Week 3: CHAMP

Question 1

why was champ created?

Answer 1

specificity and sensitivity issues for using ECochG to diagnose menieres and endolymphatic hydrops

Question 2

who created CHAMP

Answer 2

• developed by Manuel Don at House Ear Institute

* manufactured and distributed by Biologic System Corp

Question 3

what does derived band response mean

Answer 3

• in order to get “BR” responses from different areas along the cochlea partition we want to mask the cochlea with different frequenices
• uses the tonotopic organization of the cochlea

Question 4

so what exactly is CHAMP

Answer 4

• a click ABR with high pass masking noise
• uses the tonopicity of the cochlea to get frequency specific ABR responses. Uses click ABR as the 1st response to record, then start to use high pass masking noise to mask certain places of the cochlea. have to record standard ABR 1st to get a response to the whole band of the click. look at latency shift because the lower frequencies take more time to travel through the cochlea (prolonged)
• –higher frequency are more basal so shorter latency
• –lower frequency are more apical so longer latency

Question 5

what is the goal of CHAMP

Answer 5

trying to get frequency specificity without using a TB. Testing from all the cochlea and then high to low masking (base to apex). Must compare the response with masking from that of just the click then you will be looking at the response from just the black area because when you subtract the masked from the OG everything will cancel out except for the high frequency band that is only seen in the click. this is why it is called the derived band response. Amplitude gets lower with the low frequency because we dont have as much neureal connection there and less synchrony in the low frequencies

Question 6

endolymphatic hydrops and undermasking

Answer 6

• hydrops alters the response properties of the BM and changes how the cochlea processes auditory stimuli
• low frequency masking noise is less effective for masking activity in high frequency regions
• there is undermasking in the high pass responses
• –this is observed during recording ABR using click stimuli and high-pass masking noise
• reduced masking effectiveness of high pass noise=undermasking
• —-basically, with hydrops you will see undermasking which is not the normal shift because of the changes mechanical properties of the BM, You will not really see a latency shift

Question 7

what does CHAMP stand for?

Answer 7

• cochlear hydrop analysis masking procedure
• based on the assumption that cochlear hydrops alters the response properties of the basilar membrane, resulting in reduced masking effectiveness of masking noise on the ABR to broad-band click stimuli
• a measure of an undermaskerd component to assess meniere’s desease/ cochlear hydrops

Question 8

what is champ looking at/ measuring

Answer 8

measures of wave V latency change caused by the addition of the high pass masking noise are used in combination with amplitude measures to assess the presence and characteristics of an undermasked response

Question 9

sensitivity and specificity of CHAMP to endolymphatic hydrops

Answer 9

*Don (2005) found 100% sensitivity and 100% specificity, but it was done on only those individuals in an active stage of menieres disease

Question 10

HL configuration and CHAMP results

Answer 10

any audiometric configuration can be found with a positive CHAMP result

• hearing within 15dB or better will have a negative champ though if not during active stage until the HL gets worse
• generally the more symptoms in addition to HL, the better the CHAMP will be at detecting menieres (more sensitive)

Question 11

relation of CHAMP latency delay and average HL

Answer 11

no clear relationship between degree of HL and CHAMP latency delay