To compare imaging and outcome data in cochlear implant (CI) patients with and without cochlear nerve deficiency (CND).Study Design:
Retrospective study comparing presurgical imaging (via high-resolution computed tomography and three-dimensional magnetic resonance imaging) to postsurgical auditory outcomes in CI patients with and without CND.Patients:
Forty-three CI patients with CND diagnosed according to preoperative imaging were included in the CND group. A control group (non-CND; n = 43) was matched to the CND group in terms of age at implantation, CI device type, preoperative hearing threshold, and sex.Results:
Across all subjects, internal auditory canal (IAC) diameter, cochlear nerve canal (CNC) diameter, and the number of nerve bundles were significantly correlated with all auditory outcome measures (p < 0.0125 in all cases). Across CND subjects, CNC diameter was significantly correlated with SIR, MUSS, and MAIS-IT/ MAIS scores (p < 0.0125 in all cases). Auditory outcomes were significantly poorer for CND patients with one rather than two nerve bundles. Across non-CND subjects, CNC diameter was significantly correlated only with SIR scores (p < 0.0125). IAC diameter, CNC diameter, and the number of nerve bundles were significantly smaller, and auditory outcomes were significantly poorer for the CND group than for the non-CND group (p < 0.05 in all cases). Results were similar when data only from patients ≤ 5 years old (n = 31) were analyzed.Conclusions:
CNC diameter and the number of nerve bundles can significantly predict auditory outcomes for CI patients with CND. The results suggest that presurgical imaging may be useful in predicting CI outcomes for congenitally deaf patients.