An ABR is a screener. They are not for diagnostic levels, nor can one test for discrimination abilities or get an accurrate dB level. Input from the child is required for definitive diagnosis.
A sedated ABR can go frequency by frequency. It is considered diagnostic.
• Diagnostic ABR assessment:
o Obtain a threshold search to a click ABR in 10 or 20 dB steps (this varies by clinic however 10 dB steps
are recommended, particularly when approaching threshold)
o Tone bursts at 500 Hz or 1000 Hz and at a high frequency (3000 Hz or 4000 Hz)
o Responses should be assessed at 90-95 dB nHL if no responses are observed at softer levels.
o If an absent ABR response is noted, it is recommended that a study be performed comparing a high
intensity (90dB nHL) rarefaction click stimulus to a high intensity condensation click stimulus to
determine if cochlear microphonic reversal occurs when the polarity of the click stimulus is reversed. If
there is cochlear microphonic reversal combined with an absent Wave V response, auditory dyssynchrony
should be suspected. Correlation with OAE should be made.
o Bone conduction click ABR if air conduction click ABR threshold is elevated or abnormal
o Click ABR at a high intensity to assess the latency and morphology of I, III, V, I-III, III-V
and I-V for the purpose of retro-cochlear evaluation (optional)