2017) argue that the currently applied criteria for CI result in underreferral of persons who could potentially benefit, and that “traditional” CI candidates are underreferred, as are persons who meet expanded guidelines.
Another important purpose in carrying out a comprehensive evaluation for IHDs is to prepare the candidate and the implant team for postimplantation needs. With thorough assessment, rehabilitative planning or support services can be made available in anticipation of the implantee’s needs or limitations. For example, some studies have shown that vertigo or dizziness is not only a risk factor following cochlear implantation (Spitzer et al., 2015), but many times also presents as a preoperative complaint in implant candidates (Rah et al., 2016). For these individuals, vestibular rehabilitation may be indicated in an extended recovery period, and alerting the candidate to this possibility is essential to acceptance.
Assessment in the Historical Context
Assessment has been at the heart of demonstrating to governmental agencies (especially the FDA), the professional community, the Deaf community, and the general public that IHDs are safe and provide substantial benefit that outweighs the risks. Beginning in the 1970s, clinical trials with CIs received considerable media attention. Early work with the single-channel CI was criticized as having excessive reliance on anecdotal reporting of benefit. Thus, later studies, such as the randomized trial by the Department of Veterans Affairs (Cohen et al., 1991), needed to be more fastidious in producing tight pre- and postdesigns to document safety and efficacy.
Multichannel CI devices have undergone a stepwise progression in hardware and software design. With each iteration, the clinical trials have had rigorous, structured baseline testing with contemporary hearing aids and postoperative examination using reliable measures in controlled test environments. Many of the procedures that were used in the clinical trials of the 1980s and 1990s are still used in the post-FDA approval clinical milieu. As new IHDs are developed, with differing target patient populations and divergent capabilities, it is reasonable to project that the clinical protocols in use today will require modification to demonstrate that advanced features make a significant difference in patient outcomes. The CI battery for adults was revised nearly a decade ago to address the observation that many CI users demonstrated ceiling effects on the previous generation of tests (Gifford et al., 2010; New Minimum Speech Test Battery, 2011). Further change can be anticipated relating to all types of IHDs. For other IHDs, there is also an increasing interest in speech perception measures in noise (Snapp et al., 2010).
Selection Criteria: Influence on Assessment Methods
In designing an evaluation protocol, documentation of preintervention function is needed to serve as a baseline. The assessment methods should be clearly related to determining whether the selection criteria are met. The dimensions to be assessed should address areas known to be affected by the intervention with an IHD, as well as parameters that may have an indirect impact. The bone-anchored hearing implant or osseointegrated device (also known as a bone-anchored cochlear stimulator, implantable prosthetic device, or bone-anchored implant; formerly known as a bone-anchored hearing aid) will be used as an illustration of how the evaluation components need to address selection criteria and form a relevant baseline against which comparisons can be made effectively. For the purposes of this chapter, we will refer to this category of implanted devices as osseointegrated devices (OIDs). It should also be noted OIDs include both percutaneous and transcutaneous stimulation, as well as a new category of nonimplantable devices that deliver a bone-conducted signal across the skin.
As seen in Table 9–1, outlining the evaluation protocol for OIDs, multiple dimensions of patient characteristics and performance are examined. The medical criteria relate to factors intrinsic to the patient, such as age or diagnosis (e.g., congenital aural atresia), or historical information, such as prior surgery for cholesteatoma, in addition to physical findings. The otologist will initiate the requests for computed axial tomography (CAT or CT scan) or magnetic resonance imaging (MRI), dependent on the underlying pathology and device option being explored, to visualize the anatomy to determine if a condition exists that precludes implantation or that may alter the surgical approach.
At various points during the evaluation protocol, the otologist may seek input or clearance from the primary care physician or specialists, especially in regard to the candidate’s ability to undergo surgery and the impact of health conditions on the healing process and implications for choice of transcutaneous or percutaneous devices. For example, a patient with diabetes may pose a problem in terms of healing of incisions, or a percutaneous OID may prevent the healing of the skin around the abutment. For a user of a transcutaneous device, pressure between internal and external components should be monitored periodically to avoid necrosis (Chen, Mancuso, & Lalwani, 2017). In such a condition, the physician’s monitoring of the patient may be more vigilant than in a less complex case.
Audiologically, the scenarios that are appropriate for OID candidates may entail bilateral conductive or mixed hearing loss, unilateral conductive hearing loss, or unilateral profound sensorineural hearing loss, also called “single-sided deafness (SSD)” (Wazen et al., 2003). Attention is directed to the levels of bone-conducted responses, which cannot exceed 45 dB Hearing Level (HL) for the standard head-level OID devices and 55 dB HL for power models. In cases of bone conduction responses up to 65 dB HL, a body processor is on the market that can accommodate that level of conductive component. In terms of performance with a hearing aid or OID on a headband, there are no explicit candidacy requirements for the extent of aided threshold improvement or speech recognition performance. OID is an example, albeit a rarity in the field of IHDs, of a situation in which we can evaluate the candidate with a simulator (usually a power model OID on a headband) to obtain preoperative data. This also affords the patient an opportunity to listen to a sound that simulates the postoperative outcome; while there may be some underestimation of the gain to be obtained, the candidate nonetheless can formulate an impression of the sound quality to be achieved with an OID.
The audiologic procedures of interest for OIDs are to demonstrate improved auditory sensitivity, speech recognition in quiet and noise, and localization ability. Thus, the preoperative baseline can include conditions that pose communicative difficulty for the candidate’s level and configuration of hearing loss. It is also generally accepted in evaluation of IHDs, particularly with middle ear implants and CIs, that evaluation should be accomplished after the candidate has had sufficient experience with competitive, less invasive technology to permit the assessment to reflect maximal performance. Thus, a trial with a Contralateral Routing of Signal (CROS) hearing aid or equivalent, such as a power aid fitting to promote hearing crossover, may precede an evaluation of a candidate for the SSD application of an OID or CI. The audiologist must ensure the trial is with a device that truly is competitive technology, and neither outdated as some candidates’ older personal hearing aids might be, nor suboptimal as in an underpowered in-the-canal hearing aid for a severe to profound hearing loss.
It is worthwhile to explore responses to noise in differing juxtapositions to the listener. As in Figure 9–1A, unaided speech recognition testing or measurement with an adaptive procedure such as the Hearing-in-Noise Test (HINT) (Nilsson, Soli, & Sullivan, 1994), the BKB Sentences (Bench, Kowal, & Bamford, 1979; Etymotic Research, 2005), AzBio Sentences (Spahr & Dorman, 2004), or the QuickSIN™ (Etymotic Research, 2001) can document for both the SSD patient and the clinician the disadvantage experienced in conditions when speech originates on the poorer side and noise is on the better side (Bosman et al., 2011). The results of this condition are then compared to those in the aided condition, as in Figure 9–1B, when the IHD is in place. Such testing can provide reinforcing data to the potential IHD user as an illustration of the advantage to be gained (see Case Study 9–1, below). In addition to audiometric measures, Ortega et al. (2011) have demonstrated cross-validation of perceived improvement in noise using questionnaires.
The audiologist also has a significant role in determining whether the candidate can contend with the IHD’s practical application. Verification that the patient has adequate manual dexterity or a support system for management of the day-to-day maintenance of the device can be accomplished by watching the patient handle a demonstration device and batteries. In the case of OIDs, the audiologist and/or otologist must determine how the patient will be able to care for the abutment site and surrounding skin interface, or whether the patient will need assistance with visual inspection of the area.
Psychological Dimension and Assessment of Handicap
Although involvement of a psychologist is highly variable in current implant team settings, some form of psychological screening or full evaluation is generally acknowledged as necessary to examine such intrinsic factors as psychological status and acceptance of implantation whenever questions arise. The general understanding is that a candidate must have realistic expectations about outcomes from the IHD. The method for determining that someone has realistic expectations is also highly variable, and may be based on a team consensus. Extrinsic factors that may have an impact on the candidate’s success with an IHD should also be addressed, including family support, social network, vocational demands, and avocational interests. In some teams, the latter issues are addressed by a social worker, but these social dimensions often arise in counseling sessions with the audiologist as well. When psychologists are involved in the initial assessment, it is reasonable for them to follow the implantee over time to assess the impact of implantation (Knutson et al., 1998). Individuals with hearing impairment (and their spouses) often experience greater incidence of social isolation, depression, suspiciousness, and loneliness than the general population (Knutson, Johnson, & Murray, 2006), and may experience greater psychological burden that could make the auditory rehabilitation process more difficult following implantation (Brüggemann et al., 2017).
Figure 9–1. A. Speech recognition performance: unaided. B. Speech recognition performance: aided. Note. Figures 9–1A and 9–1B illustrate the use of speech in noise testing. In comparing speech recognition performance in the unaided (A) and aided (B) conditions with noise on the side of the better hearing ear, it is possible to demonstrate the advantage offered in the Single-Sided Deafness (SSD) scenario to a potential BAHA user. This arrangement of noise and speech may be useful in demonstrating benefit to users of other IHDs.
Adjustment to hearing loss and its impact on social, emotional, and vocational aspects can also be assessed formally using self-assessment and hearing handicap scales. Selecting the appropriate scale for the level of hearing loss is critical. Thus, using the Hearing Handicap Inventory for Adults (HHIA) (Newman, Weinstein, Jacobson, & Hug, 1990, 1991) for adults under 60 years old, or the Hearing Handicap Inventory for the Elderly (HHIE) (Ventry & Weinstein, 1982; Weinstein & Ventry, 1983) for adults over 60 years old, would be reasonable for mild to moderate levels of hearing loss. Other scales, such as the Screening Test for Hearing Problems (Demorest et al., 2011), should also be considered depending on the depth of information sought. When the loss is severe to profound, however, a scale should be selected that is aimed at the communicative challenges associated with that level of loss, such as the Performance Inventory for Severe and Profound Loss (PIPSL) (Owens & Raggio, 1988). Specialized scales have been developed to assess the impact of cochlear implantation (e.g., the Nijmegen Cochlear Implantation Questionnaire [NCIQ], Hinderink, Krabbe,, & van den Broek, 2000). In the setting of SSD, a scale that provides insight into problems with localization and speech in noise is suggested (e.g., Speech Spatial Qualities [SSQ], Gatehouse & Noble, 2004; Noble et al., 2013). When selecting a handicap scale, it is important to keep test-retest reliability in mind, since high reliability is required (Weinstein, Spitzer, & Ventry, 1986) if the measurement is to be repeated postintervention and periodically thereafter; in this way, changes measured can be attributed to the impact of intervention, rather than variability inherent to the handicap scale. (Editors’ note: For further information about use of handicap scales, the reader is referred to Chapter 6 in this text.)
Reviewing the handicap scale responses with the candidate and communication partner(s) is a suitable method to launch discussions of adjustment to loss, coping mechanisms, need for changes in or implementation of repair strategies, and how the postoperative function may be significantly improved on an auditory basis but still require use of strategies to maximize successful communication. These discussions in a family context can reveal the level of support available to the potential implantee and what obstacles must be addressed in the family milieu.
Other Nonauditory Factors
It is important to determine if there are any visual limitations that may impinge on the ability to access visual communication information. Sometimes, visual deficits become apparent during meetings with other team members. It is often in the formal assessment of baseline communication abilities, as carried out by the speech-language pathologist, audiologist, or auditory-verbal therapist, that limitations in accessing visual communication are discovered. When such visual deficits are identified, it is necessary to obtain consultation with an optometrist to improve or correct refraction or with an ophthalmologist to address any remediable ocular problem. Although good vision is not a prerequisite for IHDs, and in fact persons with low vision or blindness have been implanted with OID or CIs (Daneshi & Hassanzadeh, 2007; Saeed, Ramsden & Axon, 1998; Damen et al., 2006), maximization of communication skills through every available modality should be part of the preoperative phase.
Current Audiologic Methods
There is no universally accepted test battery for IHDs. If a device is in clinical trials, its assessment must follow a rigorous protocol to document safety and efficacy. After FDA approval in the United States, considerable discretion is applied, with implant centers seeking an economical balance (Cheng & Niparko, 1999) between scientific rigor and clinical feasibility. The pressure to streamline assessment is a reality that each practitioner must face.
A test battery should be device oriented so that assessment reflects areas in which a particular IHD will or may provide benefit. For example, Gifford et al. (2010) described a revision of a cochlear implant battery, which was adapted in 2011. The new battery added elements to challenge the prospective (and eventual implant) candidate in competing noise or speech babble. A brief summary of the current audiologic benefits of IHDs appears in Table 9–2.
Table 9–2. Sample Audiologic Benefits With Current Generation of Implantable Hearing Devices (IHDs)
aHL (hearing loss).
bThe only FDA-approved devices at the time of writing are the Envoy Medical Esteem, Med-El Vibrant Soundbridge, Otologics MET, Otologics Carina, Ototronix Maxum, and Soundtec (inactive).
cSNHL (sensorineural hearing loss).
dNot an FDA-approved application at the time of writing.
Threshold and speech recognition improvement are documented in a straightforward manner, using measures with which audiologists are very familiar; however, the standard battery of tests should be “sharpened” by consistent use of recorded speech stimuli to control test-retest variability influences and routinely obtaining the maximum speech recognition scores (phonetically balanced maximum performance or PBmax). It is also worthwhile to remember that the preoperative examination is a medicolegal document, which substantiates the need for intervention, conformance with accepted selection criteria or, where there are deviations from such criteria, the rationales or aspects of performance that motivated a surgical treatment.
In the selection protocol, there is a focus on speech perception performance that (1) establishes preoperative function; and (2) is used to determine conformance with published guidelines. For example, the current criteria for adult candidacy for a traditional CI include speech recognition for sentence material no better than 50% in the ear to be implanted, and no better than 60% in the opposite ear. Gifford et al. (2010) suggested that these criteria be modified to no better than 40% correct on a monosyllabic test in the ear to be implanted. In the case of implantable middle ear hearing devices (IMEHDs), this criterion is often stated as a wide range, such as 20% to 80% correct for monosyllables, and is sometimes not stated explicitly (Magnan, Manrique, Dillier, Snik, & Hausler, 2005).
Hybrid CIs entail the application of electrical stimulation and acoustic stimulation in the same ear. This is one form of electroacoustic stimulation (EAS). Hybrid criteria rely heavily on performance in noise as the potential candidate, someone who has residual hearing in the low to mid frequencies, is likely to perform better on speech recognition tasks in quiet than those being assessed for traditional CI devices (Woodson et al., 2010). The addition of electrical stimulation is intended to supplement acoustic cues. Thus, a hybrid candidate, having residual hearing, risks losing that function upon introduction of an electrode into the cochlea. Determination of candidacy for EAS devices is heavily reliant on demonstrating a speech perception breakdown in various noise conditions.
The following case study demonstrates that a single test protocol, in this case to determine candidacy for an OID, may not be an appropriate approach. Both flexibility and creativity must be employed to demonstrate the potential benefit of an IHD to a given patient.
Case Study 9–1. Applying an Evaluation Protocol
Patient S. M., a 20-year-old male, was referred to our center for evaluation of candidacy for OID implantation.
Clinical History
The patient’s mother reported that he was born full-term via forceps delivery. The patient presented with left congenital aural atresia and stenosis. The right pinna appeared normal; however, the patient’s mother reported an unspecified abnormality of the ossicular chain in the right ear. The patient took synthroid for hypothyroidism. He was also a longtime wearer of a digital behind-the-ear-style hearing aid in the right ear.
Summary of Audiologic Findings
A Type A tympanogram was obtained in the right ear (−75 daPa peak pressure). Ipsilateral acoustic reflexes were absent in the right ear at equipment limits. Immittance testing could not be performed for the left ear due to the aforementioned stenosis. As seen in Figure 9–2, the results showed a moderate to profound mixed hearing loss, bilaterally. Due to the masking dilemma, it was not possible with currently available equipment to determine the exact, ear-specific bone-conduction thresholds for all test frequencies in each ear. However, unmasked bone conduction thresholds reveal that at least one ear has sufficient bone conduction thresholds to consider OID implantation. Additionally, though the masked air-conduction thresholds indicate a profound impairment, the unmasked thresholds were used in judging candidacy, as this reflected his hearing status in the real world without the presence of masking noise. The speech recognition thresholds corroborated pure-tone averages bilaterally.
Figure 9–2. Case Study 1: Audiologic findings for S. M., the 20-year-old described in the case study.
Aided soundfield evaluation was completed. For the majority of the evaluation, the patient wore a Baha™ demo OID on the left side. The left side was chosen because the patient was unable to wear a conventional hearing aid on that side due to the aforementioned stenosis/aural atresia. Pure-tone thresholds were obtained, along with speech testing using a 50-word CNC list and HINT sentences. All speech testing was performed using recorded materials, and stimuli were presented at 70 dB HL, with the patient seated in front of the loudspeaker at 90 degrees azimuth. Aided hearing was within normal limits for pure tones from 500 Hz to 2000 Hz. The CNC phonemes correct score was 89%; the HINT sentences score was 98% in quiet, 0% in noise with the Baha™ in “omni” mode, and 74% in noise (+10 dB S/N ratio) with the directional microphone engaged. The patient also used his personal high-end digital power BTE during the evaluation, as it was likely he would continue to do so regardless of whether or not he ultimately elected to pursue OID implantation. The HINT score in quiet for the hearing aid only was 98% phonemes correct, whereas the HINT in noise (+10 dB S/N ratio) with the hearing aid in directional mode was 18%. The combined performance of the Baha™ and the hearing aid in noise (also +10 dB S/N ratio) was 73% of words correctly identified. The patient also expressed a favorable opinion of the sound quality of the Baha™.
Summary of Candidacy Findings
Results of this evaluation indicated that the patient was an excellent OID candidate. That is, this patient was unable to use a conventional aid due to the stenosis on the left side. Audiologists measured substantial improvement in speech perception in noise over the hearing aid alone, and the patient’s reaction to the device was positive. It was likely that the patient would continue to use a hearing aid on the side opposite the Baha™. Speculatively, this may yield improved sound localization relative to using the Baha™ only. Additionally, due to the presence of bilateral conductive pathology, the patient was also a candidate for future evaluation to consider bilateral Baha™ implantation.
Treatment Plan
Appropriate manufacturer’s literature was provided to the patient, and he was referred back to his otologist to further discuss the medical and surgical considerations associated with OID implantation.
Discussion
This case illustrates that the clinician cannot be content with the utilization of a cookie-cutter approach when evaluating OID candidacy. Frequently, as in this case, the patient’s individual needs and issues will provide the impetus to modify the typical evaluation protocol. In this case, assessment of the patient’s performance using his hearing aid was added to the usual protocol, and the inability to determine ear-specific masked bone-conduction thresholds for the majority of frequencies tested was considered but not found to be an impediment to the patient’s candidacy. Other possible scenarios that may require modification of the “standard” protocol include patients with SSD, patients with congenital versus acquired hearing loss, duration of hearing loss, the patient’s performance in noise, the patient’s listening environments and lifestyle issues, the patient’s ability to perform the whole test battery (i.e., younger children who may have reduced attention span). During the OID evaluation, as with virtually any other audiological test battery, flexibility and insight on the part of the clinician are paramount to successful outcome.
Auditory Electrophysiology
Auditory electrophysiologic tests have an essential role in preoperative assessment of hearing when the candidate is young or otherwise difficult to test behaviorally due to comorbid conditions. Auditory Brainstem Response (ABR) and/or Auditory Steady State Response (ASSR) are commonly used to estimate the configuration, type, and degree of hearing loss (Spraggs, Burton, & Graham, 1994) and, in combination with otoacoustic emissions (OAEs), to identify the profile referred to as auditory neuropathy/auditory dyssynchrony spectrum disorder (Shallop, Peterson, Facer, & Fabry, 2001). In an unselected sample of people with congenital hearing loss, Cross, Stephens, Francis, Hourihan, and Reardon (1999) demonstrated that a functional overlay or nonorganic hearing loss may be encountered. For adults who can reliably perform behavioral audiometric testing, the electrophysiological tests are not commonly included in the preoperative assessment. However, in the interest of differential diagnosis and/or ruling out a functional component in an adult IHD candidate, ABR/ASSR may contribute to confirm hearing loss degree.
For cochlear implantation, promontory electrical stimulation via a transtympanic electrode was historically evaluated as a means for distinguishing between sensory and neural etiologies for individuals with profound hearing loss (House & Brackmann, 1974). As candidacy has relaxed to include individuals with residual hearing, and with high resolution imaging available to assess the physical structure of the auditory system, there is less concern about implanting an ear that will not be stimulable. Even so, outcomes with implantation remain variable, and promontory stimulation has continued to be explored as a means for estimating residual neural function and predicting outcomes. Although there is some indication that preoperative measures of auditory sensation with promontory stimulation are correlated with postoperative speech-perception scores (Kileny et al., 1991), this procedure is not used widely for preoperative assessment.
Vestibular
Electro- or videonystagmography (E/VNG), vestibular-evoked myogenic potentials (VEMPs), the head impulse test (HIT), and the Dizziness Handicap Inventory (DHI) (Jacobson & Newman, 1990) are examples of commonly used vestibular assessments used by some cochlear implant teams to document pre- and postoperative vestibular function (Abouzayd et al., 2017; Brey et al., 1995). Given the time-intensive nature of the audiological portion of the preoperative assessment, and that vestibular function does not have strong predictive value for CI speech perception performance outcomes (Chen, Shipp, Al-Abidi, Ng, & Nedzelski, 2001), vestibular testing is often eliminated from the protocol. However, not only do candidates sometimes report vestibular symptoms preoperatively, but also balance problems sometimes accompany insertion of the IHD electrode as it entails invasion of the cochlea or round window (RW) or placement of a vibrating prosthesis in the RW (see Abouzayd et al., 2017 for review of cochlear implantation; see Klein, Nardelli, & Stafinski, 2013 regarding dizziness in Vibrant Soundbridge). The frequency of postoperative symptoms reported in the literature ranges from 6% to 80% and the timing can vary from immediate to delayed. Patients over age 60 years appear more at risk (Abouzayd et al., 2017). This suggests that if vestibular assessment is eliminated from the general IHD protocol, there may be value in retaining the test for older candidates or those with a history of dizziness to have both baseline information on those candidates and insight into the mechanism for postimplantation recovery of function.
Self-Reporting in IHD Evaluation
A variety of self-reported measures have been used to evaluate candidates for IHDs. In CI candidates, assessment has employed questionnaires in hearing (Spitzer, Kessler, & Bromberg, 1992; Vermeire et al., 2006), tinnitus (Tyler, 1995), dizziness (Enticott et al., 2006; Jacobson & Newman, 1990), handicap scales, balance confidence (Enticott et al., 2006), quality of life assessment (Faber & Grøntved, 2000; Spitzer et al., 1992; Vermeire et al., 2006; Wanscher, Faber, & Grøntved, 2006), and employment and job satisfaction (Fazel & Gray, 2007). (Editors’ note: For a review of self-reports of the impact of hearing impairment and tinnitus, the reader is referred to Chapter 6 in this text.) As is true in other applications, self-reported measures may provide a starting point for counseling based on responses to the scales or questionnaires.
In addition to handicap and quality of life assessments, other scales have been used extensively with OID and to a lesser extent with middle ear implants, such as the Med-El Vibrant Soundbridge and Otologics MET. These other scales include the Abbreviated Profile of Hearing Aid Benefit (APHAB) (Cox & Alexander, 1995), Glasgow Hearing Aid Benefit Profile (Kemper & Holmes, 2004), and a sound quality rating (Gabrielsson, Hagerman, Bech-Kristensen, & Lundberg, 1990). Table 9–3 summarizes the outline of audiologic methods for evaluation of IHDs in adults and illustrates the linkage with various dimensions of anticipated benefit.
Implantee Contact
Many IHD teams routinely set up a meeting or contact between a current IHD user and an IHD candidate. When a prospective implantee has the opportunity to meet with a current user, there are information and emotional exchanges that cannot be conveyed by the professionals on the team. Such a meeting can promote realistic expectations and reduce fears about implantation. If an appropriate experienced user is not available from within the evaluating clinic, it is possible to provide a contact from an external pool. The CI manufacturers, recognizing the potential benefit to persons undergoing evaluation, have facilitated meetings with CI users through associations of implantees, such as the Bionic Ear Association (Advanced Bionics) and online resources, such as the Nucleus Forum, the Cochlear™ Community (a website for CI and Baha™ users by Cochlear Americas), and Hearing Companions (Med-El Corporation). There are parallel opportunities to meet previous implantees with bone-conduction stimulators and middle ear implants as well. These resources allow users to express their viewpoints and provide opinions, in much the same way as self-help organizations do.
The Special Case of Single-Sided Deafness (SSD)
The handicap imposed by Single-Sided Deafness (SSD) represents a unique problem for the implant team. SSD has been recognized in the audiologic otologic communities as imposing communicative, localization, speech-in-noise, and psychologic functional challenges for the person with this hearing loss picture (Spitzer, Korres, & Lalwani, 2015). Additionally, suppression of tinnitus after CI has also been reported (Amoodi et al., 2011; Arts et al., 2012). While the use of OID for improvement of communication, especially in noise, is well documented, cochlear implantation remains controversial due to technical issues in fitting and, though generally favorable, some mixed outcome reports. The situation is reflected in the results of a survey of otolaryngologists’ practices by the American Neurotological Society (Carlsen et al., 2018) in which CIs were provided to adults with asymmetrical hearing (in which at least one ear was better than the established performance criteria cutoff, representing 61% of respondents) and in single-sided deafness (37, 46% of respondents), illustrating a trend toward off-label implantation in SSD.
For example, Sladen et al. (2014) presented the preliminary findings of an SSD study at two CI centers. Their data demonstrated improvements in speech recognition for monosyllables and sentences in quiet in pre- and postimplantation comparisons. There was also a trend toward improved speech recognition in noise, but it did not reach statistical significance. Among those who reported preoperative tinnitus, 12 out of 13 reported improvement in annoyance and the 13th indicated no change.
Table 9–3. Outline of Audiologic Methods for Evaluation of Implantable Hearing Devices (IHDs) in Adults: Linkage With Dimensions of Anticipated Benefit
aPostoperatively and at intervals required for confirmation of impact of surgery and standard of care.
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