Cochlear Implantation in Children With Anomalous Cochleovestibular Anatomy

Abstract

The authors have been continuing to assess the candidacy of each child applying for cochlear implantation individually, and the results of present study have suggested that the presence of anomalous cochleovestibular anatomy, with the exception of narrowing of the internal auditory canal/cochlear canal, should not play a significant role in candidacy assessment. Children with narrow internal auditory canal/cochlear canal should be carefully and individually considered. In children with anomalous cochleovestibular anatomy, the potentially increased difficulty in the establishment of optimal stimulation levels and the higher potential for surgical difficulty must be weighed in candidacy decisions but do not universally preclude successful implantation and a good outcome.

Facial nerve anomalies in paediatric cochlear implant candidates: radiological evaluation

“…The frequency of facial nerve anomalies in normal ears is reported to be 0.3 per cent. 4 Facial nerve anomalies coincident with vestibulocochlear anomalies was reported to be 16 per cent by Papsin, 16 per cent by Hoffman et al and 0.7 per cent by Song et al 3,5,6 The rate was 8 per cent in the present study. These differences might result from the different patient numbers in each study.…”

“…3 Papsin stated that it is necessary to dissect the promontory anteriorly to enter the cochlea. 5 He added that the facial nerve may be split and a second anteriorly displaced nerve may be found in addition to the one in the normal position (posterior to the facial recess). McElveen et al described a transmastoid labyrinthotomy approach to common cavity malformations to minimise the injury risk for an aberrant facial nerve.…”

Pediatric Sensorineural Hearing Loss, Part 1: Practical Aspects for Neuroradiologists

“…Normally, the transverse diameter of this bony island measures between 2.6 and 4.8 mm. 17 Children with milder inner ear malformations (eg, vestibular aqueduct enlargement, IP-II, and partial SCC dysplasias) tend to perform better on tests of speech perception following cochlear implantation than children with other malformations (eg, common cavity or cochlear hypoplasia) or syndromes such as CHARGE syndrome, 18,19 but even the presence of a severe malformation (provided a cochlea is present) does not preclude implantation. Identification of these anom- alies is important in surgical planning, however, because the presence of cochlear malformations may make implant placement more challenging and also increases the risk for perilymph/CSF leak, postimplantation meningitis, and potential electrode misplacement, including placement into the IAC.…”

“…In addition, the facial nerve course is aberrant in approximately 15%-32% of patients with cochleovestibular anomalies, a finding that influences surgical planning and occasionally precludes placement of the cochleostomy in the optimal position in relation to the round window. 18,19 CND CND refers to the absence or reduction in caliber of the cochlear nerve and is observed in 12%-18% of ears affected with SNHL. 10,20 In pediatric patients, CND is usually congenital, but it can occasionally develop subsequent to birth due to atrophy of the nerve in patients who previously demonstrated normal hearing in the affected ear.…”

“…Children with narrow IACs on CT perform worse following implantation than those with normal caliber IACs, presumably because the cochlear nerve is likely to be absent or small when the IAC is narrow. 19 Cochlear nerveϪdeficient ears may demonstrate normal caliber BCNCs in Յ23% of cases 9 and normal sized IACs in Յ73% of cases. 26 …”