title: Round window chamber and fustis: endoscopic anatomy and surgical implications.
abstract: The round window region is of critical importance in the anatomy of the middle ear. The aim of this paper is to describe its anatomy from an endoscopic point of view, emphasizing structures that have important surgical implications, in particular the fustis and the subcochlear canaliculus. The fustis, a smooth bony structure that forms the floor of the round window region, is a constant and important structure. It seems to indicate the round window membrane and the correct position of scala tympani. A structure connecting the round window region to the petrous apex, named the subcochlear canaliculus, is also described. A retrospective review of video recordings of endoscopic dissection and surgical procedures, carried out between June 2014 and February 2015, was conducted across two Tertiary university referral centers. A total of 42 dissections were analyzed in the study. We observed the fustis in all the cases and we identify two different anatomical conformations. The subcochlear canaliculus was found in 81.0 %, with a pneumatization direct to the petrous apex in 47.7 %. Conformation and limits of the round window niche may influence the surgical view of the round window membrane. Endoscopic approaches allow a very detailed view, which enables a comprehensive exploration of the round window region. Accurate knowledge of the anatomical relationships of this region has important advantages during middle ear surgery.
authors.affiliation: Otolaryngology Department, University Hospital of Verona, Piazzale Stefani 1, Verona, Italy.
authors.forename: Daniele
authors.initials: D
authors.lastname: Marchioni
authors.affiliation: Otolaryngology Department, University Hospital of Verona, Piazzale Stefani 1, Verona, Italy.
authors.forename: Davide
authors.initials: D
authors.lastname: Soloperto
authors.affiliation: Otolaryngology Department, University Hospital of Verona, Piazzale Stefani 1, Verona, Italy. elenacolleselli@gmail.com.
authors.forename: Elena
authors.initials: E
authors.lastname: Colleselli
authors.affiliation: Otolaryngology Department, University Hospital of Verona, Piazzale Stefani 1, Verona, Italy.
authors.forename: Maria Fatima
authors.initials: MF
authors.lastname: Tatti
authors.affiliation: Kolling Deafness Research Centre, Royal North Shore Hospital and Macquarie University, Sydney, Australia.|Discipline of Surgery, Sydney Medical School, University of Sydney, Sydney, Australia.|Sydney Endoscopic Ear Surgery Research Group, Sydney, Australia.
authors.forename: Nirmal
authors.initials: N
authors.lastname: Patel
authors.affiliation: Kolling Deafness Research Centre, Royal North Shore Hospital and Macquarie University, Sydney, Australia.|Discipline of Surgery, Sydney Medical School, University of Sydney, Sydney, Australia.|Sydney Endoscopic Ear Surgery Research Group, Sydney, Australia.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Jufas
mesh_terms: D004724:Endoscopy; D006801:Humans; D013506:Otologic Surgical Procedures; D012189:Retrospective Studies; D012405:Round Window, Ear / Q000033:anatomy & histology*; D012533:Scala Tympani / Q000033:anatomy & histology
keywords: Endoscopic anatomy; Fustis; Middle ear; Round window region; Subcochlear canaliculus