Audiological issues and hearing loss among Veterans with mild traumatic brain injury.

INTRODUCTION A dramatic increase in the use of explosive devices in Operation Enduring Freedom and Operation Iraqi Freedom is responsible for a significant shift in the types of injuries experienced among soldiers. Between 2003 and 2005, 68 percent of combat injuries were blast related [1]. Head and neck injuries have increased in proportion relative to previous conflicts, and 78 percent of these injuries were consequential to explosions caused by devices such as improvised explosive devices (IEDs), land mines, mortars, bombs, or grenades [2]. Mild traumatic brain injury (TBI) can result from these types of blast-related injuries [3], and their prevalence in modern combat has increased dramatically. An estimated 20 percent, or 300,000 of the 1.6 million soldiers deployed to Iraq and Afghanistan, have mild TBI [4]. Individuals with mild TBI can present clinically with cognitive, physical, or behavioral problems [5]. Individuals also often present with complaints of anxiety, depression, apathy, and mood swings [5]. In conjunction with the increase in mild TBI, blast-related injuries also result in auditory and vestibular issues. Because the human ear is designed to be sensitive to changes in pressure, it is the most susceptible organ to damage from the pressure created by a blast wave [6]. Previous studies have found that 62 percent of blast-related TBI patients admitted after the onset of Operation Iraqi Freedom complained of hearing loss and 38 percent reported tinnitus [7]. Hearing problems were also found to be present in TBI patients who had not experienced a blast, with 44 percent complaining of hearing loss and 18 percent reporting tinnitus [7]. A study of 12,521 Veterans with TBI found that 34.6 percent of the cohort self-reported auditory impairment and an additional 9.9 percent reported both auditory and visual impairment. Of these, Veterans who experienced blast-related injuries were found to have the highest rate of self-reporting both auditory and visual impairment [8]. Ear and hearing injuries may significantly affect the daily lives of soldiers, both in and out of combat. Permanent hearing loss has been reported to contribute to psychosocial and physical health problems, such as depression, decreased social and emotional function, personal relationships, and decreased cognitive function [9-11]. While studies have examined the link between TBI and hearing loss, the mild TBI population specifically has not been widely studied. A previous study of 36 American adults with a history of mild TBI found that when compared with the normative values, these individuals performed significantly worse on the Dichotic Word Listening Task [12]. Additionally, more than one-third of individuals with a mild TBI were found to fail at least one condition of a dichotic word recall task [13]. However, these studies do not include information about clinical testing and results. METHODS A retrospective chart review of 250 Veterans with mild TBI was performed at a single, midwestern Department of Veterans Affairs (VA) medical center. Individuals with a confirmed diagnosis of mild TBI between June 15, 2007, and July 15, 2009, were identified by local physicians based on TBI reports to the Veterans Health Administration (VHA) Support Service Center and considered for inclusion. Patients with moderate/severe TBI, a prior history of ear disease or hearing loss, or non-VA care for hearing loss were excluded. Veterans with mild TBI and hearing problems were identified using the VA's comprehensive second-level TBI evaluation. Veterans are referred for a comprehensive second-level evaluation after receiving an initial positive mild TBI screening. The initial screening is administered by a healthcare provider and consists of four questions regarding exposure to a mild TBI event(s), immediate symptoms, and current symptoms. Further information regarding the VHA's mild TBI screening process is described by Donnelly et al. …