A Protocol to Investigate Deep Brain Stimulation for Refractory Tinnitus: From Rat Model to the Set-Up of a Human Pilot Study.

BACKGROUND: Chronic tinnitus can have an immense impact on quality of life. Despite recent treatment advances, many tinnitus patients remain refractory to them. Preclinical and clinical evidence suggests that deep brain stimulation (DBS) is a promising treatment to suppress tinnitus. In rats, it has been shown in multiple regions of the auditory pathway that DBS can have an alleviating effect on tinnitus. The thalamic medial geniculate body (MGB) takes a key position in the tinnitus network, shows pathophysiological hallmarks of tinnitus, and is readily accessible using stereotaxy. Here, a protocol is described to evaluate the safety and test the therapeutic effects of DBS in the MGB in severe tinnitus sufferers. METHODS: Bilateral DBS of the MGB will be applied in a future study in six patients with severe and refractory tinnitus. A double-blinded, randomized 2 × 2 crossover design (stimulation ON and OFF) will be applied, followed by a period of six months of open-label follow-up. The primary focus is to assess safety and feasibility (acceptability). Secondary outcomes assess a potential treatment effect and include tinnitus severity measured by the Tinnitus Functional Index (TFI), tinnitus loudness and distress, hearing, cognitive and psychological functions, quality of life, and neurophysiological characteristics. DISCUSSION: This protocol carefully balances risks and benefits and takes ethical considerations into account. This study will explore the safety and feasibility of DBS in severe refractory tinnitus, through extensive assessment of clinical and neurophysiological outcome measures. Additionally, important insights into the underlying mechanism of tinnitus and hearing function might be revealed. TRIAL REGISTRATION: ClinicalTrials.gov NCT03976908 (6 June 2019).

Positive Health dialogue tool and value-based healthcare: a qualitative exploratory study during residents' outpatient consultations.

OBJECTIVE: To explore how residents experienced the application of the Positive Health dialogue tool (PH-tool) during outpatient consultations and its influence on the delivery of value-based healthcare (VBHC). DESIGN: Qualitative study using non-participant observations of outpatient consultations during which residents used the PH-tool, followed by longitudinal individual, semistructured interviews. To analyse the data from observations and interviews, observational form notes' summarisation and categorisation, and an iterative-inductive thematic approach was used. PARTICIPANTS: Eight residents-five from the ear, nose, and throat-department and three from the gastroenterology-hepatology-department-were selected through convenience sampling, accounting for 79 observations and 79 interviews. RESULTS: Residents had bivalent experiences with using the PH-tool. Residents discussed three main benefits: a gained insight into the individual patient's context and functioning, a changed dynamics in resident-patient communication, and an increased awareness regarding value in terms of patient-related outcomes and healthcare costs. Three barriers became apparent: doubts regarding the PH-tool's relevance and scope, boundaries of superspecialised medical professionals, and a lack of demarcation in clinical practice. CONCLUSION: The PH-tool use can be beneficial for residents during outpatient consultations with new patients and follow-up in cases of multidimensional problems, particularly in cases of chronic conditions and generalist care. In these situations, the tool yielded valuable patient information beyond physical health, helped foster patient engagement, and enabled tailoring the treatment plan to individual patients' needs. On the other hand, the PH-tool was not a good fit for simple problems, clearly demarcated help requests, periodic follow-up consultations, or verbose patients. In addition, it was not suitable for superspecialised care, because it yielded an abundance of general information. For particular patients and problems, using the PH-tool seems a promising strategy to increase VBHC delivery. Nevertheless, further research and detailing is needed to better align the PH-tool's broad intent and clinical practice.

Sound therapy for cochlear implant users with tinnitus.

OBJECTIVE: Despite the positive effect of a cochlear implant (CI) on tinnitus in many patients, tinnitus remains a problem for a significant proportion of CI users. We investigated the acceptability and effect of sound therapy (a combination of natural background sounds and one concise tinnitus counselling session) on tinnitus and speech perception in CI users who still experienced tinnitus during CI use. DESIGN AND STUDY SAMPLE: Thirty-two CI users (32-78 years) participated in phase 1: a test at the clinic to evaluate six background sounds provided by the sound processor. Eighteen out of the 32 CI users participated in phase 2: an optional take-home evaluation of 2 weeks without sound therapy, followed by 5 weeks with sound therapy, ending with an evaluation visit. RESULTS: Thirty subjects (93.8%) found at least one background sound acceptable. In phase 2, a small improvement with sound therapy was found for tinnitus loudness, annoyance, and intrusiveness. 50% of the subjects subjectively reported benefit of sound therapy. Especially the sense of control on their tinnitus was highly appreciated. No detrimental effect on speech perception was observed. CONCLUSION: The background sounds were acceptable and provided tinnitus relief in some CI users with tinnitus during CI use.

Self-assessment of unilateral and bimodal cochlear implant experiences in daily life.

OBJECTIVE: The subjective experiences were assessed of cochlear implant (CI) users either wearing or not wearing a hearing aid (HA) at the contralateral ear. DESIGN: Unilateral CI-recipients were asked to fill out a set of daily-life questionnaires on bimodal HA use, hearing disability, hearing handicap and general quality of life. STUDY SAMPLE: Twenty-six CI-recipients who regularly use a contralateral HA (bimodal group) and twenty-two CI-recipients who do not use a HA in the contralateral ear (unilateral group). RESULTS: Comparisons between both groups (bimodal versus unilateral) showed no difference in self-rated disability, hearing handicap or general quality of life. However within the group of bimodal listeners, participants did report a benefit of bimodal hearing ability in various daily life listening situations. CONCLUSIONS: Bimodal benefit in daily life can consistently be experienced and reported within the group of bimodal users.

The effect of tinnitus specific intracochlear stimulation on speech perception in patients with unilateral or asymmetric hearing loss accompanied with tinnitus and the effect of formal auditory training.

OBJECTIVES: Previous studies show that intracochlear electrical stimulation independent of environmental sounds appears to suppress tinnitus, even long-term. In order to assess the viability of this potential treatment option it is essential to study the effects of this tinnitus specific electrical stimulation on speech perception. DESIGN: A randomised, prospective crossover design. STUDY SAMPLE: Ten patients with unilateral or asymmetric hearing loss and severe tinnitus complaints. RESULTS: The audiological effects of standard clinical CI, formal auditory training and tinnitus specific electrical stimulation were investigated. Results show that standard clinical CI in unilateral or asymmetric hearing loss is shown to be beneficial for speech perception in quiet, speech perception in noise and subjective hearing ability. Formal auditory training does not appear to improve speech perception performance. However, CI-related discomfort reduces significantly more rapidly during CI rehabilitation in subjects receiving formal auditory training. Furthermore, tinnitus specific electrical stimulation has neither positive nor negative effects on speech perception. CONCLUSIONS: In combination with the findings from previous studies on tinnitus suppression using intracochlear electrical stimulation independent of environmental sounds, the results of this study contribute to the viability of cochlear implantation based on tinnitus complaints.

The Benefits of Bimodal Aiding on Extended Dimensions of Speech Perception: Intelligibility, Listening Effort, and Sound Quality.

The benefits of combining a cochlear implant (CI) and a hearing aid (HA) in opposite ears on speech perception were examined in 15 adult unilateral CI recipients who regularly use a contralateral HA. A within-subjects design was carried out to assess speech intelligibility testing, listening effort ratings, and a sound quality questionnaire for the conditions CI alone, CIHA together, and HA alone when applicable. The primary outcome of bimodal benefit, defined as the difference between CIHA and CI, was statistically significant for speech intelligibility in quiet as well as for intelligibility in noise across tested spatial conditions. A reduction in effort on top of intelligibility at the highest tested signal-to-noise ratio was found. Moreover, the bimodal listening situation was rated to sound more voluminous, less tinny, and less unpleasant than CI alone. Listening effort and sound quality emerged as feasible and relevant measures to demonstrate bimodal benefit across a clinically representative range of bimodal users. These extended dimensions of speech perception can shed more light on the array of benefits provided by complementing a CI with a contralateral HA.

Monaural Beamforming in Bimodal Cochlear Implant Users: Effect of (A)symmetric Directivity and Noise Type.

OBJECTIVE: To evaluate monaural beamforming in bimodally aided cochlear implant (CI) users. DESIGN: The study enrolled twelve adult bimodal listeners with at least six months of CI-experience and using a contralateral hearing aid (HA) most of the daytime. Participants were uniformly fitted with the same CI speech processor and HA, giving access to an identical monaural beamformer in both ears. A within-subject repeated measures design evaluated three directional configurations [omnidirectional, asymmetric directivity (in CI alone) and symmetric directivity (in both CI and HA)] in two noise types [stationary and fluctuating]. Bimodal speech reception thresholds (SRT) as well as listening effort ratings were assessed in a diffuse noise field. RESULTS: Symmetric monaural beamforming provided a significant SRT improvement of 2.6 dB SNR, compared to 1.6 dB SNR for asymmetric monaural beamforming. Directional benefits were similarly observed in stationary and fluctuating noise. Directivity did not contribute to less listening effort in addition to improvement in speech intelligibility. Bimodal performance was about 7 dB SNR worse in fluctuating than in stationary noise. CONCLUSIONS: Monaural beamforming provided substantial benefit for speech intelligibility in noise for bimodal listeners. The greatest benefit occurred when monaural beamforming was activated symmetrically in both CI and HA. Monaural beamforming does not bridge the gap between bimodal and normal hearing performance, especially in fluctuating noise. Results advocate further bimodal co-operation. TRIAL REGISTRATION: This trial was registered in www.trialregister.nl under number NTR4901.

Tinnitus Suppression by Intracochlear Electrical Stimulation in Single Sided Deafness - A Prospective Clinical Trial: Follow-Up.

INTRODUCTION: Earlier studies show that a Cochlear Implant (CI), capable of providing intracochlear electrical stimulation independent of environmental sounds, appears to suppress tinnitus at least for minutes. The current main objective is to compare the long-term suppressive effects of looped (i.e. repeated) electrical stimulation (without environmental sound perception) with the standard stimulation pattern of a CI (with environmental sound perception). This could open new possibilities for the development of a "Tinnitus Implant" (TI), an intracochlear pulse generator for the suppression of tinnitus. MATERIALS AND METHODS: Ten patients with single sided deafness suffering from unilateral tinnitus in the deaf ear are fitted with a CI (MED-EL Corporation, Innsbruck, Austria). Stimulation patterns are optimized for each individual patient, after which they are compared using a randomized crossover design, with a follow-up of six months, followed by a 3 month period using the modality of patient's choice. RESULTS: Results show that tinnitus can be suppressed with intracochlear electrical stimulation independent of environmental sounds, even long term. No significant difference in tinnitus suppression was found between the standard clinical CI and the TI. CONCLUSION: It can be concluded that coding of environmental sounds is no requirement for tinnitus suppression with intracochlear electrical stimulation. It is therefore plausible that tinnitus suppression by CI is not solely caused by an attention shift from the tinnitus to environmental sounds. Both the standard clinical CI and the experimental TI are potential treatment options for tinnitus. These findings offer perspectives for a successful clinical application of the TI, possibly even in patients with significant residual hearing. TRIAL REGISTRATION: TrialRegister.nl NTR3374.

Revisiting Place-Pitch Match in CI Recipients Using 3D Imaging Analysis.

OBJECTIVE: To improve the estimation of the perceived pitch in a single-sided deaf cochlear implant (CI) listener by using accurate 3-dimensional (3D) image analysis of the cochlear electrode positions together with the predicted tonotopical function for humans. METHODS: An SSD CI user underwent a Cone-Beam computed tomography (CBCT) scan. Electrode contacts were marked in 3D space in relation to the nearest point on the cochlear lateral wall. Distance to the base of the lateral wall was calculated and plotted against the place-pitch function for humans. An adaptive procedure was used to elicit the perceived pitch of electrically evoked stimulation by matching it with a contralateral acoustic pitch. RESULTS: The electrically evoked pitch percept matched well with the calculated frequency. The median mismatch in octaves was 0.12 for our method in comparison to 0.69 using the conventional Stenvers view. CONCLUSION: A method of improved image analysis is described that can be used to predict the pitch percept on corresponding cochlear electrode positions. This method shows the potential of 3D imaging in CI fitting optimization.

Bimodal Hearing Aid Retention after Unilateral Cochlear Implantation.

The goal of this study was to investigate contralateral hearing aid (HA) use after unilateral cochlear implantation and to identify factors of influence on the occurrence of a unilateral cochlear implant (CI) recipient becoming a bimodal user. A retrospective cross-sectional chart review was carried out among 77 adult unilateral CI recipients 1 year after implantation. A bimodal HA retention rate of 64% was observed. Associations with demographics, hearing history, residual hearing and speech recognition ability were investigated. Better pure-tone thresholds and unaided speech scores in the non-implanted ear, as well as a smaller difference in speech recognition scores between both ears, were significantly associated with HA retention. A combined model of HA retention was proposed, and cut-off points were determined to identify those CI recipients who were most likely to become bimodal users. These results can provide input to clinical guidelines concerning bimodal CI candidacy.

Tinnitus Suppression by Intracochlear Electrical Stimulation in Single-Sided Deafness: A Prospective Clinical Trial - Part I.

Cochlear implantation is a viable treatment option for tinnitus, but the underlying mechanism is yet unclear. Is the tinnitus suppression due to the reversal of the assumed maladaptive neuroplasticity or is it the shift in attention from the tinnitus to environmental sounds and therefore a reduced awareness that reduces tinnitus perception? In this prospective trial, 10 patients with single-sided deafness were fitted with a cochlear implant to investigate the effect of looped intracochlear electrical stimulation (i.e. stimulation that does not encode environmental sounds) on tinnitus, in an effort to find optimal stimulation parameters. Variables under investigation were: amplitude (perceived stimulus loudness), anatomical location inside the cochlea (electrode/electrodes), amplitude modulation, polarity (cathodic/anodic first biphasic stimulation) and stimulation rate. The results suggest that tinnitus can be reduced with looped electrical stimulation, in some cases even with inaudible stimuli. The optimal stimuli for tinnitus suppression appear to be subject specific. However, medium-to-loud stimuli suppress tinnitus significantly better than soft stimuli, which partly can be explained by the masking effect. Although the long-term effects on tinnitus would still have to be investigated and will be described in part II, intracochlear electrical stimulation seems a potential treatment option for tinnitus in this population.

Optimizing intracochlear electrical stimulation to suppress tinnitus.

OBJECTIVES: Research on tinnitus suppression by intracochlear electrical stimulation has gained interest over the past few decades and it has become easier to apply since the introduction of cochlear implants (CI). This study attempted to gain more insight into optimal stimulation characteristics for tinnitus suppression. DESIGN: Eleven subjects with unilateral CI and tinnitus were recruited from our CI clinic. Electrical stimulation, independent of acoustic sounds, was generated using their CI. The current prospective (single blinded) experimental study systematically assessed two stimulation parameters, namely current level and the anatomical stimulation site inside the cochlea and their short-term effect on tinnitus. RESULTS: Approximately one-third of the tested conditions were successful in which case tinnitus loudness was reduced by at least 30%. At least one successful condition was achieved for nine subjects (82%). Complete suppression was achieved in 6 out of 107 tested conditions (6%). The effect of subthreshold electrical stimulation on tinnitus suppression did not differ significantly from above threshold electrical stimulation. However, a positive relation between mean percentage tinnitus suppression and current level was observed. Pitch-matched electrical stimulation did not appear to suppress tinnitus better than other tested conditions. CONCLUSIONS: The majority of the subjects were able to experience tinnitus reduction through intracochlear electrical stimulation independent of acoustic sounds. Tinnitus can be reduced with audible or even inaudible, subthreshold stimuli. Clear trends in optimal stimulation characteristics were not found. Optimal stimulus characteristics for tinnitus reduction therefore appear to be highly subject-specific.

[Hearing implants]. / Gehoorimplantaten.

In the Netherlands, more than 1.5 million people suffer from sensorineural hearing loss or deafness. However, fitting conventional hearing aids does not provide a solution for everyone. In recent decades, developments in medical technology have produced implantable and other devices that restore both sensorineural and conductive hearing losses. These hearing devices can be categorized into bone conductive devices, implantable middle ear prostheses, cochlear implants and auditory brainstem implants. Furthermore, new implants aimed at treating tinnitus and loss of vestibular function have recently been developed.

Cognitive abilities relate to self-reported hearing disability.

PURPOSE: In this explorative study, the authors investigated the relationship between auditory and cognitive abilities and self-reported hearing disability. METHOD: Thirty-two adults with mild to moderate hearing loss completed the Amsterdam Inventory for Auditory Disability and Handicap (AIADH; Kramer, Kapteyn, Festen, & Tobi, 1996) and performed the Text Reception Threshold (TRT; Zekveld, George, Kramer, Goverts, & Houtgast, 2007) test as well as tests of spatial working memory (SWM) and visual sustained attention. Regression analyses examined the predictive value of age, hearing thresholds (pure-tone averages [PTAs]), speech perception in noise (speech reception thresholds in noise [SRTNs]), and the cognitive tests for the 5 AIADH factors. RESULTS: Besides the variance explained by age, PTA, and SRTN, cognitive abilities were related to each hearing factor. The reported difficulties with sound detection and speech perception in quiet were less severe for participants with higher age, lower PTAs, and better TRTs. Fewer sound localization and speech perception in noise problems were reported by participants with better SRTNs and smaller SWM. Fewer sound discrimination difficulties were reported by subjects with better SRTNs and TRTs and smaller SWM. CONCLUSIONS: The results suggest a general role of the ability to read partly masked text in subjective hearing. Large working memory was associated with more reported hearing difficulties. This study shows that besides auditory variables and age, cognitive abilities are related to self-reported hearing disability.

Effects of reverberation and masker fluctuations on binaural unmasking of speech.

In daily life, listeners use two ears to understand speech in situations which typically include reverberation and non-stationary noise. In headphone experiments, the binaural benefit for speech in noise is often expressed as the difference in speech reception threshold between diotic (N(0)S(0)) and dichotic (N(0)S(π)) conditions. This binaural advantage (BA), arising from the use of inter-aural phase differences, is about 5-6 dB in stationary noise, but may be lower in everyday conditions. In the current study, BA was measured in various combinations of noise and artificially created diotic reverberation, for normal-hearing and hearing-impaired listeners. Speech-intelligibility models were applied to quantify the combined effects. Results showed that in stationary noise, diotic reverberation did not affect BA. BA was reduced in conditions where the masker fluctuated. With additional reverberation, however, it was restored. Results for both normal-hearing and hearing-impaired listeners were accounted for by assuming that binaural unmasking is only effectively realized at low instantaneous speech-to-noise ratios (SNRs). The observed BA was related to the distribution of SNRs resulting from fluctuations, reverberation, and peripheral processing. It appears that masker fluctuations and reverberation, both relevant for everyday communication, interact in their effects on binaural unmasking and need to be considered together.

Review: cochlear implants as a treatment of tinnitus in single-sided deafness.

PURPOSE OF REVIEW: Tinnitus is a symptom that is highly associated with hearing loss. Its incidence is expected to increase due to the detrimental effects of occupational and leisure noise. Even though no standard treatment is currently available, the effect of cochlear implants on tinnitus in single-sided deafness (SSD) is under scientific attention. This review reveals an overview of all publicly available reports about cochlear implant as a treatment for tinnitus in SSD. RECENT FINDINGS: Cochlear implantation in SSD suppresses tinnitus in most of the cases. Some studies even demonstrate complete tinnitus suppression after implantation. No tinnitus worsening is reported in any of the cases. Furthermore, tinnitus does not restore during the electrical stimulation presented by the cochlear implant. The tinnitus level seems to stabilize after 3-6 months after the first fitting. SUMMARY: Although the underlying mechanism responsible for the observed tinnitus suppression is not yet clear, cochlear implantation should be considered as a treatment option for tinnitus arising from SSD. However, appropriate patient selection is essential as it is expected that it is a requirement that tinnitus arises from cochlear deafferentation.

Measuring the effects of reverberation and noise on sentence intelligibility for hearing-impaired listeners.

PURPOSE: The Speech Transmission Index (STI; Houtgast, Steeneken, & Plomp, 1980; Steeneken & Houtgast, 1980) is commonly used to quantify the adverse effects of reverberation and stationary noise on speech intelligibility for normal-hearing listeners. Duquesnoy and Plomp (1980) showed that the STI can be applied for presbycusic listeners, relating speech reception thresholds (SRTs) in various reverberant conditions to a fixed, subject-dependent STI value. The current study aims at extending their results to a wider range of hearing-impaired listeners. METHOD: A reverberant analogue of the SRT is presented--the speech reception reverberation threshold (SRRT)--which determines the amount of reverberation that a listener can sustain to understand 50% of the presented sentences. SRTs are performed and evaluated in terms of STI for 5 normal-hearing participants and 36 randomly selected hearing-impaired participants. RESULTS: Results show that differences in STI between reverberant and noisy conditions are only small, equivalent to a change in speech-to-noise ratio < 1.3 dB. CONCLUSION: The STI appears to be a convenient, single number to quantify speech reception of hearing-impaired listeners in noise and/or reverberation, regardless of the nature of the hearing loss. In future research, the SRRT may be applied to further investigate the supposed importance of cognitive processing in reverberant listening conditions.

The combined effects of reverberation and nonstationary noise on sentence intelligibility.

Listening conditions in everyday life typically include a combination of reverberation and nonstationary background noise. It is well known that sentence intelligibility is adversely affected by these factors. To assess their combined effects, an approach is introduced which combines two methods of predicting speech intelligibility, the extended speech intelligibility index (ESII) and the speech transmission index. First, the effects of reverberation on nonstationary noise (i.e., reduction of masker modulations) and on speech modulations are evaluated separately. Subsequently, the ESII is applied to predict the speech reception threshold (SRT) in the masker with reduced modulations. To validate this approach, SRTs were measured for ten normal-hearing listeners, in various combinations of nonstationary noise and artificially created reverberation. After taking the characteristics of the speech corpus into account, results show that the approach accurately predicts SRTs in nonstationary noise and reverberation for normal-hearing listeners. Furthermore, it is shown that, when reverberation is present, the benefit from masker fluctuations may be substantially reduced.

The development of the text reception threshold test: a visual analogue of the speech reception threshold test.

PURPOSE: In this study, the authors aimed to develop a visual analogue of the widely used Speech Reception Threshold (SRT; R. Plomp & A. M. Mimpen, 1979b) test. The Text Reception Threshold (TRT) test, in which visually presented sentences are masked by a bar pattern, enables the quantification of modality-aspecific variance in speech-in-noise comprehension to obtain more insight into interindividual differences in this ability. METHOD: Using an adaptive procedure similar to the SRT test, the TRT test determines the percentage of unmasked text needed to read 50% of sentences correctly. SRTs in stationary noise (SRT(STAT)), modulated noise (SRT(MOD)), and TRTs were determined for 34 participants with normal hearing, aged 19 to 78 years. RESULTS: The results indicate that about 30% of the variance in SRT(STAT) and SRT(MOD) is shared with variance in TRT, which reflects the shared involvement of a modality-aspecific cognitive or linguistic ability in forming meaningful wholes of fragments of sentences. CONCLUSION: The TRT test, a visual analogue of the SRT test, has been developed to measure the variance in speech-in-noise comprehension associated with modality-aspecific cognitive skills. In future research, normative data of the TRT test should be developed. It would also be interesting to measure TRTs of individuals experiencing difficulties understanding speech.