Auditory characteristics and therapeutic effects of enzyme replacement in mouse model of the mucopolysaccharidosis (MPS) II.

Mucopolysaccharidosis (MPS) II is an X-linked metabolic disorder caused by dysfunction of iduronate-2-sulfatase (I2S). This abnormality causes the progressive accumulation of incompletely degraded glycosaminoglycans (GAGs) in the lysosomes. The auditory characteristics of MPS II in mouse models have not been reported. In this study, we evaluated the auditory characteristics of the MPS II in IDS knock-out (IDS-KO) mice. In addition, the effect of enzyme replacement therapy (ERT) on hearing was studied. The IDS-KO mice had normal histology of the cochlea and retained good hearing at 7 weeks of age. However, at 17 weeks of age, the hearing thresholds of the IDS-KO mice were elevated and exudates were found in the middle ear. The hearing thresholds of the enzyme-treated IDS-KO (IDS-ERT) mice were similar to the wild-type (WT) mice at 17 weeks. Moreover, the microstructure of the inner ear was similar to the IDS-KO by transmission electron microscopy. The histology findings indicated that the microstructure of the inner ear was similar in comparisons between IDS-KO and IDS-ERT mice, even after 10 weeks of treatment. However, the hearing deficits in the MPS II mouse model can be prevented if ERT is started before the onset of hearing impairment.

Performance after timely cochlear implantation in prelingually deaf children with cerebral palsy.

OBJECTIVES: To investigate auditory perception, speech production, and language ability of prelingually deaf toddlers with cerebral palsy (CP) who were implanted within a sensitive period and who received proper speech therapy. Comparison of their outcomes with age- and sex-matched CI recipients without additional disabilities was also performed. METHODS: We retrospectively reviewed a cohort of pediatric CI in Samsung Medical Center. Eight CP subjects who received CI before 3 years of age and age-sex matched control recipients who had no additional disabilities except idiopathic sensorineural hearing loss (SNHL) were included for the analysis. Preoperative evaluation included the Categories of Auditory Performance (CAP) score, Korean Version of the Ling's Stage (K-Ling), Sequenced Language Scale for Infants (SELSI), Bailey Scales of Infant Development II assessment, Social Maturity Scale test, and grading of CP severity using severity level and Gross Motor Function Classification System for CP (GMFCS). To measure the outcome, the CAP scores, K-Ling, and SELSI were performed at 3, 6, 12, and 24 months after implantation. RESULTS: Four CP children with outstanding performances showed comparable achievement with matched control recipients. These patients had less severe motor disabilities (mild-moderate severity, GMFCS level 1-3), better social quotient, and better cognitive abilities. Although the others showed poor language abilities and hardly produced meaningful speech, their CAP scores reached 1 or 2 in 24 months after implantation. CONCLUSIONS: Deaf children with CP could have various ranges of benefits up to the levels of normal peers whose only disability was hearing loss, when CI was performed within a critical period. Especially, children with mild or moderate CP had a favorable outcome after CI, equivalent to that of normal peers.

New idea of hearing aid algorithm to enhance speech discrimination in a noisy environment and its experimental results.

A hearing aid can help the hearing impaired to listen to speech by amplifying its sound. However, amplification cannot always improve speech perception. To improve speech perception in a noisy environment, we proposed a new hearing aid algorithm that combines independent component analysis (ICA) with multiband loudness compensation. The proposed method was applied to a behind-the-ear type (BTE) dual microphone hearing aid. The proposed method successfully separated a target speech signal from background noise such as babble, car noise, factory noise. This method may help hearing aid users to hear the speech that he or she wishes to hear clearly in noisy conditions.