The fully updated comprehensive anatomical guide on surgery of the paranasal sinuses and skull base As in the acclaimed prior editions, Endoscopic Sinus Surgery, Fourth Edition focuses strictly on anatomy, 3D reconstruction, and step-by-step surgical techniques. Written by Peter-John Wormald, the richly illustrated text details anatomy and operative treatment of sinonasal conditions such as nasal polyposis, chronic rhinosinusitis (CRS), Samter's triad, eosinophilic mucus CRS, exophthalmos, acute orbital hemorrhage, orbital subperiosteal abscess, and a wide array of tumors. The fourth edition reflects simplified anatomical nomenclature published in 2016 by Wormald et al, including reclassification of cells in the frontal recess and the extent of surgery of frontal sinus surgery (EFSS). This enables clearer understanding of impacted anatomy, most notably the frontal sinus drainage pathways. New and revised evidence-based procedures include the mega-antrostomy and pre-lacrimal approach to the maxillary sinus and use of anterior based pedicled flaps for frontal drillout. Refinements in other surgical techniques include endoscopic medial maxillectomy and resection of sinonasal neoplasms. Anatomy and surgical approaches elucidated through 1,000 images including CTs, illustrations, and diagrams Exquisite dissections by Rowan Valentine, who worked in the anatomy laboratory of the late Albert L. Rhoton Jr., internationally renowned author, educator, brain anatomist, and neurosurgeon Delineation of variations in frontal recess anatomy and difficult regions adjacent to the sinuses provides important surgical guidance Seventy operative videos detail potential anatomical variations seen in the frontal sinuses, ancillary procedures such as DCR, orbital decompression, CSF leak closure, and skull base surgical approaches This classic reference is a must-have for otolaryngologist-head and neck surgeons, as well as residents and fellows seeking a robust tutorial on the latest functional endoscopic sinus surgery (FESS) techniques. It enables 3D understanding of diseased anatomy, associated surgical treatment decision making, and safer surgery.