Electrical Evoked ABR (EABR) Testing
Cochlear implantation is a proven treatment for auditory neuropathy. Although for clinicians the outcomes is still a huge challenge. Electrical Evoked Auditory Brainstem Response (EABR) imparts valuable findings in selecting ear for surgery. It is also helpful in determining key information responses of auditory neurons to electrical stimulation.
What is EABR?
It is an effective tool for measuring integrity in the auditory nerve and predicting performance outcome. Electrical Evoked Auditory Response is a modern technique for measuring ABR using an electrical stimulus. Instead of a conventional acoustic stimulus, the auditory brainstem or cochlear implant develops a stimulus that evokes the ABR.
EABR is a functional and objective examination technique, which allows audiologist to measure the performance of auditory nerve fibers as well as to verify site of the auditory nerve lesion.
- Verify placement of electrodes during the surgery for cochlea implant or auditory brainstem implant
- To estimate hearing threshold level in infants and young children those cannot address using behavioural therapy
- Map device in cochlear implant or auditory brainstem implant
- Assess interaction between channels of electrodes
- Detect rate of stimulation
What to expect?
A patient should lie down in a quiet environment or should go to sleep. The patient should be relaxed with closed eyes during the test. In some cases, a patient may be given a mild anesthesia.
For acquiring eABR, standard ABR surface electrodes are attached each at the contralateral side. One electrode is connected to the cochlear implant and other to the computer to record the readings. The triggered signals are passed from the electrodes to develop a stimulation signal.
Importance of EABR in Auditory Neuropathy
Auditory neuropathy (AN) is a variety of healing loss disorder caused by damage to the auditory nerve that is responsible for sound transmitting from inner hair cells to the brain. It can affect people of all ages, from infant to an adult. A clinical characteristic of auditory neuropathy includes:
- Joint sensorineural hearing loss of any degree
- Normal outer hair cell function evidenced by preservation of otoacoustic emissions (OAEs) and/or cochlear microphonics (CM)
- Abnormal auditory brainstem responses (ABRs)
- Disproportionate difficulties in speech discrimination.
Traditional hearing aids are barely effective in auditory neuropathy patients. Because of the uncertainty in site lesion for patients with auditory neuropathy, the effectiveness of cochlea implantation is questioned.