How the BERA Test Works and What Results to Expect

Ear

The BERA test (Brainstem Evoked Response Audiometry) is an advanced procedure used to diagnose hearing loss and to assess the nervous system that carries sound signals from the ear to the brain. It is essential for identifying hearing disorders and neurological problems in people who cannot give a subjective response, particularly infants and adults with disabilities. In this post we look at how the BERA test works and what results can be expected from it.

What Is the BERA Test and Why Is It Used?

The BERA test is an objective method used to measure the brain's responses to sounds delivered to the ear. Measurements are taken through adhesive electrodes placed on the head, which record the electrical signals produced in the brainstem. The test provides detailed information about how the auditory system is functioning and is widely used for:

  • Early diagnosis of hearing loss in infants and young children.
  • Identifying neurological disorders that affect the transmission of sound.
  • Assessing hearing in people who cannot give a subjective response or who have disabilities.

BERA is a non-invasive and painless test, usually carried out in a clinical setting.

How Is the BERA Test Performed?

  1. Preparing the Patient
    The BERA test requires a quiet and comfortable environment. The patient is usually placed in a relaxed position and, in infants, the test is often performed while they are asleep. Adhesive electrodes are placed on the head and near the ears to capture the electrical activity produced in response to sound stimuli.
  2. Sound Stimulation
    The BERA equipment delivers sound impulses to the patient's ears through special headphones, while the electrodes record the electrical responses travelling through the brainstem. These impulses are usually clicks or various tones that help analyse the response of the auditory system.
  3. Recording the Results
    The BERA device produces a graph showing the electrical activity in the patient's brain in response to the sounds. These graphs, or recorded waves, are interpreted by the audiologist in order to evaluate the function of the auditory nerve and of the nervous pathway that carries sound to the brain.

What Results Can Be Expected from the BERA Test?

The results of the BERA test are presented as a graph with several waves representing the electrical responses in the patient's brain. The main waves analysed by audiologists include:

  • Wave Latency: Each wave has a specific latency (delay) measured in milliseconds. These latencies help audiologists determine whether there are unusual delays that may indicate a problem in the auditory system.
  • Shape and Position of the Waves: Among the main waves analysed are Wave I, III and V, which represent different points along the path that sound follows to the brain. Any deviation in the shape or position of these waves may indicate a possible problem with the auditory system or with the nerves involved in conducting sound.
  • Stimulus Intensity and Sensitivity of Responses: The brain's response to low- and high-intensity stimuli helps determine the patient's hearing sensitivity. A weak response to low-intensity stimuli may suggest hearing loss.

What Can the BERA Test Diagnose?

  1. Hearing Loss at the Level of the Auditory Nerve
    The BERA test can help detect damage to the auditory nerve or to the nerve pathway that transmits sound to the brain. This is useful in distinguishing sensorineural hearing loss (in the inner ear) from hearing loss originating in the auditory nerve.
  2. Neurological Disorders
    BERA is valuable for diagnosing neurological disorders that affect hearing, such as tumours of the auditory nerve (acoustic neuroma), brainstem damage or other conditions affecting the auditory pathways.
  3. Hearing Assessment for Special Groups
    In infants and young children, or in people with disabilities, BERA is the primary way to obtain an accurate hearing assessment, as the test requires no active cooperation from the patient.

Conclusion

The BERA test is an accurate and reliable diagnostic method for assessing hearing and detecting disorders of the auditory and nervous systems. By providing an objective assessment without requiring any subjective response from the patient, it is particularly useful for special groups such as infants and people with neurological disorders. When detected early, hearing loss and the neurological problems identified by the BERA test can be treated more effectively, significantly improving the person's quality of life.

Read also: BERA/ABR for the early diagnosis of hearing loss in children

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