Auditory brainstem evoked potential-auditory brainstem evoked potential [noun explanation]

Auditory brainstem evoked potential-Auditory brainstem evoked potential[Glossary]

“Listening to the sound” in our concept of conventional thinking is what the ear hears. In fact, the ear is only a transmission link in the process of “listening to the sound”. The real feeling that the sound exists is the auditory center of the human brain. The sound is generated and transmitted in nature is actually a kind of vibration (sound wave), but the auditory center of the human brain cannot directly feel the vibration, so this vibration must be converted into an electrical signal in the cochlea of ​​the inner ear, and then passed. The nerve fibers (like wires) are transmitted to the auditory center, and people can feel the presence of sound.

The cochlear hair cells convert the sound energy of the outer ear and the middle ear to the inner ear into bioelectrical signals and then pass through the auditory nerve to the cerebral cortex, so that people can hear the sound, from the inner ear hair cells to the electrical conduction to the cerebral cortex. After a lot of transfer structures (neurons are graded), they are roughly as follows: cochlear spiral ganglion, brain stem (cochlear nucleus, olive nucleus, etc.), thalamus, cerebral cortex, cerebral cortex, transverse gyrus. This bioelectrical signal is not fundamentally different from the weak DC signal transmitted by our usual internetwork, except that his voltage is much smaller, usually measured in millivolts or even microvolts. In the process of transmitting the electrical signal in the above-mentioned parts, we can detect the electrical activity related to the hearing by using a special potential detecting instrument by attaching the electrode to the relevant part of the human body. The detecting instrument uses the oscillating mode (waveform) to The potential is shown, which is the evoked potential detection map we have seen.

Because the vocalization (so that the headphones are heard by the headphones), the ear can hear the sound before the electrical activity can be detected at these locations, so it is called the auditory evoked potential. Normal hearing children use very small sounds (generally no more than35dBnHLThe sound intensity) allows the potentiometer to detect this audible potential associated with hearing. But for children with hearing loss, they often need a lot of sound (such as70,80dBnHLIn order to detect evoked potentials, children with very severe deafness often do not detect evoked potentials for large sounds (eg100dBnHLCan not induce any potential changes).

There are many types of auditory evoked potentials. According to the location and duration of the change to the potential after the sound stimulation is given, the auditory potential can be divided into short, medium and long three auditory evoked potentials with different reaction latency. At present, the auditory evoked potentials commonly used in clinical practice mainly include the following:ABR(auditory brainstem evoked potential, short latency),ASSR(Aural steady-state evoked response, commonly known as multi-frequency steady state, medium latency),40HZRelated potential (medium long latency),P300(long incubation period).

ABRWhen the waveform differentiation is better, you can usually see5-7Peaks, the degree of hearing loss of the subject is multiple, That is, the hearing loss threshold, mainly to observe the V wave (5Wave) The strength of the lure threshold is judged. In order to make the judgment accurate, it is usually necessary to5Or10Decibel is a progressive test of evoked potential waveforms at multiple sound intensities. The hearing loss threshold of the subject is judged according to the amplitude of the V wave and the law of the appearance time.

ABR(auditory brainstem evoked potential), belonging to the short latency response evoked potential, after recording the sound18msWithin the internal and auditory related potential responses, the recorded electrical activity sites were mainly from the cochlea to the brainstem level.ABRThe stimulus is generally chosen as2KHZ-4KHZ(Positive high frequency) short sound, can more objectively reflect the hearing loss of the high frequency part. The degree of hearing loss in the low frequency part is often undetermined.

ABRFor an objective means of detection, it is more common to say that the greater the intensity of the tester can hear the sound is judged based on the detected potential change, not the subject himself consciously telling you to hear or not. In addition, because most hospitals use only one short sound to judge the subject threshold,ABRThere is no frequency (no thickness and different frequency sound) characteristics and threshold accuracy problems in the threshold strength judgment. So, if you are going to have a hearing aid for a child or if you want to implant a cochlear implant,ABRIt can only be used as a reference test method and cannot replace subjective behavioral audiometry. According to the author, I have been making short sounds for some children.ABRDetection and behavioral listening and contrast, short soundABRThreshold and behavioral audiometry4KHZThe thresholds are very close.

In addition, although many hospitals also do short-pound auditory brainstem evoked potentials with frequency characteristics, the accuracy of threshold judgment is much worse than that of short acoustic evoked potentials.