Duration of unilateral auditory deprivation is associated with reduced speech perception after cochlear implantation: A single-sided deafness study

Abstract

Objective: Examine the relationship between duration of unilateral deafness and speech perception outcomes after cochlear implantation in adults with single-sided deafness.

Methods: A systematic review of PubMed articles containing individual speech perception and duration of deafness data from single-sided deaf adults. Studies were selected for detailed review and duration of deafness and speech perception outcomes were extracted, with speech scores reported as percent correct. A linear regression as a function of study and length of deafness was performed.

Results: A statistically significant negative effect of duration of unilateral deafness on speech perception was found, but there was substantial uncertainty regarding the strength of the effect.

Discussion: Existing data make it difficult to either support or reject a hard 5- or 10-year unilateral auditory deprivation limit on cochlear implant (CI) candidacy for patients with single-sided deafness. This is because the totality of available data are consistent with a very small effect, perhaps negligible in practical terms, and just as consistent with a very large effect. Regardless of effect size, the present results have important basic implications. They suggest that unilateral sound deprivation may have a deleterious effect on auditory processing even though more central parts of the auditory system have continued to receive input from a contralateral normal ear.

Conclusions: Speech perception scores in SSD patients are negatively correlated with duration of deafness, but the limited amount of data from cochlear implant users with long-term single-sided deafness leads to substantial uncertainly, which in turn precludes any strong clinical recommendations. Further study of SSD CI users with long-term deafness will be necessary to generate evidence-based guidelines for implantation criteria in this population.

Keywords: Cochlear Implant; Single-sided Deaf; Speech Perception.

FIG. 1.

(A) Raw speech perception score (percent correct) as a function of duration of unilateral deafness in eight separate studies. (B) 95% confidence interval of the linear regression slope for each study, and for all studies combined. Negative slope indicates deterioration in speech perception as a function of duration of unilateral deafness. *, p<0.05; **, p<0.01.

FIG. 2.

Raw speech perception score (percent correct) plotted against duration of unilateral deafness in eight separate studies (A-H). Specific test is indicated for each study on y-axis and linear regression is plotted. Studies 1, 3, and 5 have negative slopes that are statistically significant; circles indicate single data points that, if excluded, render the regression slope non-statistically significant for each study.