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Flashcards in NRI Overview Deck (18):
1

What is NRI used for

• estimate psychophysical levels
• verify patient's levels
• assess auditory nerve's response to electrical stimulation
• as a counseling tool
• determine auditory nerve is responsive
• establish a baseline
• to assist with programming
• to provide reassurance to family or recipient (that nerve is functioning)

2

What is NRI?

• measurement of Electrically Evoked Compound Action Potential (ECAP) using the system's telemetry and intracochlear electrodes

• Most commonly used objective measure in the clinic

3

What is AP

• action potential
• a small change in voltage resulting from the firing of nurons

4

What is CAP

• the synchronous firing of neurons creates Compound Action Potential

5

NRI vs. ABR

Stimulus Type

• NRI: electrical
• ABR: acoustical

6

NRI vs. ABR

electrodes

• NRI: intracochlear
• ABR: skin surface

7

NRI vs. ABR

Averaging

• NRI: 128
• ABR: >1000

(how many times you have to run this before you get a clean, non-changing signal)

8

NRI vs. ABR

Sedation

• NRI: No
• ABR: Yes

9

NRI vs. ABR

Benefits

• NRI: verify neural functioning an assist in programing
• ABR: estimate hearing level

10

ECAP consists of which peaks

Negative peak (N1) followed by positive peak (P2)

11

N1 latency

typically between 0.2-0.5ms

12

P2 latency

typically less robust

latency occurring before ~1ms

13

amplitude of response between N1 and P2

measured in uV (microvolts)

varies from 20-1500 uV

14

What is tNRI?

NRI threshold

Where we measure/estimate the threshold to be

15

Advantages of tNRI

• faster and easier to measure
• less contaminated by noise floor
• less subject among clinicians

16

Limitations of tNRI

• too few data points can result in an inaccurate regression line (but this is preventable)

17

NRI advantages

• predictor of audibility
• doesn't require use of additional equipment
• easy to record in a relatively short period of time
• doesn't require sedation

18

Limitations of NRI

• doesn't provide info for higher level functioning (peripheral level only)
• cannot be conducted on C1 patients
• not always present