Spontaneous bone bed formation in pediatric cochlear implantation is associated with duration of implantation.

Objectives: This study investigated the long-term postoperative spontaneous formation of a bone bed in pediatric cochlear implant patients for whom no bone bed was drilled during the surgery.

Methods: A cross-sectional observational study of skull thickness under and on the edges of the cochlear implant receiver/stimulator in children with computed tomography (CT scan) ≥6 months after implantation was performed. In total, 37 pediatric patients from a single tertiary center underwent cochlear implantation without bone bed drilling and with screw fixation of the receiver/stimulator.

Results: The patients were on average 36.2 ± 20.5 months at implantation (range 8-96 months). At the time of the CT scan, the average duration of implantation was 25.3 ± 17.9 months (range 6-91 months). The average depth of the bone bed that formed spontaneously since implantation was 1.83 ± 0.39 mm (range 0.39-3.04 mm). Linear regression identified that the depth of the bone bed increased significantly with duration of implantation (β = 0.389, p = 0.009), but age at implantation was not associated with bone bed depth.

Conclusions: A spontaneously formed temporal bone bed was observed in pediatric CI patients already six months after implantation. A deeper bone bed was measured in children who have had their CI for a longer period. A spontaneously formed bone bed is likely to combine the benefits of a surgically drilled bone bed, whilst limiting the duration of the surgery and thereby associated costs.