title: The sensitivity and accuracy of a cone beam CT in detecting the chorda tympani.
abstract: The facial recess approach through posterior tympanotomy is the standard approach in cochlear implantation surgery. The size of the facial recess is highly variable, depending on the course of the chorda tympani. Despite their clinical importance, little is known about the sensitivity and accuracy of imaging studies in the detection of the chorda tympani. A total of 13 human temporal bones were included in this study. All of the temporal bones were submitted to a cone beam CT (Accuitomo, Morita, Japan). The multi-planar reconstruction images were rotated around the mastoid portion of the facial nerve to locate the branches of the facial nerve. A branch was diagnosed as the chorda tympani when it entered the tympanic cavity near the notch of Rivinus. The distance between the bifurcation and the tip of the short crus of the incus was measured. In all temporal bones, the canal of the chorda tympani or the posterior canaliculus was detected. In the CT-based evaluation, the average distance from the bifurcation to the incus short crus was 12.6 mm (8.3-15.8 mm). The actual distance after dissection was 12.4 mm (8.2-16.4 mm). The largest difference between the distances evaluated with the two procedures was 1.1 mm. Cone beam CT is very useful in detecting the course of the chorda tympani within the temporal bone. The measured distance is accurate.
authors.affiliation: Department of Otolaryngology, Head and Neck Surgery, Iwate Medical University, 19-1, Uchimaru, Morioka, Iwate, 020-8505, Japan. hhiraumi@ent.kuhp.kyoto-u.ac.jp.|Department of Otolaryngology, Head and Neck Surgery, Kyoto University, Graduate School of Medicine, Kyoto, Kyoto, Japan. hhiraumi@ent.kuhp.kyoto-u.ac.jp.
authors.forename: Harukazu
authors.initials: H
authors.lastname: Hiraumi
authors.affiliation: Department of Otolaryngology, Head and Neck Surgery, Kyoto University, Graduate School of Medicine, Kyoto, Kyoto, Japan.
authors.forename: Ryo
authors.initials: R
authors.lastname: Suzuki
authors.affiliation: Department of Otolaryngology, Head and Neck Surgery, Kyoto University, Graduate School of Medicine, Kyoto, Kyoto, Japan.
authors.forename: Norio
authors.initials: N
authors.lastname: Yamamoto
authors.affiliation: Department of Otolaryngology, Head and Neck Surgery, Kyoto University, Graduate School of Medicine, Kyoto, Kyoto, Japan.
authors.forename: Tatsunori
authors.initials: T
authors.lastname: Sakamoto
authors.affiliation: Department of Otolaryngology, Head and Neck Surgery, Kyoto University, Graduate School of Medicine, Kyoto, Kyoto, Japan.
authors.forename: Juichi
authors.initials: J
authors.lastname: Ito
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002102:Cadaver; D002814:Chorda Tympani Nerve / Q000000981:diagnostic imaging*; D019929:Cochlear Implantation; D054893:Cone-Beam Computed Tomography / Q000379:methods*; D004432:Ear, Middle / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D015203:Reproducibility of Results; D013701:Temporal Bone / Q000000981:diagnostic imaging*
keywords: Chorda tympani; Cochlear implant; Computed tomography; Facial nerve; Posterior canaliculus; Posterior tympanotomy