title: The incidence of double hypoglossal canal in Japanese: evaluation with multislice computed tomography.
abstract: OBJECTIVE
  Double hypoglossal canal, namely a hypoglossal canal bridging, is a normal variation of the hypoglossal canal. Racial differences in the prevalence of double hypoglossal canal have been reported. We evaluated the prevalence of double hypoglossal canal in a Japanese population with multidetector computed tomography (MDCT).
  
  
  METHODS
  We reviewed five hundred and ninety consecutive patients (mean age, 61 years: range, 15-94 years: 254 men, 336 women) who underwent computed tomographic angiography (CTA) of the brain for a variety of CNS abnormalities. Two radiologists achieved consensus on the canal being single or double, and measured the sizes of single canals on CT images. Kappa statistics was used to test the reliability between the 2 investigators. A logistic regression was used to evaluate the prevalence of double hypoglossal canal and the following factors: sex, age, and laterality. Student's t-test was used to evaluate the asymmetry of single hypoglossal canal diameters. Statistical significance was accepted at P < 0.05.
  
  
  RESULTS
  Double hypoglossal canal was identified in 16.9% of the patients, and was bilateral in 2.2%. Double hypoglossal canal was significantly more frequent on the left side than right (P = 0.004, odds ratio = 1.79) and in males than females (P = 0.011, odds ratio = 1.67). A larger left or right-sided canal was found in 31.6% and 12.2% of the patients, respectively, following the same side preference as that of double hypoglossal canal. Almost perfect agreement was achieved between the two readers (k = 0.975).
  
  
  CONCLUSIONS
  In this Japanese population, the prevalence of a double hypoglossal canal was 16.9%, of which 2.2% were bilateral. Double hypoglossal canal was more frequent in males than females, and on the left side than right.
authors.affiliation: Department of Radiology, Teikyo University School of Medicine, Tokyo, Japan.
authors.forename: Tomonori
authors.initials: T
authors.lastname: Kanda
authors.affiliation: Department of Radiology, Teikyo University School of Medicine, Tokyo, Japan.
authors.forename: Tomoki
authors.initials: T
authors.lastname: Kiritoshi
authors.affiliation: Department of Radiology, Teikyo University School of Medicine, Tokyo, Japan.
authors.forename: Marie
authors.initials: M
authors.lastname: Osawa
authors.affiliation: Department of Radiology, Teikyo University School of Medicine, Tokyo, Japan.
authors.forename: Keiko
authors.initials: K
authors.lastname: Toyoda
authors.affiliation: Department of Radiology, Teikyo University School of Medicine, Tokyo, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Oba
authors.affiliation: Department of Radiological Technology Faculty of Medical Technology, Teikyo University School of Medicine, Tokyo, Japan.
authors.forename: Jun'ichi
authors.initials: J
authors.lastname: Kotoku
authors.affiliation: Department of Radiology, Kobe University Graduate School of Medicine, Kobe, Japan.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Kitajima
authors.affiliation: Department of Radiology, Teikyo University School of Medicine, Tokyo, Japan.
authors.forename: Shigeru
authors.initials: S
authors.lastname: Furui
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000792:Angiography; D005260:Female; D006801:Humans; D015994:Incidence; D007564:Japan / Q000453:epidemiology; D008297:Male; D008334:Mandible / Q000000981:diagnostic imaging*; D008875:Middle Aged; D061330:Multidetector Computed Tomography; D055815:Young Adult