By

- Dr. Veethika Kapur - Audiologist & Speech Language Therapist

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Brainstem Evoked Response Audiometry (BERA)

‍Anatomy Overview

Eighth Cranial Nerve (Vestibulocochlear Nerve): Responsible for transmitting auditory and balance signals from the inner ear to the brainstem.

• Cochlea: Inner ear structure involved in hearing.
• Vestibular Portion: Inner ear component responsible for maintaining balance.
• Brainstem: Key part of the brain involved in processing auditory signals.

‍Introduction to BERA

• BERA is an objective test measuring electrical waves from the eighth cranial nerve to the brainstem in response to click noises.
• Developed by Jewett and Williston in 1971.
• Typically performed and interpreted by audiologists.

Hearing Process Overview

• Sound Transmission: Sound reaches the eardrum, travels through the outer ear canal, and stimulates the ear.
• Middle Ear: Malleus, incus, and stapes transmit vibrations to the inner ear.
• Inner Ear: Cochlea (hearing) and vestibular portion (balance) are located in the inner ear.
• Eighth Cranial Nerve: Also known as the vestibulocochlear nerve, transmits hearing and balancing signals from the inner ear to the brainstem.

BERA Test: Purpose and Price

• Detects abnormalities in the eighth cranial nerve or brainstem.
• Recommended for newborns at risk of hearing loss and those unable to undergo standard audiometry.
• Cost ranges from INR 1440 to INR 3000.

‍BERA Test Procedure

• Painless and safe.
• Conducted while the individual is asleep, lying motionless, and with eyes shut.
• ABR test can be done during sleep for infants under six months.
• For older children, the BERA test can be performed while awake in a sound-treated room.
• ABR test under anesthesia for children aged 6 months to 7 years.
• The test takes approximately 1 to 1.5 hours without anesthesia and up to four hours with anesthesia.

Indications for BERA Test

• To locate the source of hearing loss.
• Auditory diagnostic test for hyperactive or mentally challenged individuals.
• Asymmetric hearing loss.
• Hearing test for newborns at high risk.
• Hyperbilirubinemia (excess bilirubin)
• Head deformities or abnormalities
• Head injuries
• Nervous system anomalies and suspected acoustic neuroma.

Interpreting BERA Test Results

• Measures audio-evoked potential signals recorded as waves with peaks and troughs.
• Positive potentials recorded as Wave I, Wave II, and so on until Wave VII.
• Interpretation involves analyzing the amplitude and latency of these waves.
• Preparation for BERA Exam:
• Ensure oil-free hair for the test.
• Shampoo bath is recommended before the test.
• For children, mild sedative may be given for comfort during the test.

Conclusion: BERA is a valuable diagnostic tool, especially for detecting hearing issues in newborns and individuals who may not respond well to traditional audiometry. The test's ability to assess the integrity of the auditory pathway from the ear to the brainstem makes it an essential component of audiological evaluations.

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