Objectives 1) Identify anatomic variations of the temporal bone in children with and without cochlear malformations who experienced an intra-operative cerebrospinal fluid (CSF) gusher at the time of cochlear implantation. 2) Compare the anatomic findings in the current study to those described in prior studies. Methods A retrospective case-controlled chart review was performed on patients undergoing cochlear implant surgery. Computerized tomography images were analyzed in a single-blind fashion for characteristics and measurements of both the right and left cochlea, internal auditory canal, cochlear aperture, facial nerve canal, vestibular aqueduct, cochlear aqueduct, oval window, round window, vestibule, mastoid, tegmen tympani and semi-circular canals. After verifying equal variances, data was statistically evaluated utilizing the paired 2-tailed t test with criterion for statistical significance set at p < 0.05. Results The average age at implantation for this series of children was 4 years old. 70% of patients had cochlear malformations. 25% of patients had an abnormal internal auditory canal (IAC) and 30% had a widened cochlear aperture. Most patients with an abnormal IAC had an abnormal cochlear aperture; however, some patients with a normal IAC also had an abnormal cochlear aperture. Correlations between the temporal bone anatomy and the incidence of CSF gushers will be discussed. Conclusions Specific characteristics of the temporal bone anatomy may lead to an increased incidence of CSF gusher in cochlear implant surgery. Computerized tomography of the temporal bone can assist in the surgeon in evaluation and planning for cochlear implantation.
Evaluation of the positional accuracy of the RoboJig for minimally invasive cochlear implant surgery