Is very early hearing assessment always reliable in selecting patients for cochlear implants? A case series study

Introduction: This study concerns a case series of 23 infants with a diagnosis of severe-to-profound
hearing loss at 3 months old, who significantly improved (even reaching a normal auditory threshold)
within their first year of life.
Methods: All infants were routinely followed up with audiological tests every 2 months after being fitted
with hearing aids as necessary. A reliable consistency between the various test findings (DPOAE, ABR,
behavioral responses, CAEP and ECoG) clearly emerged in most cases during the follow-up, albeit at
different times after birth.
Results: The series of infants included 7 cases of severe prematurity, 6 of cerebral or complex syndromic
malformations, 5 healthy infants, 2 with asymptomatic congenital CMV infection, and 1 case each of
hyperbilirubinemia, hypoxia, and sepsis.
All term-born infants showed a significant improvement over their initial hearing threshold by 6
months of age, while in most of those born prematurely the first signs of threshold amelioration occurred
beyond 70 weeks of gestational age, and even beyond 85 weeks in one case.
Conclusions: Cochlear implantation (CI) should only be considered after a period of auditory stimulation
and follow-up with electrophysiological and behavioral tests, and an accurate analysis of their
correlation. In our opinion, CI can be performed after a period of 8 months in all term-born infants with
persistent severe-to-profound hearing loss without risk of diagnostic error, whereas the follow-up for
severely preterm infants should extend to at least 80 weeks of gestational age.