Is the brainstem auditory evoked potential accurate?

Many people think that hearing is closely related to our ears, but this is not the case. When our ears receive signals, they need to be fed back to our brain so that our brain can react in time to what we hear. Therefore, the brainstem is crucial to us, and in many cases the brainstem needs to induce hearing. So is the brainstem hearing evoked potential accurate?

Brainstem auditory evoked potential (BAEP) is a relatively sensitive objective indicator of brainstem damage. It is the electrical activity of nerve impulses caused by sound stimulation in the brainstem auditory conduction pathway. It can objectively and sensitively reflect the function of the central nervous system. BAEP records the neural potential activity in the auditory conduction pathway and reflects the functional status of related structures from the cochlea to the brainstem. Any lesions or damage involving the auditory channel will affect BAEP. Often, BAEP changes occur when the brainstem is slightly damaged and there are no clinical symptoms or signs.

How to operate

BAEP is 6 to 7 positive waves recorded within 10ms after the earphone delivers a short sound stimulus. These waves may have a complex origin at multiple sites, but we can simply assume that wave I is the action potential of the auditory nerve, wave II originates from the cochlear nucleus, wave III comes from the superior olivary nucleus and trapezoidal body of the pons, waves IV and V represent the lateral lemniscus and the inferior colliculus of the midbrain respectively, and waves VI and VII are the action potential waveforms of the medial geniculate body of the thalamus and the auditory radiation. Therefore, waves I and II actually represent the peripheral wave groups of the auditory afferent pathway, and the subsequent waves represent the action potentials of the central segment. The first five waves, wave I to wave V, are the most stable, among which wave V has the highest amplitude and can be used as a sign to identify the waves of BAEP. Under normal circumstances, wave II and wave I, or wave VI and wave VII often merge to form a composite waveform.

The wave I latency represents the peripheral conduction time of the auditory pathway, while the inter-wave latency (IPL) of waves I to V is the central auditory conduction time of the brainstem segment, and also represents the integrity of brainstem function. The development of the brainstem auditory conduction pathway is basically consistent with that of other brainstem structures. Therefore, BAEP testing can not only reflect the development of brainstem auditory function but also, to a certain extent, reflect the developmental status of the entire brainstem function. [Data show that the BAEP abnormality rate in children with hypoxic-ischemic encephalopathy is 64.3%, the BAEP abnormality rate in children with language development disorders is 56.6%, the BAEP abnormality rate in children with hyperbilirubinemia is 52.6%, and the BAEP abnormality rate in children with cerebral palsy is 52.4%.

If BAEP cannot be elicited, severe damage to the proximal cochlear segment of the auditory nerve may be considered; if wave I or waves I and II disappear, severe damage to the intracranial segment of the auditory nerve or brainstem may be considered. The absolute latency (PL) of each wave of BAEP is prolonged and bilaterally symmetrical. If the IV latency (IPL) is not long, it may be conductive hearing loss until the proximal cochlear segment of the auditory nerve is damaged; if the IV IPL is prolonged, it may indicate that the brainstem auditory pathway is affected.