The Long-Term Stability of the Electrical Stapedial Reflex ... · A group of us were interested in...

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The Long-Term Stability of the Electrical Stapedial Reflex

Threshold; A Retrospective Chart Review

Cache Pitt, AuD, CCC-AKaren Munoz, EdD, CCC-AMcKay Kunz, AuD, CCC-A

Presenter

Presentation Notes

I am Cache Pitt, clinical assistant professor at Utah State University. A group of us were interested in looking at the long-term stability of eSRT over time.

Disclosure

Employed at Utah State University

Audiology Advisory Board Member, MedEl

Presenter

Presentation Notes

I am employed at Utah State University and I am a member of the MedEl Audiology Advisory Board. I have no financial interests in the outcomes of this study.

Introduction

The electrical stapedial reflex threshold (eSRT) is a valid and reliable tool for establishing upper limits of loudness Hodges, et al 1997

Brickley, et al 2005

Walkowiak et al 2010

Presenter

Presentation Notes

Both objective and subjective measures are used clinically to establish upper limits of loudness. Subjective measures may include loudness scales or balancing loudness across electrodes. Objective measures include evoked potentials, such as NRT, NRI, and ART. The eSRT was first reported by Annelle Hodges et. Al in 1997, and has been proven over time and across multiple studies to be a valid and reliable measure for setting a patient’s upper limit of loudness.

Introduction

Purpose of the study – 2 questions 1. Investigate the stability of eSRT over time…How much does eSRT change

over time?

2. What is the relationship between eSRT and the upper limit of loudness…Where do I put the upper limit of loudness (C, M, MCL) based on eSRT

Presenter

Presentation Notes

Knowing that eSRT is a valid and reliable tool, we wanted to know how much does eSRT change over time? We wanted to know how frequently we need to measure eSRT. We also wanted to establish a clinical guideline for where to set the upper limits of loudness based on eSRT for each manufacturer.

Methods

Study design (Utah State University IRB Approved)

206 clinic files were reviewed between January 2013 and December 2015

% (n) M (SD)Subject Demographics

Male 55% (113)Female 45% (93)Age at implantation (in months) 15 (24)Age at hearing loss onset (in months) 5 (14)Bilateral implants 61% (125)Unilateral right implant 22% (46)Unilateral left implant 17% (35)

Presenter

Presentation Notes

We developed a retrospective study reviewing the files all individuals who had been seen during a 3-year time span between the beginning of 2013 and the end of 2015. In the end, 206 clinic files were reviewed. Of the 206 files, gender distribution is fairly equal…

Methods





Presenter

Presentation Notes

…and the age of implantation of 15 months is representative of our clientele, which is mostly pediatric.

Methods





Presenter

Presentation Notes

Most, or 61% of our patients are bilateral. Interestingly, of the unilateral implants, the distribution between right and left ear is fairly equal.

Results

Other subject demographics% (n) M (SD)

Individual Participants with eSRT 77% (159)eSRT obtained ipsilaterally 64% (102)eSRT obtained ipsilaterally & contralaterally 26% (42)eSRT obtained contralaterally 10% (15)

Individual Participants without eSRT 23% (47)Total Appointments (n=903)

eSRT obtained 59% (537)No reflex present 21% (189)eSRT not tested 20% (181)

Reason eSRT not tested Patient behavior (e.g., cooperation) 35% (64)Other (e.g., hookup appointment) 35% (63)Middle ear (e.g., present tubes, fluid) 20% (36)History that patient could not tolerate loudness 6% (10)Equipment problem 4% (8)

Presenter

Presentation Notes

At Utah State University, our clinic protocol is to measure eSRT at every appointment on each patient, unless they have a history of no eSRT that has been established over multiple appointments. That provided a lot of data points for this type of file review. Of the 206 files reviewed, 77% of the patients had a present eSRT.

Results






Presenter

Presentation Notes

Of the 77%, or 159 patients who had a present eSRT, 64% of them were always recorded in the ipsilateral ear and an additional 26% were recorded both ipsilaterally and contralaterally at different times. Our default is to start in the ipsilateral ear, but in some cases for example, a specific individual may have had fluid in one ear, so recording contralaterally would have been required.

Results






Presenter

Presentation Notes

Of the 159 patients with present eSRT, only 10% of them had eSRT that could only be recorded contralaterally. That does include individuals who are bilateral, so for some reason or another, one of the implanted sides required contralateral recording while its counterpart ear was recorded in an ipsilateral condition.

Results






Presenter

Presentation Notes

In addition to analyzing the total number of patients, we also analyzed the total number of appointments during the 3-year time frame, which means that most people had multiple data points, which was true for those who had a history of eSRT or not. In total, we analyzed 903 appointments. So, while the range of the number of appointments per person is large, the average number of appointments per person was 4.4 during the 3-year period.

Results






Presenter

Presentation Notes

The number of appointments with no eSRT was comparable to the number of patients with no eSRT, comparing 21% of appointments with no eSRT with 23% of individual patients with no eSRT.

Results






Presenter

Presentation Notes

Note that of the 903 appointments, eSRT was not attempted 20% of the time or for 181/903 appointments.

Results






Presenter

Presentation Notes

Since measuring eSRT is clinic protocol, it was conveniently noted in the patient chart why eSRT was not attempted at that given appointment. The following reasons were cited for not completing eSRT: patient behavior, it was an activation appointment, they historically could not tolerate loudness, or there were middle ear problems, whether it was tubes or fluid. Interestingly, when I talk to people about why they do not include eSRT as a standard protocol, these reasons are most frequently cited, but our experience indicates that these are not significant barriers, especially when you take note that we are evaluating appointments, not individuals, and given the ages of the patients with these risk factors, they will have contributed to many of the appointment type data points.

Results

Relationship between eSRT and upper limits of loudness Established by globally decreased M, C, MCL until patient reported overall

loudness comfort.

Advanced Bionics Cochlear MedEl

10% 3%19 units

Presenter

Presentation Notes

One of our main study goals was to identify the relationship between eSRT and the patient’s upper limit of loudness, in other words, how much do you turn down the upper limit of loudness after measuring eSRT. We found this value by globally decreasing the upper limit of loudness until the patient reported overall loudness comfort, then compared that value with the eSRT value. For Advanced Bionics, the mean decrease is 10%, for Cochlear it is 19 clinical units, and for MedEl it is a 3.4% decrease.

Results

Long-term stability of eSRT

Established by comparing eSRT values for at least 3 different points in time within the same individual (linear regression line) 43% of the patients met this criteria

Time Span of 3 appointments

Mean 20.7 Months

Median 23 Months

Range 4-34 Months

Presenter

Presentation Notes

Another main study goal was to understand the stability of eSRT over time. Does it change over time or not? To study this, we used a linear regression analysis of individuals who had a minimum of 3 appointments over time. 43% of the subjects met the criteria of 3 minimum appointments. All data points in excess of 3 appointments were included in the analysis. The mean time span of the first and final appointments was 20.7 months apart with a median of 23 months and a range of 4- 34 months.

Results

Rate of change in eSRT per year

Advanced Bionics 3 clinical units

Cochlear -1.4 clinical units

MedEl 0.4 clinical units

Presenter

Presentation Notes

Over the course of time, the eSRT increased by 3 clinical units per year for Advanced Bionics, decreased by 1.4 clinical units for Cochlear, and increased by 0.4 clinical units for MedEl. This data indicates that there is very little change in eSRT over time.

Conclusions

Sample is very large

eSRT is stable over time for at least a period of 20 months

The relationship between eSRT and upper limit of loudness was established

Other interesting conclusions include eSRT is present in most cases (77%) and

eSRT is recorded in the ipsilateral condition the majority of the time (64%)

Presenter

Presentation Notes

Because of our clinic protocol of measuring eSRT on all patients, the sample size of this retrospective chart review is very large. We learned from this study that the eSRT is stable over time for a period of at least 20 months. We also established the relationship between eSRT and the upper limit of loudness so that we can get an idea of how much to decrease the upper limit of loudness after measuring eSRT. We also learned some other interesting points, such as most people have a present eSRT and the it can be recorded in an ipsilateral condition the majority of the time.

Contact

[email protected]

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The Long-Term Stability of the Electrical Stapedial Reflex ... · A group of us were interested in...

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