[CT study on the development of facial nerve canal in children]

Objective: To assess the characteristics of facial nerve canal between normal anatomy and dysplasia of children in different ages. Methods: A total of 492 health ears were divided into six groups, neonatal group (<1 m , n=42), infancy group(1 m-1 y, n=106), toddler group(1-3 y, n=102), preschool group (3-6 y, n=100), school group(6-10 y, n=60)and adolescent group (10-14 y, n=82). The length and diameter of facial nerve canal and that angles of first and second genu were measured with CT in each group. Results: ①The lengths of facial nerve canal in neonatal and infancy group were shorter than other four groups, especially in the mastoid segments of facial nerve canal. The lengths of mastoid segments in neonatal, infancy, toddler, preschool, school and adolescent groups were 5.03±0.84, 6.25±1.40, 8.34±1.38, 9.70±1.34, 10.84±1.41 and 12.17±1.83 mm, with P<0.05, respectively. After school age, the lengths of labyrinthine and tympanic segment grew slowly or developed completely (P>0.05). ② The diameter of labyrinth and tympanic segment in neonatal group were narrower than other five groups (P<0.05), but no significant difference among them in other groups (P>0.05). ③The dysplasia of facial nerve canal were occurred on 978 locations. Among them, the percentage of dehiscence, aberrance, partially expanding and bifurcation were 72.9%(713/978), 5.1%(50/978), 18.9%(185/978) and 3.1%(30/978) respectively. The percentage of dehiscence in geniculate fossa segment was decreased significantly with age (neonatal group 85.7%(36/42), infancy group 59.4%(63/106), toddler group 39.2%(40/102), preschool group 33%(33/100), school group 30%(18/60)and adolescent group 26.8%(22/82), with P<0.05). Except the dehiscence of geniculate fossa and mastoid segment, there was no significant difference in the occurrence rate of the other variants (P>O.05). Conclusions: The growth of length and dehiscence in labyrinth segment of facial nerve canal are significant in difference ages. The changes of diameter and angles of first and second genu in facial nerve canal, and the rate of other dysplasia are individual.