Establishing the test retest reliability of contralateral auditory suppression of transient evoked oto-acoustic emissions in a cohort of normal healthy individuals

Information sheet for Participants.

Welcome, my name is Pradeepa Mahawattage, and I am a graduate student working with Dr. Montelpare in the Faculty of Science. We would like to invite you to participate in our study, however, before you agree to participate we would like you to understand why the study is being done and what it will involve. Please, feel free to ask questions if anything is unclear to you or if you would like to have further information. Please note that this research project has been approved by the UPEI Research Ethics Board.

What is the name of the research project?
Establishing the test-retest reliability of contralateral auditory suppression of transiently evoked otoacoustic emissions  (CAS TEOAE) in a cohort of normal healthy individuals, 16-50 years of age.

Previous researchers have noted that otoacoustic emissions (OAEs) can be described as physiologically produced subtle sounds in the inner ear that can be recorded in the external ear canal in normally hearing individuals using a sensitive recording mechanism. Yet what is extremely valuable to concussion researchers, from a clinical perspective, is that the OAEs can be stimulated (transiently evoked) in the healthy cochlea by presenting a brief auditory stimulus in the form of clicks. This stimulating (transient) maneuver is referred to as TEOAEs and has been used to determine hearing impairments in several cohorts, including newborns.

Moreover, during the application of TEOAEs a well-established phenomenon can be stimulated in normal ears. That is, during the TEOAE test, the response of the ipsilateral ear can be significantly reduced (suppressed) by presenting an alternative sound to the opposite (contralateral) ear. This fascinating physiological process is known as contralateral acoustic suppression (CAS) of TEOAEs and the most important element in CAS TEOAE is that this suppression effect is mediated by auditory neuronal activity.

The suppression activity is possible only when the auditory neural connections between the right and left cochleae are intact, which suggests that if the normal neuronal activity of the auditory system is disrupted, as in a concussion or mild traumatic brain injury, then the potential suppression activity of the contralateral stimulus may be minimized or absent.

What is the purpose of the study?
The purpose of this study is to assess the test-retest reliability of the CASTEOAE procedure. The CASTEOAE procedure will be conducted on a convenience sample of 30 asymptomatic participants aged between 16 to 50 years with no history of hearing impairment and head injuries.

Why are we conducting this study?
Despite the various tests and screening tools that have emerged over the past few years to assess the concussion condition following a mild traumatic brain injury, there is currently no single gold standard test or mechanism for determining in general terms, the magnitude of a concussion.
Quite simply, there is a need for better criteria to establish the point at which an individual can return to play/physical activity without risking further injury following a concussion. As a general rule, most research indicates that the safest practice following a mild traumatic brain injury is that the concussed individual should not return to play until completely without symptoms, both at rest and during physical exertion tests.

At the University of Prince Edward Island, we are conducting a research study to establish the test-retest reliability of the CAS TEOAE test, as a measure of auditory neuronal activity of the brain. The study was designed to test the statistical stability of this specific neurophysiological activity and is considered to be a preliminary step in developing an evaluation tool for concussion.

We expect that through this process we will be able to identify a more accurate method by which we can provide support for the return to play/work decisions. Our expectation is that by evaluating individuals on several physiological parameters we can reduce the risk of sending an individual back to play or work without appropriate recovery.

Why have I been asked to participate?
You have been asked to participate because you are currently a student attending the University of Prince Edward Island, and between 19 and 50 years of age.

Do I have to take part?
Participation in this study is entirely voluntary. If you decide to take part please, complete the letter of informed consent. This requires access to the internet and your e-mail will be requested as part of the registration. This information sheet is yours to keep and is also available on the website, as is a copy of the consent form which you should read and agree to if you decide to participate in this study. You can save or print a copy of the consent form from the website for your records. We explicitly seek your consent for the use of direct quotations which will be anonymised. If you take part and change your mind, you have the option of withdrawing from the study at any point without giving any reasons. If you withdraw we seek your consent to retain and use any data (anonymously, using a personal identify number or pseudonym) which you will have given, previously.

Submitting responses to the letter of informed consent is considered your virtual agreement to the terms of the study which are specifically noted as follows: All information collected throughout this study will remain confidential and securely stored using a firewall-protected secure server accessible via password for security and safety at the University of Prince Edward Island for a period of five years. You are NOT obligated to complete any forms and may withdraw from the study at any time without fear of reprisal.

What will I have to do if I agree to take part?
This study requires participants to register on the project website by first completing the letter of informed consent (http://projects.upei.ca/wise/cas-teoae-letter-of-consent) and then you will receive an email that will direct you to our server where you will be asked to complete the following documents:

  1. the About You form to provide demographic information
  2. the Concussion History form
  3. the Otological Normality questionnaire

Once you have completed these forms, the researcher will contact you to set up an appointment to visit the clinic for the first day of two test days.
All tests will be conducted using Otodynamics ILO292 otoacoustic analysis system. On the day of testing an external ear examination will be performed with an otoscope prior to the CASTEOAE testing and the total time for testing will be approximately 30 minutes per testing session.

On the day of testing, a standard otoscopic examination will be conducted using an auri-scope to ensure that there are no abnormalities in the external ear canal or perforations of the tympanic membrane.
The CAS TEOAE test consists of 4 sub phases:
The standard transient evoked (TE) (oto acoustic emission: OAE) test
The spontaneous OAE test
The Contralateral auditory suppression of Transient oto acoustic emission test with the suppression of 60 dB SPL
The contralateral auditory suppression of Transient oto acoustic emission test with suppression of 80 dB SPL.

Transient-evoked otoacoustic emissions (TEOAEs) are physiologically produced sounds that can be recorded in the ear canal of a normally hearing ear in response to stimulation by clicks. It is well established that in normal ears the size of TEOAEs can be significantly reduced (suppressed) by the presence of noise in the opposite (contralateral) ear. This is known as contralateral acoustic suppression (CAS) of TEOAEs. CAS TEOAE is possible due to the normal functioning of nerve pathways that link right and left ears via central areas of the brain. Where these pathways are disrupted, CAS TEOAE is reduced or absent. Therefore, CAS TEOAE represents a test of the integrity of central nerve pathways.

All participants will have an opportunity to review their own performance scores after completing the second trial.

Are there any disadvantages associated with participating in this research study?
There are no reasonable foreseeable discomforts or risks involved in participating as you could respond to the web-based surveys at any time and place. Your data will be stored in a secure password protected server.

If there is any unexpected discomfort, disadvantage or risk to you during the course of this research, please, bring it to the attention of the project coordinator to help you find support or use the link for support on the study website.

What if something goes wrong?
There are no known risks or harm with this research. If you are harmed by taking part in this research, there are no special compensation arrangements. If the harm to you is due to someone’s negligence, then you may have grounds for legal action but you may have to pay for it. Regardless of this, you may wish to complain or have any concerns about any aspect of the way you have been approached or treated during the course of this study, you may contact the UPEI research ethic board at ( 902) 620 5104 or by email at reb@upei.ca. The normal UPEI complaints mechanisms will still be available to you. If you wish to make a complaint, then please contact the project coordinator on how to proceed.

What are the possible benefits of taking part?
There are no immediate benefits for those participating in the study, but the study will contribute to the knowledge base and inform policy. You may gain some personal benefits or support from writing or discussing your views with other participants.

Will my participation be kept confidential?
Yes, all information collected will be kept strictly confidential. You will be assigned a personal identification number (ID) or pseudonyms to identify your responses. Personal identifiers will be removed from responses during the analysis of the data and replaced with pseudonyms. During the study the chief investigator and academic supervisors will have access to your personal data. Your ID and personal details will be stored in a password-protected computer. Your anonymised responses will not be held together with your personal details. Data will be stored on the University of PEI firewall protected secure server that is only accessible via password for security and safety. After finishing this study the data will be stored in password protected computer accessed by the lead supervisor (Dr WIlliam Montelpare) for 5 years and then destroyed according to the University policy on data protection.

What type of information will be sought and why the collection of this information?
The information we need will be your responses to the survey questions that will be presented to you in the process of data collection when you register for the study. In addition, we will need your response to the CAS TEOAE tests. The surveys include: basic demographic measures such as age, sex, year of birth, as well as responses on the Otological Normality Scale, and the record of your concussion history. This will enable the overall aim of the study to be achieved — which is — to establish the statistical stability of the CAS TEOAE test.

What will happen to the results of the research project?
A summary of the findings will be available for all participants electronically.  Findings will be published in academic journals and presented at academic and professional conferences.

Who is organizing and funding the research?
The study is being conducted as part of my graduate program at UPEI. This study which is to establish the reliability of the CAS TEOAE, is part of a larger project being conducted in conjunction with the PEI Workers Compensation Board.

Thank-you for being interested in this important process. Please click the following link to complete the letter of informed consent — http://projects.upei.ca/wise/cas-teoae-letter-of-consent