In the early years of cochlear implantation and throughout the 1990s, adults who had experienced early deafness (either born deaf or having lost hearing during early childhood), were generally considered unsuitable candidates for cochlear implantation. This perspective was guided by research on children. Research demonstrated the significant impact of a child's age at implantation; children implanted at a younger age, on average, have better outcomes. The expectation was also driven by outcomes of adult CI recipients who lost their hearing as adults, findings which have consistently demonstrated diminished outcomes with longer duration of hearing loss among the population whose hearing loss was within the CI candidacy range.

Perspectives on CI in Adults with Childhood Deafness has Changed

In the early 2000s, there were important technological improvements in cochlear implants, such as advances in processing strategies and electrode array designs. Patient outcomes in this population of early deafened adults—once thought to be poor candidates—improved and CI candidacy guidelines were expanded. Many more adults with early deafness received cochlear implants. Studies from the 1990s rarely demonstrated open-set perception skills among adults with early deafness (i.e., few could repeat words or sentences without speech reading). Studies on this population a decade later demonstrated significant speech perception skills that allowed many recipients to perceive words and sentences presented in open-set tests. At the same time, there was variability in speech perception outcomes among these adults which made it difficult for clinicians to provide a simple answer to the often asked question "How will I benefit from cochlear implantation?"

Variability Explained

Adults with early deafness are a heterogeneous group. Studies have sought to explain the variability in CI outcomes for individuals and individuals’ personal characteristics. The variables found to be positively correlated with speech perception outcomes were:

• Consistent use of the CI
• Higher number of hours of CI usage each day
• Better speech intelligibility and speech perception skills prior to cochlear implantation
• Mainstream education that emphasized use of spoken language
• Spoken language as the main communication mode pre-implantation

Age at time of CI and duration of deafness were not found to be significantly correlated with speech perception outcomes in this group of adults—contrary to what has been found for children with congenital deafness and for adults with post-lingual deafness. The type of cochlear implant (i.e., manufacturer) was also not found to be correlated with outcomes in this group of adults.

Quality of Life Effects

Improved speech perception outcomes are only one aspect of how someone may benefit from cochlear implantation. For people with early deafness, relying solely on speech perception to evaluate CI benefits is problematic for two reasons:

• Variability and the wide range of results among this group of CI users
• Although many of these early deafened adult recipients fail to reach open-set speech perception skills, most still use their CI regularly and enjoy it.

A growing number of studies are focusing on the contribution cochlear implants to an individual’s quality of life. This is consistent with the World Health Organization's perspective that an evaluation of a health intervention should include assessment of the degree to which it improves one’s ability to carry out activities of daily living and contributes to overall quality of life. Studies indicate that most adults with early deafness believe that their CI has made a significant contribution to their quality of life. An important study funded by American Cochlear Implant Alliance explores this topic in detail https://www.acialliance.org/page/QOLMeasures by developing and testing new measures of quality of life associated with cochlear implantation.

CI recipients note that they:

• Are more aware of environmental sounds
• Benefit from improved speech comprehension
• Benefit from speechreading that is more accurate and less labored
• Are more confident and independent while communicating in everyday situations
• Feel less stress and more control while engaging in social activities
• Feel less lonely
• Have become more involved in hearing-based activities such as listening to music, watching TV, and talking on the telephone

Importantly, most studies did not find a significant relationship between quality of life benefits and and speech perception outcomes. This further supports the finding that the benefit many adults with early deafness enjoy from their CIs is not necessarily a function of their speech perception results.

Concluding Thoughts

To answer the question "How do adults with early deafness benefit from a cochlear implantation?" we need to appreciate the challenges faced, as well as the diversity, of this group of people. For these CI recipients, evaluating benefit based solely on objective auditory measures does not provide a full indication of outcomes and satisfaction. We must also assess the contribution in terms of quality of life benefits. The cochlear implant enhances communication and social functioning, contributes to one’s sense of well-being, and often improves overall quality of life. Quality of life should be part of any pre- and post- implantation assessment and should also be considered in an individual’s rehabilitation program. Considering communication and quality of life while also respecting the adult population’s diversity and the range of personal variables associated with CI outcomes will allow more adults with early deafness to benefit from a cochlear implantation later in life.

Further Reading

Craddock L, Cooper H, Riley A, Wright T (2016). Cochlear implants for pre-lingually profoundly deaf adults, Cochlear Implants International, 17(1), 26-30.

Florli F, Turchetti G, Bellelli S, Fortunato S, Bruschini, Barillari MR, Berrettini S (2017). Cochlear implants in prelingually deafened oralist adults:speech perception outcomes, subjective benefits and quality of life improvement. Acta Otorhinolaryngologica Italica, 37(5), 412-422.

Lammers MJW, Versnel H, Topsakal V, van Zanten GA, Grolman W (2018). Predicting performance and non-use in prelingually deaf and late-implanted cochlear implant users. Otology& Neurotology, (39),436-442.

Most T, Shrem H (2010). Cochlear implantation in late-implanted adults with prelingual deafness. American Journal of Otolaryngology, 418-423.

O’Gara SJ, Cullington HE, Grasmeder ML, Adamou M, Matthews ES (2016) . Factors affecting speech perception improvement post implantation in congenitally deaf adults, Ear & Hearing, 37(6), 671-679.

Straatman LV, Huinck WJ,  Langereis MC, Snik AFM, Mulder JF (2014). Cochlear implantation in late-implanted prelingually deafened adults: changes in quality of life. Otology & Neurotology: 35(2), 253–259.