Traumatic brain injuries, including concussion, may lead to hearing and vision problems. Sometimes, these hearing and vision injuries are either not immediately apparent or require additional testing to be diagnosed, according to experts from the Defense Health Agency. These injuries may show up together.
If you think you have a concussion, known as mild TBI, and may be experiencing hearing or vision changes, here’s what to know.
Those diagnosed with mild TBI should have a complete set of hearing tests to see if they’ve been affected.
“Oftentimes, TBI patients are informed they do not have hearing loss despite their perceived listening difficulties, which is why additional measures to establish auditory processing abilities are required,” said National Intrepid Center of Excellence researcher Melissa Kokx-Ryan, who holds a doctorate in audiology and in hearing, speech, and language sciences. NICoE is the center of DHA’s TBI clinical care, research, and education and is located at Walter Reed National Military Medical Center in Bethesda, Maryland.
“A standard audiometric evaluation for a TBI patient should start with a traditional hearing test but also include measures of auditory processing abilities in complex environments,” she explained. Complex environments can be situations with multiple talkers or a lot of background noise such as a restaurant or meeting. “Typically, these patients do well in quiet listening environments with one talker who is looking at them but add in background noise and someone not facing them while talking and they start to struggle.”
According to DHA’s Hearing Center of Excellence, auditory processing disorder symptoms may include struggling to understand speech in noisy settings; problems recognizing spoken words or keeping up with telephone conversations; finding it hard to tell the difference between words that sound alike; and feeling uncertain about where the words you hear are coming from.
Tinnitus, a buzzing, hissing, humming, or high-pitched tonal and continual ringing sound heard in the head or ears, can also be associated with hearing loss and TBI.
How Hearing Injuries are Treated
Audiologists use communication strategies and hearing aids to treat hearing loss and tinnitus. Depending on the patient’s individual needs, the clinician may “supplement tinnitus treatment with additional ambient noise smartphone or machines, and refer to the Progressive Tinnitus Management course when appropriate,” Kokx-Ryan said. The course is a stepped-care approach at military bases run by an audiologist and a behavioral health provider.
NICoE works extensively with DHA’s Traumatic Brain Injury Center of Excellence through the NICoE Brain Fitness Center in Bethesda on research and “auditory training to supplement when appropriate,” Kokx-Ryan said. The Brain Fitness Center is an adjunct to traditional cognitive therapies offered by speech and occupational therapy and receives referrals from the entire multi-disciplinary team at NICoE and Walter Reed for multiple symptoms and patient populations beyond auditory concerns.
“NICoE was among the first military audiology clinics pioneering the use of low-gain hearing aids to treat auditory processing deficits despite normal hearing sensitivity, which is now becoming more mainstream,” Kokx-Ryan explained. These devices enhance speech while making loud sounds quieter and reducing background noise.
Her current TBI research focuses on providing evidence to support the use of low-gain hearing aids for treating auditory processing disorders. Kokx-Ryan works primarily with the TBI population; however, her research applies to “other service members with perceived hearing difficulties who have a history of significant noise or blast exposure in the absence of a formal TBI diagnosis,” she said.
She’s also involved with several protocols looking into “multisystem integration,” such as how vision, vestibular, and hearing affect one another. The vestibular system relates to movement, gravity, or your balance system. The HCE trains clinicians how to treat dizziness and imbalance in patients with concussion.
The Department of Defense and the Department of Veterans Affairs issued new practice guidelines for evaluating and managing dizziness associated with TBI in October 2023.
Military sensory research—and the development of clinical best practices—are fueled by vision and hearing injury registries that collect bidirectional data on service members and veterans from their point of injury to recovery or rehabilitation.
HCE hosts the Joint Hearing Loss and Auditory Injury Registry. and Vision Center of Excellence hosts the Defense and Veterans Eye Injury Vision Registry.
Vision Injury Common with TBI But May Not Be Readily Apparent
Visual dysfunction is common in even mild TBI patients, but not everyone who sustains a TBI will have vision dysfunction. “Many visual symptoms after a TBI resolve on their own without treatment,” said Natasha Merezhinskaya, a health science specialist at the VA and VCE, who holds a doctorate in biophysics.
According to Merezhinskaya, a number of studies have found that visual dysfunctions were reported in as many as 43% of patients diagnosed with mild traumatic brain injury.
“Often these injuries are not visible if one just looks at the eye,” said Chrystyna Rakoczy, a doctor of optometry with the VA and VCE. “Instead, TBI can affect the ability of the eyes to work together, follow objects, or focus well. As a result, a person can experience blurry vision, difficulties reading, and increased sensitivity to light. Sometimes the ability of the eyes to see objects on the side of the vision (vision fields) can be affected as well,” she explained.
Merezhinskaya and Rakoczy focus on characterizing eye and vision injuries in service members and veterans after TBI and the development of the recommendations for eye doctors to diagnose and treat these injuries.
Some people can experience TBI-related symptoms for a long period of time.
“These individuals may not realize that their visual system has been affected as symptoms such as headaches, poor reaction time, poor concentration, and loss of balance are typically not associated with eyes and vision. These conditions require accurate evaluation of visual function and performance to tease out dysfunctions of our sensory systems,” Merezhinskaya said.
The way we see and interpret visual information involves many different areas of our brain.
“Seventy percent of all sensory data enters through the eyes, which serve like a camera. The images are then evaluated for a form, color, depth perception, motion, and the sense of body position, and compared with known images using cognitive memory,” Merezhinskaya said.
Multiple areas of the brain participate in image processing.
“For example, the vestibular/balance system keeps visual images generated by both eyes superimposed and locked while our heads and bodies are in motion so we don’t feel dizzy,” Rakoczy said. “Different systems in the brain need to process visual information appropriately and efficiently for us to function properly and to be safe. If the brain cannot interpret data coming through the eyes because it is damaged, our bodies cannot react appropriately in a timely manner.”
The Brain’s Response
Our brain and bodies work together, and if injured, treatment needs to address all aspects of those injuries.
“Vision, vestibular, hearing, and cognitive dysfunction often occur simultaneously as the result of a brain injury. Assessment and rehabilitation of vision dysfunction in those cases cannot occur in isolation. State-of-the-art treatment of sensory deficits associated with TBI for best and quickest return to duty depends on coordinated multisensory interdisciplinary rehabilitation,” Rakoczy said.
If you suspect you have hearing or vision injuries as the result of a concussion, see your provider. Early diagnosis and treatment may lessen the impact of those injuries.