Auditory and vestibular dysfunction associated with blast-related traumatic brain injury

Abstract

Abstract-The dramatic escalation of blast exposure in military deployments has created an unprecedented amount of traumatic brain injury (TBI) and associated auditory impairment. Auditory dysfunction has become the most prevalent individual service-connected disability, with compensation totaling more than 1 billion dollars annually. Impairment due to blast can include peripheral hearing loss, central auditory processing deficits, vestibular impairment, and tinnitus. These deficits are particularly challenging in the TBI population, as symptoms can be mistaken for posttraumatic stress disorder, mentalhealth issues, and cognitive deficits. In addition, comorbid factors such as attention, cognition, neuronal loss, noise toxicity, etc., can confound assessment, causing misdiagnosis. Furthermore, some auditory impairments, such as sensorineural hearing loss, will continue to progress with age, unlike many other injuries. In the TBI population, significant clinical challenges are the accurate differentiation of auditory and vestibular impairments from multiple, many times overlapping, symptoms and the development of multidisciplinary rehabilitation strategies to improve treatment outcomes and quality of life for these patients.

Multisensory impairment reported by veterans with and without mild traumatic brain injury history

“…This was based on a factor analysis performed on the same data set in which these three symptoms loaded as a separate factor [50]. For ease of phrasing, "vestibular" was used as an umbrella term to encompass the three aforementioned symptoms, but we acknowledge that these symptoms may not physiologically derive from the inner ear (vestibule) and could be either peripheral or central in origin [29]. An a priori decision was made to compute vestibular scores only for patients who answered at least two of the three vestibularrelated questions.…”

“…For example, many OIF/OEF veterans with mTBI also have comorbid physical and psychiatric conditions [46]. These conditions themselves, or the medications prescribed to treat them [29], may negatively affect the visual, auditory, and vestibular systems.…”

“…In one study, damage to the ears was the most common single injury type, accounting for approximately 1 in 4 injuries [24]. Hearing impairment associated with combat injury can result in peripheral or central dysfunction [25][26][27][28][29].…”

Preliminary studies on differential expression of auditory functional genes in the brain after repeated blast exposures

“…Battlefield blast exposure is reported to cause auditory impairment in a large population of military personnel deployed to Iraq and Afghanistan [1][2]. Auditory/vestibular injuries from blast traumatic brain injury (TBI) can cause increased incidence of tinnitus and hearing loss, which worsens over time if not treated [1][2][3][4].…”

“…Auditory/vestibular injuries from blast traumatic brain injury (TBI) can cause increased incidence of tinnitus and hearing loss, which worsens over time if not treated [1][2][3][4]. Shock waves generated from explosive blasts are reported to be destructive to both gas-and fluid-filled structures of the body, including the lungs, intestines, brain, eyes, nose, and middle ear [5][6][7][8][9].…”