title: High resolution CT study of the chorda tympani nerve and normal anatomical variation.
abstract: OBJECTIVE
  The aim of this study was to define the normal anatomical variation of the course of the CTN through the mastoid temporal bone on high resolution CT (HRCT).
  
  
  METHODS
  Retrospective review of 27 consecutive normal HRCT bilateral temporal bones (n = 54, 14 males and 13 females, mean age 41 years) reconstructed at 0.4-mm slice thickness specifically measuring (1) origin of CTN from the posterior genu of the facial nerve (CNVII) and (2) the lateral-most position of the CTN from the mastoid segment of CNVII.
  
  
  RESULTS
  The mean distance of the CTN origin from the mastoid segment of CNVII was 11.5 mm (standard deviation, SD = 3.2, 95% CI 10.7-12.3) with no statistically significant difference between the left and right side observed (p = 0.08). The most lateral distance of the CTN from CNVII was a mean of 1.3 mm (SD = 0.6, 95% CI 1.2-1.7), range 0-2.5 mm and again no statistical significance between contralateral sides was observed (p = 0.11). These measurements demonstrated an excellent level of agreement between observers as assessed by intraclass correlation calculation.
  
  
  CONCLUSIONS
  Reproducible measurements demonstrate variability of the CTN in both its origin from the mastoid segment of CNVII and its lateral-most course. Precise description of the course of the CTN with HRCT may be useful for planning of otologic surgery and limiting inadvertent nerve injury.
authors: Department of Medical Imaging, Gold Coast University Hospital, 1 Hospital Boulevard, Gold Coast, QLD, 4215, Australia, dsingh1386@gmail.com.
authors: Dalveer
authors: D
authors: Singh
authors: Charlie Chia-Tsong
authors: CC
authors: Hsu
authors: Gigi Nga Chi
authors: GN
authors: Kwan
authors: Sandeep
authors: S
authors: Bhuta
authors: Matt
authors: M
authors: Skalski
authors: Rhondda
authors: R
authors: Jones
mesh_terms: D000328:Adult; D002814:Chorda Tympani Nerve / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008297:Male; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed