The pattern of auditory brainstem response wave V maturation in cochlear-implanted children.

Area of Science:

• Neuroscience
• Audiology
• Developmental Biology

Background:

• Auditory brainstem response (ABR) maturation in hearing children continues for two years post-birth.
• ABR wave V latency decrease follows a model of two decaying exponential functions.
• Electrically evoked auditory brainstem responses (EABR) track auditory pathway maturation in deaf children with cochlear implants.

Purpose of the Study:

• To investigate EABR maturation in 55 deaf children post-cochlear implantation.
• To model EABR maturation based on the onset of deafness.
• To compare EABR maturation patterns with normal ABR maturation in hearing children.

Main Methods:

• Analyzed EABR wave V latency changes over two years in two groups: early-onset (n=41) and late-onset (n=14) deafness.
• Modeled EABR latency changes using mean values from each group to compare maturation rates.
• Assessed differences in EABRs between basal and apical electrode array ends.

Main Results:

• Significant EABR wave V latency maturation occurred in early-onset deafness, following a biphasic exponential decay similar to normal ABR.
• Time constants for EABR maturation in early-onset deafness (3.9 and 68 weeks) aligned with established ABR models.
• Children with late-onset deafness showed minimal EABR maturation; basal electrode sites consistently had longer latencies than apical sites.

Conclusions:

• Auditory pathways in early-onset deafness appear 'frozen' and resume normal maturation post-implantation.
• Late-onset deafness suggests some pre-deafness maturation, leading to less EABR change with implantation.
• Rehabilitation-induced plasticity may not yield similar neurophysiological outcomes in late versus early auditory deprivation.