmos and left hemifacial hypoesthesia due to a left spheno-orbital lesion invading the ITF and causing severe optic nerve compression. The lesion was successfully removed through a transzygomatic transmandibular approach with excellent clinical results. The patient was discharged home fully independent with no new neurological deficits, complete regression of the exophthalmos, improvement of the left inferior hemianopsia and complete restoration of left hemiface sensation with no new episodes of trigeminal neuralgia.
Conclusion: The transzygomatic transmandibular approach is a useful tool in the armamentarium of a skull base neurosurgeon. This approach provides direct access through the middle fossa to lateral and medial pterygoid plate, internal maxillary artery, sphenoid and maxillary sinuses, maxilla and parapharyngeal area while preserving trigeminal nerve.
Presenting a complete and detailed step- by- step cadaveric dissection of the approach and related neuroanatomy facilitates a deep understanding of this complex skull base region and permits skull base neurosurgeons and trainees to gain more confidence in using this approach for lesions extending into the infratemporal fossa.