Clinical observations and molecular variables of patients with hearing loss and incomplete partition type III

Objectives/HypothesisTo analyze the clinical manifestations and genetic features of patients with hearing loss (HL) and incomplete partition (IP) type III malformation, and to evaluate speech performance after cochlear implantation (CI) in these patients. Study DesignIndividual retrospective cohort study. MethodsOf 206 probands with inner ear malformations (IEMs), we constructed a homogeneous cohort of 11 genetically documented IP type III (DFNX2). Mutations affecting POU3F4 were classified as extension (n = 2), truncation (n = 3), large genomic deletion (n = 2), or missense substitution (n = 4). Postoperative outcomes were rigorously assessed with focus on POU3F4 genotypes and compared with 80 age-matched implantees without IEMs. ResultsHL in our cohort was prelingual in onset irrespective of degree. Serviceable hearing was obtained by wearing conventional hearing aids in three, and eight subjects required CI. No correlation was found between mutation types and initial auditory phenotype. As for the eight cochlear implantees, average Categories of Auditory Perception score was <1 preoperatively and 3.9 at 2 years post-CI. Speech performances improved over the first 3 months postoperatively in a manner comparable to implantees without IEMs. However, it then tended to slow down until 1 year postoperatively, leading to worse scores at 2 years than implantees without IEMs. Furthermore, this was more evident in those with a truncation or deletion mutation. ConclusionsCI surgeons should be aware that postoperative auditory performance may be not as good in IP type III patients as in patients without IEMs. In particular, our study implies that certain types of POU3F4 mutations may have poorer prognoses than other types after CI.