Nervus Intermedius Guides Auditory Brainstem Implant Surgery in Children with Cochlear Nerve Deficiency

Area of Science:

• Neurosurgery
• Pediatric Otology
• Auditory Implants

Background:

• Cochlear nerve deficiency presents surgical challenges for auditory brainstem implant (ABI) placement.
• Precise identification of neuroanatomical landmarks is crucial for successful ABI surgery in children.

Purpose of the Study:

• To investigate the anatomy of the nervus intermedius and cranial nerve VII in children with cochlear nerve deficiency.
• To determine if the nervus intermedius can serve as an additional landmark for guiding ABI electrode placement.

Main Methods:

• Retrospective chart review and analysis of high-definition videos from retrosigmoid surgeries in 64 children undergoing ABI placement.
• Examination of nervus intermedius bundles and associated facial nerve anomalies.

Main Results:

• Cranial nerve VI, VII, and VIII absence was noted in 3, 6, and all 64 children, respectively.
• Facial nerve abnormalities were present in 15 children.
• The nervus intermedius was identifiable in 46 children (with intraoperative monitoring assistance in 12), varying from 1 to 6 bundles. It aided in identifying the foramen of Luschka.

Conclusions:

• The nervus intermedius is consistently identifiable and serves as a valuable landmark in pediatric ABI surgery.
• This study provides the first description of nervus intermedius anatomy and its relationship to surrounding structures in children with cochlear nerve deficiency.