Exam 3 Part 3 Flashcards
Electrical activity in response to a stimulus that can be picked up by electrodes on the head; measures physiological response
Auditory brainstem response
ABR is an ____ test
Objective
Can you fake an ABR?
No
What is an ABR like for people who are deaf?
Action potentials won’t send and won’t see electrical activity
What part of the EEG is an ABR?
Beginning
What does the beginning of an ABR show?
Initial brainstem response
What does wave I represent?
Distal 8th nerve and inner hair cells
What does wave II represent?
Proximal 8th nerve
What does wave III represent?
Cochlear nucleus
What does wave IV represent?
Superior olivary complex
What does wave V represent?
Lateral lemniscus and inferior colliculus
Neurons firing at the same time
Neural synchrony
What is neural firing like in a pathological ear?
Not firing at the same time; won’t be able to measure ABR
Neural activity is measured along the…
ascending auditory pathway
What type of stimulus do we use in ABR?
Evoked; usually clicking noises
What are the 2 clinical implications we can make with ABR?
Inferences about hearing, inferences about site of lesion
Behavioral hearing (AC) thresholds are __ dB better than the lowest level at which you can measure an ABR
10
What wave is last to disappear in an ABR?
Wave V
Why does wave V disappear in ABR?
As sound gets softer it takes longer for it to reach threshold in the inferior colliculus and get processed
What happens to amplitude as you decrease the intensity of the stimulus?
Decrease
Latency that is from initial stimulus to wave V
Absolute latency
Time it takes to generate wave I to wave V; best measure to make inferences on
Relative latency/ neural conduction time
What are some significant findings that we can use to determine the pathology of an ear?
Prolonged absolute latency, prolonged relative latency, intramural latency differences, absence of wave I and II, absence of ABR with normal or mild hearing, ABR is not replicable
Tumor that can grow between the cochlear and vestibular nerve; always benign never metastasize
Acoustic neuroma
Comparing absolute latencies between both ears
Interaural latency differences
