Results of second cochlear implant with long inter-implant delay.

Background: Implantation at a young age enables exposure to language and speech during the critical age for language acquisition. Long duration of auditory deprivation may lead to less optimal results.

Methods: A retrospective review of cases was performed. A young girl with congenital bilateral profound sensorineural hearing loss received her first cochlear implant on the right side at the age of 2½ years and successfully developed good speech and language. At the age of 10 years, explantation had to be performed, and as reimplantation could not be done on the same side, the implantation was done on the left ear, which had never received auditory stimulation. Two age-matched girls with bilateral sequential implantation, in whom the second sound-deprived ear was implanted after a long duration, were studied as well.

Results: A year after implantation, in two of the cases there was very good speech perception, even in noise. In one case, the second ear never attained the ability to understand speech.

Conclusions: These results can be explained in light of recent findings that early unilateral stimulation can result in bilateral representation in the auditory cortex.