Have you been diagnosed with a traumatic brain injury (TBI) or concussion? Remember your ears. Airbag injuries or blasts, for example, can affect them and trigger ringing in the ears, dizziness and hearing loss.

Anyone can have a TBI, but these events are more likely to be serious among older people. In the United States, people 75 years and older have the highest numbers and rates of TBI-related hospitalizations.

The first goal for doctors in the aftermath of a TBI is to stabilize the patient. It may take some time before “the patient reports signs and symptoms of audiological disorders or family members start noticing the signs,” notes Shahrzad Cohen, an audiologist based in Sherman Oaks, Calif., in a webinar for the Hearing Loss Association of America.

Sometimes problems are identified long afterward. If you have a TBI in your history, even a mild one, be sure to tell your doctor or hearing provider. Hearing loss and other auditory issues may have been missed or misdiagnosed.  

What is a traumatic brain injury (TBI)?

The medical definition of a traumatic brain injury is a head trauma that temporarily impairs the normal function of the brain. Falls cause nearly half of all TBIs, followed by car crashes and assaults. Any bump, blow, or jolt that makes the head and brain move rapidly back and forth can make the brain bounce or twist within the skull, triggering chemical changes. It may also damage cells, as you can see in this illustration from the Centers for Disease Control and Prevention.

Note that the blow doesn’t have to be directly to your head; for instance, if you are in a car accident and lurch forward violently, you could have a TBI even if your head doesn’t hit anything. Also, your brain may be injured even if you did not lose consciousness.

Doctors may use the word “concussion” rather than brain injury, especially when talking to parents, because it is less alarming. But a concussion is still a TBI. There is some evidence hospitals are undertreating TBIs considered mild. In a study of 395 patients age 14 and older who came to an urban hospital with a mild TBI, among those who met the usual criteria to be sent home without a follow-up, 27 percent actually turned out to have lasting cognitive problems, researchers said, and needed therapy.

Acoustic trauma

When the head injury predominantly affects the ears (such as a blow directly to the ear, or a blast of noise at close range), it is known as an acoustic trauma. Veterans are at particularly high risk for this kind of injury, resulting in high rates of tinnitus and hearing loss in the veteran community.

What auditory problems can be triggered by a TBI?

Auditory (hearing) problems may include:

• tinnitus (ringing in the ears)
• hearing loss, especially asymmetrical hearing loss or "double hearing"
• noise sensitivity or loudness intolerance
• decreased sound tolerance for specific sounds
• aural fullness (ears feel like they can't pop)
• auditory processing problems (you pass a hearing test but struggle to understand speech)

Vestibular (balance) problems may include:

• dizziness
• vertigo attacks
• balance problems
• BPPV, or benign paroxysmal positional vertigo (the sensation of spinning)
• motion sickness
• general unsteadiness

Tinnitus after a concussion or brain injury

More than half of TBI patients develop tinnitus, also known as ringing in the ears, and that number is higher if they experienced a blast. The phantom sounds—which range from hissing to buzzing—“are the first and most reported issue with traumatic brain injury," Cohen said. Tinnitus may have a big emotional impact. "It is a major issue for our patients," she added.

Among retired military service members, tinnitus is the #1 service-connected reason veterans file for compensation disability.

Tinnitus can be a direct consequence of the injury or a side effect of medications commonly used to treat symptoms linked to a TBI, including the SSRI anti-depressants (Prozac and others), ordinary over-the-counter pain medications (aspirin and others) and anti-anxiety benzodiazepines (Xanax, Klonopin and more).

Most people with tinnitus also have hearing loss, even if they don’t realize it. State-of-the-art hearing aids can be programmed to mask the phantom sounds, and are especially helpful along with cognitive-behavioral therapy and/or tinnitus sound therapy.

Lingering inflammation

In mild cases, standard neuroimaging is unlikely to find structural brain damage. However, it may miss subtle changes that are common with mild TBIs, Cohen reports. When the brain shifts and rotates inside the bony skull, long connecting nerve fibers may be torn, a problem technically called diffuse axonal injury. Those tears are often microscopic and may not be evident on computed tomography (CT scan) or magnetic resonance imaging (MRI) scans. Yet they may lead to ongoing inflammation.

If you have a head injury in your history, even a mild one, be sure to tell your doctor or hearing provider. Hearing loss and other auditory issues may have been missed or misdiagnosed.  

Backing up this idea, blood tests revealed unusual signs of inflammation in veterans with a history of mild TBIs, even years later, one study found.

In other evidence of lingering effects, TBIs increase your chance of insomnia, sleep apnea, and other sleep problems as much as 14 years later, according to a study of nearly 200,000 veterans. The risk of a sleep disorder was greater if your TBI was mild. That might be because people in this group are more likely to have had repeated injuries that led to diffuse inflammation rather than a single severe TBI, the researchers suggested.

Hearing loss is a common outcome from a TBI

A 2018 review of existing science concluded that even among TBI patients who didn’t break any bones in their head, 58 percent had some related hearing loss, though sometimes only temporarily. In a study of more than 1.6 million people in Taiwan, TBIs more than doubled the chance of hearing loss over the next decade

Why would this be? It helps to review how the ear works. The middle ear contains the eardrum, a layer of tissue that vibrates in response to sound. It communicates that vibration to three small bones, called ossicle bones. The vibration of those bones travels to fluid in the inner ear and the cochlea, which communicates with the auditory nerve.

Problems can occur at any point in this process, for example:

• If the eardrum is torn, blood can accumulate in the middle ear, a condition called hemotympanum.
• If the ossicular bones are damaged or dislodged, sound may not travel properly. The three bones can fuse and become stiff and no longer vibrate, a condition called otosclerosis.
• Sometimes brain injuries trigger abnormal bone growth, called heterotopic ossification, which can affect your hearing if it occurs within the ear.
• Meniere’s syndrome, also known as hydrops, is caused by excess pressure in the inner ear chambers that contain fluid. It may develop a month after a TBI or years later.
• Airbag injuries or blasts can damage hair cells in the cochlea, even if there no other bone breaks, triggering tinnitus, dizziness and hearing loss.
• A bone fracture can sever the auditory nerve.
• A TBI can injure the hair cells within the cochlea (which are responsible for detecting soundwaves).
• A TBI can cause damage to the auditory regions of the deep brain that process language or sound.

How is hearing loss related to TBIs treated?

If you notice symptoms after any kind of head trauma, be sure to have your hearing checked as part of your workup.

Treatment will depend on the symptom and its cause. A ruptured eardrum, for example, can recover on its own in about a month. Damaged ossicular bones can be repaired or replaced surgically. Dizziness from Meniere’s syndrome can be treated with medications, but you will not be able to reverse hearing loss.

In many cases, hearing aids can be helpful to amplify muffled sounds and reduce awareness of tinnitus. Ask if hearing aids with tinnitus masking features might be the best option to help you

Key message: Be sure to get an auditory evaluation after any incident that might have injured your brain and mention your history when you speak to a doctor about any current hearing or balance issues.