Term
| Identify individuals credited with ECochG discovery |
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Definition
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Term
-The goal is to identify up to 3 (electrical) components
that come from the cochlea: ___, ___, and ___
-A ___-___ response recorded by an electrode in the electrical field generated by activating the ___
-Implication: the electrode must be placed as ___ to the cochlea as possible |
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Definition
| CM, AP, and SP; near-field; cochlea; close |
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Term
ECochG – Components & Their Origins:
-Cochlear Microphonic (CM): generator is the _______
-Summating Potential (SP): generator is mostly the _______
-Action Potential (AP): Generator is the ___________ fibers |
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Definition
| OHCs; IHCs; distal auditory nerve |
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Term
Cochlear Microphonic (CM):
-Generated by ______
-An alternating current (AC) voltage that ___ the waveform
of the stimulus
-Limitation: May be hard to separate CM from ___ ___
-Value: Helpful in diagnosing ___ ___ |
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Definition
| OHCs; mirrors; stimulus artifact; auditory neuropathy (AN) |
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Term
Summating Potential (SP):
-Generated primarily by _______
-A ____ current that shows the ___-___ pattern of the cochlear partition in response to a stimulus
-Limitation: Can be hidden by the ___ ___ or ___ ___ |
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Definition
| IHCs; direct; time-displacement; CM; stimulus artifact |
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Term
Action Potential (AP):
-Generated by _____________ fibers
-An ___ ___ potential that represents the summed response of
synchronous neural firing
-Has 2 ___ peaks (N1 & N2). The same as ABR waves __ and __ |
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Definition
| distal auditory nerve; AC; negative; I & II |
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Term
ECochG Value & Protocol:
-Helps diagnose ____ disease
-Helps diagnose ___ ___
– Why?
-ECochG protocol is similar to ABR protocol, with one exception: ____________________ |
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Definition
| Meniere’s; auditory neuropathy (AN); Generators are pretty well defined; Type & location of electrodes |
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Term
Electrode Types that Allow Near-Field Recordings:
-____ electrode: tip of electrode is placed on the TM by audiologist. Designed for safe placement, non-invasive
-__________ electrode: needle (inserted by physician) through the TM until the tips sits on the promontory |
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Definition
| TM; Trans-tympanic needle |
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Term
| What is a third electrode option? |
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Definition
-Ear canal electrode: aka “TIPtrode”
-Technically not in electrical field assoc. with ECochG activity
-Sometimes used in ears with normal hearing
-Limitation: may NOT see CM &/or SP clearly |
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Term
Comparisons of Electrode Types:
-Closer to ___ (TT-Promontory) provides larger response: AP grows more than ___ ___. ___ normative values required. More likely to record AP with ___-___ loss
-latency does not vary as a function of ___ ___
-Patient comfort & pragmatic issues: Which one is the easiest, cheapest, and most comfortable to use? Which one is the least comfortable? TT-promontory is fairly comfortable with local ___; requires ___. |
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Definition
| cochlea; SP; Separate; severe profound; electrode location; ear canal electrode; TM electrode; anesthesia; surgeon |
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Term
| Describe an ECochG protocol |
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Definition
1. Preparation, pt instructions
2. Otoscopy
3. Attach all electrodes except TM electrode; plug electrodes into electrode box receptacles
4. Ask pt to report any sensation (tickle, discomfort, pain, pressure, cough reflex).
5. Put conducting gel on TM end of electrode and ask pt to report when electrode is on TM
6. Ask patient to lay on side with test ear upward
7. Hold TM electrode placement with finger and place insert earphone in canal
8. Allow foam plug to expand against electrode lead
9. Tap electrode lead and ask pt to report sensation
10. Plug acoustic tubing from ER 3A transducer into the stalk tube of the insert earplug (for TIPtrode)
11. Plug TM electrode pin into electrode box
12. Verify electrode impedance for all electrodes
13. Present stimulus to ear with TM electrode
14. Inspect waveform for AP in the 1.5 to 2.0 msec region
15. AP amplitude should exceed 1.0 even in mild to moderate hearing loss |
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Term
| What if reliable AP is not observed? |
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Definition
| Withdraw TM electrode and reinsert. If no response is observed on 2nd try, remove TM electrode and inspect for damage to electrode. Replace if needed. Proceed with ECochG measurement and analysis |
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Term
Primary Clinical Applications:
-Enhancing ABR wave __ when loss is present
-Confirming ___ ___
-Diagnosing/monitoring ___ ___ |
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Definition
| I; auditory neuropathy (AN); Meniere’s disease |
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Term
Normal ECochG Results:
-CM: ___ stimulus in time
-ABR looks the ___ whether rarefaction or condensation clicks are used
-CM changes polarity when ___ polarity is changed - confirms that CM is ___ |
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Definition
| follows; same; stimulus; present |
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Term
Horizontal Montage:
-Stimulus ear: ___ electrode
-Opposite ear: ____ electrode
-Forehead: ___ electrode |
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Definition
| inverting; non-inverting; ground |
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Term
ECochG and ABR:
-Purpose: to enhance ABR wave __; to detect or rule out ___ ___
-Use ___ (instead of ipsilateral) electrode array. Place inverting electrode on ___ ear. Place non-inverting electrode on the ___ ear. |
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Definition
| I; AN; horizontal; stimulus; opposite |
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Term
| What kind of results does someone with AN have? |
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Definition
| Absent ABR and present CM |
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Term
Expected ECochG Results in Meniere’s Disease:
-Abnormally ___ SP amplitude
-Abnormally ___ SP/AP amplitude ratio
-Depending on the electrode site, the ___ ___ amplitude & ___/___ amplitude ratio will differ
-AP amplitude is ___ when inverting electrode is closer to cochlea
-SP amplitude ________ as stimulus site moves closer to cochlea |
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Definition
| large; large AP; SP/AP; higher; stays constant |
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