The main topic of the conference was application of hearing implants, especially cochlear implants, in single-sided deafness. Persons with single-sided deafness are a new, relatively large group of patients who, until recently, had not been considered in terms of cochlear implant candidacy. Presently there are more and more reports from different centers around the world (particularly in Europe, where this treatment method has been in use for several years) that confirm the benefits of cochlear implantation in this group of patients, especially in patients with single-sided deafness and vexing tinnitus. Tinnitus is a complementary indication for applying the electric stimulation that, as confirmed by scientific research and clinical experience, facilitates their habituation. In the United States the program of cochlear implantation in single-sided deafness is in its infancy, because the Federal Drug Administration is still conducting the studies of this procedure before allowing it for clinical practice. This is why the Americans have invited scientists from Europe, also from Poland, to share their experience in management of patients with this kind of hearing problems.
People with single-sided deafness using implants are perfect candidates for research on the impact of electric stimulation. Such person is uniquely positioned to compare what she hears through the implant to what she can hear with the other, normally functioning ear. It is an extraordinary chance to enlarge our understanding of auditory perception through cochlear implant, which may bring about new, more effective methods of rehabilitation and therapy.
During the Toronto conference this subject had been raised in the invited lecture of Prof. Michael Dorman from the Arizona State University in USA. His research on implant users with single sided deafness is aimed to help create an improved simulation of hearing through implant. His results suggest that earlier models of hearing though implant – elaborated based on our understanding of implant functioning (in the Institute of Physiology and Physiology of Hearing such model had been a PhD thesis of Adam Walkowiak) do not fully reflect the reality and quality of sound transmitted by the device in not as bad as everybody thought. Studies of quality of hearing in cochlear implant users are presently one of the major research directions in this field. It is a novelty, because until recent times the researchers focused on issues related to speech understanding and methods of improving speech perception. Today more and more implant users are able to discriminate speech not only in silence, but also in noise and research is increasingly focusing on improving the sound’s ‘aesthetics’. It is very important for e.g. listening to music. Its perception has other needs than perception of speech, which can be understandable even when it sounds a little unpleasantly. Therefore even a patient with good speech discrimination can still have problems with perception of music, which may for him sound unattractively.
Improvement of sound aesthetics is thus another barrier that we have to break in cochlear implants. How to make it? We can try improving the design of an implant and electrode, perfect the techniques for its precise placement in a cochlea – in optimal distance from neurons, can work on improving sound coding strategies and in patients with partial deafness develop even better methods of combining their natural hearing and electric hearing. We can also develop special rehabilitation programs taking advantage of brain plasticity for improving the quality of heard sounds.
In many of these activities very useful is information provided by studies with people with single sided deafness. They are also conducted in the Institute of Physiology and Pathology of Hearing who has under its care one of the largest in the world groups of patients with normal hearing in one ear and implant in the other. The results of innovative studies performed with their participation presented in Toronto dr. Artur Lorens from Implants and Auditory Perception Department. For this group of patients the Institute had developed a special rehabilitation program presented at Toronto by Dorota Pastuszak, who stressed the necessity of adjusting the rehabilitation activities to answer the needs of new groups of implant users.
A new group is also people with partial deafness who have correct hearing up to 1500 Hz, who are using an electric complementation to natural hearing. This group of patients presented in Toronto Prof. Henryk Skarżyński who, speaking about the extension of indications for implantation mentioned that it is possible thanks to his atraumatic method of electrode insertion which enables preserving patient’s low frequency hearing. Hearing preservation in these frequencies after cochlear implantation is very important also for music perception.
At the Toronto conference there had been much attention given to the role of music in the therapy of patients using implants. Dr Charles Limb for the University of California in his invited lecture had presented the project involving creation of music adjusted to the perception abilities of cochlear implant users, allowing for the limitations in sound transmission of these devices. He had noted the individual dimension of music perception, comparing it to wine tasting. There are individuals whose taste sensations are so refined that they are able to tell cheap wine from good vintage and others, for whom both wines will taste similar. This rule applies also to music perception.
The fact that not all implant users are satisfied with music reception is not only due to the limitation of the device. People with musical training may have very high expectations with regard to sound perception, which the implant is not able to meet. Thus music it is transmitting can be unsatisfactory for them. For other, less demanding listeners, it may be perfect. Nevertheless many papers on rehabilitation underline that auditory training utilizing music can have a very good effect on speech understanding of implant users.
Prof. Warren Estabrooks from Canada had presented a lecture rehabilitation issues related to adults, especially those who change hearing aids to cochlear implants and those with the single sided deafness. He had investigated what rehabilitation programs are offered to patients in different countries. It turns out there are very little centers globally providing rehabilitation care for all patients, as it is done in the Institute of Physiology and Pathology of Hearing.
During sessions dedicated to rehabilitation of children panelists discussed such topics as utilization of sign language to support the development of language skills in an oral language. In the USA and Canada, where language and cultural identity of the Deaf is very strongly manifested, there is a pressure that all people with hearing loss, also implant users, should learn the sign language. Andrea Warner-Czyż from the University of Texas had investigated if sign language is in fact supportive in rehabilitation of children using cochlear implants. Observing for two years a group of such children she had noted the delay in development of oral language in implanted children who had additionally been using the sign language. Due to the short follow-up time we should not draw any hasty conclusions, as there is a rule, relating also to children raised in bilingual families, them children using two languages at the beginning acquire skills in both languages more slowly, but with time their language development level evens out. This may also apply to implanted children developing simultaneously oral and sign language. Further in-depth scientific investigation of this issue is indispensable.
Małgorzata Zgoda from the Institute of Physiology and Pathology of Hearing had presented in Toronto the results of original research relating to the influence on socioeconomic factors on school results of children using implants. Family income was found to have no influence on children’s school results, but there was observed a significant influence of the education level of child’s guardians. Children of parents with lower education obtained worse results at school than children of mothers and fathers with higher education. This is a challenge for rehabilitation specialists who often treat a parent as a passive observer of therapy, forgetting that an aware, educated parent is the best source of support for a child. It may be a source of the efficacy of the auditory-verbal therapy method, used also in the Institute, which places a high importance on parents’ participation in therapy.
At the International Conference on Cochlear Implants and Other Implantable Technologies in Toronto there were almost 2000 participants and more than 470 papers presented.
There were also presentations relating to the middle ear implants. The Institute of Physiology and Pathology of Hearing is one of the first centers globally introducing the newest types of these devices into the clinical practice. Ass. Prof. Piotr Skarzynski presented very good results obtained in the Institute with these implants.
On the Toronto conference there was only a 7-person delegation from the Institute representing Poland (Prof. Henryk Skarżyński, Ass. Prof. Artur Lorens, Ass. Prof. Piotr H. Skarżyński, Ass. Prof. Monika Ołdak, dr. Adam Walkowiak, Małgorzata Zgoda and Dorota Pastuszak). The Institute has under its care one of the largest in the world groups of patients with different hearing disorders treated with implantable devices. Twenty two papers presented by this group mirror the newest research in hearing implants.