Images on the Way to the Cochlear Nucleus Complex for Auditory Brainstem Implantation in Children

Abstract

Objectives: Identify and differentiate among the cranial nerves (CN) and vessels close to the foramen of Luschka (FL) and improve the understanding of the normal and abnormal microanatomy in children with cochlear nerve deficiency (CND) fitted with auditory brainstem implants (ABI). Methods: From 2000 to 2013, 64 children ranging in age from 8 months to 16 years (2.92 ± 1.54) with CND and several degrees of cochlear abnormalities were video-recorded during retrosigmoid surgery for ABI fitting. Four independent experts retrospectively examined all the videos. CNs VI, VII, IX, X, XI and the vascular structures around the FL were identified either by surgical inspection and/or intraoperative neurophysiological monitoring. Results: Cranial nerves VI, VII, VIII were absent respectively in 3, 8 and 64 children; CN VII had an aberrant course in the CPA in 18 children; bifurcated in 4 and trifurcated in 3; CNs IX, X and XI were observed in all children; a double CN XI was observed in 2 children; and the nerve root bundles of the cranial and spinal segment of CN XI were identified in 48 and 52 children, respectively. Landmarks useful in identifying the FL included the nervus intermedius, CNs VII and IX, and the choroid plexus of the lateral recess. Conclusions: The collection of surgical images allowed a successful display of the detailed normal and abnormal anatomy of the CNs and vessels around the area of the FL. These data have the potential to facilitate an uneventful approach to the FL and a correct insertion of the ABI array.