MMP-9 plasma level as a biomarker of cochlear implantation outcome in cohort study of deaf children

Abstract Objective: If before cochlear implantation it was possible to assay biomarkers of neuroplasticity, it might identify those children with congenital deafness who were at risk of poor speech and language rehabilitation outcomes later on. Study Design: a prospective cohort study Methods: a group of 40 children aged up to 2 years old with DFNB1-reated congenital deafness was observed over three follow-up intervals up to 18 months after cochlear implant (CI) activation. Children were assessed for auditory development by using the LittlEARS Questionnaire (LEAQ) score and at the same time measurements were made of matrix metalloproteinase-9 (MMP-9) plasma levels. Results: There were significant negative correlations between plasma levels of MMP-9 at 8 months follow-up and LEAQ score at cochlear implantation (p = 0.04) and LEAQ score at 18 months follow-up (p = 0.02) and between MMP-9 plasma levels at 18 months follow-up and LEAQ score at cochlear implantation (p = 0.04). As already reported, we confirmed a significant negative correlation between MMP-9 plasma level at cochlear implantation and LEAQ score at 18 months follow-up (p = 0.005). Based on this latter correlation, two clusters of good and poor CI performers could be isolated. Conclusions: The study shows that children born deaf who have an MMP-9 plasma level of less than 150 ng/ml at cochlear implantation have a good chance of attaining a high LEAQ score after 18 months of speech and language rehabilitation. This indicates that MMP-9 plasma level at cochlear implantation is a good prognostic marker for CI outcome.