[Retrospective analysis of auditory neuropathy patients after cochlear implantation]

Objectives: To study an effects on hearing ability and speech performance of the patients with auditory neuropathy (AN) after cochlear implantation (CI). Methods: Thirty-five AN patients (26 males and 9 females) after CI in our center since 2007 were chosen, including 5 postlingual patients (implanted age from 14.3 to 38.6 years old) and 30 prelingual patients (implanted age from 1.1 to 13.7 years old). Hearing sensitivity and speech performance were estimated via following methods: (1) implanted hearing thresholds by sound field audiometry; (2) speech audiometry, including monosyllable, disyllable and sentences recognition test by computer-controlled software and sentence recognition test under noise condition (signal to noise ratio=+ 10dB); (3) Mandarin Early Speech Perception test (MESP), Mandarin Pediatric Speech Intelligibility test (MPSI), MAIS, or IT-MAIS for prelingual AN implantees. Results: The average implanted hearing threshold (250-4 000 Hz) was (41.1±11.7) dBHL in 22 AN implantees, while those prelingual implantees was (39.1±10.9) dBHL, and (44.9±12.3) dBHL in postlingual implantees. Speech audiometry were implemented in four of 5 postlingual AN implantees, the results showed increasing tendency in monosyllable recognition scores, dramatic individual variation in computer-controlled disyllable and sentences recognition test, and poor scores (<30%) in speech recognition test in noise condition. Four of 30 prelingual implantees reconstruct their speech recognition ability within 1-3 years after switch-on, characterized as recognition scores (>60%) in monosyllable, disyllable and sentences. The one of prelingual implantee gained recognition scores of speech in noise within 1 year after switch-on. MAIS or IT-MAIS were implemented in twenty-five prelingual implantees, the average score in these patients was 28.6±11.7. Conclusion: Cochlear implant can improve the hearing thresholds of AN patients, however, the improvement in speech performance presented significant variations among the implanted individuals.