Does choosing the "worse" ear for cochlear implantation affect outcome?

Saccades Matter: Reduced Need for Caloric Testing of Cochlear Implant Candidates by Joint Analysis of v-HIT Gain and Corrective Saccades

Objectives: Video head impulse test (v-HIT) is a quick, non-invasive and relatively cheap test to evaluate vestibular function compared to the caloric test. The latter is, however, needed to decide on the optimal side to perform cochlear implantation to avoid the risk on inducing a bilateral vestibular areflexia. This study evaluates the effectiveness of using the v-HIT to select cochlear implant (CI) candidates who require subsequent caloric testing before implantation, in that way reducing costs and patient burden at the same time.

Study Design: Retrospective study using clinical data from 83 adult CI-candidates, between 2015 and 2020 at the Leiden University Medical Center.

Materials and Methods: We used the v-HIT mean gain, MinGain_LR, the gain asymmetry (GA) and a newly defined parameter, MGS (Minimal Gain & Saccades) as different models to detect the group of patients that would need the caloric test to decide on the ear of implantation. The continuous model MGS was defined as the MinGain_LR, except for the cases with normal gain (both sides ≥0.8) where no corrective saccades were present. In the latter case MGS was defined to be 1.0 (the ideal gain value).

Results: The receiver operating characteristics curve showed a very good diagnostic accuracy with and area under the curve (AUC) of 0.81 for the model MGS. The v-HIT mean gain, the minimal gain and GA had a lower diagnostic capacity with an AUC of 0.70, 0.72, and 0.73, respectively. Using MGS, caloric testing could be avoided in 38 cases (a reduction of 46%), with a test sensitivity of 0.9 (i.e., missing 3 of 28 cases).

Conclusions: The newly developed model MGS balances the sensitivity and specificity of the v-HIT better than the more commonly evaluated parameters such as mean gain, MinGain_LR and GA. Therefore, taking the presence of corrective saccades into account in the evaluation of the v-HIT gain can considerably reduce the proportion of CI-candidates requiring additional caloric testing.

Cochlear implantation in adults with auditory deprivation: What do we know about it?

INTRODUCTION

In the ENT community, auditory deprivation is frequently considered as a negative prognostic factor for a good hearing outcome of cochlear implantation (CI), even if a growing literature suggests that this is not completely true. The purpose of this study is to evaluate the results of CI in patients with hearing deprivation, to compare them to results from non-deprived patients and then estimate how time of deprivation impacts on CI outcome and how a bilateral deprivation can affect the outcome compared to a unilateral deprivation.

METHODS

Seventy-eight adults with severe to profound post-verbal hearing loss, with and without auditory deprivation history, received CI; audiological results obtained at 3-6-12-24 months follow up post CI were analyzed.

RESULTS

No differences were founded between patients with unilateral deprivation and patients with no deprivation. Patients with bilateral deprivation seem to have a worse hearing outcome compared to that of those patients with unilateral deprivation or no deprivation at all. Long time deprivation (>15 years) seems to have a negative influence on the hearing outcome but results with CI remain excellent.

CONCLUSIONS

Auditory deprivation should not be considered a contraindication to CI. The duration of auditory deprivation in the implanted ear seems to be a negative prognostic factor only for ears deprived from more of 15 years.

Idiopathic sensorineural hearing loss in the only hearing ear

A retrospective chart review was used for 31 patients with sudden, progressive or fluctuating sensorineural hearing loss (SHL) in the only hearing ear who had been consecutively evaluated at the ENT, Audiology and Phoniatrics Unit of the University of Pisa. The group of patients was evaluated with a complete history review, clinical evaluation, imaging exam (MRI, CT), audiologic tests (tone and speech audiometry, tympanometry, study of stapedial reflexes, ABR and otoacoustic emission) evaluation. In order to exclude genetic causes, patients were screened for CX 26 and CX30 mutations and for mitochondrial DNA mutation A1555G. Patients with sudden or rapidly progressive SHL in the only hearing ear were treated with osmotic diuretics and corticosteroids. In patients who did not respond to intravenous therapy we performed intratympanic injections of corticosteroid. Hearing aids were fitted when indicated and patients who developed severe to profound SHL were scheduled for cochlear implant surgery. The aim of this study is to report and discuss the epidemiology, aetiopathogenesis, therapy and clinical characteristic of patients affected by SHL in the only hearing hear and to discuss the issues related to the cochlear implant procedure in some of these patients, with regard to indications, choice of the ear to implant and results.

Which ear should we choose for cochlear implantation in the elderly: The poorer or the better? Audiometric outcomes, quality of sound, and quality-of-life results

CONCLUSIONS

Cochlear implantation in the poorer ear of an elderly patient does not predict poorer post-operative audiological, quality-of-life (QoL), and quality of sound results.

OBJECTIVES

To determine whether choosing the 'better' or the 'poorer' ear for cochlear implantation impacts performance outcome in an elderly population.

METHODS

Forty-two out of 73 elderly (≥ 60 years) cochlear implant users with some residual hearing in at least one ear were selected. Three criteria were used to group the patients as 'better' or 'poorer' ear implanted; (C1) based on previous use of hearing aid, (C2) pre-operative PTA, and (C3) pre-operative speech discrimination. The Glasgow Benefit Inventory (GBI) and the Hearing Implant Sound Quality Index (HISQUI) were used to measure QoL and quality of sound, respectively.

RESULTS

The mean post-operative PTA was 38.7 ± 7.2 dBHL. In quiet, the mean disyllabic SDS at 65dBSPL was 75.4 ± 18.5, whereas the discrimination of sentences was 95.0% ± 6.9. The mean total GBI score was 30.9 ± 21.8, 92.9% of patients reporting a positive score. The mean HISQUI score was 111.3 ± 36.0, which corresponds to 'moderate' sound quality. No significant differences were found between both groups in terms of audiological outcomes, HISQUI scores or GBI scores when considering each of the three criteria.

Long-term asymmetric hearing affects cochlear implantation outcomes differently in adults with pre- and postlingual hearing loss

In many countries, a single cochlear implant is offered as a treatment for a bilateral hearing loss. In cases where there is asymmetry in the amount of sound deprivation between the ears, there is a dilemma in choosing which ear should be implanted. In many clinics, the choice of ear has been guided by an assumption that the reorganisation of the auditory pathways caused by longer duration of deafness in one ear is associated with poorer implantation outcomes for that ear. This assumption, however, is mainly derived from studies of early childhood deafness. This study compared outcomes following implantation of the better or poorer ear in cases of long-term hearing asymmetries. Audiological records of 146 adults with bilateral hearing loss using a single hearing aid were reviewed. The unaided ear had 15 to 72 years of unaided severe to profound hearing loss before unilateral cochlear implantation. 98 received the implant in their long-term sound-deprived ear. A multiple regression analysis was conducted to assess the relative contribution of potential predictors to speech recognition performance after implantation. Duration of bilateral significant hearing loss and the presence of a prelingual hearing loss explained the majority of variance in speech recognition performance following cochlear implantation. For participants with postlingual hearing loss, similar outcomes were obtained by implanting either ear. With prelingual hearing loss, poorer outcomes were obtained when implanting the long-term sound-deprived ear, but the duration of the sound deprivation in the implanted ear did not reliably predict outcomes. Contrary to an apparent clinical consensus, duration of sound deprivation in one ear has limited value in predicting speech recognition outcomes of cochlear implantation in that ear. Outcomes of cochlear implantation are more closely related to the period of time for which the brain is deprived of auditory stimulation from both ears.

Choice of cochlear implant side in a paediatric population

Objective:

To compare the effect of right- or left-sided cochlear implantation on listening skills in a paediatric population.

Methods:

A retrospective analysis was conducted on the listening skills performance data of children who were operated on and followed up at the Çukurova University Department of Otorhinolaryngology between 2007 and 2011. Sixty-three patients were included in the study. Patients were evaluated using the Listening Progress Profile, the Meaningful Auditory Integration Scale and the littlEARS test.

Results:

The mean age of the children was two years (range of one to five years). Twenty-nine patients were male and 34 were female. Twenty-eight patients were implanted in the right ear and 35 in the left ear. There were no statistically significant differences between right and left ear implantees in terms of listening skills performance.

Conclusion:

This study indicates that the choice of cochlear implant side is not crucial for the development of listening skills.

[Vestibular dysfunction after cochlear implant in adults]

BACKGROUND

According to the literature, clinical vertigo after cochlear implant (CI) occurs in 0.33-75%, a peripheral vestibular loss of function in 20-75%.

MATERIALS AND METHODS

Between 2006 and 2009, 30 adults were implanted with a 22-channel Nucleus Freedom CI (41 operations). Cochleostomy was performed anterocaudal of the round window and the electrode inserted using the "off-stylet" technique into the scala tympani.

RESULTS

Clinical vertigo occurred after 10/41 (24.4%) operations: acutely in 5/41 (12.2%), continuous in 1/41 (2.4%), delayed for 6-18 months in 5/41 (12.2%). In the calorimetry, 3/27 (11.1%) vestibular organs displayed a loss of function (p = 0.16). Three of 8 patients (37.5%) with clinical vertigo after surgery showed a loss of vestibular function (p = 0.08).

CONCLUSION

Using the described techniques and materials, the risk of loss of vestibular function and the incidence of clinical vertigo can be minimized. Postoperative vertigo did not occur more often in patients with preoperative diminished vestibular function than in patients with normal findings. Therefore, preoperative vestibular function tests cannot be an indicator for the frequency of vertigo after CI. If one vestibular organ shows preoperative dysfunction, the non-affected normal vestibular organ should not be implanted.

Pre-, per- and postoperative factors affecting performance of postlinguistically deaf adults using cochlear implants: a new conceptual model over time

OBJECTIVE

To 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 DESIGN

Retrospective multi-centre study.

METHODS

Data 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.

RESULTS

The 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.

CONCLUSIONS

A 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.

Relative importance of monaural sound deprivation and bilateral significant hearing loss in predicting cochlear implantation outcomes

OBJECTIVES

Making evidence-based recommendations to prospective unilateral cochlear implant recipients on the potential benefits of implanting one or the other ear is challenging for cochlear implant teams. This particularly occurs in cases where a hearing aid has only been used in one ear for many years (referred to here as the "hearing ear"), and the contralateral ear has, in essence, been sound-deprived. In such cases, research to date is inconclusive, and little anecdotal evidence exists to inform the debate and support best clinical practice.

DESIGN

Retrospective data on speech recognition outcomes of 16 adult participants who received a cochlear implant in an ear deprived of sound for a minimum of 15 yr were analyzed. All subjects were implanted through the Quebec Cochlear Implant Program and were provided with personalized intensive rehabilitation services. Data obtained from clinical records included demographic data and speech recognition scores measured after implantation with the sentences of a multimedia auditory test battery in the auditory-only condition. Speech recognition outcomes were compared with the duration of auditory deprivation in the implanted ear, bilateral significant hearing loss, and auditory stimulation before bilateral significant hearing loss.

RESULTS

Using nonparametric correlation analyses, a strong negative correlation was demonstrated between speech recognition scores and the duration of bilateral significant hearing loss and with the duration of auditory stimulation before bilateral significant hearing loss. No significant correlation with the duration of auditory deprivation or with the duration of prior auditory stimulation in the implanted ear was found.

CONCLUSIONS

These findings suggest that functional outcomes of cochlear implantation for unilateral sound deprivation may be more strongly influenced by central processes than peripheral effects stemming from the deprivation per se. This indicates the relevance of considering the client's history of binaural hearing rather than the hearing in each ear individually when discussing possible outcomes with a cochlear implant.

When do we choose the 'better balance' ear for cochlear implants?

OBJECTIVES

In cochlear implant planning, the ear with poorer vestibular function, as determined through electronystagmography (ENG), is often selected as the site for implantation since surgery carries a low risk of iatrogenic labyrinthine injury. We sought to determine reasons for placing a cochlear implant in the 'better balance' ear.

METHODS

A retrospective cohort study of patients implanted with a cochlear implant at a tertiary care center from 1984 to June 2009 was performed. Based on ENG results, patients with asymmetric caloric reduction were identified. Of these patients, those who were implanted in the 'better balance' ear were selected for chart review. The charts were reviewed to determine rationale for ear selection.

RESULTS

Of the 724 cochlear implant patients implanted from 1984 to June 2009, ENG tests demonstrated that 130 (18%) had asymmetric abnormal responses. Thirty five (27%) of the patients with asymmetric abnormal responses were implanted in the 'better balance' ear. Review of these 35 patient charts revealed that reasons for selection of the 'better balance' ear fell into four categories: anatomical contraindications, attempting to attain binaural hearing, avoiding implantation of an ear with marked auditory deprivation, and patient preference.

DISCUSSION

Based on our current practice, we have identified four situations in which patients were implanted in the 'better balance' ear, and subsequently developed an algorithm to aid surgeons in side selection for cochlear implantation. Further study and validation of this algorithm is recommended.

Intra-individual assessment of speech and music perception in cochlear implant users with contralateral Cochlear™ and MED-EL™ systems

CONCLUSION

Whilst objective testing on music perception showed no individual differences between cochlear implant (CI) devices, subjective music perception was found to be superior with the MED-EL device in the majority of cases evaluated.

OBJECTIVE

To compare speech and music perception through two different CI systems in the same individuals.

METHODS

Six post-lingually deaf patients, who had been implanted with a Cochlear™ Nucleus(®) device in one ear and a MED-EL SONATATI(100) on the contralateral side were evaluated. One subject was excluded from group analysis because of significant differences in performance between ears. Subjects completed a questionnaire designed to assess implant users' listening habits. Subjective assessments of each subject were made for comparison of speech and music perception with each system and preferences of system. The subjects consecutively used each system with the contralateral device turned off, and were objectively assessed for specific musical skills. Speech perception in quiet and in noise was tested.

RESULTS

For all objective tests of music discrimination and speech perception in noise, there were no statistically significant differences between MED-EL and Cochlear CI systems. Subjectively, four subjects thought their MED-EL device was better than their Cochlear device for music appreciation. Four thought that music sounded more natural, less tinny and more reverberant with their MED-EL CI than with their Cochlear CI. One subject rated all these to be equal.

Benefit from bimodal hearing in a group of prelingually deafened adult cochlear implant users

PURPOSE

People who receive a unilateral cochlear implant find speech perception in acoustically complex situations very challenging, in part because they do not have access to binaural hearing. For cochlear implant patients with some residual hearing in the nonimplanted ear, bilateral auditory input can be obtained by the use of a cochlear implant and a contralateral conventional hearing aid. This condition is referred to as "bimodal hearing."

MATERIALS AND METHODS

We evaluated the benefits from bimodal stimulation in a group of 10 prelingually deafened adult cochlear implant users, submitted to unilateral cochlear implantation at the ENT Unit of the University of Pisa.

RESULTS

Of 10 patients, 9 decided to continue using bimodal stimulation and demonstrated improvements in speech perception both in quiet and in noise condition from bimodal hearing, in comparison to the cochlear implant alone condition.

CONCLUSIONS

Our results show that bimodal hearing offers some advantages in speech understanding in quiet and noise conditions also in prelingually deafened adults. Moreover, most of our patients reported advantages from bimodal hearing in localizing sound and in perceiving a more natural sound.

Cochlear implantation in postlingually hearing-impaired adults: choosing the most appropriate ear

Choice of the most appropriate ear for CI in postlingually hearing-impaired adults is becoming more relevant as more patients are considered eligible for intervention. The aim of this study is to review factors that influence this choice and to formulate a flowchart. An extensive Medline search was performed. Factors can be divided into surgical, audiological, and patient factors. Surgical factors are anatomic variation and otological medical history. Both are divided in absolute and relative contraindications. Duration of deafness and residual hearing are combined in the audiological factor. Likeliness of improvement of speech perception after CI at different durations of deafness is estimated. This is followed by comparison of between-ear differences in duration of deafness. If there is a large difference, above the presented 5% interval, the ear with the shortest duration is preferred. This review and its flowchart are an aid for decision making in the choice of ear for CI. Being as representative of current knowledge as possible, future refinements may occur as new insights are gained.

Natural history of contralateral residual hearing in binaural-bimodal hearing

CONCLUSIONS

The range of evaluation tools used in deciding which ear to implant and which to designate for a hearing aid (HA) should be expanded to include additional aspects to those tested by audiometry and basic speech perception. Residual hearing in non-implanted ears remains stable for at least 3 years after unilateral cochlear implantation, but regular refitting and monitoring of the HA function combined with cochlear implant (CI) mapping are mandatory for maximizing benefit from binaural-bimodal hearing.

OBJECTIVES

To examine whether the clinical decision-making tools currently used to assess hearing are reliable guides when choosing the preferred ear for CI, and to determine the rate of residual hearing deterioration in the non-implanted ear over 36 months post-CI as a guide to recommending subsequent continued use of a contralateral HA as opposed to CI.

PATIENTS AND METHODS

This was a retrospective evaluation of patients' charts. The pre-CI choice of the ear for implantation in a group of 37 binaural-bimodal users was re-evaluated. In a second group of 22 patients, residual hearing deterioration was followed for 36 months post-implantation.

RESULTS

In the group of 37 patients, subjective identification of the worse-hearing ear was in agreement with audiometric results in 28 cases, but disagreed with the unaided audiometric results in the other 9. Mean threshold values for the group of 22 patients remained stable over 36 months post-CI, except for the aided threshold at 4.0 kHz, which deteriorated by 10.9 dB (p=0.003).

Central Effects of Residual Hearing: Implications for Choice of Ear for Cochlear Implantation

OBJECTIVES/HYPOTHESIS

The study tested the hypothesis that among patients with similar levels of residual hearing in the nonimplanted ear, speech perception outcome is the same whether or not the implanted ear has profound or severe levels of hearing loss.

STUDY DESIGN

Retrospective.

METHODS

Levels of hearing loss in postlingually deafened adults who had cochlear implantation at Johns Hopkins University (Baltimore, MD) between 1991 and 2002 were classified according to pure-tone averages as bilateral severe (n = 20), severe-profound (severe in one ear and profound in the other) (n = 23), and bilateral profound (n = 43). There was no significant difference in the age at onset and duration of deafness among the three patient groups. Individuals in the bilateral severe and severe-profound groups had comparable levels of severe hearing loss in their nonimplanted ears, whereas those in severe-profound and bilateral profound groups had comparable levels of profound hearing loss in their implanted ears. Speech perception performance was evaluated using words from the Consonant Nucleus Consonant word list, Hearing in Noise Test sentences in quiet, and Central Institute for the Deaf sentences through recorded presentation at 70 dB sound pressure level (SPL).

RESULTS

Despite the profound hearing loss of the implanted ear in the asymmetrical group, there was no significant difference in mean speech perception scores compared with the bilateral severe group within the first year after implant surgery. By comparison, the bilateral profound group had lower speech perception results compared with patients with residual hearing in one or both ears.

CONCLUSION

The study results suggest that implantation of the profoundly deafened ear does not diminish the functional advantage conferred by residual hearing in a patient with asymmetrical hearing loss. Therefore, the central auditory pathway may be the site at which persistent auditory function has its most beneficial effects.

Cochlear implant outcome is not influenced by the choice of ear

OBJECTIVES

This study tested the hypothesis that patients with residual hearing in the nonimplanted ear had the same cochlear implant benefit whether the implanted ear had profound or severe hearing loss.

DESIGN

A retrospective chart review of adult cochlear implant recipients with postlingual hearing loss. Patients were categorized according to the pure-tone average of the implanted and contralateral ears as (a) bilateral profound, (b) severe-profound, and (c) bilateral severe. The results of a test battery of spoken language measures were compared among patients belonging to these hearing categories at 6, 12, and 24 months after surgery, using a t-test and multivariate regression analyses.

RESULTS

The presence of residual hearing in one or both ears was associated with significantly higher postoperative speech perception scores compared with participants with bilateral profound hearing loss. Among participants with similar amounts of residual hearing in the nonimplanted ear, however, there was no difference in speech recognition scores between those with profound and those with severe hearing loss in the implanted ear.

CONCLUSIONS

Among participants with asymmetric hearing loss, there is no additional benefit to implanting the better-hearing ear that can be preserved for use with a hearing aid for better speech understanding in noise and sound localization. These results suggest that the additional benefit received by patients with residual hearing is mediated by trophic effects on crossed pathways in the central nervous system and is independent of the preoperative functional status of the implanted ear.

Criteria of candidacy for unilateral cochlear implantation in postlingually deafened adults I: theory and measures of effectiveness

OBJECTIVES

The objectives of this study were to distinguish the equivalent-effectiveness, health-economic, and actuarial approaches to specifying criteria of candidacy for medical interventions; to apply the equivalent-effectiveness approach to unilateral cochlear implantation for postlingually deafened adults; and to determine whether the criterion should take age at implantation and duration of profound deafness into account.

DESIGN

The study was designed as a prospective cohort study in 13 hospitals with four groups of severely-profoundly hearing-impaired subjects distinguished by their preoperative ability to identify words in sentences when aided acoustically. The groups represent a progressive relaxation of criteria of candidacy: Group I (N=134) scored 0% correct without lipreading and did not improve their lipreading score significantly when aided; group II (N=93) scored 0% without lipreading but did improve their lipreading score significantly when aided; group III (N=53) scored 0% without lipreading when the to-be-implanted ear was aided but between 1% and approximately 50% when the other ear was aided. Group IV (N=31) scored between 1% and approximately 50% without lipreading when the to-be-implanted ear was aided. Measures of speech intelligibility, health utility, and otologically relevant quality of life were obtained before surgery and 9 mo after surgery from each subject. Measures of effectiveness were calculated as the difference between 9-mo and preoperative scores.

RESULTS

Effectiveness differed only slightly between groups. Effectiveness was not strongly associated with age at the time of implantation. Greater effectiveness was associated with implantation in the ear with the shorter duration of profound deafness. Cochlear implantation was least effective when the preoperative audiological status of the better-hearing ear was good and the duration of profound deafness of the implanted ear was long. As a result, effectiveness was not significant for the subsets of groups III and IV, who were given implants in ears that had been profoundly deaf for more than 30 yr.

CONCLUSIONS

The effectiveness of cochlear implantation differs little between groups of candidates who score zero with acoustic hearing aids before surgery and groups who score up to approximately 50% correct, thereby justifying a relaxation of the criterion of candidacy to embrace some members of the latter groups. The criterion should be based not only on preoperative speech intelligibility but also on duration of profound deafness in the to-be-implanted ear.

Choice of ear for cochlear implantation: the effect of history and residual hearing on predicted postoperative performance

OBJECTIVE

This study used mathematical formulas predicting cochlear implant outcomes to investigate the effects of implantation in the poorer ear on postoperative speech recognition.

DESIGN

Retrospective cohort study with mathematical and statistical analyses. This study used the University of Iowa formula for predicting outcomes derived from implantation of the better ear on the basis of duration of deafness and preoperative speech understanding, applying this predictive model to a cohort of patients undergoing implantation in the poorer ear at The Johns Hopkins Medical Center.

SETTING

Tertiary referral center with active cochlear implant program.

PATIENTS

Postlingually deafened adults (n = 58) with preoperative Central Institute for the Deaf sentence scores less than or equal to 40%.

INTERVENTION

Cochlear implantation with all three Food and Drug Administration-approved devices.

MAIN OUTCOME MEASURE

Postoperative monosyllabic word recognition scores and correlations between actual and predicted results.

RESULTS

There was good statistical correlation between the predicted postoperative performance using the University of Iowa formula and the actual performance of our cohort of patients undergoing implantation in the poorer ear (r = 0.50, p < 0.0001). In addition, as a population, our cohort had a mean postoperative consonant-nucleus-consonant word score of 41.8%, which was statistically the same as that predicted by the University of Iowa formula (43.6%).

CONCLUSIONS

The postoperative performance of cochlear implant patients is most closely correlated with duration of deafness. However, our results indicate that this measure may not be ear specific and is more reflective of the total auditory receptivity of the patient. These observations help to form guidelines for choice of ear for implantation.

Cochlear and brainstem implantation

Cochlear implantation is an established habilitative and rehabilitative option for profoundly deafened individuals over 1 year of age who derive limited benefit from conventional hearing aids. Auditory performance varies among individuals and is determined primarily by age at implantation, pre-existence of speech and language skills, and the time interval between onset of deafness and implantation. Successful implant users generally demonstrate improved auditory abilities and speech production skills beyond those achieved with hearing aids. Multichannel ABIs can provide useful auditory information to patients with NF-2 who have lost integrity of auditory nerves following removal of vestibular schwannomas. The implant allows for awareness of environmental sounds and, potentially, speech recognition. Most patients undergoing implantation demonstrate improved lip-reading skills, and exceptional performers achieve understanding of open-set speech.