BORDERLINE PATIENTS AND THE BRIDGE BETWEEN HEARING AIDS AND COCHLEAR IMPLANTS

Transcription

1 BORDERLINE PATIENTS AND THE BRIDGE BETWEEN HEARING AIDS AND COCHLEAR IMPLANTS Richard C Dowell Graeme Clark Chair in Audiology and Speech Science The University of Melbourne, Australia Hearing Aid Developers Forum, Oldenburg, 2017

2 Declaration and acknowledgment The University of Melbourne receives research funding from Cochlear Ltd and Sonova The author acknowledges the work of many colleagues at the University of Melbourne who have contributed to the studies in this presentation The staff of the Melbourne Cochlear Implant Clinic are also acknowledged for collecting the outcomes and demographic data presented here

3 Quick history of cochlear implants Trials of the first commercial multichannel systems began in the early 1980s with numbers of CI users now approaching 500,000 Once technology and reliability caught up with ideas for sound coding, hearing outcomes were surprisingly good Early scepticism, the involvement of surgery, and costs, have meant that the analysis of benefits has been necessarily rigorous and long term

4 Speech perception results for adult cochlear implant users showing improvements due to changing signal coding ( ) Dowell (2012)

5 Pre and post-implant comparison of speech perception 310 consecutive adults ( ) Dowell (2012)

6 Speech perception and cochlear implants In general terms, speech perception requires simultaneous transmission of information about the spectral and amplitude envelope of the acoustic signal Frequency resolution of 1/3 octave and temporal resolution <10ms required for good speech perception This is necessary but not sufficient as the central auditory system must process this information rapidly and access the stored lexicon and language knowledge in order to understand the message Cochlear implants can provide spectral envelope information by stimulating selectively along the cochlea, and amplitude envelope information by varying stimulation current

7 Speech perception and hearing loss Information content in speech is mainly transmitted by consonants which generally have shorter duration, higher frequency and lower amplitude SN hearing loss, as it becomes more severe, affects detection, frequency resolution and sometimes temporal resolution, and distorts amplitude information There is a point where this loss of information makes a CI a better option but this remains difficult to predict

8 What is the down side for cochlear implants? The CI signal is a poor simulation of the normal firing patterns in the auditory nerve It is possible, however, to provide sufficient temporal, spectral and amplitude information in a form that is recognizable to the higher auditory centres Fine time structure of the acoustic signal is not well transmitted and perception of musical pitch is very limited in range and resolution Residual hearing is often lost during or after implant surgery

9 Clinical outcomes Somewhat surprisingly, most adults (85%) with acquired hearing loss develop good open set speech perception adequate for conversational telephone use Performance and speed of learning is affected by duration of auditory deprivation, age and pre-implant hearing Those with onset of hearing loss at birth or in early childhood perform much worse and may be non-users in the long term

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11 Cochlear implants plus hearing aids Now, around 70% of adults who use CIs also use a conventional hearing aid in the opposite ear There was initial concern that patients would find the combination difficult and bimodal interaction may reduce speech perception BUT Studies have consistently shown that after an initial learning period a large majority use both devices and obtain significant speech perception benefits

12 Bimodal advantage for speech perception (N= 750 unselected CI adults, clinical outcomes)

13 Results (courtesy of Dr Kerrie Plant, Cochlear Ltd) Bimodal SRT in Babble 37.5% of variance explained by: Age at implantation Contralateral PTA* Duration SPHL implanted ear Plant (2016) PhD Thesis

14 Preserving natural hearing and EAS Residual hearing can be preserved following cochlear implantation and appears to depend on Trauma during electrode insertion Inflammatory response within the cochlea (during surgery or later) Depth of electrode insertion Some reports can be difficult to interpret as hearing preservation has been quantified in many different ways If hearing is preserved at useful levels electrical and auditory stimulation can be used in the same ear (EAS)

15 Audiometric variations in implant candidates (courtesy of Dr Kerrie Plant Cochlear Ltd) N=19 (pre-op phoneme score >46% both ears) Best aided pre & 12M evaluation Implanted Ear Word Score: Mean 22% Range 11-62% Contralateral Ear Word Score: Mean 40% Range 16-75% Plant (2016) PhD Thesis

16 Improvement for CI adults with significant residual hearing who lost hearing after surgery (n=19) Significant group mean post-operative benefit on all measures No subjects showed reduction in performance > critical difference on the test measure Plant (2016) PhD Thesis

17 Hearing Stability after hearing preservation surgery 17 Plant (2016) PhD Thesis

18 Speech perception benefit: acoustic hearing in implanted ear (EAS) (courtesy of Dr Kerrie Plant, Cochlear Ltd) CUNY sentences in babble; within-subject comparison; 16 subjects at +5 or+10 db SNR Bimodal (CI+contralateral HA) vs combined (CI+2 hearing aids) S0N0 S0 N90 (Side of SP) S0 N90 (Side of HA) Plant & Babic (2016) Int J Aud

19 References Simpson, A., McDermott, H.J., Dowell, R.C. Benefits of audibility for listeners with severe high-frequency hearing loss. Hearing Research 210: (2005) Dowell, R. Evaluating cochlear implant candidacy: recent developments. The Hearing Journal 58(11) 9-23 (2005) Mok M, Grayden D, Dowell RC and Lawrence D (2006). Speech perception for adults who use hearing aids in conjunction with cochlear implants in opposite ears. Journal of Speech, Language and Hearing Research 49(2) Dettman, S.J., Pinder, D., Briggs, R. J. S., Dowell, R. C., & Leigh, J. R. (2007). Communication development in children who receive the cochlear implant younger than 12 months: Risks versus benefit. Ear and Hearing, 28, Galvin, K., Mok, M., Dowell, R. C., & Briggs, R. (2008). Speech detection and localization results and clinical outcomes for children receiving sequential bilateral cochlear implants before 4 years. International Journal of Audiology 47(10): Simpson, A., McDermott, H. J., Dowell, R. C., Sucher, C., & Briggs, R. J. S. (2009). Comparison of two frequency-toelectrode maps for acoustic-electric stimulation. Int J Audiol, 48(2). Mok, M., Galvin, K. L., Dowell, R. C., & McKay, C. M. (2010). Speech Perception Benefit for Children with a Cochlear Implant and a Hearing Aid in Opposite Ears and Children with Bilateral Cochlear Implants. [Article]. Audiology and Neuro-Otology, 15(1),

20 References Dowell, R., Galvin, K., Dettman, S., Leigh, J., Hughes, K., and R. van Hoesel. "Bilateral Cochlear Implants in Children." Seminars in Hearing 32 1 (2011): Leigh, J.R., Dettman, S.J., Dowell, R.C. and Sarant J.Z. (2011) Evidence-based approach for making recommendations for cochlear implantation for infants with residual hearing Ear and Hearing 32(3) Boisvert, I., McMahon, C. M., & Dowell, R. C. (2012). Long-term monaural auditory deprivation and bilateral cochlear implants. [Article]. Neuroreport, 23(3), Blamey P., Artieres F., Başkent D., Bergeron F., Beynon A.,Burke E., Dillier N., Dowell R. et al. (2013) Factors Affecting Auditory Performance of Postlinguistically Deaf Adults Using Cochlear Implants: An Update with 2251 Patients. Audiol Neurotol 18 Dowell RC. (2016) The case for earlier cochlear implantation in postlingually deaf adults. Int J Audiol. DOI: / Rousset A, Dowell RC, Leigh JR. (2016) Receptive language as a predictor of cochlear implant outcome for prelingually deaf adults. Int J Audiol. DOI: / Leigh JR, Moran M, Hollow R, Dowell RC. (2016) Evidence-based guidelines for recommending cochlear implantation for postlingually deafened adults. Int J Audiol. DOI: / Dettman SJ, Dowell RC, Choo D,et al. (2016). Long term communication outcomes for children receiving cochlear implants younger than 12 months: a multi-centre study. Otology & Neurotology

21 Talking points What audiometric configuration is suitable for CI? What would be the ideal settings for acoustic amplification devices for use with CIs? Can bimodal performance be improved if Cis and hearing aids talk to each other? Are cochlear implants likely to improve further? If so, how will this be achieved

22 Our panel of experts Professor Tom Francart, KU Leuven, Belgium Dr Volkmar Hamacher, Advanced Bionics, European Research Center Professor Andreas Buchner, Scientific Director, Hannover Medical School Professor Tim Juergens, Research Center Neurosensorics and cluster of excellence Hearing4all Dr Waldo Nogueira, Auditory Prosthetic group, Hannover Medical School

23 Program of short talks followed by discussion Introduction Panel Chair Richard Dowell What can hearing aids do well (better than cochlear implants)? - Tom Francart What can cochlear implants do well (better than hearing aids)? - Volkmar Hamacher What factors are important in predicting success with a cochlear implant? - Andreas Buchner How well do cochlear implants work with hearing aids in the opposite ear? - Tom Francart Electrical and auditory stimulation in the same ear (EAS) - Waldo Nogueira Latest results for preservation of residual hearing after CI - Volkmar Hamacher Bilateral cochlear implants - Tim Juergens