Objective: To update a 15-year-old study of 800 postlinguistically deaf adult patients showing how duration of severe to profound hearing loss, age at cochlear implantation (CI), age at onset of severe to profound hearing loss, etiology and CI experience affected CI outcome. Study Design: Retrospective multicenter study. Methods: Data from 2251 adult patients implanted since 2003 in 15 international centers were collected and speech scores in quiet were converted to percentile ranks to remove differences between centers. Results: The negative effect of long duration of severe to profound hearing loss was less important in the new data than in 1996; the effects of age at CI and age at onset of severe to profound hearing loss were delayed until older ages; etiology had a smaller effect, and the effect of CI experience was greater with a steeper learning curve. Patients with longer durations of severe to profound hearing loss were less likely to improve with CI experience than patients with shorter duration of severe to profound hearing loss. Conclusions: The factors that were relevant in 1996 were still relevant in 2011, although their relative importance had changed. Relaxed patient selection criteria, improved clinical management of hearing loss, modifications of surgical practice, and improved devices may explain the differences.

ObjectiveTo test the influence of multiple factors on cochlear implant (CI) speech performance in quiet and in noise for postlinguistically deaf adults, and to design a model of predicted auditory performance with a CI as a function of the significant factors.Study DesignRetrospective multi-centre study.MethodsData from 2251 patients implanted since 2003 in 15 international centres were collected. Speech scores in quiet and in noise were converted into percentile ranks to remove differences between centres. The influence of 15 pre-, per- and postoperative factors, such as the duration of moderate hearing loss (mHL), the surgical approach (cochleostomy or round window approach), the angle of insertion, the percentage of active electrodes, and the brand of device were tested. The usual factors, duration of profound HL (pHL), age, etiology, duration of CI experience, that are already known to have an influence, were included in the statistical analyses.ResultsThe significant factors were: the pure tone average threshold of the better ear, the brand of device, the percentage of active electrodes, the use of hearing aids (HAs) during the period of pHL, and the duration of mHL.ConclusionsA new model was designed showing a decrease of performance that started during the period of mHL, and became faster during the period of pHL. The use of bilateral HAs slowed down the related central reorganization that is the likely cause of the decreased performance.

Cochlear implants work well, yet the outcome is not fully accounted by the data routinely available to the clinician, and remains unpredictable. A more in-depth understanding of the neural mechanisms that determine the clinical recovery after cochlear implantation is warranted, as they may provide the background for an accurate individual prognosis. In this study in post-lingually deaf adults, we show that while clinical data offer only prognosis trends, fMRI data can prospectively distinguish good from poor implant performers. We show that those deaf cochlear implant (CI) candidates who will become good performers rely on a dorsal phonological route when performing a rhyming task on written regular words. In contrast, those who will become poor performers involve a ventral temporo-frontal route to perform the same task, and abnormally recruit the right supramarginal gyrus, a region that is contralateral to classical phonological regions. These functional patterns reveal that deafness either enhances "normal" phonological processing, or prompts a substitution of phonological processing by lexico-semantic processing. These findings thus suggest that a simple behavioral pre-operative exploration of phonological strategies during reading, to determine which route is predominantly used by CI candidates, might fruitfully inform the outcome.

Using different and adapted brain-imaging techniques in congenitally deaf children and postlingually deafened adults, we identified neural patterns that are consistently predictive of speech perception performance with a cochlear implant. Deaf subjects who show neural activity in ventral regions of the brain during deafness, whether to communicate or just when idling at rest, tend to become poor performers. By contrast, those who involve dorsal brain regions in the same cognitive situations tend to become good performers. We further show that cortical reorganization does not only reflect hearing loss and its duration, but also the functional relevance of the cognitive operations that are performed during deafness. We argue that the trajectory toward one or the other pattern of cortical activity could be controlled by appropriate cognitive training during the period of deafness preceding cochlear implantation.Learning Outcomes: As a result of this activity, the participant will be able to (1) list the functional neuroanatomical hallmarks of good and poor cochlear implant prognosis, and (2) describe the methodologies that can be used to track good and bad functional reorganization in deaf patients with and without cochlear implants. Cochlear implants (CI) work very well incongenitally deaf children and adults presenting severe to profound sensory hearing loss. In both populations, the success of implantation is inversely proportional to the duration of deafness. 1-3 Yet, there is huge performance variability for equal deafness durations in both populations. 4 We set out to explore whether 1 Ecole Normale Supérieure, Département d'Etudes Cognitives, Inserm U960,

Post-lingual deafness induces a decline in the ability to process phonological sounds or evoke phonological representations. This decline is paralleled with abnormally high neural activity in the right posterior superior temporal gyrus/supramarginal gyrus (PSTG/SMG). As this neural plasticity negatively relates to cochlear implantation (CI) success, it appears important to understand its determinants. We addressed the neuro-functional mechanisms underlying this maladaptive phenomenon using behavioral and functional magnetic resonance imaging (fMRI) data acquired in 10 normal-hearing subjects and 10 post-lingual deaf candidates for CI. We compared two memory tasks where subjects had to evoke phonological (speech) and environmental sound representations from visually presented items. We observed dissociations in the dynamics of right versus left PSTG/SMG neural responses as a function of duration of deafness. Responses in the left PSTG/SMG to phonological processing and responses in the right PSTG/ SMG to environmental sound imagery both declined. However, abnormally high neural activity was observed in response to phonological visual items in the right PSTG/SMG, i.e., contralateral to the zone where phonological activity decreased. In contrast, no such responses (overactivation) were observed in the left PSTG/SMG in response to environmental sounds. This asymmetry in functional adaptation to deafness suggests that maladaptive reorganization of the right PSTG/SMG region is not due to balanced hemispheric interaction, but to a specific take-over of the right PSTG/SMG region by phonological processing, presumably because speech remains behaviorally more relevant to communication than the processing of environmental sounds. These results demonstrate that cognitive long-term alteration of auditory processing shapes functional cerebral reorganization. Hum Brain Mapp 00:000-000,

While many individuals can benefit substantially from cochlear implantation, the ability to perceive and understand auditory speech with a cochlear implant (CI) remains highly variable amongst adult recipients. Importantly, auditory performance with a CI cannot be reliably predicted based solely on routinely obtained information regarding clinical characteristics of the CI candidate. This review argues that central factors, notably cortical function and plasticity, should also be considered as important contributors to the observed individual variability in CI outcome. Superior temporal cortex (STC), including auditory association areas, plays a crucial role in the processing of auditory and visual speech information. The current review considers evidence of cortical plasticity within bilateral STC, and how these effects may explain variability in CI outcome. Furthermore, evidence of audio-visual interactions in temporal and occipital cortices is examined, and relation to CI outcome is discussed. To date, longitudinal examination of changes in cortical function and plasticity over the period of rehabilitation with a CI has been restricted by methodological challenges. The application of functional near-infrared spectroscopy (fNIRS) in studying cortical function in CI users is becoming increasingly recognised as a potential solution to these problems. Here we suggest that fNIRS offers a powerful neuroimaging tool to elucidate the relationship between audio-visual interactions, cortical plasticity during deafness and following cochlear implantation, and individual variability in auditory performance with a CI.

The cochlear implant (CI), by enabling oral communication in severely to profoundly deaf subjects, is one of the major medical advances over the last fifty years. Despite the globally very satisfactory results, individual outcomes vary considerably. The objective of this review is to describe the various factors influencing the results of CI rehabilitation with particular emphasis on the better understanding of neurocognitive mechanisms provided by functional brain imaging. The following aspects will be discussed: 1. Peripheral predictors such as the degree of preservation of nerve structures and the positioning of the electrode array. 2. The duration of auditory deprivation whose influence on brain reorganization is now becoming more clearly understood. 3. The age of initiation of hearing rehabilitation in subjects with pre-lingual deafness influencing the possibility of physiological maturation of nerve structures. 4. The concepts of sensitive period, decoupling and cross-modality. 5. In post-lingually deaf adults, brain plasticity can allow adaptation to the disability induced by deafness, subsequently potentiating CI rehabilitation, particularly as a result of audiovisual interactions. 6. Several studies provide concordant evidence that implanted patients present different phonological analysis and primary linguistic capacities. The results of CI rehabilitation are dependent on factors situated between the cochlea and cortical associative areas. The importance of higher cognitive influences on the functional results of cochlear implantation justify adaptation of coding strategies, as well as global cognitive management of deaf patients by utilising brain plasticity capacities.

The outcome of adult cochlear implantation is predicted positively by the involvement of visual cortex in speech processing, and negatively by the cross-modal recruitment of the right temporal cortex during and after deafness. How these two neurofunctional predictors concur to modulate cochlear implant (CI) performance remains unclear. In this fMRI study, we explore the joint involvement of occipital and right hemisphere regions in a visual-based phonological task in post-lingual deafness. Intriguingly, we show that some deaf subjects perform faster than controls. This behavioural effect is associated with reorganized connectivity across bilateral visual, right temporal and left inferior frontal cortices, but with poor CI outcome. Conversely, preserved normal-range reaction times are associated with left-lateralized phonological processing and good CI outcome. These results suggest that following deafness, involvement of visual cortex in the context of reorganized right-lateralized phonological processing compromises its availability for audio-visual synergy during adaptation to CI.