You can never be too young or too thin, the saying goes. But in the case of cochlear implant (CI) surgery, just how young can a patient with profound hearing loss be—and still qualify as a viable and safe candidate for the procedure?
Explore this issue:August 2012
The FDA has recognized that there are risks associated with CIs in younger patients. For example, the general anesthesia required by the surgery has been linked to the development of long-term learning disabilities (Anesthesiology. 2009;110:796-804). Partly due to these risks, CI surgery has been approved by the FDA in the U.S only for children 12 months of age or older. But in Italy, a team of pediatric specialists is pushing the age envelope and implanting children as young as two months of age. They are reporting, for the first time, that the procedure can yield significant improvements in speech perception and several other auditory outcomes, with little to no risk to these younger patients (Otolaryngol Head Neck Surg [published online ahead of print March 27, 2012]).
The rationale for performing CI surgery in infants has a logical basis in physiology, according to Vittorio Colletti, MD, a surgeon in the ENT department at the
University of Verona, Italy, and senior author of the new study. “At birth, the auditory sensory mechanism of the human neonate is fully functional and ready to establish neural connections based on auditory experience,” wrote Dr. Colletti and his colleagues in the study. “Early language exposure, through social interaction, shapes the developing nervous system. Without this, linguistic ability diminishes quickly, and only early access to language”—for example, via CI implantation—“provides a profoundly deaf child an opportunity to develop within the normal continuum.”
To assess whether CIs can indeed help patients achieve that normal continuum of hearing, the investigators focused on a group of 45 patients culled from 386 children who received the implants from Dr. Colletti and his team of pediatric specialists. Of those 45 patients, 12 infants were aged two to six months (Group 1), nine were aged seven to 12 months (Group 2), 11 were aged 13 to 18 months (Group 3) and 13 were aged 18 to 24 months (Group 4).
A wide range of pre-implant audiologic and radiologic assessments was performed in all of the study patients to ensure that CI surgery was an appropriate therapeutic intervention. The tests included otomicroscopy, tympanometry, acoustic reflex thresholds and click auditory brainstem response threshold assessments, as well as computed tomography, magnetic resonance imaging and and pediatric and neuropsychiatric evaluations, as needed.