Cochlear trajectory in pediatric patients

Abstract

Objectives/hypothesis: As cochlear implantation increases, surgeons are noting possible anatomical differences in pediatric population. Outcome objectives were to study pediatric temporal bone anatomy using high-resolution temporal bone imaging, and analyze the anatomical differences in group 1 (<12 months) versus group 2 (1-4 years) versus group 3 (5-10 years) versus group 4 (10-18 years).

Study design: Retrospective chart and radiologic review.

Methods: A retrospective chart and radiologic review of pediatric patients undergoing high-resolution computer tomography of the temporal bones from April 2001 to February 2013 was conducted. Scans were reviewed to record the transmastoid angle and transcanal angle.

Results: Seven hundred fifty patients were identified. A total of 1,426 ears were reviewed. The age range was 8 days to 21 years. Of the patients, 57.0% (n = 407) were male. The patients were divided into four groups: group 1 (<12 months), group 2 (1-4 years), group 3 (5-10 years), and group 4 (10-18 years). The transmastoid angle was observed to have variability. Significant differences were observed between groups 2 and 3 (P = .0028) and groups 2 and 4 (P = .0432). Analysis on the transcanal angle was performed. Significant differences existed between age groups 1 and 3 (P = .0150), groups 1 and 4 (P = .0038), and groups 2 and 4 (P = .0358).

Conclusions: Considerable variation exists in pediatric temporal bones. The largest difference in the transmastoid angle was seen in children aged 1 to 4 years. The largest variability in the transcanal angle is between the infant (<12 months) and children >4 years of age. These differences are surgically relevant for round window identification and facial nerve safety during cochlear implant surgery in infants.

Keywords: Cochlear implant; cochlear anatomy; electrode trajectory.