Do the Age of Implantation, the Widths of Internal Acoustic Canal and Bony Cochlear Nerve Canal Affect the Auditory Performance of Primary School Children with Bilateral Cochlear Implants?

OBJECTIVE: To reveal the correlation between implantation age, the internal acoustic canal (IAC) width, bony cochlear nerve canal (BCNC) width, and auditory performance in primary school children with bilateral cochlear implantation (CI). METHODS: Preoperative IAC and BCNC widths of 57 pre-lingually deaf children aged 7–11 years who had previously undergone bilateral CI in our institution were reviewed and cut-off values were calculated. Twenty-four patients who had additional problems and could not attend school and those who refused to participate in the study were excluded. The remaining 33 were invited to the hospital, and their speech perception tests, and language development scores were analyzed (16 of 33 patients had been operated on before the age of 24 months). RESULTS: The cut-off values calculated from the 114 ears of 57 patients were 3.86 mm for IAC width and 1.56 mm for BCNC width. The auditory performances of the 33 patients after CI were not significantly different in the narrow and normal width groups. However, speech perception test results, and language development scores of patients implanted before the age of 24 months were significantly higher. CONCLUSION: There are some studies showing that children with bilateral sensorineural hearing loss have narrower IAC and BCNC widths. However, we concluded that the widths of the IAC and the bone cochlear nerve canal did not affect auditory performance. We found that implantation age is the single most important determinant of speech-language development after CI.