Electrical Stimulation of the Cochlea to Reduce Tinnitus Richard S., Ph.D. 1 Overview 1. Mechanisms of influencing tinnitus 2. Review of select studies 3. Summary of what is known 4. Next Steps 2 The University of Iowa 1
1. Mechanisms of influencing tinnitus 3 Mechanisms of tinnitus Differences across subjects is large Must be perceived in the auditory temporal lobe Can have source any place in auditory system Can be influenced by cochlea activity 4 The University of Iowa 2
Evidence of central involvement (, 1981) Heard in 1 ear, 8 th nerve cut, no change in perception mask ipsilaterally, tinnitus can be heard in the other ear can be masked at low levels in contralateral ear 5 Tinnitus in the temporal lobe 1. Increased spontaneous activity fed by increase, decrease, or edge (e.g. Davis, 1948; Kiang et al., 1970) 2. Cross-fiber correlation (Eggermont, 1984; Moeller, 1984) normal or increased spontaneous activity 3. More fibers with similar best frequency following hearing loss (Salvi et al., 1996) 4. Periodic spontaneous activity 6 The University of Iowa 3
Mechanisms of influencing tinnitus from the cochlea Must change spontaneous activity of nerve fibers Increase activity Decrease activity De-synchronize activity across nerve fibers Interfere with periodic activity 7 2. Review of studies Cochlear implant studies Kuk et al. (1989) Hazell et al. (1989) McKerrow et al. (1991) Dauman and (1993) Rubinstein et al. (2004) 8 The University of Iowa 4
Cochlear implant studies 9 Effectiveness- Cochlear implant speech processors and Kelsay (1990) 34/42 better 1/42 worse Gibson (1992) 25/42 better 4/42 worse Souliere et al. (1992) 20/26 better Demajundar et al., (1999) 62/80 better 10 The University of Iowa 5
Cochlear implant use: effect on contralateral ear Demajundar et al., (1999) 14/70 patients reported tinnitus abolished 11 Cochlear implant use : post stimulus relief Souliere et al. (1992) 14/28 patients 4 greater than 2 hours Kim et al., (1995) Present in 12/13 patients 12 The University of Iowa 6
Kuk et al., (1989) Eardrum stimulation ball electrode placed forehead ground 13 Subjects constant, non-fluctuating tinnitus 1 unilateral, 9 bilateral high-frequency hearing losses, 1 within normal limits 14 The University of Iowa 7
Stimuli square, sine, triangular waveforms 62-8000 Hz 15 Treatment maximum tinnitus reduction at lowest current was determined for different waveforms and frequencies optimum stimulus presented for 10 minutes ratings and noise masking measured in contralateral ear 16 The University of Iowa 8
5 non-responders no tinnitus reduction 5 responders tinnitus reduced Results 17 18 The University of Iowa 9
Conclusions tinnitus reduction without stimulus audibility in 3/5 unilateral in 3/4 bilateral patients Optimum stimuli varied among patients 10-minute Treatment Phase post-stimulation reduction lasted from 40 s to 4 hours 19 Hazell et al. (1989) 6/6 totally deaf patients round window implant sinusoids 20 The University of Iowa 10
Hazell et al., 1989 21 Hazell et al. (1989) 5/8 hearing patients platinum ball electrode round window Only effective for stimuli < 400 Hz 22 The University of Iowa 11
Hazell et al., 1989 23 Dauman, & Aran (1993) 2 cochlear implant patients Evaluated frequency of pulse trains and electrode position Stimulated randomly between threshold and Uncomfortable Loudness Level, 3 replications Individual rate and electrode preferences 24 The University of Iowa 12
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27 Summary Intracochlear low frequency pulses 80-250 Hz can reduce tinnitus, some better than others Stimulus always heard Electrode position and inter-electrode distance matters 5 min stimulation resulted in 15 min of poststimulus suppression 28 The University of Iowa 14
McKerrow et al. (1991) 6 patients with University of San Francisco cochlear implant control - 2-6 MHz carrier, inaudible Experimental condition noise at comfortable level 29 Condition 1. Inaudible 2-6 MHz Stimulation 30 minute 3/6 patients - suppression of tinnitus 1 lasted 10-15 minutes then habituated 1 bilateral effect 1 increase in tinnitus for 5 min, following by brief decrease after 10 m of stimulation 30 The University of Iowa 15
1991 31 Condition 2. Noise at comfortable level 30 minutes noise 5/6 rapid decrease to inaudible tinnitus 4/5 bilateral 1 tinnitus continued to decrease over 30 minute trial 32 The University of Iowa 16
Post stimulation 2/6 Gradual or 3/6 rapid return 1/6 tinnitus continued to decrease for another 30 minutes 33 Rubinstein et al., 2003, 2004 34 The University of Iowa 17
conditioner stimulus High rate (3-5 khz) pulses can produce spontaneous-like activity Poisson Spike Timing Across-fiber independence 35 CI subject AG,4800 pps on one electrode 2 stimulus levels 36 The University of Iowa 18
Results CI subjects (N = 2) complete suppression: 1 no suppression: 1 Transtympanic subjects (N = 7) suppression without percept: 3 suppression with percept: 3 no suppression or percept: 1 37 Several minutes of stimulation Tinnitus initially unaffected Reduction after several minutes Tinnitus can start to emerge again Can re-suppress tinnitus with change (level, rate) of stimulation 38 The University of Iowa 19
TINNITUS QUESTIONNAIRE_TOTAL SCORE (max. 84) Managing the Tinnitus Patient Single sided incapacitating tinnitus and sensorineural deafness treated with cochlear implantation Univ Dept Otorhinolaryngology, Head & Neck Surgery BRAI²N: Brain Research Antwerp Centre for Interdisciplinary an Innovative neuromodulation Antwerp University Hospital, Belgium Nko@uza.be Paul Van de Heyning Professor and Chairman ENT, Katrien Vermeire Audiologist PhD Dirk De Ridder, Professor Neurosurgery 90 80 70 60 50 40 30 20 10 0 pre-op 1 month 3 months 6 months 12 months TIME AFTER FIRST FITTING significant improvement up to 24 months (p<0.001) 18 months 24 months 40 The University of Iowa 20
3. Summary of what is known Effectiveness of stimulation Tinnitus can be reduced in some proportion of patients Optimal stimulus parameters May be different for different subjects Ear of stimulation Usually monaural effect, binaural effect in some patients 41 Laboratory trials Unpublished Electric pulse trains Electrodes basal, mid, apical Durations 2, 8, 20 minutes Levels sub, at threshold, MCL Wave files mixed with signal from speech processor The University of Iowa 21
Effect of Location of Stimulated Electrode on the Perceived Loudness of Tinnitus Electrode Locations: Base (#16), Middle (#8) and Apex (#1) Stimulus Level: Most comfortable Rate of Stimulation: 3569 pps Duration of Stimulation: 2 minutes Normalized Ratings of Perceived Loudness (0= inaudible; 100= loudest) 100 80 60 40 20 0 During Stimulation Post-stimulation 0 1 2 3 4 5 6 7 8 9 10 11 Time (minutes) Perceived loudness of stimulus (basal electrode) Perceived loudness of stimulus (middle electrode) Perceived loudness of stimulus (apical electrode) Perceived loudness of tinnitus (basal electrode) Perceived loudness of tinnitus (middle electrode) Perceived loudness of tinnitus (apical electrode) 43 44 The University of Iowa 22
Effect of Location of Stimulated Electrode on the Perceived Loudness of Tinnitus (DR) Electrode Locations: Base (#1), Middle (#3) and Apex (#6) Stimulus Level: Most comfortable Rate of Stimulation: 2400 pps Duration of Stimulation: 2 minutes Nucleus Hybrid Device (Rt ear) Normalized Ratings of Perceived Loudness (0= inaudible; 100= loudest) 100 80 60 40 20 0 During Stimulation Post-stimulation 0 1 2 3 4 5 6 7 8 9 10 11 Time (minutes) Perceived loudness of stimulus (basal electrode) Perceived loudness of stimulus (middle electrode) Perceived loudness of stimulus (apical electrode) Perceived loudness of tinnitus (basal electrode) Perceived loudness of tinnitus (middle electrode) Perceived loudness of tinnitus (apical electrode) 45 Effect of Stimulus Level on the Perceived Loudness of Tinnitus (DR) Electrode Location: Mid (#3) Rate of Stimulation: 2400 pps Duration of Stimulation: 2 minutes Nucleus Hybrid Device (Rt ear) Normalized Ratings of Perceived Loudness (0= inaudible; 100= loudest) 100 80 60 40 20 0 During Stimulation Post-stimulation 0 1 2 3 4 5 6 7 8 9 10 11 Time (minutes) Perceived loudness of stimulus (sub threshold) Perceived loudness of stimulus (just noticeable) Perceived loudness of stimulus (most comfortable) Perceived loudness of tinnitus (sub threshold) Perceived loudness of tinnitus (just noticeable) Perceived loudness of tinnitus (most comfortable) Perceived loudness of tinnitus (no signal) 46 The University of Iowa 23
Effect of Duration of Stimulation on the Perceived Loudness of Tinnitus (DR) Electrode Location: Mid (#3) Stimulus Level: Most comfortable Rate of Stimulation: 2400 pps Duration of Stimulation: 2*, 8 & 20 minutes Nucleus Hybrid Device (Rt ear) *=Data for 2 minutes have been replicated from that obtained for effect of duration. There wasn't enough time to obtain data for 2 and 4 minutes of duration. Normalized Ratings of Perceived Loudness (0= inaudible; 100= loudest) 100 90 80 70 60 50 40 30 20 10 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 Time (minutes) Perceived loudness of stimulus (2 minutes) Perceived loudness of stimulus (8 minutes) Perceived loudness of tinnitus (2 minutes) Perceived loudness of tinnitus (8 minutes) Perceived loudness of stimulus (20 minutes) Perceived loudness of tinnitus (20 minutes) Arrows indicate the point in time when the stimulus was switched off. 47 Summary lab studies Optimal stimulus parameters are different for different subjects Perception of tinnitus suppression signal can decrease over time Effectiveness of signal to suppress tinnitus can, over time Become less effective Become more effective Effectiveness during continuous stimulation can be prolonged/improved by changing (e.g. modulating) stimulus Post-stimulation effects In some, tinnitus reduced minutes to hours after stimulus turned off 48 The University of Iowa 24
Preliminary field trials 3 patients 1.CI plus contralateral Hearing Aid 2.CI patient 3.CI patient Method field trial 1 1 patient HA and contralateral CI Odd electrodes Speech Even electrodes tinnitus suppression signal (2 different one alternated daily) The University of Iowa 25
Tinnitus Rating (0-100) (The higher, the worse) Managing the Tinnitus Patient 100 Tinnitus Performance 80 Tinnitus Loudness Ratings Hearing aid 60 Cochlear Implant #1 40 20 CCIS CIS HA Cochlear Implant #2 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 Day 51 Method field trial 2 Wave files mixed with signal from speech processor Speech and tinnitus suppression signal on together Preliminary laboratory trial selecting likely beneficial tinnitus suppression signals Alternate daily tinnitus suppression signal Loudness, Annoyance, Acceptability Ratings The University of Iowa 26
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3. Summary of what is known Effectiveness of stimulation Tinnitus can be reduced in some proportion of patients Optimal stimulus parameters May be different for different subjects Ear of stimulation Usually monaural effect, binaural effect in some patients 57 Audibility of stimulation Can suppress stimulus without percept Possible advantage of conditioner Adaptation of continuous stimulation Effectiveness can decrease over time with same stimulation Post-stimulation effects In some, tinnitus reduced minutes to hours after stimulus turned off Tinnitus can re-emerge after being suppressed with continuous stimulation, and can be re-suppressed with stimulus change in level or periodicity 58 The University of Iowa 29
Next Steps Studies are needed to determine what changes in the stimulus are needed to maintain reduction during continuous stimulation 59 The University of Iowa 30