Acoustic trauma – causes, symptoms & therapy

In the medical field, acoustic trauma is used when the hearing organ suffers damage due to short-term exposure to noise or pressure. The ear has the ability to withstand and compensate for a certain level of volume and pressure – but if the values ​​significantly exceed this level, the ear will be damaged.

The hearing organ in humans consists of an outer part, which is divided into the auricle, auditory canal and middle ear. The middle ear is separated from the auditory canal by the eardrum – an elastic membrane. The outer part is, so to speak, a sound-conducting apparatus on which the sound hits and is transmitted from here to the inner ear.

The inner ear consists of the cochlea and the vestibular system. The cochlea, which is a very sensitive part of the ear, receives the sound and transmits the signals to the brain. Now, when strong noise in the form of a sudden bang hits the ear, blast trauma occurs.

causes

Acoustic trauma usually occurs when a volume of more than 150 db hits the ear for less than 3 ms. Such effects on the ear can arise, for example, from firecrackers or also from gunshots.The deployment of an airbag, lightning strikes, explosions or a strong blow to the ear can also lead to blast trauma. This leads to damage to the hair cells, which leads to a lack of oxygen and the formation of free radicals.

In this context, mechanical damage can also occur as a result. Usually the basal area of ​​the cochlea is affected first, which also describes the high-frequency range.

symptoms and course

Typical symptoms of acoustic trauma:

• ringing in ears

• dizziness

• balance disorders

• noise hypersensitivity

In the case of acoustic trauma, those affected complain that the ear feels as if it were blocked. Acoustic trauma is usually accompanied by hearing loss in the affected ear. Other symptoms often include tinnitus (ringing in the ears), dizziness, balance disorders or hyperacusis (oversensitivity to noise).

The blast trauma often only affects one side, so that the symptoms improve in the first few days, and progression of the symptoms is usually not to be expected. In general, a blast trauma often results in permanent hearing loss . The extent to which the ability to hear will be impaired in the future can be determined by the doctor with a hearing test (so-called audiogram).

Diagnose

In order to be able to clearly diagnose acoustic trauma, the ENT doctor will prepare a hearing curve. The so-called audiogram shows whether there is a sensorineural hearing loss. The audiogram can show either a drop in the curve for high-frequency sounds or a dip at 4,000 Hz.

The so-called SISI test (Short Increment Sensitivity Index) is positive, which reflects the existence of a positive recruitment. This shows that the range between the hearing threshold and the so-called discomfort threshold of the hearing area is smaller than for people with normal hearing. There is a faster increase in loudness due to damage to the outer hair cells.

Hair cells that are not damaged can amplify soft sounds and weaken loud sounds. This makes it possible for healthy people to perceive a large variety of sounds. If the hair cells are damaged due to a bang trauma, then this modification does not apply and otoacoustic emissions cannot be measured in the damaged area. Since the test represents a significant noise exposure for the ear, it is usually only carried out by the ENT doctor a week after the traumatic event.

complications

As a rule, the further symptoms and complications of an acoustic trauma depend very much on the severity of the trauma. Complications do not have to occur in every case, so that in some cases the symptoms disappear completely.

However, acoustic trauma can also lead to permanent hearing loss. Those affected suffer from severe pain in the ears, which can also spread to the head or teeth. Disturbances of balance also occur frequently in the case of acoustic trauma and make everyday life of the patient considerably more difficult.

Furthermore, the trauma leads to tinnitus , which can lead to psychological problems or even depression . Many of those affected suffer from insomnia and thus from irritability.

Dizziness and severe hearing problems also occur. Generally, it cannot be universally predicted whether the course of the disease will be positive. Direct treatment of the trauma is also not possible, so that the affected person has to protect their ears. However, the symptoms can possibly be alleviated again with the help of cortisone. The life expectancy of the patient is not negatively influenced by the acoustic trauma.

treatment and therapy

The hemorheological infusion therapy with HAAES (hydrocyethylstarch) and procaine is the first therapeutic measure after an acoustic trauma. It is also possible to administer cortisone . If both therapies fail, hyperbaric oxygen therapy may be indicated. For the further course, however, an early start of therapy is generally important. The risk of permanent damage is lower the earlier the therapy is started.

Surgical therapy is only indicated if one or both windows in the inner ear are damaged or a so-called perilympus fistula has formed. The perilympus fistula is a pathological connection between the perilymphatic space (surroundings of the sensory cells in the hearing organ) and the middle ear. During a surgical procedure, the eardrum is opened, the damaged windows or the possible fistula are repaired.In general, the prognosis for acoustic trauma is good. The symptoms improve within 6 weeks of the event, and the symptoms often disappear completely within this period. If the symptoms do not disappear within the 6 weeks mentioned, the prognosis is rather poor – therapy is then usually no longer promising.

causes

A bang trauma can only be prevented if you avoid places with corresponding noise pollution. For example, blasts should be observed with earplugs if possible. Especially at the turn of the year, you should avoid standing directly next to firecrackers.