ENDOSCOPIC TRANSMAXILLARY APPROACHES TO THE SKULL BASE Anatomy, Step-by-Step Guide, and Case Examples Hasan ZAIDI, Ali ELHADI, Douglas HARDESTY and Andrew S. LITTLE ENDOSCOPIC TRANSMAXILLARY APPROACHES TO THE SKULL BASE Anatomy, Step-by-Step Guide, and Case Examples Hasan ZAIDI,* Ali ELHADI,* Douglas HARDESTY* and Andrew S. LITTLE* *| MD, Barrow Pituitary and Cranial Base Center and the Barrow Neurosurgery Research Laboratory, Phoenix, AZ, USA 4 Endoscopic Transmaxillary Approaches to the Skull Base Illustrations by: Endoscopic Transmaxillary Approaches Mr. Satyen Tripathi to the Skull Base – Anatomy, Step-by-Step Guide, www.stillustration.com and Case Examples E-mail: [email protected] Hasan Zaidi,* Ali Elhadi,* Douglas Hardesty* and Andrew S. Little* * | MD, Barrow Pituitary and Cranial Base Center and the Barrow Neurosurgery Research Laboratory, Phoenix, AZ, USA Correspondence address of the author: Andrew S. 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Thus, no liability shall be accepted for content within the 3rd party publication(s) or 3rd party websites and no guarantee is given for any other work or any other websites at all. ISBN 978-3-89756-819-8 Endoscopic Transmaxillary Approaches to the Skull Base 5 Table of Contents 1 Introduction to Endoscopic Transmaxillary Approaches . 6 1.1. Introduction . 6 1.2. History and Evolution of Transmaxillary Approaches . 6 1.3. Surgical Indications . 7 1.4. Clinical Evaluation . 8 1.5. Diagnostic Imaging . 8 1.6. Surgical Planning and Approach Selection . 8 1.7. Endoscopic Instrumentation . 9 1.8. Operative Set-Up and Surgical Ergonomics. 9 2 Anatomical Review . 10 2.1. Nasal Cavity . 10 2.2. Maxillary Sinus . 11 2.3. Sphenoid Sinus . 12 2.4. Pterygopalatine Fossae . 13 2.5. Infratemporal Fossa . 13 2.6. Internal Maxillary Artery (IMA) . 13 3 Endoscopic Transmaxillary Approaches and Variations . 13 3.1. Endoscopic Endonasal Transmaxillary Approach . 14 3.1.1. Nasal Stage . 14 3.1.2. Maxillary Sinus Stage . 14 3.2. Endoscopic Sublabial Anterior Antrostomy Transmaxillary Approach . 15 3.2.1. Surgical Technique . 16 3.2.2. Transpterygoid Extension . 16 3.3. Utility of Combined Surgical Approaches . 16 3.4. Surgical Pitfalls and Clinical Pearls . 16 3.5. Postoperative Endoscopic Transmaxillary Approach Management . 16 4 Case Examples . 17 4.1. Case 1 . 17 4.2. Case 2 . 17 4.3. Case 3 . 17 5 References . 18 6 Endoscopic Transmaxillary Approaches to the Skull Base 1 Introduction to Endoscopic Transmaxillary Approaches 1.1. Introduction The endoscopic transmaxillary corridor is a versatile visualization that previously would have required more avenue to address diverse skull base pathology in extensive surgical approaches and tissue destruction.3 challenging anatomical regions of the anterolateral In general, endoscopic approaches through the maxillary skull base.10 Because of enhanced collaboration with sinus utilize the nasal cavity (i.e. endonasal transmaxillary otolaryngology, improved endoscopy equipment and approach) or direct anterior approach through a sublabial surgical instrumentation, and improved conceptual incision (i.e. sublabial transmaxillary approach). While understanding of the relevant anatomical constraints, each approach has its unique benefi ts and limitations, endoscopic transmaxillary approaches are increasingly they have both been used to access neoplasms such being offered to patients as minimal access alternatives as juvenile nasal angiofi bromas, schwanommas, to open approaches. These robust approaches exploit chordomas, spontaneous spinal fl uid leaks, and the maxillary sinus, a large air-fi led space adjacent to meningoencephaloceles amongst other lesions.1 In this traditionally diffi cult-to-access anatomical regions, such reference manual, we will review the relevant anatomy of as the pterygopalatine fossa, infratemporal fossa, the region, provide a step-by-step guide to performing cavernous sinus, and jugular fossa. Endoscopy can transmaxillary approaches, and describe illustrative case exploit this space to provide maneuverability and superior examples. 1.2. History and Evolution of Transmaxillary Approaches Open, microsurgical transfacial or sublabial transmaxillary has evolved in parallel to endonasal transsphenoidal approaches to the anterolateral skull base have been endoscopy. Seminal work by teams in Pittsburgh, USA utilized by otolaryngologists and neurosurgeons since (Drs. Jho, Carrau, Prevedello, Snyderman and Kassam ),6, 7 the time of Harvey Cushing. Drs. Caldwell and Luc in Naples, Italy (Drs. Cappabianca, de Divitiis and Cavallo), each approached the maxillary sinus in an open fashion and Bologna, Italy (Drs. Frank and Pasquini) expanded via the sublabial approach that now bears their names the use of skull base endoscopy beyond the sella and in the last decade of the 1800s.10 In the late 1960s, pituitary to include regions of the anterior skull base Fisch et al. described the infratemporal fossa approach traditionally addressed through open approaches.2 The for maxillary sinus lesions, which became a popular endoscopic tranxmaxillary approach to the anterolateral approach among open skull base surgeons.9 For most of skull base has been refi ned for the last two decades. A the 20th century, such approaches were performed using plethora of literature regarding all endoscopic approaches, loupe magnifi cation. The advent of the surgical micro- including the transmaxillary approach, has dominated the scope refi ned these approaches in the latter half of the publications of skull base surgery in the 21st century. 20th century.5 The endoscopic transmaxillary approach Endoscopic Transmaxillary Approaches to the Skull Base 7 1.3. Surgical Indications A wide area of the anterolateral cranial base can be including the middle cranial fossa, cavernous sinus, accessed