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Background: Facial nerve stimulation (FNS) is a wellknown complication of cochlear implant (CI) restricting optimal use of the device. It was reported to be associated with various anomalies of cochlea or otosclerosis. In the same context, recently spotlighted narrow bony cochlear nerve canal (BCNC) could be a possible cause of FNS possibly by elevating the stimulating current level and finally result in leaking current to elicit FNS. The aim of this study was to evaluate the correlation between narrow BCNC and FNS after CI to predict the risk of FNS preoperatively and to see its underlying mechanisms. Methods: A total of 64 cases who underwent CI in Seoul National University from 1998 to 2013 were included for this study. Only pediatric patients were included and all cases of inner ear anomaly or otosclerosis were excluded. Among them, 32 cases experienced facial nerve stimulation after CI and another 35 cases were selected from our total cohort of 817 pediatric cases by stratified random sampling for age and gender. The width of BCNC, T-levels, C-levels were compared between groups. Strategies for eliminating the FNS and their results including CAP scores were also analyzed. Results: The FNS group had significantly narrow BCNC (1.06 ± 0.51 mm) over control group (2.00 ± 0.59 mm, p<0.01). The FNS group also recorded significantly higher T-level (168.5 ± 28.7 μA) and C-level (201.0 ± 26.9 μA) over control group (T-level: 141.7 ± 21.4 μA, p<0.01, Clevel: 188.9 ± 21.7 μA, p=0.043). T-level showed significantly negative correlation with the width of BCNC (R=- 0.372, p=0.001, Pearson's correlation test). If the cases were divided into normal BCNC (≥1.4 mm) and narrow BCNC (<1.4 mm) group by definition, cases with FNS had significantly narrower BCNC (p<0.01), higher T- (p=0.007) and C-level (p=0.033) only for normal BCNC group. The immediate onset group (0.74 mm, 42.9%, prior to the completion of initial mapping) had significantly narrow BCNC width over late onset group (0.91 mm, p=0.134). Adjustment of C-levels and/or pulse width, switching off offending electrodes was tried for eliminating FNS. Successful elimination was achieved in 71.4% of cases. FNS group showed significantly low CAP scores (3.00 ± 1.90) over control group (5.94 ± 1.41, p<0.01) after adjustment. Conclusion: A narrow BCNC could be a cause of FNS after CI. Therefore, careful selection of the side for CI and programing strategies are required for reducing FNS. [ABSTRACT FROM AUTHOR]

Introduction and Objectives: Among patients with partial deafness, there is a group of patients with normal low-frequency hearing. They seem to hear well, but they have difficulty in doing professional work because of the poor speech intelligibility. They have tried to wear a hearing aid but have failed. The remaining method for these patients is cochlear implant and we wanted to study the following. 1. Is Electrical partial stimulation beneficial to hearing rehabilitation in language and music? 2. Hearing preservation results in this group. 3. Is there a subjective satisfaction with the patient after the operation? 4. Proper fitting method for Electrical partial stimulation Materials and Methods: From August 2012 to July 2017, data were retrospectively analyzed in 10 patients who underwent CI surgery in Soree Ear Clinic. Their hearing was normal at low frequencies and suddenly dropped to high frequencies. The age of the patients was 20-48 years. The mean age was 34.2 years (7 female and 3 male). We analyzed these data. Speech performance (syllable, sentence, HINT), music evaluation according to time before and after surgery. Hearing preservation rate (Correction by reduction of opposite hearing) Nijmegen cochlear implant questionnaire. (before and after surgery) and fitting results. Results: Electrical partial stimulation is effective for hearing rehabilitation for these partial deafness patients. Speech performance was improved and music score was maintained. Hearing preservation rate was 80% and residual hearing was well maintained over time. There were two patients with hearing loss, but the two patients were using EAS(hybrid) mode. Nijmegen cochlear implant questionnaire showed improved life quality especially self-esteem. The proper fitting method of Electrical partial stimulation was GAP. Conclusion: In patients with partial deafness, especially in patients with low frequency hearing, electrical partial stimulation can improve speech performance while preserving low frequency hearing and may be the best way to overcome the limitations of current CI. [ABSTRACT FROM AUTHOR]