Sept 2017 Proceedings National Academy of Sciences

Following sensory deprivation, the sensory brain regions can become colonised by the other intact sensory modalities. In deaf individuals, evidence suggests that visual language recruits auditory brain regions and may limit hearing restoration with a cochlear implant. This suggestion underpins current rehabilitative recommendations that deaf individuals undergoing cochlear implantation should avoid using visual language. However, here we show the opposite: Recruitment of auditory brain regions by visual speech after implantation is associated with better speech understanding with a cochlear implant. This suggests adaptive benefits of visual communication because visual speech may serve to optimise, rather than hinder, restoration of hearing following implantation. These findings have implications for both neuroscientific theory and the clinical rehabilitation of cochlear implant patients worldwide.

It has been suggested that visual language is maladaptive for hearing restoration with a cochlear implant (CI) due to cross-modal recruitment of auditory brain regions. Rehabilitative guidelines therefore discourage the use of visual language. However, neuroscientific understanding of cross-modal plasticity following cochlear implantation has been restricted due to incompatibility between established neuroimaging techniques and the surgically implanted electronic and magnetic components of the CI. As a solution to this problem, here we used functional near-infrared spectroscopy (fNIRS), a noninvasive optical neuroimaging method that is fully compatible with a CI and safe for repeated testing. The aim of this study was to examine cross-modal activation of auditory brain regions by visual speech from before to after implantation and its relation to CI success. Using fNIRS, we examined activation of superior temporal cortex to visual speech in the same profoundly deaf adults both before and 6 mo after implantation. Patients’ ability to understand auditory speech with their CI was also measured following 6 mo of CI use. Contrary to existing theory, the results demonstrate that increased cross-modal activation of auditory brain regions by visual speech from before to after implantation is associated with better speech understanding with a CI. Furthermore, activation of auditory cortex by visual and auditory speech developed in synchrony after implantation. Together these findings suggest that cross-modal plasticity by visual speech does not exert previously assumed maladaptive effects on CI success, but instead provides adaptive benefits to the restoration of hearing after implantation through an audiovisual mechanism.

Sept 2017 Smooth FM  and

Liz Zappia was just 15-months-old when she began to lose her hearing, she's now a married mother-of-two and had not ever heard her children's voices. The fact she couldn’t hear her babies and know whether they were in pain has meant her anxiety has increased a lot in the years since she became a mother.  “Most of my life, I coped OK. It wasn’t until I became a mum that the challenge started for me. Not being able to hear them cry, I had to rely a lot on body language and process of elimination to figure out what they wanted.” In order to get some hearing back, Liz got a cochlear implant.  After having it switched on, Liz found it quite overpowering and couldn’t really hear anything straight away.  

Liz Zappia

About five to six weeks after having the implant turned on, Liz began hearing sounds like the water from the tap and the clattering of cutlery. When she finally began hearing her kids' voices, she said she felt much more connected to them as a mother. 

Her husband David said “It’s wonderful, the result that she’s gotten… Before she got the implant she used to question her ability as a mum – I don’t know why – but it’s good to see now that she’s thriving. Even without the implant she was phenomenal, and what she achieved in her life before, but this has taken it to a whole new level.”

Sept 2017 Scicasts and

Hearing loss, sometimes associated with other disorders such as balance defects, is the most common sensory deficit, affecting more than 280 million people worldwide, according to WHO.

Over the past 20 years, scientists have made remarkable progress in deciphering the genetic origins of congenital hereditary hearing loss, which is usually caused by inner ear dysfunction. The inner ear comprises the hearing organ or cochlea, together with the five balance organs (the saccule, utricle and three semicircular canals), which contain the sensory cells, or hair cells, that detect mechanical vibrations and convert them into electrical signals. To date, mutations in more than 100 genes have been associated with inner ear defects, and it is estimated that mutations in more than 100 genes can cause genetic forms of deafness.

The various hereditary forms of hearing loss include Usher syndrome type 1 (USH1), a particularly severe clinical form of deaf-blindness, and specifically the USH1G genetic form. USH1G patients are profoundly deaf and have no balance function at birth, and they subsequently suffer from prepubertal-onset sight loss leading to blindness. USH1G syndrome is due to mutations in the gene encoding the scaffold protein sans, which is essential for the cohesion of the hair bundle of the inner ear hair cells.

Patients with hearing loss and balance dysfunction are currently fitted with auditory prostheses and may be given balance rehabilitation therapy, but the outcomes are variable. One possible alternative for treating such hereditary inner ear defects is gene therapy. This approach entails transferring a healthy (non-mutant) copy of the defective gene to restore the expression of the missing protein. So far, gene therapy attempts have only resulted in partial improvements of hearing in mouse models of specific human deafness forms that did not include severe anomalies in hair cell structure. 

Hair bundlesHair bundles of vestibular sensory cells analyzed using scanning electron microscopy. The image shows a normal hair bundle with its characteristic "staircase" pattern (in yellow), a defective Usher type 1G hair bundle (in pink) and a treated Usher type 1G hair bundle (in green), whose normal/characteristic form was restored with gene therapy. 

In this context, scientists from the Institut Pasteur, Inserm, the CNRS, Collège de France, University Pierre et Marie Curie, and University Clermont Auvergne, have now succeeded in restoring hearing and balance in a mouse model of USH1G syndrome using gene therapy. With a single local injection of the USH1G gene just after birth, the scientists observed a restoration of the structure and mechanosensory function of the inner ear hair bundles - profoundly damaged before birth - resulting in a long-term partial recovery of hearing, and complete recovery of vestibular function in these mice. These results unexpectedly establish that inner ear defects due to major morphogenetic abnormalities of the hair bundle can be reversed even after birth, with durable efficacy, by gene therapy.

The scientists injected the USH1G gene into the inner ear using the innocuous AAV8 virus, which enabled them to specifically target the hair cells. The expression of the therapeutic gene was detected 48 hours after injection. The team demonstrated that a single injection to restore the production and localisation of the missing protein in hair cells successfully improved hearing and balance functions in the young mice. These findings suggest that the therapeutic protein was able to interact normally with its binding partners among the USH1 molecular complex as required for the mechanoelectrical transduction apparatus of the hair bundle to function correctly.

As Saaïd Safieddine, CNRS Director of Research at the Institut Pasteur and co-senior author of the study with Prof. Christine Petit (head of the Genetics & physiology hearing unit), explains, "we have just shown that it is possible to partially correct a specific form of hereditary hearing loss accompanied by balance problems using local gene therapy performed after the embryogenesis of the ear, which is primarily affected by the mutation responsible for the disorder.” This study represents a significant step towards the development of clinical trials in gene therapy for the curative treatment of hereditary deafness and balance loss in humans.

Sept 2017

Med-El launched a cochlear implant audio processor featuring wireless charging at the 61st Austrian National Otorhinolaryngology, Head and Neck Surgery Conference. The RONDO 2 frees implant users from the need to regularly replace batteries, making the device easy to use, more cost effective and friendlier to the environment. Wireless charging allows users to power their implant with 18 hours of battery life for each four hour charge, giving users a full day of hearing from one overnight charge. It also saves users from the hassle of replacing the disposable batteries that power the device. In a single year, powering the device every day would require more than 700 batteries. “We are so used to charging our devices at home overnight,” says Gregor Dittrich, Director of Product Management for MED-EL. “You charge your phone and tablet in this way, so why not your audio processor? It’s the next logical step for cochlear implants and we are so excited to be pioneering the way forward.” RONDO 2, and its accessories, will available from the end of 2017.