A novel method for device-related electroencephalography artifact suppression to explore cochlear implant-related cortical changes in single-sided deafness.

BACKGROUND: Quantitative electroencephalography (qEEG) is effective when used to analyze ongoing cortical oscillations in cochlear implant (CI) users. However, localization of cortical activity in such users via qEEG is confounded by the presence of artifacts produced by the device itself. Typically, independent component analysis (ICA) is used to remove CI artifacts in auditory evoked EEG signals collected upon brief stimulation and it is effective for auditory evoked potentials (AEPs). However, AEPs do not reflect the daily environments of patients, and thus, continuous EEG data that are closer to such environments are desirable. In this case, device-related artifacts in EEG data are difficult to remove selectively via ICA due to over-completion of EEG data removal in the absence of preprocessing. NEW METHODS: EEGs were recorded for a long time under conditions of continuous auditory stimulation. To obviate the over-completion problem, we limited the frequency of CI artifacts to a significant characteristic peak and apply ICA artifact removal. RESULTS: Topographic brain mapping results analyzed via band-limited (BL)-ICA exhibited a better energy distribution, matched to the CI location, than data obtained using conventional ICA. Also, source localization data verified that BL-ICA effectively removed CI artifacts. COMPARISON WITH EXISTING METHOD: The proposed method selectively removes CI artifacts from continuous EEG recordings, while ICA removal method shows residual peak and removes important brain activity signals. CONCLUSION: CI artifacts in EEG data obtained during continuous passive listening can be effectively removed with the aid of BL-ICA, opening up new EEG research possibilities in subjects with CIs.

Hearing performance in single-sided deaf cochlear implant users after upgrade to a single-unit speech processor.

INTRODUCTION: Single-sided deaf (SSD) patients report multiple benefits after cochlear implantation (CI), such as tinnitus suppression, speech perception, and sound localization. The first single-unit speech processor, the RONDO, was launched recently. Both the RONDO and the well-known behind-the-ear (BTE) speech processor work on the same audio processor platform. However, in contrast to the BTE, the microphone placement on the RONDO is different. The aim of this study was to evaluate the hearing performances using the BTE speech processor versus using the single-unit speech processor. Subjective and objective outcomes in SSD CI patients with a BTE speech processor and a single-unit speech processor, with particular focus on spatial hearing, were compared. METHODOLOGY: Ten adults with unilateral incapacitating tinnitus resulting from ipsilateral sensorineural deafness were enrolled in the study. The mean age at enrollment in the study was 56 (standard deviation, 13) years. The subjects were cochlear implanted at a mean age of 48 (standard deviation, 14) years and had on average 8 years' experience with their CI (range, 4-11 yr). At the first test interval (T0), testing was conducted using the subject's BTE speech processor, with which they were already familiar. Aided free-field audiometry, speech reception in noise, and sound localization testing were performed. Self-administered questionnaires on subjective evaluation consisted of HISQUI-NL, SSQ5, SHQ, and a Visual Analogue Scale to assess tinnitus loudness and disturbance. All 10 subjects were upgraded to the single-unit processor and retested after 28 days (T28) with the same fitting map. At T28, an additional single-unit questionnaire was administered to determine qualitative experiences and the effect of the position of the microphone on the new speech processor. RESULTS: Equal hearing outcomes were found between the single-unit speech processor: median PTA(single-unit) (0.5, 1, 2 kHz) = 40 (range, 33-48) dB HL; median Speech Reception Threshold in noise = -1.00 (range, -8.50 to +1.00) dB SNR; median Root Mean Square Error of sound localization = 45 (range, 19-139) degrees; HISQUI = 128 (range, 106-180); SHQ = 68 (range, 45-83); SSQ5 = 6 (range, 3-9) and the BTE speech processor: median PTA(BTE) (0.5, 1, 2 kHz) = 41 (range, 30-53) dB HL; median Speech Reception Threshold in noise = -0.25 (range, -7.00 to +4.00) dB SNR; median Root Mean Square Error of sound localization = 38 (range, 26-164) degrees; HISQUI = 144 (range, 120-183); SHQ = 56 (range, 47-85); SSQ5 = 6 (range, 3-9). The results in the condition with the single-unit speech processor were not significantly influenced by the position of the microphone. CONCLUSION: The study showed that long-term BTE speech processor SSD users are able to be upgraded to a single-unit speech processor without compromising their speech performance, aided hearing thresholds, sound localization, objective speech quality, hearing abilities, sound localization, and tinnitus reduction. Microphone position on the single-unit speech processor did not influence the outcomes measures. Moreover, after a short time of experience, 80% of the users preferred the single-unit processor.

Changes over time of psychoacoustic outcome measurements are not a substitute for subjective outcome measurements in acute tinnitus.

The aim of this study was to assess correlations between the changes over time of various tinnitus measurements. A longitudinal prospective study comparing two test moments was performed: before treatment and after 90 days. Tinnitus assessment consisted of psychoacoustic outcome measurements (minimal masking level and loudness matching at 1 kHz) and subjective outcome measurements (Tinnitus Impairment Questionnaire, Tinnitus Questionnaire and Numeric Rating Scale of loudness and annoyance). Additionally, the effect size was measured. 35 subjects were included in this study. The subjects had a permanent, non-pulsatile tinnitus acquired <3 months previously. Weak or no significant correlations were found between ∆psychoacoustic outcome measurements and ∆subjective outcome measurements. The effect size showed that subjective outcome measurements were the most responsive to measure change in tinnitus complaints. We can conclude that psychoacoustic outcome measurements of tinnitus cannot substitute subjective outcome measurements in patients with acute tinnitus. The authors recommend subjective outcome measurements as primary outcome measurements in a clinical setting. In research, however, it is meaningful to quantify tinnitus in both ways.

Perceptual changes in place of stimulation with long cochlear implant electrode arrays.

Long (31.5 mm) electrode arrays are inserted deeper into the cochlea than the typical 1.25 turn insertion. With these electrode arrays, the apical electrodes are closer to (and possibly extend past) the end of the spiral ganglion. Using multi-dimensional scaling with patients implanted with a 31.5 mm electrode array, the perceptual space between electrodes was measured. The results suggest that deeper insertion increases the range of place pitches, but the perceptual differences between adjacent electrodes become smaller in the apex.

Long-term follow-up of hearing preservation in electric-acoustic stimulation patients.

BACKGROUND: Hearing preservation (HP) surgery was initiated more than 10 years ago for combined electric and acoustic stimulation (EAS). Preserved residual low-frequency hearing has been demonstrated to improve speech perception in noise as well as music appreciation in EAS users up to 2 years. Multiple study groups aimed to evaluate initial loss of residual hearing (RH) as a consequence of HP surgery. However, after 1 year and 2 years of follow-up, further decline was reported. This study aimed to determine RH, speech perception, and the subjective benefits of EAS 10 years after HP surgery. SUBJECTS AND METHODS: Nine postlingual EAS partially deaf patients who underwent HP surgery at Antwerp University Hospital were included in this study (11 implanted ears). Hearing preservation (0% = loss of hearing; >0%-25% = minimal HP; >25%-75% = partial HP; >75% = complete HP), speech perception and subjective benefits were evaluated preoperatively; at 3, 6, 12, 18, and 24 months postoperatively; and annually thereafter. RESULTS: Complete HP was obtained in three of 11 ears; partial HP in five of 11 ears; and minimal HP in two of 11 ears, measured during their most recent follow-up. One subject lost his RH completely across time. The mean rate of HP was 48% (ranging from 6 months up to 10 years postoperatively). Speech perception analysis up to 10 years showed a continuous statistically significant improvement. The maximum subjective benefit was reached 3 months after implantation and subsequently remained statistically significant unchanged for the next 10 years. CONCLUSION: Long-term HP in EAS users after HP surgery is feasible, although a small continuous decline of HP rate of 3% per year was observed (measured from first fitting up to 6 years postoperative). Nevertheless, a continuous improvement was found in the speech perception results of the EAS users across 10 years. Moreover, the positive subjective benefit, assessed 3 months postoperative, remained stable up to 10 years.

Self-assessment of hearing disabilities in cochlear implant users using the SSQ and the reduced SSQ5 version.

OBJECTIVES: Routine clinical assessment to evaluate the hearing performance in a cochlear implant (CI) population should include individual self-assessment tools. Because of pragmatic and psychometric considerations, there's a growing need for reduced self-assessment questionnaires. The aim of the study is twofold. First, the study aims to ascertain a disability profile, using the Speech, Spatial and Qualities of Hearing Scale (SSQ), in a CI population and to compare this profile with a hearing impaired group with similar average hearing thresholds. The second aim of the study is to investigate the degree of agreement between the total SSQ scores and the total scores of the reduced 5-item version of the SSQ, namely, the SSQ5. METHODS AND SUBJECTS: This cross-sectional study uses the SSQ obtained from CI patients from the Ear, Nose and Throat (ENT) department of the Antwerp University Hospital. Fifty-four postlingually deaf CI patients completed the SSQ questionnaire. All subjects were implanted with a CI at an average age of 55 years. At the time they completed the questionnaire, they had, on average, 3 (SD, 3) years of CI experience. To determine the disability profile in a CI population, the following criteria were assayed: standard values, internal consistency, sensitivity, and floor (or ceiling) effects of the SSQ. These criteria were compared with those of a hearing-impaired group (n = 153) reported in the original study.Second, Spearman correlations coefficients and intraclass correlations coefficients (ICCs) were used to determine the degree of agreement between the total SSQ scores and the total SSQ5 scores. RESULTS: Analysis of internal consistency, sensitivity, and floor and ceiling effects showed that self-assessment using the SSQ is feasible in a CI population. The obtained disability profile presents a mean total SSQ(C I group) of 4:25 ( S D = 1:65). When comparing item results, significant differences were found between CI users and moderate hearing-impaired patients (SSQ(hearing impaired group) = 5.5; S D1:9). Intraclass correlation (ICC = 0.78; p < 0.01) and Spearman correlations coefficients (R = 0.77; p < 0.01) indicate a significantly high degree of agreement between the total SSQ scores and the total SSQ5 scores. CONCLUSION: This article shows the disability profile in a CI population, using SSQ. Significant differences regarding dynamic aspects of hearing between CI users and moderate hearing-impaired patients were found, to the detriment of the CI users. The static aspects of hearing represented in the Speech section, on the other hand, showed more similarities. The reduced 5-item version of the SSQ, namely, the SSQ5, is robust to effectively measure evolutions in hearing (dis)abilities in CI users.

Neural substrates predicting improvement of tinnitus after cochlear implantation in patients with single-sided deafness.

Notwithstanding successful reduction of tinnitus after cochlear implantation (CI) in patients with single-sided deafness (SSD) in recent studies, neither the exact mechanism of suppression nor the predictors of the amount of improvement are fully understood yet. We collected quantitative electroencephalography (qEEG) data from nine SSD patients who underwent CI for tinnitus management. By correlating the degree of improvement in tinnitus intensity and tinnitus-related distress with preoperative source-localized qEEG findings and comparing qEEG findings of patients with marked improvement after CI with those with relatively slight improvement with regard to source-localized activity complimented by connectivity analysis, we attempted to find preoperative predictors of tinnitus improvement. Our results showed increased activities of the auditory cortex (AC), posterior cingulate cortex (PCC) and increased functional connectivity between the AC and PCC as negative prognostic factors for the reduction of tinnitus intensity after CI in patients with SSD. Also, relatively increased activity of the right dorsolateral prefrontal cortex and decreased connectivity between distress-related areas such as the orbitofrontal cortex/parahippocampus and sensory-perception areas such as the AC/precuneus were found in patients with relatively slight improvement in tinnitus-related distress as compared with those with marked improvement. The current study suggests that preoperative cortical oscillations can be applied to predict post-CI tinnitus reduction in patients with SSD.

On the necessity of full length electrical cochlear stimulation to suppress severe tinnitus in single-sided deafness.

BACKGROUND: Cochlear implantation (CI) has proven in long term prospective trials to reduce significantly incapacitating tinnitus in single sided deafness (SSD). Discussion arises whether electrical stimulation near the round window (RW) is also able to reduce tinnitus. AIM: to assess whether electrical stimulation of the basal first 4 intracochlear electrodes of a CI could sufficiently reduce tinnitus and to compare these results with stimulation with all CI electrodes. MATERIAL AND METHODS: 7 patients who met the criteria of severe tinnitus due to SSD were implanted with a Med-El Sonata Ti100 with a FlexSoftTM or Flex24TM electrode. After 4 weeks only the basal electrode pair (E12) nearest to the RW was activated. Each week the following pair was activated until the 4th pair.Thereafter all electrodes were activated. Tinnitus was assessed before CI surgery and before each electrode pair was activated. When all electrodes were fitted, evaluation was done after 1, 3 and 6 months.Tinnitus was assessed with Visual Analogue Scale (VAS) for loudness, psychoacoustic tinnitus loudness comparison at 1 kHz and Tinnitus Questionnaire (TQ) for the effect on quality of life. To evaluate the natural evolution, a tightly matched control group with severe tinnitus due to SSD was followed prospectively. RESULTS: All the tinnitus outcome measures remained unchanged with 1, 2, 3 or 4 activated electrode pairs. With complete CI activation, the tinnitus decreased significantly comparable with earlier reports.Pre-implantation the tinnitus loudness was 8.2/10 on the VAS and was reduced to 4.1/10 6 months postimplantation.Psychometrically the loudness level went from 21.7 dB SL (SD: 16.02) to 7.5 dB SL (SD: 5.24)and the TQ from 60/84 to 39/84. The non-implanted group had no decrease of the tinnitus, the average VAS remained stable at 8.9/10 throughout the follow-up period of 6 months. CONCLUSION: with the current stimulation parameters electrical stimulation in the first 8e10 mm of the basal part of the scala tympani is insufficient to reduce tinnitus. However, stimulation over the complete CI length yields immediate tinnitus reduction confirming earlier results.

Cochlear implantation as a durable tinnitus treatment in single-sided deafness.

INTRODUCTION: Severe tinnitus can seriously impair patients in their activities in daily life and reduce their quality of life. The aims of this prospective clinical study were to assess the long-term effects of cochlear implantation (CI) on tinnitus in patients with single-sided deafness and ipsilateral incapacitating tinnitus, and to investigate whether CI could treat various types of tinnitus. MATERIALS AND METHODS: Twenty-six subjects with unilateral severe-to-profound sensorineural hearing loss received a CI. Patients suffered from severe tinnitus greater than 6/10 on a visual analogue scale (VAS) due to unilateral deafness. Assessment consisted of a tinnitus analysis including determination of tinnitus type, frequency, and loudness. A tinnitus questionnaire (TQ) measured tinnitus distress. VAS and TQ were administered pre-implantation and post-implantation. RESULTS: All 26 patients reported a subjective benefit from CI. Tinnitus loudness reduced significantly after CI from 8.6 to 2.2 on the VAS (scale: 0-10). The TQ total score decreased significantly and the mean tinnitus degree decreased from severe to mild. No differences were observed between patients with pure-tone tinnitus, narrow band noise tinnitus, or polyphonic tinnitus. The degree of tinnitus loudness reduction remained stable after CI. CONCLUSIONS: CI can successfully be used as treatment of severe tinnitus in patients with single-sided deafness and is equally effective for pure tone, narrow band noise, and polyphonic tinnitus. Long-term results show that implantation provides durable tinnitus relief in these patients. These results support the hypothesis that physiopathological mechanisms after peripheral deafferentation are reversible when hearing is restored. Single-sided deafness accompanied by severe tinnitus is a new indication for CI.

Better speech recognition in noise with the fine structure processing coding strategy.

BACKGROUND: Recently, a new speech coding strategy named 'fine structure processing' (FSP) has been launched. METHODS: 32 subjects, all users of the MED-EL PULSARCI(100) system, have been switched over from a TEMPO+ to an OPUS 2 speech processor. In 22 subjects, the FSP strategy could be implemented (FSP group), in 10 patients not (high-definition continuous interleaved sampling, HDCIS, group). Subjects were tested with the Tempo+ (CIS+) just before switch-over and after 12 months of OPUS 2 (FSP/HDCIS) use. Performance with FSP/HDCIS was tested at switch-over, and after 1, 3, 6 and 12 months. A sentence-in-noise test and a Speech Spatial and Qualities of Hearing Scale (SSQ) questionnaire were assessed at each test interval. RESULTS: In the FSP group, the speech reception threshold shows a deterioration of 3.3 dB (n.s.) at the acute switch-over interval, but a significant improvement over time (p < 0.001) with a final benefit of 6.5 dB after 12 months of FSP use. A significant improvement over time can also be seen on the spatial subscore of the SSQ questionnaire (p = 0.009). No significant differences could be seen in the HDCIS group. CONCLUSION: The results show that by enhancing fine structure coding in the lower frequencies, as implemented in the FSP coding strategy, speech perception in noise can be enhanced.