title: The cochlea in skull base surgery: an anatomy study.
abstract: OBJECTIVE The object of this study was to examine the relationships of the cochlea as a guide for avoiding both cochlear damage with loss of hearing in middle fossa approaches and injury to adjacent structures in approaches directed through the cochlea. METHODS Twenty adult cadaveric middle fossae were examined using magnifications of ×3 to ×40. RESULTS The cochlea sits below the floor of the middle fossa in the area between and below the labyrinthine segment of the facial nerve and greater petrosal nerve (GPN) and adjacent to the lateral genu of the petrous carotid. Approximately one-third of the cochlea extends below the medial edge of the labyrinthine segment of the facial nerve, geniculate ganglion, and proximal part of the GPN. The medial part of the basal and middle turns are the parts at greatest risk in drilling the floor of the middle fossa to expose the nerves in middle fossa approaches to the internal acoustic meatus and in anterior petrosectomy approaches. Resection of the cochlea is used selectively in extending approaches through the mastoid toward the lateral edge of the clivus and front of the brainstem. CONCLUSIONS An understanding of the location and relationships of the cochlea will reduce the likelihood of cochlear damage with hearing loss in approaches directed through the middle fossa and reduce the incidence of injury to adjacent structures in approaches directed through the cochlea.
authors.affiliation: 1Department of Neurosurgery/Neuro-Oncology, Sun Yat-sen University Cancer Center, Guangzhou, Guangdong, People's Republic of China.
authors.forename: Jian
authors.initials: J
authors.lastname: Wang
authors.affiliation: 4Department of Neurosurgery, University of Florida, Gainesville, Florida.
authors.forename: Fumitaka
authors.initials: F
authors.lastname: Yoshioka
authors.affiliation: 2Department of Neurosurgery, Catholic University of Korea, Uijeongbu St. Mary's Hopsital, Gyeonggi-do, Korea.
authors.forename: Wonil
authors.initials: W
authors.lastname: Joo
authors.affiliation: 3Department of Otorhinolaryngology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan; and.|4Department of Neurosurgery, University of Florida, Gainesville, Florida.
authors.forename: Noritaka
authors.initials: N
authors.lastname: Komune
authors.affiliation: 4Department of Neurosurgery, University of Florida, Gainesville, Florida.
authors.forename: Vicent
authors.initials: V
authors.lastname: Quilis-Quesada
authors.affiliation: 4Department of Neurosurgery, University of Florida, Gainesville, Florida.
authors.forename: Albert L
authors.initials: AL
authors.lastname: Rhoton
mesh_terms: D002102:Cadaver; D003051:Cochlea / Q000033:anatomy & histology*; D006801:Humans; D019291:Skull Base / Q000033:anatomy & histology* / Q000601:surgery*
keywords: GPN = greater petrosal nerve; cochlea; facial nerve; internal acoustic meatus; internal carotid artery; microsurgical anatomy; skull base surgery