Cochlear implantation improves autonomy and the QoL in the elderly. Cognitive functions are not influenced by surgery, but executive functions appear to benefit from implantation. Age should not be a limiting factor, and cochlear implantation can be proposed as an efficient treatment for severe-to-profound hearing loss in the elderly.

BackgroundUsher syndrome (USH) combines sensorineural deafness with blindness. It is inherited in an autosomal recessive mode. Early diagnosis is critical for adapted educational and patient management choices, and for genetic counseling. To date, nine causative genes have been identified for the three clinical subtypes (USH1, USH2 and USH3). Current diagnostic strategies make use of a genotyping microarray that is based on the previously reported mutations. The purpose of this study was to design a more accurate molecular diagnosis tool.MethodsWe sequenced the 366 coding exons and flanking regions of the nine known USH genes, in 54 USH patients (27 USH1, 21 USH2 and 6 USH3).ResultsBiallelic mutations were detected in 39 patients (72%) and monoallelic mutations in an additional 10 patients (18.5%). In addition to biallelic mutations in one of the USH genes, presumably pathogenic mutations in another USH gene were detected in seven patients (13%), and another patient carried monoallelic mutations in three different USH genes. Notably, none of the USH3 patients carried detectable mutations in the only known USH3 gene, whereas they all carried mutations in USH2 genes. Most importantly, the currently used microarray would have detected only 30 of the 81 different mutations that we found, of which 39 (48%) were novel.ConclusionsBased on these results, complete exon sequencing of the currently known USH genes stands as a definite improvement for molecular diagnosis of this disease, which is of utmost importance in the perspective of gene therapy.

Lichtenstein-Knorr syndrome is an autosomal recessive condition that associates sensorineural hearing loss and cerebellar ataxia. Here, we report the first identification of a gene involved in Lichtenstein-Knorr syndrome. By using a combination of homozygosity mapping and whole-exome sequencing, we identified the homozygous p.Gly305Arg missense mutation in SLC9A1 that segregates with the disease in a large consanguineous family. Mutant glycine 305 is a highly conserved amino acid present in the eighth transmembrane segment of all metazoan orthologues of NHE1, the Na(+)/H(+) exchanger 1, encoded by SLC9A1. We demonstrate that the p.Gly305Arg mutation causes the near complete de-glycosylation, mis-targeting and loss of proton pumping activity of NHE1. The comparison of our family with the phenotypes of spontaneous and knockout Slc9a1 murine models demonstrates that the association between ataxia and hearing loss is caused by complete or near complete loss of function of NHE1 and altered regulation of pHi in the central nervous system.

Many studies were interested in the consequence of vestibular dysfunction related to cochlear implantation on balance control. This pilot study aimed to assess the effects of unilateral cochlear implantation on the modalities of balance control and sensorimotor strategies. Posturographic and vestibular evaluations were performed in 10 patients (55 ± 20 years) with profound hearing loss who were candidates to undergo unilateral multichannel cochlear implantation. The evaluation was carried out shortly before and one year after surgery. Posturographic tests were also performed in 10 age-matched healthy participants (63 ± 16 years). Vestibular compensation was observed within one year. In addition, postural performances of the patients increased within one year after cochlear implantation, especially in the more complex situations, in which sensory information is either unavailable or conflicting. Before surgery, postural performances were higher in the control group compared to the patients' group. One year after cochlear implantation, postural control was close to normalize. The improvement of postural performance could be explained by a mechanism of vestibular compensation. In addition, the recovery of auditory information which is the consequence of cochlear implantation could lead to an extended exploration of the environment possibly favoring the development of new balance strategies.

This study aimed to evaluate the impact of cochlear implantation on quality of life (QoL), using general and cochlear implant (CI) specific questionnaires and to determine the relationship of phone ability with QoL, speech recognition abilities and tinnitus. Twenty-six adult volunteers with a post-lingual profound deafness, unilaterally implanted with a CI, were included in this study. All subjects had used a CI for at least 1 year. The Glasgow benefit inventory (GBI) and Nijmegen cochlear implant questionnaire (NCIQ) were administered to assess QoL. Speech recognition was tested using phonemic Lafon's lists. The subjective tinnitus severity scale (STSS) questionnaire was used to determine the effects of tinnitus. CI users were split into four groups according to their phone ability. There was an improvement in QoL after cochlear implantation. The NCIQ showed significant (p < 0.001) improvements in the total score and in all subdomains after CI. A significant relationship between phone ability, QoL and speech recognition was found. Improving phone ability led to higher QoL (p < 0.05) and speech recognition (p < 0.01) scores. The CI use decreased significantly the occurrence of tinnitus, but its severity was not correlated with QoL. Post-surgery assessment should include speech recognition measures and QoL evaluation. The NCIQ appeared more effective than the GBI in its ability to detect improvements in QoL. Assessing phone ability represents an easy and fast approach to evaluate hearing performances and QoL, and may reflect global outcomes of CI.