Advances in Cochlear Implantation

Cochlear implants (CIs) have proven to be an invaluable rehabilitative option for children and adults with severe-to-profound hearing loss, providing improved access to the acoustic environment and, especially, to speech. The first trial of electrical stimulation of the cochlear nerve was conducted in 1953 by Djourno ed Eyries on a patient operated for chronic otitis media and facial palsy. In 1970, William House in California implanted the first single-channel stimulating electrode to an adult deaf patient, who reported he could perceive sound. Since then, the advancements in CI technology have ben continuous and comparable to “quantum leaps”: in 1984, multichannel CI were developed; strategies of speech processing were progressively improved; at the dawn of the new millennium, CIs were approved for use also in children, and they are now considered the gold standard for profound congenital bilateral hearing loss, with the age at implantation being progressively reduced. Based on the clinical outcomes, the audiological criteria for implantation are currently expanding, in adults, to asymmetric hearing losses, high-frequency losses (“ski-slope audiograms) and also to single-side deafness. Furthermore, children with additional disabilities are not excluded any longer from the opportunity to regain contact with sound. Meanwhile, molecular genetics allowed to map more than 150 mutations responsible for isolated deafness, imaging can depict the subtle changes in the inner ear compartments, and speech training methods have evolved from language articulation to cognitive tasks based on the improved sensorial input. However, outcomes with a CI can vary significantly, owing to the several factors impacting on performance. It is imperative to address and improve each of these relevant factors, in order to maximize the benefits, that will affect the recipient across his/her lifespan.