Audiological changes over time in adolescents and young adults with auditory neuropathy spectrum disorder.

Auditory neuropathy spectrum disorder (ANSD) describes a condition in which a patient's otoacoustic emissions (OAE) are (or were at one time) present and auditory brainstem responses (ABR) are abnormal or absent. ANSD is also diagnosed based on the presence of cochlear microphonics and abnormal or absent ABRs with or without abnormalities of OAE. We noted the changes in audiological characteristics over time with respect to pure tone thresholds, OAEs and Speech Identification Scores (SIS) in seven individuals with ANSD. The results indicated that all the individuals with ANSD had decreased SIS over time, whereas there was subsequent reduction in pure tone thresholds only in nine out of fourteen ears. There was absence of OAEs for two individuals in both ears during the follow-up evaluations. There was no regular pattern of changes in pure tone thresholds or SIS across all individuals. This indicates that there may be gradual worsening of hearing abilities in individuals with ANSD. Thus, regular follow-up and monitoring of audiological changes are necessary for individuals with ANSD. Also, longitudinal studies need to be done to further add evidence to the audiological changes over time in individuals with ANSD.