| Objective: To measure the normal values of external, middle and inner ear of Chinese children from 0 year to 15 years and to study normal imaging characteristics of temporal bone in order to aid for clinical treatment, research and teaching.Methods:96 cases between 0 to 15 years randomly chosen in pediatric hospital of Shanxi province were performed multi-slice spiral CT(MSCT) scanning who showed no obvious ear abnormality. After acquiring original images, multi-planar reformation(MPR) was performed to obtain measurement layer. And then the main structures of temporal bone were measured and recorded. The results were analyzed and compared between groups of different ages or sex.Results:(1) external ear: The antero-posterior distance of external auditory meatus isthmus was 3.58±0.83mm. (2) middle ear: The length and width of the epitympanic recess was 4.18±1.13mm and 3.47±0.82mm respectively. The antero-posterior distance of attic was 6.90±1.02mm, while the left-to-right distance 5.58±0.88mm, width of aditus ad antrum 2.50±0.57mm, depth of antrum tympanicum 10.60±3.01mm, depth of sinus tympani 3.19±0.80mm. (3) inner ear: The height of cochlear was 3.63±0.54mm, while the length and width of the basal turn were 6.15±1.05mm and 1.27±0.28mm. The superior-to-inferiorand left-to-right distance of vestibule were 5.43±0.50mm and 2.86±0.35mm. The LSCC and SSCC bony island width was 3.93±0.52mm and 6.10±0.63mm respectively. The length, aperture and width of the internal acoustic meatus was 6.53±1.05mm,5.76±1.64mm and 4.31±0.83mm, respectively. The transverse diameter of cochlear nerve foremen was 2.12±0.51mm. (4) facial nerve:The length and width of the labyrinthinesegment was 3.04±0.68mm and 0.88±0.38mm. The length of the tympanic facial canal was 9.40±3.15mm, and the shortest distance between it and short crus of incus tip was 2.41±0.79mm. The distance from the mastoid facial canal to the posterior wall of external auditory meatus, to posterior edge of external acoustic pore and to the anterior wall of groove of sigmoid sinus(GSS) was 2.74±0.63mm,14.6±4.39mm and 11.18±1.55mm, respectively. (5) mastoid process:Its height was 22.49±9.18mm, antero-posterior distance 18.96±5.44mm. The distance between sigmoid sinus and the posterior wall of external auditory meatus was 12.94±1.71mm. (6) There was no significant difference in the values between different sex, and between different age groups for the length of epitympanic recess, left-to-right distance of attic, width of aditus ad antrum, cochlear height, vestibule, LSCC bony island width, SSCC bony island width, transverse diameter of cochlear nerve foremen, the shortest distance between tympanic facial canal and short crus of incus tip, distance from the mastoid facial canal to the anterior wall of GSS. The isthmus of the external auditory meatus, sinus tympani, the length and width of basal turn of cochlear, the length and width of the internal acoustic meatus and the distance between the mastoid facial canal to the posterior wall of external auditory meatus or to posterior edge of external acoustic pore developed distinctly in 1 year. Epitympanic recess development after birth mainly embodied in its width. The antero-posterior distance of attic grew distinctly before 5 years. Antrum tympanicum developed during 1 to 5 years. The aperture of the internal acoustic meatus and width of facial nerve labyrinthinesegment changed mainly between 1 to 10 years. The tympanic facial canal length, mastoid process and the distance between sigmoid sinus and the posterior wall of external auditory meatus kept growing before 15 years. changed distinctly in 1 year.Conclusion:(1) The diagnostic criteria,<4mm, for bony external auditory canal stenosis could not be applied to children before 6 years. The study about bony external acoustic meatus might be performed from 2 months old children. (2) The age factor could not affect significantly on bony structure of cochlear, vestibule and semicircular canal among the structure of inner ear. (3) There are different characteristics for development of most structure of external, middle ear and internal acoustic meatus, which suggests that age factor should be sufficiently considered for clinic diagnosis and surgeon.
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