Katrien Vermeire

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

Abstract 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.

Neural tonotopy in cochlear implants: An evaluation in unilateral cochlear implant patients with unilateral deafness and tinnitus

In cochlear implants, the signal is filtered into different frequency bands and transmitted to electrodes along the cochlea. In this study the frequency-place function for electric hearing was investigated as a means to possibly improve speech coding by delivering information to the appropriate cochlear place. Fourteen subjects with functional hearing in the contralateral ear have been provided with a MED-EL cochlear implant in the deaf ear in order to reduce intractable tinnitus. Pitch scaling experiments were performed using single-electrode, constant-amplitude, constant-rate stimuli in the implanted ear, and acoustic sinusoids in the contralateral ear. The frequency-place function was calculated using the electrode position in the cochlea as obtained from postoperative skull radiographs. Individual frequency-place functions were compared to Greenwoods function in normal hearing. Electric stimulation elicited a low pitch in the apical region of the cochlea, and shifting the stimulating electrode towards the basal region elicited increasingly higher pitch. The frequency-place function did not show a significant shift relative to Greenwoods function. In cochlear implant patients with functional hearing in the non-implanted ear, electrical stimulation produced a frequency-place function that on average resembles Greenwoods function. These results differ from previously derived data.

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 PULSARCI100 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.

Good speech recognition and quality-of-life scores after cochlear implantation in patients with DFNA9.

Objective: To compare audiometric and quality-of-life results in DFNA9 patients who received a cochlear implant with cochlear implant patients with adult-onset progressive sensorineural hearing loss. Study Design: Prospective comparative design; results were collected cross-sectionally. Setting: Tertiary referral center. Patients: Eleven DFNA9 patients were included in the study as well as a comparative group of 39 postlingually deafened cochlear implant subjects with adult-onset progressive sensorineural hearing loss. Interventions: All patients received a cochlear implant. Subjects were implanted with either the Nucleus 24M/RCS or Med-el Combi 40+ cochlear implant systems implementing the SPEAK, ACE, or CIS+ coding strategies. Mean Outcome Measures: Speech recognition was determined by means of phonetically balanced monosyllabic word lists. The Hearing Handicap Inventory for Adults, the Glasgow Benefit Inventory, and the Scale for the Prediction of Hearing Disability in Sensorineural Hearing Loss were used to quantify the quality of life. Results: The results show that the speech perception and the quality of life of the DFNA9 patients do not differ significantly from the control group (p = 0.179; p = 0.56). Conclusion: In spite of the fact that DFNA9 is a disease that is known to involve cochlear dendrites, cochlear implantation is a good option for treatment of deafness in DFNA9.

Frequency-place map for electrical stimulation in cochlear implants: Change over time

The relationship between the place of electrical stimulation from a cochlear implant and the corresponding perceived pitch remains uncertain. Previous studies have estimated what the pitch corresponding to a particular location should be. However, perceptual verification is difficult because a subject needs both a cochlear implant and sufficient residual hearing to reliably compare electric and acoustic pitches. Additional complications can arise from the possibility that the pitch corresponding to an electrode may change as the auditory system adapts to a sound processor. In the following experiment, five subjects with normal or near-to-normal hearing in one ear and a cochlear implant with a long electrode array in the other ear were studied. Pitch matches were made between single electrode pulse trains and acoustic tones before activation of the speech processor to gain an estimate of the pitch provided by electrical stimulation at a given insertion angle without the influence of exposure to a sound processor. The pitch matches were repeated after 1, 3, 6, and 12 months of experience with the sound processor to evaluate the effect of adaptation over time. Pre-activation pitch matches were lower than would be estimated by a spiral ganglion pitch map. Deviations were largest for stimulation below 240° degrees and smallest above 480°. With experience, pitch matches shifted towards the frequency-to-electrode allocation. However, no statistically significant pitch shifts were observed over time. The likely explanation for the lack of pitch change is that the frequency-to-electrode allocations for the long electrode arrays were already similar to the pre-activation pitch matches. Minimal place pitch shifts over time suggest a minimal amount of perceptual remapping needed for the integration of electric and acoustic stimuli, which may contribute to shorter times to asymptotic performance.

Bilateral Electric Acoustic Stimulation: A Comparison of Partial and Deep Cochlear Electrode Insertion

BACKGROUND/AIMS A patient with bilateral severe, sloping, high-frequency hearing loss was treated with sequential bilateral electric acoustic stimulation (EAS) using the MED-EL Duet EAS cochlear implant. On one side, a partial 18-mm insertion of the electrode array (M-type) in the cochlea was performed. The contralateral side was implanted 39 months later with a deep 30-mm insertion of the electrode array (FLEX(soft) type). The aims were to assess whether low-frequency hearing could be preserved after deep electrode insertion, as well as to assess the benefit of bilateral EAS surgery compared to monaural EAS. METHODS Hearing thresholds and speech recognition outcomes were measured preoperatively and up to 48 months postoperatively. Outcomes from the partial and deep insertion side are compared. The benefit of EAS in daily life was assessed with the Abbreviated Profile of Hearing Aid Benefit questionnaire. Benefits of bilateral EAS were calculated from speech reception thresholds measured using the LINT speech-in-noise number test. Speech was always presented from the front. Noise was either presented from the front, from the left side, or from the right side. Each condition was measured for unilateral and bilateral EAS use. RESULTS Partial as well as deep insertion of the electrode array resulted in hearing preservation and significant speech recognition in this particular case. Both EAS devices provided more than 80% speech recognition in noise at a 10-dB signal-to-noise ratio. Bilateral EAS was beneficial for speech reception in noise compared to monaural EAS. A head shadow effect of 3.4 dB, binaural squelch effect of 1.2 dB and binaural summation effect of 0.5 dB were measured. CONCLUSION Hearing preservation is also possible after cochlear implantation using a FLEX(soft) electrode array with a near-full insertion (30 mm) into the cochlea. Bilateral EAS was successfully implemented in this patient providing better speech recognition compared to monaural EAS.

Assessment of the Subjective Benefit of Electric Acoustic Stimulation with the Abbreviated Profile of Hearing Aid Benefit

Conclusion: This study demonstrates that electric-acoustic stimulation (EAS) significantly decreases the subjective impairment in speech perception. Objectives: To assess the subjective benefit of EAS over the first 12 months after EAS fitting using the Abbreviated Profile of Hearing Aid Benefit (APHAB). Method: Twenty-three EAS users, implanted with either the PULSARCI100 FLEXEAS provided with the DUET EAS processor or the COMBI40+ Medium provided with the TEMPO+ speech processor, were included. Electric stimulation was activated about 1 month postoperatively; ipsilateral acoustic stimulation was added 2 months thereafter. EAS benefit was measured preoperatively with only a hearing aid and postoperatively at EAS fitting and then 3, 6 and 12 months after EAS fitting using the APHAB. Results: Subjects reported significant improvements in the global score with a mean decrease in impairment from 74% preoperatively to 45% after 3 months of EAS use. Furthermore, clinical relevance was demonstrated in multiple subscales between preoperative and first fitting reflecting a true benefit of EAS with a probability of 95%.