Pre-Operative Audiological Evaluation

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Questions and Answers

What is a key difference between EABR and ABR waveforms?

Amplitude of EABR responses always saturates at high stimulus levels.

EABR waveforms have longer latencies than ABR.

Wave eI is consistently identifiable in both EABR and ABR.

Wave eV occurs at around 4-5 ms in EABR. (correct)

What might indicate a contraindication for cochlear implantation?

Presence of auditory sensation with electrical stimulation.

Absence of any acoustic sensation with preoperative stimulation. (correct)

High amplitude responses to electrical stimuli.

Severe variability in audiological performance.

What does the EABR latency comparison indicate?

EABR and ABR latencies are identical across all conditions.

The latency of EABR components varies significantly with age.

EABR latencies occur later than ABR latencies.

EABR latencies arise 1.0 to 1.5 ms earlier than ABR latencies. (correct)

What effect is observed on the I/O function close to the threshold?

A tailing effect resulting in a shallow slope. Signup and view all the answers

Which statement is true regarding preoperative EABR testing?

It can be performed using a transtympanic needle electrode. Signup and view all the answers

What variability did Gantz et al. (1993) find regarding promontory tests?

They show considerable variability in predicting audiological performance with multichannel implants. Signup and view all the answers

How is the EABR waveform primarily affected by electrical stimuli?

It bypasses the normal transmission process of sound. Signup and view all the answers

Which waves are typically observed in EABR for estimating response threshold?

Primarily wave eV, with wave II and III in some cases. Signup and view all the answers

What does EABR primarily assess in the auditory pathway?

The integrity of the auditory pathway up to the lateral lemniscus Signup and view all the answers

Which response has been suggested as a tool to assess auditory function mechanisms in cochlear implant users?

Electrically evoked middle latency response (EMLR) Signup and view all the answers

What was the average latency measured for the Na component in EMLR according to the study?

15.41 ms Signup and view all the answers

How does the latency of the electrical Pa component compare to that of the acoustic Pa?

It is consistently shorter than that for acoustic stimulation Signup and view all the answers

Which is a true statement about EMLR thresholds in comparison to EABR thresholds?

EMLR thresholds are lower than EABR thresholds Signup and view all the answers

What is a characteristic difference between electrical and acoustic stimulation responses?

Electrical responses exhibit greater neural synchrony Signup and view all the answers

What relationship was found between EMLR amplitude variation and speech understanding?

It correlated with suprasegmental speech understanding Signup and view all the answers

Which of the following is true regarding the replicability of EMLR thresholds when using anesthetics?

Replicability remains unaffected with anesthetics Signup and view all the answers

What does the EMLR measure correlate with in cochlear implant users?

Neural survival Signup and view all the answers

Which of the following is a cognitive evoked potential that indicates discrimination or contrast perceptions?

MMN Signup and view all the answers

What is the mean latency recorded for the N1 response when stimulated?

86 ms Signup and view all the answers

How can cortical evoked potentials be recorded effectively?

Using electrical stimulation Signup and view all the answers

What might be an implication of poor speech recognition performance in cochlear implant users?

Absence of cognitive components in late auditory evoked potentials Signup and view all the answers

Which response is NOT included in the late potentials for understanding electrical stimuli registration?

N2 Signup and view all the answers

What aspect of the auditory system do cortical potentials reflect in individuals with profound hearing loss?

Degeneration and remaining plasticity Signup and view all the answers

What is one advantage of using cortical auditory evoked potentials?

Ability to record responses using speech stimuli Signup and view all the answers

Study Notes

Pre-Operative Audiological and Non-Audiological Evaluation

Pre-implant audiological tests include unaided and aided detection thresholds for pure tones and warble tones.
Unaided thresholds are measured individually in each ear.
Aided detection thresholds can be measured monaurally or binaurally.
Speech perception abilities are assessed in both monaural and binaural conditions, depending on amplification.
Speech perception measures are conducted at 60 dB SPL, using open-set word and sentence presentations, both in quiet and, if appropriate, in noise.
Other tests include otoacoustic emissions (OAEs) and immittance measurements.

Electrophysiological Measures

Electrophysiological measures assess areas of the auditory pathways.
Common measures include:
- Electrically evoked stapedial reflex (ESR)
- Electrically evoked whole nerve/compound action potential (EAP/ECAP)
- Electrically evoked auditory brainstem responses (EABR)
- Electrically evoked middle latency responses (EMLR)
- Electrically evoked cortical auditory evoked potentials (AEPs)
EABR, EMLR, and AEPs are used for pre-operative measurements.

EABR

Recorded in the pre-operative stage using electrical stimulation at the promontory or round window.
EABR, along with MRI, provides information about intact auditory neurons and patient suitability for cochlear implants.
EABR waveform characteristics are similar to ABR, but with wave I usually obscured by the stimulus artifact.
EABR wave latencies are typically 1-1.5 ms earlier than ABR.
Response amplitude doesn't usually saturate, even at high stimulus levels.
A "trailing" effect (shallow I/O function slope) is sometimes seen near threshold levels.
Wave V is often the dominant component near threshold.

EMLR

EMLR assesses underlying mechanisms of auditory function.
Average electrode latencies are approximately 15.41 and 26.37 ms.
EMLR is less susceptible to stimulus artifact contamination due to its longer latency.
EMLR thresholds often correlate well with behavioral thresholds.
Electrical stimulation produces shorter Pa latencies than acoustic stimulation.
EMLR and acoustic MLR are driven by the same central neural generators.

Cortical Evoked Potentials

Cortical responses evaluate how electrical stimuli are processed by the central auditory system.
Late cortical potentials (e.g., N1, P2, P300, MMN) can be reliably recorded with electrical stimulation.
Potentials may provide information about auditory and association cortex activation.
Late potentials can be used to assess cognitive processes.

Radiological Assessment

Preoperative imaging (e.g., HRCT, MRI) is crucial in assessing anatomical considerations like mastoid, middle ear, facial nerve, vascular anatomy, otic capsule, and cochlea.
Imaging aids in identifying any anomalies that might affect the procedure and implantation.

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Description

This quiz covers the essential pre-implant audiological evaluations, including thresholds for pure tones and speech perception abilities in various conditions. It also delves into electrophysiological measures critical for assessing auditory pathways. Test your knowledge on otoacoustic emissions and the intricacies of auditory assessments.