Bony cochlear or vestibular malformations occur in about 20% of patients with congenital sensorineural hearing loss. Intuitively, one would expect such malformations to influence surgical and audiologic outcomes in patients undergoing cochlear implantation. However, the precise impact of these malformations on surgical and audiologic outcomes has not yet been elucidated.

1. Cochlear Implant Outcomes in Adults and Children
with Inner Ear Malformations
Szudek J1, Dettman S2, Sadeghi-Barzalighi A2, Zraika L 2, and Briggs RJS1
1University of Melbourne, Department of Otolaryngology, 2University of Melbourne Department of Audiology
Introduction
Results - Adults
Bony cochlear or vestibular malformations occur in about 20% of patients with congenital
sensorineural hearing loss. Intuitively, one would expect such malformations to influence Table 3: Outcomes in Adults by Type of Congenital Malformation
surgical and audiologic outcomes in patients undergoing cochlear implantation. However,
the precise impact of these malformations on surgical and audiologic outcomes has not
yet been elucidated.
Patients and Methods
A retrospective review of the Cochlear Implant Clinic database at the University of
Melbourne identified 57 children and 31 adults with cochlear and/or vestibular
malformations who had undergone cochlear implantation. The patients’ CT and MRI scans
were classified into ordinal categories of cochlear malformation according to the scheme
of Sennaroglu1: common cavity (CC), incomplete partition -I (IP-I); IP-II with or without
enlarged vestibular aqueduct (EVA); IP-III, or EVA alone.
Duration of profound hearing loss was significantly correlated with OSW Word (r=-0.36,
Analysis of variance (ANOVA) was used to compare speech perception (open-set word, p=0.04) and BKB Sent (r=-0.41, p=0.02), but not with OSW Phon (r= -0.27, p=0.14), .
phoneme and sentence scores), language development (Peabody Picture Vocabulary
Test (PPVT) standard scores and delay), and surgical outcomes (occurrence of a CSF Table 4: Outcomes in Adults with Gushers and Incomplete Insertions
gusher and insertion depth) among the groups of malformations. Pearson’s correlation
coefficients were calculated between the duration of profound hearing loss and speech
perception and language outcomes. T-tests were used to compare speech perception and
language outcomes between groups of patients with and without gushers and incomplete
electrode insertions. SPSS5 was used to perform all statistical analyses.
Results - Children
Table 1: Outcomes in Children by Type of Congenital Malformation
Discussion
Pre-operative imaging is a routine and essential part of planning cochlear implantation.
However, based on this retrospective study of children and adults , the extent of pre-
operative cochlear/vestibular malformation alone cannot predict post-operative cochlear
implant performance (Tables 1 and 3).
On the other hand, the presence of gusher, incomplete insertion and a longer duration of
“Other” malformations in Table 1 included two IP-I cochlea, one hypoplasia and one pre-implantation hearing loss were associated with worse speech perception and
unclassified malformation. language outcomes in children and adults (Tables 3 and 4). Of the 11 gushers
encountered in children, 4 were accompanied by an incomplete insertion. Of the 5
Duration of profound hearing loss was significantly correlated with OSW Phon (r= -0.43, gushers encountered in adults, all had a complete insertion. The only incomplete insertion
p=0.004), OSW Word (r=-0.32, p=0.03), BKB Sent (r=-0.35, p=0.02), and PPVT delay in an adult did not have a gusher. This suggests that only part of the speech and language
(r=0.49, p=0.001) but not with PPVT SS (r=-0.25, p=0.1). outcome may be related to incomplete insertion. Only one adult had incomplete electrode
insertion, precluding meaningful statistical comparison (Table 4)
The post-operative speech and language scores in the present study are similar those
Table 2: Outcomes in Children with Gushers and Incomplete reported in other pediatric groups with cochlear abnormalities but lower than those with
Insertions normal cochlea and adult groups.2-4
One of the limitations of this study is the significant number of patients who did not have
complete post-operative speech perception and language testing. For example, 2 of the
patients with common cavities, 5 of those with IP-II + EVA and 2 of those with EVA alone
performed too poorly to test OSW. This may contribute to the failure of this study to show
performance differences between groups of different malformations. On the other hand,
the patients with these malformations who were tested performed well, underscoring the
wide range of outcomes that we observed within all groups of malformations
Conclusions
References
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2010;1:4-41
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performance after cochlear implantation: a 2-year follow-up in children with inner ear malformations.
Acta Otolaryngol 2007;127:252–257. ! Implant recipients with a shorter period of profound hearing loss have significantly
3. Dowell RC, Dettman SJ, Blamey PJ, Barker EJ, Clark GM. Speech perception in children using cochlear better implant performance.
implants: prediction of long-term outcomes. Cochlear Implants Int 2002a;3:1–18.
4. Gleeson, T.G., Lacy, P.D., Bresnihan, M., et al. High resolution computed tomography and magnetic ! Intra-operative gushers and the incomplete insertions are associated with worse
resonance imaging in the pre-operative assessment of cochlear implant patients. J Laryngol Otol
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implant performance
5. SPSS Base 20 for Mac. IBM SPSS Statistics. 2011