Modified Endoscopic Endonasal Approach With a Minimally Invasive Transoral Approach—An Adjunct to Infrapetrous Approaches Guillermo Maza, MD ; Ali M. Moustafa Omar, MD; Somasundram Subramaniam, MD; Bradley A. Otto, MD; Daniel M. Prevedello, MD; Ricardo L. Carrau, MD Objectives/Hypothesis: To evaluate the potential of a minimally invasive transoral–transpalatal approach (MITA) to the retrocarotid petrous apex, as an adjunct to endoscopic endonasal approaches (EEAs). Study Design: Cadaver study. Methods: Five cadaveric specimens were dissected raising an inverted U-shaped palatal mucoperiosteal flap, and drilling a rectangular palatotomy (between the greater palatine foramens, and just anterior to the palatine aponeurosis). This allowed a transpterygoid EEA with cross-court access (contralateral line of sight), followed by an extradural clivectomy that exposed the petroclival junction bilaterally. Surgical targets were marked on the posterior and medial surface of the petrous internal carotid artery (ICA), at its anterior genu, midhorizontal portion, and posterior genu. For each target and approach, the surgical freedom and angles of approach (in the horizontal and vertical planes) were calculated and statistically compared. Results: Compared to EEA, the MITA resulted in greater surgical freedom for all targets, with the highest values at the anterior genu (1,661.37 mm 2 vs. 312.76 mm 2 , P <.001), and maintaining superiority in this regard all the way to the posterior genu (847.84 mm 3 vs. 138.91 mm 3 , P < .005). MITA also offered greater angles of approach for all targets. Conclusions: This study suggests that the MITA may be indicated to supplement the exposure provided by a transptery- goid EEA. This technique, associated with low potential morbidity, offers an alternative to internal carotid lateralization while managing extradural lesions that are adjacent to the petrous ICA. Key Words: Endoscopic skull base surgery, minimally invasive approaches, petrous carotid artery, petrous apex, transpa- latal surgery. Level of Evidence: NA Laryngoscope, 129:339–343, 2019 INTRODUCTION Expanded endonasal approaches (EEA) offer a mini- mal access corridor to the ventral skull base in the sagit- tal and coronal planes. Currently, there are no general contraindications to an EEA based on tumor size, nature, or consistency, although lateral extension does represent a limitation. An EEA to the petrous apex in patients with poorly pneumatized sphenoid sinuses presents a surgical challenge. Some lesions can be managed circumventing the petrous segment of the carotid artery with angled instrumentation; however, this is done at the expense of maneuverability, which paradoxically is more critical in the proximity of the great vessels. Other alternatives, such as lateralization of the carotid artery, carry a potential risk of internal carotid artery (ICA) injury; thus, it should be undertaken by experienced surgeons. A transoral pathway offers an advantageous caudal to cephalad and medial to lateral view, which allows direct visualization and instrumentation of the petrous apex. Despite its well-established benefits, the morbidity associated with a soft palate split has detracted its use. This cadaveric study attempts to establish the feasibility, advantages, and limitations of a transoral approach through the hard palate, as an adjunct to an endoscopic transpterygoid infrapetrous approach to the petrous apex. This technique could offer a less morbid alternative to other transpalatal approaches, while reducing the need of manipulating the ICA. MATERIALS AND METHODS We studied five silicone-injected cadaveric human head specimens (10 sides). All dissections were performed in accor- dance with the institutional protocols at the Anatomical Labora- tory Toward Visuospatial Innovations in Otolaryngology and Neurosurgery at the Wexner Medical Center of The Ohio State University. All specimens underwent high-resolution computed tomography that was uploaded to an image guidance system (Stryker Navigation, Kalamazoo, MI). The surgical dissection was undertaken with standard angled suctions, burr, and dissector blades, and conducted with 0  , 45  , and 70  rod-lens endoscopes (Karl Storz Endoscopy, Tuttlingen, Germany). From the Department of Otolaryngology–Head and Neck Surgery (G.M., A.M.M., S.S., B.A.O., D.M.P., R.L.C.); and Department of Neurosurgery (B.A.O., D.M.P., R.L.C.), The Ohio State University, Columbus, Ohio, U.S.A. Editor’s Note: This Manuscript was accepted for publication July 5, 2018. Presented at the 121st Annual Meeting of the Triological Society Combined Otolaryngology Spring Meetings, National Harbor, Maryland, U.S.A., April 20–21, 2018. The authors have no funding, financial relationships, or conflicts of interest to disclose. Send correspondence to Ricardo L. Carrau, MD, Professor, Lynne Shepard Jones Chair in Head and Neck Oncology, Department of Otolaryngology–Head and Neck Surgery, The Ohio State University, 320 W 10th Avenue, Columbus OH 43210. E-mail: ricardo.carrau@osumc. edu; carraurl@gmail.com DOI: 10.1002/lary.27469 Laryngoscope 129: February 2019 Maza et al.: Modified EEA With a Transpalatal Approach 339 The Laryngoscope © 2018 The American Laryngological, Rhinological and Otological Society, Inc.