Central Auditory Processing Deficits Associated With Blast Exposure
| Status: | Active, not recruiting |
|---|---|
| Conditions: | Hospital, Neurology |
| Therapuetic Areas: | Neurology, Other |
| Healthy: | No |
| Age Range: | 18 - 90 |
| Updated: | 4/21/2016 |
| Start Date: | May 2012 |
| End Date: | September 2016 |
The current conflicts in Afghanistan and Iraq have resulted in unprecedented rates of
exposure to high-intensity blasts and resulting brain injury. This research team has
established that recently blast-exposed Soldiers show differences from controls on tests of
central auditory function. This project will 1) develop a more accurate estimate of the
prevalence of central auditory dysfunction among Veterans exposed to blasts over the past
ten years, 2) identify the functional outcomes associated with abnormal performance on tests
of central processing, and 3) improve understanding of the ways in which blast-exposure
resembles and differs from both the normal aging process and non-blast-related TBI in terms
of performance on tests of central auditory processing.
exposure to high-intensity blasts and resulting brain injury. This research team has
established that recently blast-exposed Soldiers show differences from controls on tests of
central auditory function. This project will 1) develop a more accurate estimate of the
prevalence of central auditory dysfunction among Veterans exposed to blasts over the past
ten years, 2) identify the functional outcomes associated with abnormal performance on tests
of central processing, and 3) improve understanding of the ways in which blast-exposure
resembles and differs from both the normal aging process and non-blast-related TBI in terms
of performance on tests of central auditory processing.
The current conflicts in Afghanistan (Operation Enduring Freedom; OEF) and Iraq (Operation
Iraqi Freedom; OIF) have resulted in unprecedented rates of exposure to high-intensity
blasts and resulting brain injury. Dennis (2009) reports that during 2005-2007, 68% of U.S.
military personnel injured in the OEF/OIF conflicts had blast-related injuries and 28%-31%
of those evacuated to Walter Reed Army Medical Center (WRAMC), Washington, DC had brain
injuries. While the common focus of auditory evaluation is on damage to the peripheral
auditory system, the prevalence of brain injury among those exposed to high-intensity blasts
suggests that damage to the central auditory system is an equally important concern for the
blast-exposed Veteran. Discussions with clinical audiologists and OEF/OIF Veterans Service
Office personnel suggest that a common complaint voiced by blast-exposed Veterans is an
inability to understand speech in noisy environments, even when peripheral hearing is within
normal or near-normal limits (see attached letters of support). Such complaints are
consistent with damage to neural networks responsible for higher-order auditory processing.
This proposal is the second phase of a research project focused on examining the degree to
which central auditory processing (CAP) dysfunction is a result of blast exposure. Over the
initial period of funding, data collection at WRAMC and the VA RR&D National Center for
Rehabilitative Auditory Research (NCRAR) established that CAP dysfunction is present in
Warfighters exposed to high-intensity blasts while serving in combat. Recently blast-exposed
patients with and without diagnoses of mild traumatic brain injury (mTBI) tested at WRAMC
showed differences from controls tested at NCRAR on one or more behavioral and
neurophysiological tests used to evaluate central auditory function. This project will 1)
develop a more accurate estimate of the prevalence of central auditory dysfunction among
Veterans exposed to blasts over the past ten years, 2) identify the functional outcomes
associated with abnormal performance on tests of central processing, and 3) improve
understanding of the ways in which blast-exposure resembles and differs from both the normal
aging process and non-blast-related TBI in terms of performance on tests of central auditory
processing.
Key Question 1: To what extent is CAP dysfunction observable among OEF/OIF Veterans who have
been exposed to high intensity blasts? Based on preliminary data, the investigators
hypothesize that the rate of abnormal performance on behavioral and neurophysiological tests
of CAP dysfunction will be higher in a group of Veterans exposed to blasts than it will be
in a control group of similar ages and hearing thresholds who have not been exposed to
blasts.
Key Question 2: How well can behavioral and neurophysiological tests of CAP predict
functional auditory deficits measured behaviorally and through self report? It is
hypothesized that tests of CAP ability will predict performance in a testing situation
involving multiple talkers delivering competing messages. CAP tests will also correlate with
responses blast-exposed Veterans make on the Speech and Spatial Qualities of Hearing (SSQ)
questionnaire, designed to examine functional hearing ability in various acoustically
complex environments.
Key Question 3: To what extent do blast-exposed Veterans resemble older listeners and
participants with mild TBI who have not been exposed to blasts in their performance on CAP
tests and functional tests of hearing? It is hypothesized that comparisons of the
blast-exposed group with an older group with matched pure-tone sensitivity and an age- and
hearing-matched group with non-blast-related TBI will be consistent with premature aging in
the blast-exposed group but demonstrate substantive differences with the non-blast group.
Iraqi Freedom; OIF) have resulted in unprecedented rates of exposure to high-intensity
blasts and resulting brain injury. Dennis (2009) reports that during 2005-2007, 68% of U.S.
military personnel injured in the OEF/OIF conflicts had blast-related injuries and 28%-31%
of those evacuated to Walter Reed Army Medical Center (WRAMC), Washington, DC had brain
injuries. While the common focus of auditory evaluation is on damage to the peripheral
auditory system, the prevalence of brain injury among those exposed to high-intensity blasts
suggests that damage to the central auditory system is an equally important concern for the
blast-exposed Veteran. Discussions with clinical audiologists and OEF/OIF Veterans Service
Office personnel suggest that a common complaint voiced by blast-exposed Veterans is an
inability to understand speech in noisy environments, even when peripheral hearing is within
normal or near-normal limits (see attached letters of support). Such complaints are
consistent with damage to neural networks responsible for higher-order auditory processing.
This proposal is the second phase of a research project focused on examining the degree to
which central auditory processing (CAP) dysfunction is a result of blast exposure. Over the
initial period of funding, data collection at WRAMC and the VA RR&D National Center for
Rehabilitative Auditory Research (NCRAR) established that CAP dysfunction is present in
Warfighters exposed to high-intensity blasts while serving in combat. Recently blast-exposed
patients with and without diagnoses of mild traumatic brain injury (mTBI) tested at WRAMC
showed differences from controls tested at NCRAR on one or more behavioral and
neurophysiological tests used to evaluate central auditory function. This project will 1)
develop a more accurate estimate of the prevalence of central auditory dysfunction among
Veterans exposed to blasts over the past ten years, 2) identify the functional outcomes
associated with abnormal performance on tests of central processing, and 3) improve
understanding of the ways in which blast-exposure resembles and differs from both the normal
aging process and non-blast-related TBI in terms of performance on tests of central auditory
processing.
Key Question 1: To what extent is CAP dysfunction observable among OEF/OIF Veterans who have
been exposed to high intensity blasts? Based on preliminary data, the investigators
hypothesize that the rate of abnormal performance on behavioral and neurophysiological tests
of CAP dysfunction will be higher in a group of Veterans exposed to blasts than it will be
in a control group of similar ages and hearing thresholds who have not been exposed to
blasts.
Key Question 2: How well can behavioral and neurophysiological tests of CAP predict
functional auditory deficits measured behaviorally and through self report? It is
hypothesized that tests of CAP ability will predict performance in a testing situation
involving multiple talkers delivering competing messages. CAP tests will also correlate with
responses blast-exposed Veterans make on the Speech and Spatial Qualities of Hearing (SSQ)
questionnaire, designed to examine functional hearing ability in various acoustically
complex environments.
Key Question 3: To what extent do blast-exposed Veterans resemble older listeners and
participants with mild TBI who have not been exposed to blasts in their performance on CAP
tests and functional tests of hearing? It is hypothesized that comparisons of the
blast-exposed group with an older group with matched pure-tone sensitivity and an age- and
hearing-matched group with non-blast-related TBI will be consistent with premature aging in
the blast-exposed group but demonstrate substantive differences with the non-blast group.
Inclusion Criteria:
- Aged 18-90
- Pure-tone sensitivity of 40 dB HL or better at all audiometric frequencies below 8
kHz
- English as first language.
Group membership inclusion criteria:
Group 1: Blast exposed Veterans
- Report having been exposed to high-intensity blast during the ten years prior to
enrollment
- Cognitive and physical ability to take part in these auditory evaluations
Group 2. Non-blast TBI group
- Diagnosed with mild-to-moderate TBI
Group 3. Age matched control group -18-59 years.
Group 4. Older control group
- 60-90 years.
- Older group will be aged 60 and older
Audiometric status of these groups will be required to meet the same exclusion criteria as
that of the other two groups described above
Exclusion Criteria:
- Evidence of conductive or retrocochlear dysfunction
- Hearing loss exceeding pure-tone averages for frequencies of .5, 1, 2, and 4 kHz of
35 dB HL
--Hearing loss of greater than 40 dB HL at any one of these frequencies in either ear
- Asymmetrical hearing thresholds exceeding 10 dB at any audiometric frequency below 4
kHz
- Abnormal cognitive function as indicated by scores of 23 or below on the Mini Mental
State Exam
- Indications of clinical depression as evidenced by a score of 17 or greater on the
Beck Depression Inventory
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