Outcomes Using the Optimized Pitch and Language Strategy Versus the Advanced Combination Encoder Strategy in Mandarin-Speaking Cochlear Implant Recipients.

OBJECTIVES: The experimental Optimized Pitch and Language (OPAL) strategy enhances coding of fundamental frequency (F0) information in the temporal envelope of electrical signals delivered to channels of a cochlear implant (CI). Previous studies with OPAL have explored performance on speech and lexical tone perception in Mandarin- and English-speaking CI recipients. However, it was not clear which cues to lexical tone (primary and/or secondary) were used by the Mandarin CI listeners. The primary aim of the present study was to investigate whether OPAL provides improved recognition of Mandarin lexical tones in both quiet and noisy environments compared with the Advanced Combination Encoder (ACE) strategy. A secondary aim was to investigate whether, and to what extent, removal of secondary (duration and intensity envelope) cues to lexical tone affected Mandarin tone perception. DESIGN: Thirty-two CI recipients with an average age of 24 (range 7 to 57) years were enrolled in the study. All recipients had at least 1 year of experience using ACE. Each subject attended two testing sessions, the first to measure baseline performance, and the second to evaluate the effect of strategy after provision of some take-home experience using OPAL. A minimum take-home duration of approximately 4 weeks was prescribed in which subjects were requested to use OPAL as much as possible but were allowed to also use ACE when needed. The evaluation tests included recognition of Mandarin lexical tones in quiet and in noise (signal to noise ratio [SNR] +5 dB) using naturally produced tones and duration/intensity envelope normalized versions of the tones; Mandarin sentence in adaptive noise; Mandarin monosyllabic and disyllabic word in quiet; a subset of Speech, Spatial, and Qualities of hearing questionnaire (SSQ, speech hearing scale); and subjective preference for strategy in quiet and noise. RESULTS: For both the natural and normalized lexical tone tests, mean scores for OPAL were significantly higher than ACE in quiet by 2.7 and 2.9%-points, respectively, and in noise by 7.4 and 7.2%-points, respectively. Monosyllabic word recognition in quiet using OPAL was significantly higher than ACE by approximately 7.5% points. Average SSQ ratings for OPAL were significantly higher than ACE by approximately 0.5 points on a 10-point scale. In quiet conditions, 14 subjects preferred OPAL, 7 expressed a preference for ACE, and 9 reported no preference. Compared with quiet, in noisy situations, there was a stronger preference for OPAL (19 recipients), a similar preference for ACE (7 recipients), while fewer expressed no preference. Average daily take-home use of ACE and OPAL was 4.9 and 7.1 hr, respectively. CONCLUSIONS: For Mandarin-speaking CI recipients, OPAL provided significant improvements to lexical tone perception for natural and normalized tones in quiet and noise, monosyllabic word recognition in quiet, and subjective ratings of speech intelligibility. Subjects accessed both primary and secondary cues to lexical tone for perception in quiet and noise conditions. The benefits of lexical tone recognition were attributed to enhanced F0 rate cues encoded by OPAL, especially in a noisy environment. The OPAL strategy was well accepted by many of the Mandarin-speaking CI recipients.

Vestibular function and hearing preservation in children following a minimally invasive cochlear implantation.

PURPOSE: This retrospective cohort study aimed to investigate the effect of minimally invasive cochlear implantation (CI) on the vestibular function (VF) and residual hearing (RH) as well as their relationship in pediatric recipients before and after surgery. METHODS: Twenty-four pediatric patients with preoperative low frequency residual hearing (LFRH) (250 or 500 Hz ≤ 80 dB HL) who underwent minimally invasive CI were enrolled. Pure-tone thresholds, the cervical/ocular vestibular-evoked myogenic potential (cVEMP/oVEMP), and video head impulse test (vHIT) were all evaluated in the 24 pediatric patients with preoperative normal VF before and at 1 and 12 months after surgery. The relationship between changes in hearing and VF was analyzed preoperatively and at 1 and 12 months postoperatively. RESULTS: There were no significant differences on VF preservation and hearing preservation (HP) at both 1 and 12 months post-CI (p > 0.05). At 1 month post-CI, the correlations of the variations in vestibulo-ocular reflex (VOR) gains of horizontal semicircular canal (HSC) and posterior semicircular canal (PSC) and the shift in 250 Hz threshold were negatively correlated (r = - 0.41, p = 0.04 and r = - 0.43, p = 0.04, respectively). At 12 months post-CI, the shift in 250 Hz threshold negatively correlated to the variations in VOR gain of superior semicircular canal (SSC) (r = - 0.43, p = 0.04); the HP positively correlated to the variation in oVEMP-amplitude ratio (AR) (r = 0.41, p = 0.04). CONCLUSION: Our study confirmed that there were partial correlations between VF preservation and HP both in the short- and long-terms after atraumatic CI surgery, especially with the 250 Hz threshold. Regarding the variation of PSC function, the correlation with hearing status was variable with time after atraumatic CI surgery. Minimally invasive techniques for HP are successful and effective for the preservation of VF in pediatric patients both in the short- and long-terms.

Long-Term Auditory and Speech Outcomes of Cochlear Implantation in Children With Cochlear Nerve Aplasia.

OBJECTIVES: In this study, we aimed to (1) review the long-term outcomes of cochlear implantation in children with cochlear nerve aplasia and (2) compare the development of their auditory and speech abilities to children with normal-sized cochlear nerves. DESIGN: This is a retrospective case-control study. Patients who underwent unilateral cochlear implant (CI) surgery in a tertiary referral center from September 2012 to December 2018 were reviewed. The study group included 55 children with cochlear nerve aplasia diagnosed using preoperative images. The control group included 35 children with normal-sized cochlear nerves. The control group did not differ from the study group in terms of age at implantation, pre-implantation auditory and speech abilities, or the electrode array type. Cochlear implantation outcomes were assessed using a test battery, including the Categories of Auditory Performance (CAP) score, the Speech Intelligibility Rating (SIR) score, behavioral audiometry, and closed- or open-set speech recognition tests. The development of auditory and speech abilities was compared between the two groups using Generalized Linear Mixed-effect Models. RESULTS: The mean duration of CI usage was 4.5 years (SD = 1.5, range = 2.0 to 9.5) in the study group. The CAP scores, SIR scores, and aided hearing thresholds improved significantly post-implantation in the study group, but were significantly poorer than those in the control group. Generalized Linear Mixed-effect Models showed that the development of CAP and SIR scores was significantly slower in the study group than in the control group. Overall, 27 (49%) children with cochlear nerve aplasia had some degree of open-set speech perception skills, but the monosyllabic and bisyllabic word recognition rates were significantly lower than those in the control group. CONCLUSION: For children with cochlear nerve aplasia, auditory perception and speech intelligibility continued to improve in the long-term follow-up, but this progress was significantly slower than in children with normal-sized cochlear nerves. Most children with cochlear nerve aplasia could obtain the ability of common phrase perception and understanding simple spoken language with consistent CI usage and auditory rehabilitation.