Cochlear implants have become a viable treatment option for individuals who present with severe to profound hearing loss. While there are several parameters that affect the successful use of this technology, quality programming of the cochlear implant system is crucial. This review chapter focuses on general device programming techniques, programming techniques specific to children, objective programming techniques, a brief overview of programming parameters of the currently commercially available multichannel systems, and managing patient complaints and device failures. The chapter also provides what the authors believe the future may hold for new programming techniques.
Cochlear implants have become a viable treatment for individuals who present with severe to profound hearing loss. This technology allows them to access sound in their environment and communicate more effectively with their peers. Despite the substantial benefit this treatment can provide recipients, cochlear implantation is an underutilized service. One of the Public Health Application and Outreach goals from Healthy People 2020, Objective ENT-VSL-3, is to increase the number of people who are deaf or very hard of hearing who use cochlear implants. The NIDCD’s Healthy Hearing Progress Report noted that in 2004 only 2 of every 1000 adults who are deaf or very hard of hearing received a cochlear implant. For children, Bradham and Jones reported that only 55% of children between the ages of 1 and 6 years who were appropriate for cochlear implantation were recipients of this technology.
To address this national health care issue, there has been significant emphasis on educating practitioners on candidacy criteria for cochlear implants, advancing cochlear implant device designs, surgical techniques, and programming of the device. Children who meet the Food and Drug Administration (FDA) guidelines and receive an implant early enough often develop age-appropriate language skills. Adults who are postlingually deafened and meet the FDA guidelines often receive open-set speech recognition. These successes are greatly dependent on a variety of issues, including the quality of the programming of the cochlear implant system.
The ultimate goal of device programming is to adjust a device so that it can effectively convert acoustic input into a usable electric signal for each electrode stimulated. Although this conversion varies across devices, the more accurate the process, the greater the potential for open-set speech perception. This review focuses on general (traditional) device programming, programming techniques specific to children, objective programming techniques, a brief overview of the programming parameters of the currently commercially available multichannel systems in the United States—Harmony device (Advanced Bionics Corporation, Valencia, CA), Med-El combi 40+ (Innsbruck, Austria), and the Nucleus Freedom and N5 device (Cochlear Corporation, Sydney Australia)—as well as managing patient programming complaints, device failures, and what the authors believe the future may hold for new programming techniques.
General device programming
Programming a cochlear implant is a process that can be divided into 4 time periods: preprogramming, the operating room (OR), initial stimulation, and follow-up. In order for a patient to achieve maximum benefit from the cochlear implant experience, all 4 phases need to be maximized.
Preprogramming
The goal of preprogramming is to prepare the patient for the initial stimulation. This preparatory phase is spent training auditory concepts in young children or adults who are prelingually or perilingually impaired and therefore have limited exposure to auditory stimuli. The goal is twofold:
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Establish a clear and rapid response to auditory stimulation
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Familiarize the patient with the task/procedure.
The responsibility for training these tasks typically lies with the speech pathologist working with the patient, the audiologist evaluating the patient, and occasionally the parent of the child. It is critical, at this juncture, that the type of amplification in use be appropriate; this can range from a powerful in the ear hearing aid to a postauricular aid to an FM system. The larger, more mature cochlear implant centers have instituted hearing aid loaner programs to defray the cost of purchasing expensive temporary amplification between identification and surgery, and to ensure that patients are using the most appropriate amplification during the evaluation period. Cross-modality training, using vibrotactile stimulation, has been used with some success in patients with total loss of hearing, limited exposure to auditory stimuli, and multiply handicapping conditions, for example, visual impairment. Over the last decade, as centers have gained experience with cochlear implants, the duration of preprogramming has decreased, which most likely is a result of improved hearing aid technology and facility with the overall evaluation process, especially in the pediatric population.
Intraoperative Monitoring
Over the last several years intraoperative monitoring has gained wider acceptance and, therefore, use among cochlear implant centers. Although intraoperative monitoring requires an inordinate amount of personnel time, is often not reimbursed by insurance companies, and out-of-the-box device failures are rare, it can provide the implant team with valuable information. Monitoring can confirm electrical output and patient stimulation, provide objective data that can be used as a starting point for behavioral testing (psychophysics), especially in the difficult to test, and can be a powerful counseling tool in assuaging the concerns of family members at the conclusion of the surgical procedure. The battery of tests typically performed by the audiologist in the OR include, but are not limited to, impedance telemetry, which confirms the integrity of the electrodes; and electrical stapedial reflex thresholds (ESRT) and measurement of the electrical compound action potential (ECAP), which confirm stimulation of the auditory nerve. There has been a significant amount of research on the relationship between these electrophysiological indices and psychophysical measures obtained during device programming. Over the last 10 years, implant centers have begun to use the Internet to allow audiologists to monitor devices from remote locations. In a study by Shapiro and colleagues, 8 patients were evaluated; 4 were monitored in situ and 4 from a remote location (cochlear implant center) in an effort to determine the feasibility and efficacy of remote monitoring compared with in situ monitoring. The results showed the average audiologist’s time for remote testing was 9 minutes compared with 93 minutes required for performing in situ testing. In an example, based on 170 surgeries performed by New York University in 2006, the potential for 6.35 weeks of gained productivity for the audiology staff was demonstrated. This result represents a significant reduction in time required for testing and, consequently, cost. The only additional equipment needed was an Internet connection, additional commercially available software applications, and a telephone.
Finally, a plain film is obtained in the OR to assess electrode placement and to serve as a baseline in the event of device issues at a later date. If, during intraoperative monitoring, the device does not stimulate and/or impedance measures cannot be obtained, the backup device may be used to ensure proper functioning at initial stimulation.
Initial Stimulation
The initial stimulation typically begins 10 days to 4 weeks postoperatively and lasts for approximately 2 hours per day for 2 consecutive days. This timeframe should be reduced for both a device failure, as the need to get the patient back “on the air” is crucial, and bilateral simultaneous implantation, as the patient is typically without access to their auditory environment after surgery. If intraoperative monitoring was performed, either in situ or remotely, these data should have already been loaded on the programming computer before the initial stimulation. The audiologist uses the time period between surgery and initial stimulation to set up a programming plan. The objective data obtained, along with the results of the plain film and discussions with the surgeon, are crucial to an uneventful initial stimulation; that is, stimulating an electrode that is extracochlear, which may result in a nonauditory side effect, can be counterproductive. Many centers will use the data obtained in the OR to program a device (objective programming), and this has had a positive direct impact in streamlining the programming process.
Physical environment for stimulation
Maintaining a comfortable physical environment in which device programming is performed can be crucial to the overall success of the initial stimulation, especially for children. In children a team approach, similar to traditional pediatric testing, is the preferred approach. This method will involve a primary audiologist and an audiologist, speech pathologist, or possibly a parent working with the child using either visual reinforcement auditory (VRA) or conditioned play audiometry (CPA) techniques to elicit behavioral responses to the electrical stimulation during programming. Often programming sessions may be videotaped to document a patient’s progress and to provide information about a child’s mode of response. These initial sessions are dedicated to both providing the patient with a comfortable and usable program and counseling the patient or parent about care, maintenance, and initial troubleshooting of the device. With the use of intraoperative device monitoring and streamlined programming techniques, the time required during the initial stimulation has been significantly reduced.
Psychophysical measures
Regardless of the device, traditionally two basic psychophysical measures need to be obtained on each intracochlear electrode: electrical thresholds (T level), defined as the softest level at which a patient is stimulated 100% of the time, and most comfortable loudness levels (C/M levels), defined as the loudest sound a patient can listen to comfortably for a sustained period of time. To confirm that recipients consistently hear at T levels, they may be asked to count the number of sounds they hear, referred to as “counted T level.” The methods used and the degree of difficulty in obtaining these measures will vary considerably depending on several factors (eg, patient’s chronologic age, mental status, length of deafness, other handicapping conditions, and so forth). The techniques used are similar to those used by pediatric audiologists. Using a wide range of techniques, both behaviorally and objectively, is especially important with expanded patient criteria.
Fundamental parameters
Before obtaining psychophysical measures, certain parameters typically need to be chosen (device-specific parameters are discussed later in this article). Fundamental among these parameters is the speech-processing (encoding) strategy. Encoding strategies can be defined as the method by which a given implant translates the incoming acoustic signal into patterns of electrical pulses, which then stimulate the existing nerve fibers. These strategies provide the listener with cues regarding spectral or envelope information, that is, spectral peak (SPEAK), temporal information (continuous interleaved sampling [CIS]/high resolution [high RES120]), temporal fine structure, or a combination of both, advanced combination encoder (ACE). Advances in speech-coding strategies have contributed to improved patient performance over the years. The typical device offers the audiologist more than one strategy, and there is no consensus on the most effective approach.
Historically, stimulation mode has been a parameter that requires prior choice. Stimulation mode refers to the electrical current flow, that is, the location of the indifferent (reference) electrode relative to the active electrode (stimulating) electrode. Monopolar stimulation refers to a remote ground (outside of the cochlea), whereas bipolar stimulation refers to both the active and ground electrode within the cochlea. The Nucleus device can be programmed in both monopolar and bipolar stimulation mode, and the Advanced Bionics and Med-El device can be programmed in a monopolar mode only. The wider the stimulation mode, the lower the threshold values, due to the greater physical separation of active and ground electrodes. Typically monopolar stimulation is the preferred mode, as this mode may extend battery life, allowing for a more consistent threshold and threshold value for adjacent electrodes due to a wider current spread. Therefore this mode will lend itself to interpolation of T and C/M levels in populations in whom obtaining psychophysical measure on every electrode implanted is not feasible. Research has suggested that individuals in a monopolar mode can pitch rank and perceive a monotonic decrease in pitch as the stimulating electrode is moved from the base to the apex of the cochlea. After establishing T and C/M levels, clinicians may choose to balance loudness of the electrodes at 100% and possibly 50% of the dynamic range. Experience and research suggest that achieving an equal loudness contour across the electrode array can maximize speech perception. While not difficult for postlingually deafened adults, loudness balancing can be a problematic task for the early implanted, long-term deafened, multiply handicapped, and so forth. Nevertheless, high levels of speech perception have been obtained on early implanted patients, negating the need for loudness balancing.
Program creation
After all psychophysical tasks have been completed, a program can be created and the device can then be activated for live speech. Initial reactions to speech stimuli vary widely, ranging from no reaction to an adverse reaction. Of course, this will be dependent on the patient’s previous exposure to auditory stimuli. There are several device-specific parameters that can be manipulated depending on initial reaction, discussed later.
Speech testing
Finally, informal speech testing, for example, Ling sounds, should be performed to ensure that the patient has access to various frequencies in the speech domain. In addition, Holden and colleagues suggested the use of warbled tone stimuli in the soundfield following a programming session. These investigators postulated that soundfield thresholds needed to be at 30 dB or less for a patient to have adequate access to the critical elements of the speech signal.
Bilaterally implanted patients
As more patients receive bilateral cochlear implants, a protocol for device programming of these patients needs to be implemented. Bilaterally implanted individuals require additional programming time and therefore the need for streamlined fitting procedures is critical. As the majority of device-fitting strategies use a monopolar stimulation mode, which typically has consistent thresholds and C/M levels across the array, measuring select electrodes across the array (interpolation) can be performed without sacrifice of performance. It is not uncommon for cochlear implant centers to only program one cochlear implant at the initial activation and then introduce the second device on the next day for patients who have been simultaneously implanted. Individuals implanted sequentially require a different approach to programming. Before surgery for the second side, the patient’s first device should be programmed to ensure optimal functioning, which will allow the clinician to focus programming efforts on the new side for the first 3 months (the initial phases of programming). At the 3-month interval the patient will then be scheduled as bilateral, affording the clinician more time at subsequent visits. It is likely that the second (new) side, depending on time between surgeries, will not, at least initially, function as the dominant side and it is therefore important to use a conservative approach to loudness levels on the second side. This approach will serve to reduce initial “dyssynchronization” between the ears. Finally, patients functioning in a bimodal mode (hearing aid + cochlear implant) will require similar caution during programming as well.
Counseling
Other than programming, a large part of the initial stimulation phases consists of counseling, that is, daily care, maintenance, and troubleshooting. Providing patients and parents with “front-end” counseling and a basic understanding of these concepts will reduce the time professionals need to spend on nonreimbursable activities over the long term, and streamline the process. As devices have become more sophisticated so have the patients’ instructions for use. The manufacturers have responded by including instructional CDs, online instruction manuals, and telephone support. This information has been helpful to clinics in reducing the in-clinic workload, and further streamlining the fitting process.
Objective programming techniques
Evoked Stapedial Reflex Threshold
One objective measure for programming cochlear implants is setting the upper stimulation levels (C/M levels) based on the ESRT. An acoustic immittance probe is placed in the external ear canal in the contralateral ear of the ear being programmed. With a continuous 226-Hz probe tone in the contralateral ear, the programming stimulus is presented to the cochlear implant ear in an ascending manner until there is a decrease in admittance. The decrease in admittance is observed in the ear contralateral to the cochlear implant because the stapedial reflex is a bilateral response. Typically the audiologist will measure ESRT on as many channels as possible and then interpolate the remaining channels. Then during live speech they will gradually increase the stimulation levels globally. It is important to not set the global levels at or higher than the measured ESRT levels. The ESRT is a fairly reliable predictor of upper stimulation levels.
Electrically Evoked Compound Action Potential
Not all patients can tolerate, or have absent, ESRT. The ECAP uses a lower stimulation rate than the stimuli used for programming, and thus may be more tolerated during the first 2 days of programming. The ECAP measurement system is referred to by many different names based on the manufacturer: auditory response telemetry (Med-El), neural response imaging (Advanced Bionics), and neural response telemetry (Cochlear Corporation). The ECAP is used to estimate both thresholds (T levels) and upper stimulation levels (C/M levels), and usually falls within the patient’s electrical dynamic range. Using the cochlear implant system and the specialized manufacturer software, obtaining the ECAP for each electrode can be easily accomplished. Obtaining an ECAP response provides the audiologist with a confirmation of an audible stimulation level for a particular channel/electrode and provides a baseline objective measurement for comparison later on if there are reported problems. Due to the variability in responses, researchers suggest combining the ECAP with behavioral programming levels for 1 (ie, middle of the array) to 3 (ie, apical, middle, and basal ends of the array) channels/electrodes. By measuring at least one T and C/M level, the audiologist can interpolate the remaining T and C/M levels with the ECAP responses obtained.
Objective programming techniques
Evoked Stapedial Reflex Threshold
One objective measure for programming cochlear implants is setting the upper stimulation levels (C/M levels) based on the ESRT. An acoustic immittance probe is placed in the external ear canal in the contralateral ear of the ear being programmed. With a continuous 226-Hz probe tone in the contralateral ear, the programming stimulus is presented to the cochlear implant ear in an ascending manner until there is a decrease in admittance. The decrease in admittance is observed in the ear contralateral to the cochlear implant because the stapedial reflex is a bilateral response. Typically the audiologist will measure ESRT on as many channels as possible and then interpolate the remaining channels. Then during live speech they will gradually increase the stimulation levels globally. It is important to not set the global levels at or higher than the measured ESRT levels. The ESRT is a fairly reliable predictor of upper stimulation levels.
Electrically Evoked Compound Action Potential
Not all patients can tolerate, or have absent, ESRT. The ECAP uses a lower stimulation rate than the stimuli used for programming, and thus may be more tolerated during the first 2 days of programming. The ECAP measurement system is referred to by many different names based on the manufacturer: auditory response telemetry (Med-El), neural response imaging (Advanced Bionics), and neural response telemetry (Cochlear Corporation). The ECAP is used to estimate both thresholds (T levels) and upper stimulation levels (C/M levels), and usually falls within the patient’s electrical dynamic range. Using the cochlear implant system and the specialized manufacturer software, obtaining the ECAP for each electrode can be easily accomplished. Obtaining an ECAP response provides the audiologist with a confirmation of an audible stimulation level for a particular channel/electrode and provides a baseline objective measurement for comparison later on if there are reported problems. Due to the variability in responses, researchers suggest combining the ECAP with behavioral programming levels for 1 (ie, middle of the array) to 3 (ie, apical, middle, and basal ends of the array) channels/electrodes. By measuring at least one T and C/M level, the audiologist can interpolate the remaining T and C/M levels with the ECAP responses obtained.
Device-specific programming parameters
Advanced Bionics
Advanced Bionics (AB) has two programming platforms for their cochlear implant systems. The SCLIN software platform is used with previous C1 internal devices (C1.0 and C1.2) and sound processors (Platinum Sound Processor body worn or Platinum BTE ear level). The newer CII and HiRes 90 K internal devices are programmed on the SoundWave 2.0 platform. While the Platinum Sound Processors are compatible with the new internal devices, the ear level sound processor is different. The ear level sound processor available for the internal implants is the Harmony.
The HiRes 90 K implant is a hermetically sealed titanium case with a telemetry coil attached and encased in silastic. A removable magnet is housed in a silastic sleeve in the center of the coil of the HiRes 90 K implant. The overall dimensions are approximately 28 mm wide by 56 mm long. The HiFocus and the Helix electrode arrays have 16 platinum-iridium intracochlear electrodes with two extracochlear reference electrodes. Because each electrode has its own capacitor, there are 16 independent channels that could be potentially programmed.
The Harmony sound processor has several battery-pack options to reduce the weight at the ear and for overall comfort. These devices also have an optional battery pack for bilateral cochlear implant users. The sound processors can hold up to 3 programs and offer several coding strategies: ClearVoice, HiRes-Sequential, HiRes-Paired, HiRes-Sequential Fidelity 120, HiRes-Paired Fidelity 120 (default), MPS, and CIS. With Fidelity 120, audiologists can program up to 120 independent channels of stimulation for more specific frequency and pitch information. There are two telephone options, one a built-in telecoil and the other a T-mic. Users have found that the T-mic also improves speech understanding in noise in the T-mic-only mode versus the T-mic plus microphone.
Using the SoundWave 2.0 software and the clinician’s programming interface (CPI), the audiologist may begin programming the Harmony sound processor.
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Across the ribbon bar at the top, the software alerts the audiologist of the status of the CPI, the sound processor, and the internal device.
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If all the icons are green, the audiologist can begin to program.
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If any of the lights are red, the audiologist will need to troubleshoot the system before programming.
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When all the icons are green and the patient file is open, the software will automatically measure the impedance at each of the 16 intracochlear electrodes relative to the reference electrode. Values between 1 and 30 kiloohms are within normal limits.
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If the electrode impedance is out of range (ie, open circuit), then the electrode(s) should be disabled.
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In some cases, there may be a short in an electrode. If there is a short in 2 consecutive electrodes, the recipient may have a preference for those electrodes to remain on in their programs. If the shorted electrodes are not consecutive, it is recommended that the electrode(s) be disabled.
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Conditioning is another feature available with AB. Conditioning removes any buildup of substances present on the electrode contact and is usually completed at the initial stimulation.
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When programming the AB system, setting the “M-Level” is the most important measurement obtained. Because the M-Levels and volume control are tied together, the volume control first should be set to 0% unless disabled. The M-Levels are obtained using speech-burst stimulation instead of biphasic pulses. Making 4 primary measurements, the M-Levels are set for electrodes 1 to 4, 5 to 8, 9 to 12, and 13 to 16.
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To fine-tune the measurements, the audiologist may adjust the electrodes globally to live speech and environmental sounds. M-Levels are set to the patient’s most comfortable listening level.
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The T-Levels, or thresholds, are not usually measured. Typically the audiologist will set the levels to 10% of the M-Levels. If the cochlear implant user complains of constant, low-level noise then the audiologist may want to measure the T-Levels or set them to zero charge units.
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For children, the audiologist may elect to measure T-Levels to ensure audibility. Because children usually provide minimal response levels, the audiologist should globally reduce the T-Levels by 6 to 8 charge units.
Some other programming considerations for AB include Fidelity 120, input dynamic range (IDR), and clipping. The HiRes coding strategy now comes with the option of adding Fidelity 120. During clinical trials with Fidelity 120, most users reported better sound quality for speech and music than with conventional HiRes sound processing. The IDR is the recipient’s electrical dynamic range that is mapped from the acoustic input. The default IDR is 60 dB, which is appropriate for most users. Decreasing the IDR may make soft sounds inaudible but the cochlear implant recipient may report better listening comfort, especially in noise. For improved quality with music, AB recommends allocating one program setting with a higher IDR, using a coding strategy with Fidelity 120, and disabling the automatic gain control (AGC). Clipping channels ensures that stimulation will never exceed the set M-Level for that electrode. Clipping is used primarily when facial nerve stimulation is observed. Clipping the electrode should eliminate any undesired response ( Table 1 ).
