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Determining ideal electrode insertion depth in paediatric cochlear implantation
Mohammed Rami1, Youssef Lakhdar, Mohamed Chehbouni2
1Department of Otolaryngology and Head and Neck Surgery, Faculty of Medicine and Pharmacy, Mohammed VI University Hospital, Cadi Ayyad University, Marrakech, Morocco. dr.rami.orl@gmail.com.
Background:
Speech and language outcomes following early cochlear implantation vary widely among patients. Identifying modifiable, device-specific surgical parameters contributing to this variability is essential to optimise therapeutic outcomes.
Objective:
This study investigates the association between electrode angular depth of insertion (aDOI) and speech perception outcomes in a homogeneous cohort of children implanted with a single lateral wall electrode design.
Methods:
A cohort of 25 prelingually deaf children, aged 4 to 5 years at implantation, received unilateral Oticon Neuro ZTI cochlear implants at Mohammed VI University Hospital in Marrakech. All subjects had idiopathic deafness, completed at least two years of speech therapy, and demonstrated successful electrode activation. Postoperative modified Stenvers-view radiographs were used to calculate angular depth of insertion (aDOI). Auditory outcomes were assessed using APCEI and CAP scores. Response surface regression modelling was employed to explore the non-linear relationship between aDOI and auditory performance and to estimate the device-specific angular depth associated with peak predicted outcomes.
Results:
The mean angular depth of insertion was 275°. APCEI scores ranged from 11 to 21, and CAP scores from 3 to 7. Non-linear modelling identified a predicted peak in auditory performance at approximately 340°, corresponding to an APCEI score of 17.67 and CAP score of 5.98. This value represents the model-derived optimum within the observed insertion range for the Oticon Neuro ZTI electrode platform.
Conclusion:
Within this homogeneous cohort implanted with a single lateral wall electrode design, auditory outcomes demonstrated a non-linear association with angular depth of insertion, with peak predicted performance near 340°. These findings highlight the importance of device-specific insertion strategies and careful surgical planning. The results should not be generalized to other electrode designs without dedicated validation.