Central Auditory Processing Disorders Associated With Blast Exposure

The incidence and nature of central auditory dysfunction in combat soldiers who are exposed to high-explosive blasts have not been determined. Using a battery of behavioral and neurophysiological auditory tests, we propose to evaluate central auditory function in soldiers who recently have been exposed to explosive blasts while deployed in Iraq or Afghanistan. In collaboration with the Army Audiology & Speech Center at Walter Reed Army Medical Center (WRAMC), the research will be coordinated at the National Center for Rehabilitative Auditory Research (NCRAR) at the Portland VA Medical Center, and data collection will take place both at the NCRAR and at WRAMC. The study objectives are to determine if specific central auditory processing disorders are often associated with exposure to high-explosive blasts, and if these disorders spontaneously recover or remain over time. One hundred patients who have suffered a blast exposure, but have either no brain damage or mild traumatic brain injury (TBI), will be recruited at WRAMC to participate in this research study. A battery of central auditory processing tests will be administered to participants as soon as possible after their arrival at WRAMC. Patients who demonstrate aspects of central auditory processing disorder will be invited to participate in further testing nine to twelve months later. Those subjects will be brought to the NCRAR at the Portland VA Medical Center or will return to WRAMC for two days of auditory testing, where they will undergo the same battery of tests administered initially. Control subjects who do not have a history of blast exposure and who are matched in age, gender, and audiometric configuration with the experimental subjects will also be tested at the NCRAR site. Data extracted by interview and from medical records, including details of the blast exposure, scores on overall tests of brain function administered by the WRAMC TBI team, presence or absence of post traumatic stress disorder, as well as self-report questionnaires regarding quality of life, presence of tinnitus and/or balance problems, will be used in the interpretation of results.

Inclusion criteria

Experimental group:

• Active duty soldier at Walter Reed Army Medical Center, Washington DC
• a notation in medical record of exposure to blast
• a Glasgow Coma Scale of 13-15, indicating mild or no traumatic brain injury (TBI
• cognitive and physical ability to take part in these auditory evaluations.
• Age 18 years or older
• native speaker of English (since test materials are presented in English)

Control group:

• able to commute to Portland (Oregon)VA Med Ctr.
• no exposure to blast
• cognitive and physical ability to take part in these auditory evaluations.
• age 18 years or older
• native speaker of English

Exclusion criteria

• hearing loss greater than 50 dB HL three-frequency pure tone average bilaterally