Unsedated Auditory Brainstem Response (ABR) Testing
ABRs are used to test the integrity of the auditory pathway by measuring the hearing nerves’ responses to sound. ABR waveforms represent responses from the cochlear nerve and lower brainstem.
ABRs became a standard hearing-screening tool in the 1980’s and is used in many hospitals to screen hearing in newborn infants before discharge. It can also be tested in naturally sleeping infants, resting children, and adults who may not be able to respond during behavioral hearing testing.
The test procedure is painless and noninvasive.
Hearing Threshold Testing
We can test frequency-specific, air and bone conducted stimuli using new, state-of-the-art 2-channel ABR equipment in sleeping infants to adults.
ABR threshold relates well to behavioral threshold (10 to 20 dB in the high frequencies).
The test may take about an hour for a sleeping infant and sometimes multiple visits due to infant natural sleep habits and approximately 30 minutes for an adult.
ABRs can be used if malingering is suspected.
ABRs can be used as a screening tool for vestibular schwannomas (acoustic neuromas). Specificity is around 87%-94% for acoustic neuromas around 1 cm in size and a false-negative rate of about 4%. It may be requested by a physician when there is a suspicion due to an asymmetric sensorineural hearing loss.
To be used when there is a medical contraindication for MRIs.
ABRs are ⅛ the cost of MRI scan.
Can be utilized when patients have fear of closed spaces.
Your pediatrician may recommend an ABR test if your infant fails a hearing screening or if childhood hearing loss is suspected.
Otoacoustic Emissions (OAE) Testing
Otoacoustic Emissions (OAEs) are used to test the integrity/motility of the outer hair cells (OHC) in the cochlea. They are a test of function or site of lesion, and not an exact measure of hearing. They typically do not occur in hearing loss of about 30 dB or greater and they can be affected by the status of the middle ear.
The clinical utility of OAEs have been well documented in the following areas:
Newborn hearing screening – quick, effective, inexpensive means to evaluate outer hair cell function in newborns
Ototoxicity – OAEs can be used to monitor the negative effects of ototoxic medications before they show up on the audiogram.
Tinnitus – OAEs may be abnormal in the frequency region of the tinnitus, indicating possible cochlear damage.
Noise induced hearing loss – OAEs can be used to document OHC damage due to occupational or recreational noise exposure. The damage will show on DPOAEs before they show on an audiogram.
Auditory Neuropathy – OAEs can be used with ABR testing to locate site of lesion (normal cochlear function with abnormal eighth nerve or brainstem function). Can also raise red flags regarding use of amplification.
Suspect Malingering – OAEs can be used to confirm possible hearing loss if behavioral test results are inconclusive, inconsistent, or unreliable.