"BAEPs must always be seen as a support resource for behavioural audiometry tests”

Electrophysiology

Dr. José Juan Barajas
Dr. Barajas shared insights on his career and his current research at Audiology Worldnews' booth during the ENT World Congress in Paris. © B.S.

Interview to Spaniard Dr. José Juan Barajas, recipient of the International Award in Hearing American bestowed by the Academy of Audiology and founding father of the Canary Islands clinic that carries his name. The award is given in recognition of his contribution over many years to enabling students from different countries to work in electrophysiological practices in diagnosis, treatment and rehabilitation of voice, language, and hearing disorders, as well as for other oustanding points of merit during his extensive career.

What does this award mean to you, and what aspects of your career does the American Academy of Audiology (AAA) wish to highlight by bestowing it on you?

I guess it’s for the whole of my career, for my professional dedication in relation to American audiology, which stands as a model for what we do not have in Europe, a highly clinical model. I have had plenty of contact with my colleagues there, and I believe that this acknowledgement has come because I have reproduced the American model of audiology. And to the degree to which I have expressed my gratitude to them for helping me to know who I am. It is cause for special gratitude, since one often feels an outsider; otorhinolaryngologists consider me an audiologist, and audiologists think of me as an otorhinolaryngologist. I see myself as an otorhinolaryngologist who has nurtured great enthusiasm and devotion towards audiology.

What has been your contribution to the International Society of Audiology as a researcher. How long have you worked with this organisation, of which you were president from 2010 to 2012?

My research work has been centred on the electrophysiology of the central nervous system, my studies covering from the end organ to the cortex. I am basically an electrophysiologist of the central nervous system. I have tried to be of use to international audiology from positions of top responsibility on the executive committees of different societies. I was president of the International Society of Audiology (ISA) and the International Association of Physicians in Audiology (IAPA). In my case, these tasks on international committees have been an honour as well as a motive for personal engagement and commitment. These executive activities have helped me improve my knowledge of the human condition. My conclusion is that there are no national characters, that integrity is the product of individual values, and these can blossom anywhere in the world.

Since you mention this international perspective, in the US for example, how would you define the situation in Spain?

It has improved substantially in recent years and there are now people there with medical training who have a special interest in audiology. The Spanish Society of Audiology (AEDA) works well, and its president, Franz Zenker, is one of my disciples. He has a wide vision of the discipline and knows how to interact with professionals of different backgrounds. Each year, AEDA organises very interesting and instructive conferences. In past times, audiology was looked on by otorhinolaryngologists as a minor field, so much so that anyone in my service who behaved badly was sent to carry out audiometry tests, ensuring (he laughs) they wouldn’t get to the operating theatre. I’d like to point out in this respect that I am profoundly grateful to those who helped train me. Fernando Olaizola was not only a brilliant surgeon but he also inculcated in us an academic yearning as well as stimulating us to use our critical spirit. Under his direction at Madrid’s Clínica del Trabajo, we organised the first courses in Spain on impedance testing, which had a big impact on the development of audiology in our country. For some time, I formed part of the SEORL audiology council. In 1983, I was co-author of the Spanish Society of Otorhinolaryngology presentation on evoked auditory potentials.

Dr. José Juan Barajas at IFOS 2017 in Paris
Dr. Barajas, during his lecture at the ENT World Congress in Paris, this June. © B.S.

To what extent in the future will brainstem auditory evoked potentials (BAEPs) be used in audiology practices? What will the right degree of implantation be?

They must always be seen as a support resource for behavioural audiometry tests. First, you must look at how a child reacts to sound. This concept is crucial, and independently of all types of potentials that may be used. I receive many evoked potentials with indications that are debatable. The audiologist’s primary use of evoked potentials is to identify responses up to intensities that can be correlated with psychoacoustic thresholds. It is easy to imagine that the main candidates for electrophysiological studies are those subjects who cannot cooperate in conventional psychoacoustic studies either for reasons of age (newborn and children in the first year of life) or due to congenital defects of some kind. In both cases we need not only for brain responses to be obligatory but also to make sure results are not affected by sleep or sedation. In any case, before sending a child or adult for a prosthetic fitting or a cochlear implant, one must have as clear an idea as possible of the behavioural responses. On this point it is important to corroborate that, before a definitive diagnosis is established, the different tests of varying validity and reliability that have been carried out are interpreted as a whole (cross-checking).

On the subject of tests that produce an “automatic response”, on what groups of people would it be useful to carry these out?

Evidently, with a newborn child we are always going to have to use a battery of tests that do not rely on the cooperation of the subject. It is desirable to avoid things that can contaminate the response (noise and movements). Each technique has its advantages and limitations, and it is our responsibility as therapists and/or researchers to know in each case what we want to obtain with our explorations. It is not about putting electrodes on the head of a child or adult; the important thing is to know how to design a sequential mental plan of what we wish to achieve in order to establish the audiological, neurological, or maturation status of any particular subject.

What other electrophysiological tests do you see as recommendable for everyday practice in hearing aid fitting?

BAEPs, in both click and toneburst forms, and SSEPs (steady state evoked potentials). Both BAEP and SSEP can be used in sleep and/or sedation and are complementary due to their different dynamic range. BAEP potentials are the more robust and reliable in auditory evoked responses, and they are unique in determining type of hearing loss. Despite the time that has passed since their introduction in clinics, BAEP potentials constitute the “golden rule” among auditory evoked responses.

BAEPs present a dynamic range of 80-85 dB, so they do not allow for establishing thresholds in profound hearing loss. SSEPs cover a dynamic range of 110-120 dB, so are more appropriate for indicating any mode of training/rehabilitation in subjects with profound hypoacusis. Cortical potentials, despite needing patients to be awake, are also interesting clinically. The presence of these components indicate in some way that the stimulus has unleashed a response that has reached the cortex via the auditory pathways.

What research project are you currently working on or have in view?

In correlation of sonority established through psychoacoustic tests with responses obtained through SSEPs. It is a question of setting up a series of criteria to see if we can infer sonority through these SSEPs that we would be able to obtain through psychoacoustic testing. The ultimate aim is to find out whether the amplitudes and intensities of the response of the steady state evoked potentials can be instrumentalised for hearing prosthesis fitting.

You talked, did you not, on this in your presentation at the last world otorhinolaryngology congress, IFOS 2017? You mentioned the concept of “loudness”...

Loudness is an intimate and non-transferable sensory experience. Psychoacoustic tests for loudness do not allow us to establish the sensation of loudness growth, which is precisely what we try to infer based on SSEP electrophysiological results.

Does this mean that the psychoacoustic tests could be dispensed with?

Only in population groups where we cannot obtain sonority through a psychoacoustic form. In subjects with normal hearing one can correlate sonority quite closely with electrophysiological results, but it is still to be determined whether that correlation holds up in subjects with hypoacusis.

What institution is supporting this line of research?

The Clínica Barajas and the Fundación Canaria Dr. Barajas for the prevention of deafness.

From your renowned wealth of publications—66 articles and 157 presentations, according to the American Academy—which would you highlight? Could you please mention a particular contribution you are especially proud of?

Without doubt, having been able to build a team in a small medium and in very precarious conditions. Being able to bring enthusiasm to the projects and research inquiries we have presented in top international forums. I would not value so much just one specific contribution, but having been able to inculcate enthusiasm for science in some younger colleagues. And having been able to share unforgettable moments of academic debate.

And, besides everything, on an island...?

A small island, in a small private space...It has been miraculous, and this is down largely to my having brilliant and enthusiastic people around me.

What functions do the Clínica Barajas and the Fundación Doctor Barajas fulfil, respectively? How do they complement each other?

Treatment, teaching, and research activities. Naturally, some moments have brought greater productivity than others. My main legacy is not a tangible. Life is much more interesting when we have a question to answer. I believe it is worth creating an atmosphere in which those around one are shown how enriching it is to have the possiblity to do research.

Are you, perhaps, thinking about the research situation in Spain, because it will be highly different to the US?

There is a great difference between Spain and a country like the US. Comparing the scientific production of Spain with that of the US is to lose one’s sense of proportion. In the US, the resources devoted to research are immense, and above all the most important thing is American society’s great tradition of scientific activity. In the US, two conditions are behind science being especially prosperous: 1) respect for merit; 2) the balance of power at work in general in American life, and in scientific life in particular. Spanish science has come on substantially, however. In Spain, papers are being produced with increasing rigour, there is better education in languages, and international literature is better known than before.

How, from your perspective, has technological progress influenced the production of cochlear implants and hearing aids in recent years? What challenges and unfinished business await us?

Throughout my career there have been discoveries that have changed the essence of professional practice. These frontline innovations embrace not only the diagnostic area but also treatment. My career began just when brainstem potentials were being introduced to clinics, and impedance testing was bringing a new vision of how to approach study of hearing sensitivity. Otoacoustic emissions proved fundamental in helping to achieve universal neonatal screening. Cochlear implants, imaging techniques, and so on. In my field, I have had the chance to get to know the main movers of these changes relatively well. When I think about those people and the proximity I have had to them, I feel especially fortunate.

What challenges are left from a technological perspective?

I rather believe that these are going to come from the genetic and molecular side. The future will have to be based much more on biological investigation of the end organ, in order to treat disorders without any invasive activity. Everything we are currently doing does not solve the intimate problems of the mechanisms that produce the dysfunction. Why do cells age and how can we avoid it? Today we put cables into the ear and we help the patient to have better communication. In the future, why would we not look at things in quite another way?

Source: Audio Infos América Latina

J.L.F. and J.E.