Concussion, also called mild traumatic brain injury (mTBI), is a diffuse non-penetrating head injury caused by a sudden external force, such as during contact sports or a blast in combat.1 When a sudden force moves the brain rapidly inside the close confines of the skull, it creates chemical changes, inflammation, stretching and shearing of axons, improper cell function, and cell death. This injury is often not visible on medical imaging, but it disrupts micro-second temporal computations critical for signal decoding and speech processing. Common symptoms of concussion/mTBI include cognitive impairment, attention deficits, difficulty concentrating, headaches, visual problems, anxiety, depression, irritability, and sleep disturbances. Loss of consciousness is not required for the diagnosis of concussion. However, repeated concussive or sub-concussive events, especially with loss of consciousness, can result in greater severity of the symptoms.
Generally, the symptoms resolve within three months. Some individuals, however, may continue to experience symptoms for a year or more.2 About 50 percent of individuals with a single mTBI exposure demonstrate long-term cognitive impairment and other symptoms that can interfere with returning to work or school.3, 4 Concussions, especially from blast injuries, can also damage the auditory system. The human ear is designed to be sensitive to changes in pressure; therefore, it is the organ most susceptible to pressure changes created by a blast wave. Auditory symptoms reported with mTBI or concussion include difficulty understanding speech in quiet and in noise, difficulty attending to sounds or ignoring distracting sounds, tinnitus, hyperacusis, and balance problems.1
Events that cause mTBI may result in post-traumatic stress disorder (PTSD), a psychiatric disorder that can occur in people who have difficulty recovering from experiencing/witnessing a traumatic physical or emotional event. The persistent mental and emotional distress can last over a month.5 Individuals who experienced a traumatic event that did not trigger PTSD are at an increased risk for PTSD in the future.6 Many military veterans experience multiple episodes of mTBI, which set them at a higher risk for PTSD.
Between 2000 and 2018, roughly 315,897 cases of mTBI, many of which caused by blast-related injury, were confirmed across all branches of the U.S. military.7 About 20 percent of U.S. military veterans are affected by PTSD.5 Veterans with combined mTBI and PTSD show exacerbated symptoms of decreased attention, working memory/memory deficits, executive function deficits, and hypervigilance.8 It is important to raise awareness of common behaviors and test discrepancies observed in veterans with mTBI and/or PTSD so hearing health professionals can better diagnose and counsel these patients.
Many veterans receive audiologic care outside of the Veteran's Administration Medical Center (VAMC). Our university clinic is under a contractual agreement with different veteran service groups to provide compensation and pension audiologic assessments. A subset of the veterans assessed in our clinic exhibited normal or mild pure-tone thresholds while self-reporting a much more significant hearing loss. These findings were consistent with a recent study that found that among 87 percent of veteran participants with mTBI who reported hearing loss, nearly two-thirds fell within the “normal hearing” range.9 Comorbid hyperacusis with mTBI and PTSD was common in our clinic population, which created practical problems during assessments. In some cases, when assessing acoustic reflex thresholds (ARTs), results were either inaccurate, or the test could not be completed when the louder reflex tones elicited significant physical discomfort and/or anxiety resulting in muscle tension.
Clinicians need to be vigilant in recognizing these behaviors because veterans often do not disclose hyperacusis or report any discomfort. Conversely, some veterans appeared to tolerate the ART assessment, but demonstrated sound sensitivity during pure tone evaluation to levels below those used to assess ARTs. Other issues confounding diagnosis were incomplete or unavailable medical history at the time of the appointment and veterans not always reporting combat-related injuries, mTBI, and/or PTSD.
These three cases exemplify the type of case histories, behaviors, and audiometric test results observed in the veteran population in our clinic. These three veteran patients men between 22 and 55 years old. Audiometric evaluations were performed according to the test procedures required by VAMC and using insert earphones in a sound booth. The veterans’ middle ear status was normal as determined via tympanometry and ARTs. Word recognition scores (WRS) were determined at 40 dB SL re: speech recognition threshold (SRT) in quiet. The Stenger test was performed as needed according to the VAMC protocol.
Veteran A reported a history of blast exposure, multiple concussions (>6), with reported loss of consciousness on several occasions. He reported having hearing difficulty, needing closed captioning for TV, and requesting frequent repetitions from communication partners. Figure 1A shows veteran A's audiogram. His WRS were excellent at 92 percent for the right ear and 100 percent for the left. These results were not consistent with Veteran A's subjective hearing loss. He was previously diagnosed with PTSD.
Veteran B reported a history of blast exposure and concussion. He reported having constant bilateral tinnitus, as well as difficulty communicating in noise and understanding his wife. He tolerated the ART assessment, but had anxiety and sensory overload during the hearing evaluation, which increased the test administration time. He needed the lights to be dimmed in the sound booth and test suite during the test. He also needed a water break to recuperate. Figure 1B shows his audiogram. The WRS were excellent at 92 percent for the right ear and 96 percent for the left, which were not consistent with Veteran B's subjective hearing loss. He denied having PTSD.
Veteran C reported a history of blast injury and head injury from a service-related fall. He reported requiring multiple repetitions of verbal information and missing information because of an inability to notice that he was being spoken to. He demonstrated high anxiety levels during the hearing evaluation. He denied having hyperacusis repeatedly, but became increasingly anxious as the stimulus levels for the ART assessment increased to >90 dB HL. Contralateral acoustic reflex thresholds for the higher frequencies could not be determined because the test had to be discontinued due to patient discomfort. The WRS were good at 84 percent for the right ear and 80 percent for the left. Figure 1C shows Veteran C's audiogram. The WRS were lower than expected based on age and pure tone thresholds. The veteran believed that he had PTSD, but had yet to be diagnosed.
COUNSELING VETERANS WITH MTBI/PTSD
Simply validating perceptual hearing problems can be significant for some veterans. Emphasizing counseling during and after the audiometric evaluation can provide a gateway to a veteran's whole-person health care and encourage the patient to seek additional services for mTBI and/or PTSD. Unless clinicians ask the appropriate questions, it is easy to overlook mTBI/PTSD as an underlying cause of a veteran's problems. Useful counseling strategies are shown in Table 1.
Audiologists need to be aware that the hearing complaints of veterans with mTBI or PTSD may actually be non-auditory behavioral, emotional, and cognitive/attention issues that can confound diagnosis and raise suspicion of non-compliant behaviors or non-organic hearing loss. Comprehensive assessment of the peripheral and central auditory and vestibular systems, including speech-in-noise testing, and tinnitus assessment may be necessary. Guiding veterans’ understanding that hearing goes beyond the peripheral auditory system is important to validating any perceived hearing problem. This will also help them be more responsive to counseling and other intervention services.
Thoughts on something you read here? Write to us at HJ@wolterskluwer.com.
1. Kraus N, Krizman J An auditory perspective on concussion. Audiology Today
2. Daneshvar DH, Riley DO, Nowinski CJ, McKee AC, Stern RA, Cantu RC Long-term consequences: Effects on normal development profile after concussion. Physical medicine and rehabilitation clinics of North America
. 2011;22(4),683-700. pmid:22050943.
3. Myers P, Wilmington DJ, Gallun F, Henry JA, Fausti SA Hearing impairment and traumatic brain injury among soldiers: Special considerations for the audiologist. Seminars in Hearing
. 2009;30(1),5-27. doi: 10.1055/s-0028-1111103.
4. McInnes K, Friese CL, MacKenzie DE, Westwood DA, Boe SG Mild Traumatic Brain Injury (mTBI) and chronic cognitive impairment: A scoping review. PLoS One
. 2017;12(4),e0174847. doi: 10.1371/journal.pone.0174847.
6. Haveman-Gould B, Newman C Post-traumatic stress disorder in veterans: Treatments and risk factors for nonadherence. JAAPA
. 2018;31(11),21-24. doi:10.1097/01.JAA.0000546474.26324.05.
8. Vasterling J, Verfaellie M, Sullivan D Mild traumatic brain injury and posttraumatic stress disorder in returning veterans: Perspectives from cognitive neuroscience. Clinical Psychology Review
. 2009;29:674-684. doi10.1016/j.cpr.2009.08.004.
9. Oleksiak M, Smith BM, Andre JR, Caughlan CM, Steiner M Audiological issues and hearing loss among veterans with mild traumatic brain injury. JRRD
. 2012;49(7),995-1004. doi:http://dx.doi.org/10.1682/JRRD.2011.01.0001