Central Auditory Processing Deficits Associated with Blast Exposure

描述(由申请人提供)： 目前在阿富汗(持久自由行动；OEF)和伊拉克(伊拉克自由行动；OIF)的冲突造成了前所未有的高强度爆炸和由此造成的脑损伤。Dennis(2009)报告说，2005-2007年间，在OEF/OIF冲突中受伤的美国军事人员中，68%的人与爆炸有关，28%-31%的被疏散到华盛顿特区沃尔特里德陆军医疗中心(WRAMC)的人有脑损伤。虽然听觉评估的共同焦点是周围听觉系统的损害，但暴露在高强度冲击波中的人中脑损伤的发生率表明，中枢听觉系统的损害对于接触冲击波的退伍军人来说也是同样重要的担忧。与临床听力专家和OEF/OIF退伍军人服务办公室人员的讨论表明，暴露在爆炸中的退伍军人的常见抱怨是在嘈杂的环境中无法理解言语，即使外围听力在正常或接近正常的范围内(见所附的支持信)。这种抱怨与负责高阶听觉处理的神经网络受损是一致的。这项建议是一项研究项目的第二阶段，该项目的重点是检查中枢听觉处理(CAP)功能障碍的程度是冲击波暴露的结果。在资助的最初阶段，WRAMC和VA RR&D国家康复听觉研究中心(NCRAR)的数据收集证实，在战斗中服役时暴露在高强度爆炸中的战士存在CAP功能障碍。最近，在WRAMC测试的有或没有被诊断为轻度创伤性脑损伤的冲击波暴露患者在用于评估中枢听觉功能的一项或多项行为和神经生理测试上显示出与在NCRAR测试的对照组的差异。该项目将1)对过去十年中暴露在爆炸中的退伍军人中中枢听觉功能障碍的患病率进行准确的估计，2)确定与中央处理测试中异常表现相关的功能结果，以及3)就中央听觉处理测试中的表现而言，提高对冲击波暴露与正常衰老过程和非冲击波相关脑损伤的相似和不同之处的理解。关键问题1：暴露在高强度爆炸中的OEF/OIF退伍军人在多大程度上可以观察到CAP功能障碍？根据初步数据，我们假设，在暴露于爆炸中的一组退伍军人中，CAP功能障碍的行为和神经生理测试的异常率将高于年龄和听力阈值相似的未暴露于爆炸中的对照组。关键问题2：CAP的行为和神经生理学测试能多好地预测通过行为测量和自我报告测量的功能性听觉缺陷？假设CAP能力的测试将预测在涉及多个说话者传递竞争消息的测试情况下的性能。CAP测试还将与暴露在爆炸中的退伍军人对言语和空间听力质量以及残疾调查问卷的反应相关联，该问卷旨在检查各种声学复杂环境中的功能性听力。关键问题3：爆炸暴露的退伍军人在多大程度上类似于患有轻度脑外伤的老年听众和参与者，他们在CAP测试和听力功能测试中的表现没有暴露于爆炸中？假设冲击波暴露组与纯音敏感度匹配的老年组以及年龄和听力匹配的非冲击波相关轻度创伤性脑损伤组的比较将与冲击波暴露组的过早衰老一致，但显示与非冲击波组的实质性差异。

DESCRIPTION (provided by applicant): 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 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 an 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, we 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 and Hearing Handicap Inventory questionnaires, 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 mild traumatic brain injury will be consistent with premature aging in the blast-exposed group but demonstrate substantive differences with the non-blast group.