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Temporal bone thickness in Japanese pediatric patients: Implications for the timing of bone conduction device surgery
Shinya Ohira1, Fumihiro Mochizuki1, Mei Ueda2
1Department of Otolaryngology, St. Marianna University School of Medicine, Kawasaki, Kanagawa, Japan.
Insights
Western guidelines suggest bone conduction devices (BCDs) for children aged 5+, but Japanese children may need a later age. This study found Japanese children reach optimal temporal bone thickness for BCD implantation around 6-8 years old.
Area of Science:
- Otolaryngology
- Pediatric audiology
- Medical imaging
Background:
- Western guidelines recommend age ≥5 years for bone conduction device (BCD) implantation.
- Skeletal development differences may impact BCD applicability in Japanese children.
- Temporal bone thickness is crucial for safe BCD implantation.
Purpose of the Study:
- Determine the anatomically appropriate surgical age for BCD implantation in Japanese children.
- Measure temporal bone thickness in Japanese children using computed tomography (CT).
- Correlate age with temporal bone thickness to establish surgical candidacy criteria.
Main Methods:
- Analyzed head CT scans of 217 Japanese children (0-15 years).
- Measured temporal bone thickness at two sites: Baha® (upper) and Osia® (lower).
- Determined the age at which 3 mm bone thickness was achieved at each site.
Main Results:
- Bone thickness positively correlated with age in Japanese children.
- The Baha® site showed faster bone development from age 3 onwards.
- A 3 mm thickness threshold was reached by age 5.3 (50%) and 10.3 (90%) for Baha®, and 6.6 (50%) and 12.8 (90%) for Osia®.
Conclusions:
- A conservative surgical age of 6-8 years is recommended for Japanese children, differing from the Western 5-year standard.
- For children under 10 years, a 3 mm fixture is advised to prevent complications.
- Preoperative CT assessment is vital due to significant individual variations in temporal bone thickness.
Objective:
Western guidelines for bone conduction devices (BCDs) recommend implantation at age ≥5 years, but their applicability to Japanese children remains unclear due to potential racial differences in skeletal development. This study measured temporal bone thickness in Japanese children using computed tomography (CT) to determine the anatomically appropriate surgical age.
Methods:
We analyzed head CT images from 217 Japanese children (0-15 years) without temporal bone abnormalities. Bone thickness was measured 1 cm posterior to the sigmoid sinus at two points: the "upper level" (superior semicircular canal level; Baha® site) and "lower level" (lateral semicircular canal level; Osia® site). We analyzed age-thickness correlations and determined the age at which 3 mm thickness was achieved.
Results:
Bone thickness correlated positively with age. While no difference existed between sites at ages 0-2, the upper level developed more rapidly from age 3 onwards. The 3 mm thickness threshold was reached in 50% and 90% of cases at 5.3 and 10.3 years, respectively, for the Baha site, while it was 6.6 and 12.8 years for the Osia site.
Conclusion:
Anatomically, a conservative surgical indication age of 6-8 years is reasonable for Japanese children, compared with the Western 5-year standard. For children <10 years, a 3 mm fixture is preferred to prevent complications. The Baha site offers advantageous bone thickness in children >3 years. However, due to significant individual variation, preoperative CT assessment is very important.
