Objectives: We compared the perceptual auditory abilities of 21 children with suspected cochlear nerve deficiency (CND) and a surgically verified absent cochlear nerve (CN) who first underwent cochlear implantation (CI) and subsequently underwent auditory brainstem implantation (ABI).
Methods: In this retrospective cohort study, from 2000 to 2011, 21 children initially underwent CI at an outside institution and failed to progress in their perceptual auditory abilities. Before CI, all of the children had severe to profound sensorineural hearing loss and a diagnosis of CND. Magnetic resonance imaging (MRI) documented an absent CN in 13 children and a small CN in 8 children. We performed explantation of the cochlear implant and simultaneous ABI on the same side. We performed MRI if no previous MRI results were available. All surgical videos were reviewed to determine the presence or absence of the CN. Measures of the patients' perceptual auditory abilities obtained after CI and after ABI were converted to the Category of Auditory Performance (CAP) scale.
Results: At surgery, all patients demonstrated an absent CN. After CI, all patients had a CAP score of 2 or less (mean, 0.52 +/- 0.68). After ABI, all patients had a CAP score of 2 or more (mean, 4.33 +/- 1.68); the improvement was statistically significant (p < 0.001). The complication rates were similar for CI and ABI.
Conclusions: In this cohort of patients who had poor performance after CI, ABI achieved significantly improved performance as measured by the CAP and was shown to successfully rehabilitate hearing. Cases of a small CN may in reality represent an absent CN. Although this cohort was selected from patients with failed CI, the results have implications for the selection of device for patients with CND, in that ABI is a potential alternative to CI in select cases. In patients who fail to progress with intensive rehabilitation with CI or who have no progression in evoked auditory brainstem response, ABI must be considered early.