Non-Path Subject Factors and Waveform Analysis Factors

Question 1

Name the non-pathologic subject factors that can influecne AEP’s

Answer 1

Age
Gender
Body Temperature
State of Arousal
Muscular Artifact
Drug Effects

Question 2

How does age affect AEPs?

Answer 2

• AEPs are not fully mature in preterm infants;
• shorter-latency responses mature earlier than longer-latency responses.

Question 3

What is the general maturation trend of AEPs in the auditory system?

Answer 3

Maturation progresses from peripheral to central structures and in a caudo-rostral direction in the CNS.

Question 4

Why is age considered a complex factor in interpreting AEPs?

Answer 4

Because it interacts with other subject factors (like hearing loss), stimulus parameters (like rate and intensity), and acquisition parameters (like filter settings).

Question 5

What is normothermia, and how does it affect AEPs?

Answer 5

Normothermia is a body temperature of 37°C (98.6°F); it does not influence AEPs.

Question 6

When must body temperature be considered in interpreting AEPs?

Answer 6

When the temperature deviates by 1°C or more from normal.

Question 7

Define Latency

Answer 7

Latency is the time between when the stimulus is given and when a peak or valley appears in the AEP.
* measured in milliseconds

Question 7

Which patients are at risk for temperature-related effects on AEPs?

Answer 7

Patients with infection (high temp), or those in coma, under alcohol influence, or anesthesia (low temp).

Question 8

What are the waveform anaylsis factors you look at when interpretng AEP’s?

Answer 8

• Presence vs Absence of response or landmark
• Absolute latency
• Inter-peak latency
• Amplitude
• Inter-aural difference or ratio
• Morphology and reproducibility

Question 9

____ is the most robust and reliable characteristic and provides the mainstay of ABR interpretation.

Answer 9

Absolute latency is the most robust and reliable characteristic and provides the mainstay of ABR interpretation.

Question 10

Define Absolute Latency

Answer 10

• The time from stimulus presentation to the appearance of a specific wave.
• Wave V is commonly used for measuring absolute latency.
• Absolute latency is how long it takes for each wave (e.g., Wave I, III, V) to appear after the sound is played.

Question 11

Define Inter-peak latency

Answer 11

The time between specific waveforms
* Measure wave 1-3 (~2 msec), 3-5 (~2 msec), and 1-5 (~4 msec)

Question 12

Define amplitude

Answer 12

Refers to the size/strength of the wave.
* Second major response parameter
* Described in microvolts
* 3 tecqunies are used to calcualate it

Question 13

Define Inter-aural difference or ratio

Answer 13

• Comparison between ears; symmetry is expected.
• Large differences may indicate a pathology.

Question 14

Define Morphology and reproducibility

Answer 14

• The pattern or overall shape of the waves
• Either good,fair or poor morphology
• replications are important for reliability.

Question 15

what is peak voltage?

Answer 15

The highest point (maximum amplitude) of a wave on the waveform.
* It’s typically measured in microvolts (µV).
* Represents the strongest part of the response signal.