Patterns of Tinnitus and Hearing Loss Secondary to Blast Injury
Abstract
Blast and subsequent brain concussion, or traumatic brain injury (TBI), has been the signature injury of the ongoing War on Terrorism, responsible for 75% of US combat casualties in Operation Iraqi Freedom/Operation Enduring Freedom and is associated with tinnitus in at least 30% of exposed Service members. Tinnitus, perceived as ringing in the ears, is defined as a noise perceived in the head or ears in the absence of outside sound and is described by Service members as a tone, roaring, hissing, or a combination of these. Tinnitus interferes with combat by leading to slower reaction times, decreased situational awareness, and poorer accuracy while dual tasking, even when hearing is normal. Moreover, this ringing can be permanent and devastating and has been linked to loss of sleep, stress, depression, anxiety, and possible suicide. Tinnitus is the #1 disability for the Department of Veteran s Affairs (VA), costing over one billion dollars each year in payments. Primary blast injury most commonly occurs as a result of an improvised explosive device (IED) and is due to an initial shock wave going through the brain and body, tearing microscopic blood vessels and nerve axons throughout the brain, and impacting organs, especially those containing air. The ear is particularly vulnerable, since the eardrum is thinner than paper, whereas the skull bones protect the brain. This tearing of tissues leads to the body s attempt at repair. The regrowth of nerves in the brain and ear can lead to incorrect reconnections. These misconnections may be the ultimate cause of the phantom sound perceived as tinnitus. The specific brain centers responsible for the ringing in the ears remain unknown, and treatments, including medications, cognitive therapy, and other experimental modalities, are so far universally non-curative. Although very often associated with either hearing loss or post-traumatic stress syndrome (PTSD) or both, our recent study using prospective Marine Resiliency Study data shows tinnitus to be a separate and distinct problem, related particularly to blast TBI. There is not yet an objective test for tinnitus; its diagnosis remains based on the patient s statement of "ringing in the ears." While there are questionnaires that ask about its severity and how it affects the Service member s life, as well as hearing testing and questions about whether a tone given to the member matches what he/she is hearing in his/her own head, it remains a subjective symptom. This 3-year study proposes to recall Marine and Navy participants of the Marine Resiliency Study (MRS and MRS-II) who were deployed and subject to blast-induced TBI, who had agreed to be recontacted for future studies, for permission to access past and current audiograms given by the DoD and VA and to participate in phone interviews and complete online questionnaires. Among consenting participants, 200 individuals divided among four groups will be invited to San Diego for onsite evaluations. The study groups will be: Group 1: Blast-exposed during deployment with post-concussive symptoms (PCS), new onset and persistent tinnitus; Group 2: Blast-exposed PCS, no tinnitus; Group 3: No blast-exposure during deployment, but new tinnitus; Group 4: No blast exposure, no tinnitus. The onsite evaluations will consist of a magnetoencephalography (MEG) scan and hearing tests, and well as standard MRS interviews, neurocognitive tests and questionnaires, including tinnitus questionnaires. The MEG is an imaging study of the brain, very much like an MRI, but has distinct advantages. First, it measures the nerve tracts of the brain, as well as their firing sequence in millisecond time, and it has the advantage of being quiet, so inside scanner tests can be done to assess aspects of the tinnitus while the brain is being imaged. By comparing Service members with tinnitus and those without, we hope better characterize the symptoms of blast-related tinnitus when compared t
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Apr 04, 2016
- Source ID
- W81XWH1610015
Entities
People
- Dewleen G Baker
Organizations
- United States Army
- Veterans Medical Research Foundation of San Diego