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Published on: January 9, 2019
Cochlear Implant Outcomes in Cochlea Nerve Aplasia and Hypoplasia
Catherine S Birman1, Harry R F Powell, William P R Gibson
1*Discipline of Paediatrics and Child Health, Sydney Medical School, University of Sydney †Sydney Children's Hospital Network (Children's Hospital at Westmead) ‡The Sydney Cochlear Implant Centre §Sydney Medical School, University of Sydney ||Department of Linguistics, Faculty of Human Sciences, Macquarie University, Sydney, NSW, Australia ¶The Royal National Throat Nose and Ear Hospital, London, U.K.
Insights
Cochlear implants can improve communication for children with cochlear nerve issues. Aplasia or hypoplasia of the cochlear nerve impacts outcomes, but many children still achieve some verbal understanding.
Area of Science:
- Otolaryngology
- Pediatric Audiology
- Neurosurgery
Background:
- Cochlear implantation (CI) outcomes in children with cochlear nerve (CN) aplasia/hypoplasia are not well-defined.
- Accurate assessment of the internal auditory meatus (IAM) and CN is crucial for predicting CI success.
Purpose of the Study:
- To evaluate CI outcomes in children with CN aplasia/hypoplasia.
- To identify factors influencing outcomes, including developmental delay.
- To introduce a novel grading system for IAM and CN morphology.
Main Methods:
- Retrospective review of pediatric CI recipients (0-16 years) with absent/hypoplastic CN on MRI.
- Analysis of audiological data (e.g., Categories of Auditory Perception scores) and communication modes.
- Development and application of a new IAM/CN grading system.
Main Results:
- Fifty children with CI and CN anomalies were analyzed; 64% had CN aplasia and 25% hypoplasia.
- Developmental delay and CN aplasia/hypoplasia significantly affected the main mode of communication.
- Children with CN hypoplasia (IAM grade IV) showed significantly better auditory performance (89% achieving CAP scores 5-7) than those with aplasia (47% achieving CAP scores 5-7).
Conclusions:
- CI can yield positive outcomes even in children with cochlear nerve anomalies.
- The developed grading system aids in predicting auditory performance and counseling families.
- Results support the use of CI and provide valuable prognostic information for affected children.
Objective:
To assess cochlear implant (CI) outcomes, and factors affecting outcomes, for children with aplasia/ hypoplasia of the cochlea nerve. We also developed a new grading system for the nerves of the internal auditory meatus (IAM) and cochlea nerve classification.
Study Design:
Retrospective patient review.
Setting:
Tertiary referral hospital and cochlear implant program.
Patients:
Children 0 to 16 years inclusive with a CI who had absent/hypoplastic cochlea nerve on magnetic resonance imaging (MRI).
Intervention:
Cochlear implant.
Main Outcome Measures:
MRI, trans-tympanic electrical auditory brainstem response, intraoperative electrical auditory brainstem response, Neural Response Telemetry, Categories of Auditory Perception score, Main mode of communication.
Results:
Fifty CI recipients (26 males and 24 females) were identified, 21 had bilateral CIs, 27 had developmental delay. MRI showed cochlea nerve aplasia in 64 ears, hypoplasia in 25 ears, and a normal nerve in 11 ears. Main mode of communication was analyzed for 41 children: 21 (51%) used verbal language (15 speech alone, 5 speech plus some sign, 1 bilingual in speech and sign), and 20 (49%) used sign language (10 sign alone, 9 sign plus some speech, 1 tactile sign). Seventy-three percent of children used some verbal language. Cochlea nerve aplasia/ hypoplasia and developmental delay were both significant factors affecting main mode of communication. Categories of Auditory Performance scores were available for 59 CI ears; 47% with CN Aplasia (IAM nerve grades 0-III) and 89% with CN hypoplasia (IAM nerve grade IV) achieved Categories of Auditory Performance scores of 5 to 7 (some verbal understanding) (p = 0.003).
Conclusion:
Our results are encouraging and useful when counselling families regarding the likelihood of language outcomes and auditory understanding.
