X-linked deafness revisited – longterm results following cochlear implant

Abstract

Introduction: X-linked deafness is characterised by a missing lamina cribrosa between cochlea and the internal auditory canal (IAC). Cochlear implantation (CI) may result in an insertion of the electrode array into the IAC. Up to now no data is available with regard to audiological longterm results of X-linked deafness patients after CI and mapping. Methods: 9 X-linked patients have been implanted during 1999 and 2014 with perimodiolar electrode arrays. All patients underwent first fitting and consecutive mappings. Performances (after 4 weeks, 1 and 3 years) have been matched with 3 CI patients each with normal cochlear morphology regarding sex, age, side, implant type and surgical date. Patients were followed for a mean of 9.1 years (range: 5 to 19 y.). Speech discrimination (OLSA, FBMS) has been evaluated regularly. Results: Average C-/T-level 4 weeks after CI were not significantly higher compared to the matching groups. Though, X-linked deaf patients showed a characteristical two-curved profile. While matching patients remained stable, X-linked deaf patients showed a significant increase in T-, C-levels and pulse width (up to sixfold PW over 5 to 10 years). All patients are using their CI daily. However, speech discrimination scores were lower than average scores for the implanted patients without cochlear malformation. Conclusions: CI in X-linked patients is a reliable way to achieve hearing rehabilitation. Continuous repeated mapping over several years is necessary to optimize the outcome. All patients develop a highly significant increase in pulse width over 1, 3 and 5 years. The audiological outcome is below the average for CI recipients, nevertheless X-linked patients have access to hearing and spoken language.