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POST-TRAUMATIC HEARING LOSS

Timothy C. Hain, MD

Most recent update: April 10, 2012 : This page is not written for or intended for use in legal endeavors.

Head injuries are sustained by 5% of the population annually.

Patients with head or neck injury may also have loud and disturbing tinnitus (Folmer and Griest, 2003). The literature suggests that recovery occurs in from 3-9 months in most individuals, but that symptoms persist for more than 1 year in 10 to 15%.

Symptoms:

As the area injured is usually the ear, and the ear contains both hearing and vestibular apparatus, generally there are symptoms of both hearing disturbance AND dizziness at the same time, in post-traumatic hearing loss.

Location and severity of injury.

Generally, but not always, the trauma is to the vicinity of the ear. Slaps to the ear,  blunt objects hitting the around the bone of the ear are particularly common. In the author's experience, loss of consciousness is less common than retained consciousness.

Timing:

Generally, but not always, post-traumatic hearing symptoms begin immediately after the trauma.  The main exception is the somewhat questionable entity, "delayed endolymphatic hydrops" (see below).  Also, generally speaking, hearing sympoms get better with time.

 

After a head injury, eardrum or ossicular chain damage, disruptions of intralabyrinthine fluid, cochlea, or 8th nerve may be damaged resulting in hearing loss. Tinnitus can also result from neck injury.

It is helpful to divide hearing loss according to the location of injury (see above).

Conductive hearing loss -- damage to ear drum or ossicular chain.

Disruption to the ear drum or ossicular chain can cause conductive hearing loss.  This means that hearing is better through bone than air. When the ear drum is perforated but ossicles remain attached the the reminant, hearing is reduced for air condition.  Disruption to the ossicular chain -- the tiny bones between the ear drum and inner ear, can cause nearly complete hearing loss.  Blood or fluid within the middle ear can reduce hearing. According to Grant et al (2008),  most conductive hearing loss are "closed", meaning that the TM is not perforated.  The remaining types are hemotympanum (blood in the middle ear), and perforation. 

Most patients with tympanic membrane perforations have pure conductive hearing loss.  This is also true for hemotympanum. Patients with closed post-traumatic conductive hearing loss, have roughly equal fractions of mixed and conductive hearing loss.

 

Disruption of intralabyrinthine fluid

PLF Round window fistula. A membrane "blows out" between the inner and middle ear, causing dizziness and possibly also hearing loss.

 

Perilymph fistula. Usually symptoms of imbalance and dizziness provoked by straining or blowing the nose. People with fistula may also get dizzy with loud noises (called Tullio's phenomenon). The frequency to which this syndrome occurs is controversial, but general opinion holds that it is rare.  

Post-traumatic Meniere's syndrome --Also sometimes called "hydrops". Episodes of dizziness accompanied by noises in the ear, fullness, or hearing changes. Mechanism thought to be bleeding into inner ear, followed by disturbance of fluid transport. Onset of symptoms may vary from immediate to as long as one year later. There are frequently legal implications to this diagnosis. The probability of Menieres being reasonably attributed to post-traumatic mechanisms is a function of the severity of injury (severe makes more likely), the latency from the injury (longer is less likely), the presence of a pre-existing condition, and the presence of secondary gain. Persons with the Large Vestibular Aqueduct syndrome are felt to be more likely to develop these symptoms (Berettini et al, 2000).

Cochlear hearing loss

Airbag injuries and blast injuries.   These are thought to be due to very loud noise.  There is a significant incidence of vertigo and hearing disturbance after airbag deployment (Yaremchuck and Dobie RA. 2000).

Labyrinthine "concussion". Defined as a non-persistent hearing or labyrinthine disturbance which follows a head injury, not caused by another mechanism. A hearing loss or a nystagmus must be present to make this diagnosis with a reasonable degree of medical certainty. While the name implicates an inner ear disturbance, this symptom complex may be impossible to differentiate from other entities. For example, it might be difficult to differentiate a labyrinthine "concussion" from an eighth nerve stretch injury, although newer testing modalities may help (e.g. VEMP).

Neural hearing loss

The 8th nerve is hard to access as it is encased in hard bone.  Neural hearing loss is due to damage to the 8th nerve, such as due to temporal bone fracture, or traction on the nerve between the lip of the IAC and brain.

Longitudinal temporal bone fracture Oblique temporal bone fracture

Temporal bone fracture. Severe dizziness after the injury, with skull or temporal bone CT scan indicating a fracture. Often accompanied by hearing loss or peripheral facial weakness ( Bell's Palsy). Temporal bone fractures, especially the oblique variety (see above), may impair hearing and cause dizziness. There often is blood seen behind the ear-drum (hemotympanum). Either a conductive or sensorineural hearing loss may be present. Vestibular deficits are also common, especially in the oblique variety. Bilateral vestibular problems are exceedingly rare. Treatment is conservative. Prophylactic antibiotics are given, usually for 4 weeks. Myringotomy and insertion of a ventilating tube may be indicated, especially for serious otitis that persists after one month (Pulek and Deguine, 2001).

Fistulae between the inner ear and surrounding spaces can occur in T-bone fx.  In this instance, air may be seen within the labyrinth on CT ("pneumolabyrinth). Fluid may also be seen within the mastoid.

 


Diagnosis of post-traumatic hearing loss

First the doctor will want to know exactly when and how the head or neck was injured, and the character of the symptoms.  Was there dizziness (i.e. spinning ? unsteadiness ? confusion ?). He/she will want to know if you were unconcious and the duration of time. Did the airbag deploy ? All available records from the emergency room or hospital where you were seen after the injury should be obtained and shown to your doctor. This is especially important when there is litigation as much may depend on small details.

As there is often hearing disturbance and dizziness combined,  examination for both should be performed. Audiometry should be done in all. We also favor sweep OAE testing. In patients with hearing disturbance, an "ECochG" may be done.

Next, a specialized examination for dizziness will be performed. Balance will be measured, often with moving platform posturography. A search for "nystagmus" will be made, related to head and/or neck position or to vibration of the neck. You may be checked for pressure sensitivity with the fistula test.

Should there be dizziness,  laboratory tests will be ordered. In most instances these will include an ENG, and rotatory chair test.

An MRI scan or CT scan of the inner ear (temporal bone CT scan) is usually performed. If available, a VEMP may be useful. An EEG may be obtained for persons with paroxysmal cognitive symptoms suggestive of epilepsy. Moving platform posturography is helpful to quantify balance deficits.

Psychological testing is sometimes done in persons who have entirely normal test results. They can document interactions between symptoms and personality as well as cognitive difficulties. Such testing is often useful in sorting out the situation when patients are in litigation and could benefit from an appearence of ill health.


Treatment of post-traumatic hearing loss

Treatment is individualized to the diagnosis. Treatment usually includes a combination of hearing assistive devices, medication, and counseling about prognosis. Occasionally, surgery may be recommended.


References:

 

Copyright October 6, 2013 , Timothy C. Hain, M.D. All rights reserved. Last saved on October 6, 2013