Cochlear implantations in young children with cochlear nerve deficiency diagnosed by MRI.

Objective: To investigate postoperative outcomes after cochlear implantation in young children with cochlear nerve deficiency and compare the results with those of cochlear implantation in patients with normal cochlear nerve.

Study Design: Historical cohort study.

Setting: Tertiary referral center.

Subjects And Methods: Six children under the age of 36 months with cochlear nerve deficiency, as determined by magnetic resonance imaging (MRI), received cochlear implantation between July 2006 and March 2008. Fifteen children under the age of 36 months with normal cochlear nerve in the implanted ear underwent cochlear implantation during the same period and were selected as the control group. Medical records, imaging studies, and speech evaluations were reviewed.

Results: Our study group scored lower in the Infant-Toddler Meaningful Auditory Integration Scale compared to the control group. Our study group produced categories of auditory performance scores not less than 4 except for one patient. Speech intelligibility rating scores in the control group gradually increased after cochlear implantation, but for the study group, the score remained zero 12 months after the implantation. In open-set one-syllable tests, five patients with cochlear nerve deficiency showed no response at the latest follow-up, whereas patient 6 began to show delayed improvement after 18 months. The results of the open-set two-syllable test were similar to those of the open-set one-syllable test.

Conclusion: Young children with nonvisualized cochlear nerve on MRI showed worse outcomes compared to the children with normal cochlear nerve. Cochlear nerve deficiency on MRI is a marker of very poor outcome with cochlear implantations.