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）的冲突导致了前所未有的高强度爆炸暴露率和脑损伤。Dennis（2009）报告称，2005-2007年，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%被疏散到华盛顿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重点是对外周听觉系统的损伤，但暴露于高强度爆炸的人群中脑损伤的患病率表明，对中枢听觉系统的损伤对暴露于爆炸的退伍军人来说同样重要。与临床听力学家和OEF/OIF退伍军人服务办公室人员的讨论表明，爆炸暴露退伍军人的一个常见抱怨是无法在嘈杂的环境中理解语言，即使周边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相一致。该提案是一个研究项目的第二阶段，该项目的重点是检查爆炸暴露导致的中枢听觉处理（CAP）功能障碍的程度。在资助的最初阶段，WRAMC和VA RR&D国家反射性听觉研究中心（NCRAR）的数据收集确定了CAP功能障碍存在于在战斗中服役时暴露于高强度爆炸的战士中。最近，在WRAMC测试的有和没有诊断为轻度创伤性脑损伤的爆炸暴露患者在NCRAR测试的一个或多个用于评估中枢听觉功能的行为和神经生理学测试中显示出与对照组的差异。该项目将1）准确估计过去十年暴露于爆炸的退伍军人中中枢听觉功能障碍的患病率，2）确定与中枢处理测试中异常表现相关的功能结果，和3）提高对爆炸暴露与正常老化过程和非爆炸暴露相似和不同的方式的理解，在中枢听觉处理测试方面，与TBI相关。关键问题1：在暴露于高强度爆炸的OEF/OIF退伍军人中，CAP功能障碍的程度如何？基于初步数据，我们假设CAP功能障碍的行为和神经生理学测试的异常表现率在暴露于爆炸的退伍军人组中高于未暴露于爆炸的年龄和听力阈值相似的对照组。关键问题2：CAP的行为和神经生理学测试能在多大程度上预测通过行为和自我报告测量的功能性听觉缺陷？据推测，CAP能力的测试将预测性能在测试的情况下，涉及多个谈话者提供竞争的消息。CAP测试还将与暴露于爆炸的退伍军人在听力和听力障碍的语音和空间质量问卷调查中的反应相关，该问卷旨在检查各种声学复杂环境中的功能性听力能力。关键问题3：爆炸暴露的退伍军人在多大程度上类似于老年听众和轻度TBI的参与者，他们在CAP测试和听力功能测试中的表现没有暴露于爆炸？假设爆炸暴露组与具有匹配纯音灵敏度的老年组以及具有非爆炸相关轻度创伤性脑损伤的年龄和听力匹配组的比较与爆炸暴露组的过早老化一致，但与非爆炸组有实质性差异。

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.