title: Critical distance between the cartilaginous Eustachian tube and the internal carotid artery.
abstract: During the last decade, endoscopic surgery of the Eustachian tube (ET) has been advocated for ET dilatory dysfunction and for patulous ET. The internal carotid artery (ICA) and the ET are closely related, and knowledge of their surgical anatomy has become essential. This study was designed to establish the anatomical relationships between the endoscopically critical area along the full length of the cartilaginous ET and its closest association with the ICA. The perpendicular distance between the ET lumen and the ICA was measured from head magnetic resonance images (MRI) at three levels: (A) cartilaginous and bony ET junctional point, (B) mid cartilaginous ET point, and (C) the nasopharyngeal orifice of the cartilaginous ET. Totally, 200 sides were reviewed in MRI scans of 229 patients. The mean distances for each level were: A = 4.3 mm (range 1.6-10.4 mm), B = 25 mm (range 9.0-61.6 mm), and C = 62 mm (range 34.3-84.4 mm). The perpendicular distance between ET and ICA at the nasopharyngeal orifice is large, but the distance shortens quickly while moving from the nasopharyngeal orifice of the ET to the junctional point of the ET. The potential for complications to the ICA rises as the surgical field moves closer to the isthmus of the ET because of the decreasing distance between the ET and the ICA.
authors.affiliation: Department of Otorhinolaryngology, School of Medicine, University of Tampere, Tampere, Finland.
authors.forename: Heidi
authors.initials: H
authors.lastname: Olander
authors.affiliation: Department of Radiology, Medical Imaging Center, Tampere University Hospital, Tampere, Finland.
authors.forename: Jorma
authors.initials: J
authors.lastname: Järnstedt
authors.affiliation: Department of Otolaryngology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA.
authors.forename: Dennis
authors.initials: D
authors.lastname: Poe
authors.affiliation: Department of Otorhinolaryngology, School of Medicine, University of Tampere, Tampere, Finland. ilkka.kivekas@pshp.fi.|Department of Ear and Oral Diseases, Tampere University Hospital, PL 200, 33521, Tampere, Finland. ilkka.kivekas@pshp.fi.
authors.forename: Ilkka
authors.identifier: http://orcid.org/0000-0002-6931-3641
authors.initials: I
authors.lastname: Kivekäs
mesh_terms: D000328:Adult; D000368:Aged; D002343:Carotid Artery, Internal / Q000033:anatomy & histology*; D004724:Endoscopy; D005064:Eustachian Tube / Q000033:anatomy & histology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009305:Nasopharynx / Q000033:anatomy & histology*
keywords: Eustachian tube; Internal carotid artery; MRI