Hypothesis: Auditory perception and speech discrimination among pediatric cochlear implantees may vary because of underlying deafness etiology, including connexin 26 (GJB2) gene-related deafness.
Background: Preliminary data suggest pathologic changes due to GJB2 mutations do not affect the spiral ganglion cells, which are stimulated by the cochlear implant. The survival of the spiral ganglion cells is believed to be an important determinant of outcome after surgery. Patients with GJB2-related deafness may therefore have enhanced prospects for good speech discrimination after implantation.
Methods: In an observational cohort study, GJB2 mutation analysis was performed using polymerase chain reaction amplification and direct sequencing on 31 prelingually deaf pediatric cochlear implantees, of which there were 30 with nonsyndromic deafness of unknown etiology, and one with keratitis-ichthyosis-deafness syndrome. Speech discrmination was assessed prospectively when they had reached postoperative year 3 using the IOWA Matrix Level B Sentences test and Glendonald Auditory Screening Procedure (GASP), with both patients and assessors blind to GJB2 status.
Results: Eleven patients had GJB2-related deafness and 20 patients had GJB2-unrelated deafness. IOWA Matrix scores were higher in patients with GJB2-related deafness but did not reach statistical significance. However, GASP scores were statistically significantly higher in patients with GJB2-related deafness (median word score, 92%; median sentence score, 80%), compared with those of patients with GJB2-unrelated deafness (median word score, 63%; median sentence score, 45%; word score, p = 0.037; sentence score, p = 0.045). Ordinal logistic regression analysis on IOWA Matrix and GASP sentence scores found better statistically significant scores in patients with GJB2-related deafness (p < 0.05) after adjustment for confounding variables.
Conclusion: Pediatric cochlear implantees with GJB2-related deafness appear to have equal or better speech discrimination compared with a group of prelingually deaf children with deafness of unknown etiology.