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

Hearing Research

Authors

• Andrea Kleine Punte^{a, , ,} ,
• Dirk De Ridder^b,
• Paul Van de Heyning^a

• ^a Antwerp University Hospital, Univ. Dept. of Otorhinolaryngology and Head and Neck Surgery, University of Antwerp, Wilrijkstraat 10, 2650 Edegem, Antwerp, Belgium
• ^b Antwerp University Hospital, Brain Research Center for Innovative and Interdisciplinary Neuromodulation, Antwerp, Belgium

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Abstract

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 FlexSoft™ or Flex24™ electrode. 

After 4 weeks only the basal electrodepair (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 post-implantation.

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 8–10 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.

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Highlights

► Prospective controlled study of tinnitus treatment via cochlear implantation in single-sided deafness. 
► Investigation of effectiveness of basal cochlear electrical stimulation for tinnitus reduction. 
► CI significantly reduces tinnitus in single-sided deafness, with no change in tinnitus over time in the control group. 
► Electrical stimulation in the basal part of the scala tympani via CI does not effectively reduce tinnitus.

Abbreviations

• BDI, Beck Depression Index;
• CI, cochlear implant/Cochlear implantation;
• EPS, electrical promontory stimulation;
• eSRT, electrical stapedius reflex threshold;
• MCL, maximum comfort level;
• NBN, narrow band noise;
• PL, polyphonic;
• PT, pure tone;
• RW, round window;
• SL, sensation level;
• SNHL, sensorineural hearing loss;
• SSD, single-sided deafness;
• TA, tinnitus analysis;
• TQ, tinnitus questionnaire;
• VAS, visual analogue scale

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Figures and tables from this article:

Fig. 1. Med-El FlexSoft™ electrode highlighting the first four basal electrodes activated for tinnitus reduction. Electrode 1 is located at the apical end and electrode 12 at the basal end nearest to the RW.

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Fig. 2. Average tinnitus loudness on the VAS for the CI group with CI on (filled circles, solid line) and CI off (filled circles, dashed line) and control group (unfilled circles).

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Fig. 3. Psychoacoustic tinnitus loudness in dB SL at baseline and after CI with basal and complete CI stimulation for the CI group (black bars) and the control group (grey bars).

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Fig. 4. Individual psychoacoustic tinnitus loudness measurements at baseline and after CI with basal and complete CI stimulation.

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Fig. 5. Average TQ scores at baseline and after 6 months for the CI group (black bars) and control group (grey bars).

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Table 1. Details of tinnitus characteristics for the CI group (S1-7) and control group (C1-7) showing tinnitus ear, tinnitus type, tinnitus duration, aetiology, perceived tinnitus frequency, psychoacoustic loudness and VAS scores preoperatively and 6 months later of the control group and 6 months after fitting in the CI group.

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Corresponding author. Tel.: +32 38214090; fax: +32 8290520.

Fuente:  http://dx.doi.org/10.1016/j.heares.2012.08.003

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