Download ABR Handouts for AUDs

SAMPLE ABR REPORT
Auditory evoked potentials were elicited using .1 msec rarefaction
clicks presented monaurally at 90dBHL at rates of 21.1 and 71.1
clicks per second. Dual channel recordings were made with test
electrodes on each mastoid.
Tracings were characterized by clearly formed and repeatable wave
peaks. The absolute and inter-peak intervals were within normal
limits.11 There were appropriate latency shifts with increased repetition
rates?f No significant inter-aural differences were noted.
~\hc~-t lv tk\ nO dan~ ct1 nr tuMe{trrtt ~ ~ 01, ~ n,o,( fX>~ .
Impressions:
ABR test results were within normal limits bilaterally.
TABLE 6.2.
Guidelines for a Test Protocol for Clinical Measurement of the Auditory Brainstem. Response (ABR)
PARAMETER
SELECTION
n
RATIONALE/COMMENT
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::'m=!
Stimulus Parameters
;;o
Transducer
Insert earphone
Type
Duration
Polarity
Click
0.1 ms {100 /-LS)
Rarefaction
Rate
> 20/sec, e.g., 27.3
> 90/sec, e.g., 91 .1
Intensity
Repetitions
Masking
Mode
Variable in dB nHL
Variable
Rarely needed
Monaural
There are a dozen good reasons (see Table 3.3)
Bone conduction is also feasible
Optimal, but tone bursts also feasible (see Chapter 8)
Best for transient (synchronous firing) onset
Larger amplitude and shorter latency than condensation
Change polarity if waveform is suboptimal
Faster rate saves time
Slow the rate as needed to enhance the response
An odd number reduces chance of interaction with 60 Hz
High rate may be increase likelihood of detecting retrocochlear dysfunction in neurodiagnostic ABR
High for neurodiagnosis
Perform latency-intensity function for threshold estimation
As many or few signal presentations as needed for an adequate signalto-noise ratio {SNR)
Repetitions are another term for sweeps (see below)
Only if ABR is abnormal and no wave I is detected
Ear-specific information is typically desired clinically
Acquisition Parameters
Electrodes
Non inverting
Inverting
Ground
Filters -- - - - - - HP (high pass)
LP (low pass)
Notch
Amplification
Analysis time
Prestimulus baseline
Sweeps {# stimuli)
Fz
Ai
Fpz
30Hz
3000Hz
none
100,000
15 ms
- 1 ms
Variable
A high forehead site is preferred to the vertex
Ipsilateral earlobe; a TIPtrode is sometimes indicated
A low forehead site is convenient for the common electrode
Low frequencies contribute importantly to the ABR, and are essential
for detection of an ABR from infants
1500 Hz if there is excessive high-frequency artifact
Avoid, as the notch removes important low-frequency energy in the
ABR spectrum
x 100,000 is equivalent to sensitivity of ± 25 or 50 !-LV
Encompasses ABR in all cases (except low-frequency tone-burst signals)
Information on response quality
Whatever is needed for good SNR
m
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~
~
m
;;o
_Vl
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;;o
~
0
0
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r
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z
0
'U
;;o
0
(')
m
0
c
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NORMATIVE DATA- ABR PROTOCOL
Table 2. Summary of latency values for auditory bralnstem responses elicited With dick and tOOl~ bUrst stimuli at selected intensity levels.
LATENCIES (ms)
v
Ill
L
R
L
v
R
L
R
l
R
26
26
26
25
24
..,
n
26
26
25
3
E
mean
1.64
1.7
4.06
4.09
. 6.18
6.16
6.72
8.72
1.40-1.91
1.5-2.0
3.4 -4.37
3.65-4.46
5.54-6.71
5.54-6.62
7.85-9.92
7.58· 9.92
6.06-6.30
6.07-6.26
8.52-8.92
8.45-8.99
::l
+l
i
U)
..10:
min·
.2
0
aa•;. Cl
n
16
15
16
22
18
17
16
mean
1.92
1.97
4.31
6.5
6.47
1.19
6.04
.a
Gl
c
1.46-2.36
1.55-2.24
5.9-7.37
6.02· 7.73
7.4-8.99
7.3. 1.78
..
4
4
3.46
3.63
f::l
...
0
r!
::l
.a
Gl
c
2
10
6.01
6.24
7.98
7.66
10.15
9.7
2.96-4.56
5.81-6.30
6.18-6.30
7.4-9.74
7.22· 7.66
1.84-11.48
1.57-11.22
2.95-4.31
----
5.72-6.30
6.12-6.36
0
1-
~
...
..10:
95%CI 3.11-3.81
... ' ·- ...
--~
~-~~
'"·-~-
~~
......
~~ · ~~
~
L
0
N
R
.
7.57-8.39
I"
'
-
•
-
7.42-7.90
-
--·
- __
~
_,
9.62-10.69 8.89-10.50
.. ---- - - - -- --.. . ---- --
--....,....
---~r
-··· IIJt.T:'l~~~GtT.'~-~(,"I=r~
:r.c-·:;"~· ...."A".. __~,.....,r.r:;·=a-.-.. --.-~
L
b;~~
~~ -~~Jt.-t,.; ":_:_3,,_,
?J ~ .1..JJ~J.._-~L~
'';..:..
L
IR
A
1....
...
•
L
R
L
R
;
~:r:
n
10
12
12
' 14
15
12
12
11
I!!
::l
.a
Gl
c
mean
9.67
9.53
10.22
j0.03
11.51
11.45
12.1
11.65
min-max
8-11.50
1.09-13.22
9.74-15
1.09-13.78
..
6.68-11.62 7.48-12.82 7.8L 11.6a 10.1 ·13.54
0
1-
95%CI
8.89-10.45 8.64- 10.41 9.48-10.96 9.50-10.56 10.93 -12.08 10.62-12.27 11.18-13.02 10.55-12.75
I
II
246
PART Ill AUDITORY BRAINSTEM RESPONSE (ABR) AND AUDITORY STEADY-STATE RESPONSE (ASSR)
I
'
TABLE 7.1
Selected Auditory Brainstem Response Measurement Problems and Possible Solutions
See text for discussion.
I
SYMPTOM
POSSIBLE PROBLEMS
POSSIBLE SOLUTIONS
No display
Technical
Equipment won't
average
Set up error
More than one response in analysis
time
No response
Stimulus rate vs. analysis time
incompatible
verify the system pbwer is on
verify the power co(d is plugged in
verify monitor (scr~en) power is on
verify adequate mo'nitor brightness
verify an evoked prpgram is loaded
consult the equipn1ent manual
verify stimulus repetitions are not at "0"
verify stimulus duration is not "0"
verify stimulus rate 'not too fast for the analysis time
verify all measure~ent parameters
restart computer I
consult equipment jmanual
slow stimulus rate ~o the lSI is longer than the analysis time
shorten analysis ti"?e to less than lSI
the lSI for a click is f!nalysis time/rate
perform a listening check
verify the correct tr9nsducer is used
verify the test ear is·correct
verify correct electrode sites
obtain an audiograr,n if feasible
increase stimulus i11tensity to maximum
attempt bone-conduction stimulation
1
check gain
alternate polarity 1
use insert earphon~s to separate transducer from electrode
verify electrode wires are not near power cords
verify electrode wirJs are not near earphone wires
reduce stimulus intensity
use post-stimulus time delay
stimulus artifact is expected for bone-conduction stimulus
attempt to relax patient
encourage sleep
sedate patient
J
~~!~~ ~~~~Js;ss filte lcutoff frequency
No stimulus
Improper electrode site or array
Severe hearing loss
Excessive early
artifact
Large, slow artifact
. Inadequate amplification
Stimulus interference
Muscular artifact
1
Poor waveform
morphology
High-frequency loss or retrocochlear dysfunction?
Excessive noise,
spikes, or small
fluctuations in
waveform
High-frequency electrical
interference
Small or no wave I
High-frequency hearing loss
verify artifact rejection is on
increase stimulus intensity
slow stimulus rate :
change stimulus polarity
increase number of sweeps
record multiple replicated waveforms
sum replicated waveforms
use click versus tone-burst stimuli
open filter settings I
analyze a prestimult;.s baseline
verify that the artifaCt rejection is on
rule out electrical dJvices and lines
verify good ground I
alter stimulus rate '
lower low-pass filter
alter electrode array:
increase sweeps
verify adequate electrode impedance
increase intensity
decrease rate
verify ipsilateral electrode site
use earlobe versus mastoid electrode
i
\
CHAPTER 7 ABR ANALYSIS AND INTERPRETATION
'I
'
'
POSSIBLE PROBLEMS
SYMPTOM
Small or no wave I
(continued)
I'
POSSIBLE SOLUTIONS
i
,Delayed wave I
Conductive hearing loss
~Bifid wave I
f'
Which peak is used ~or latency
calculations?
,
iSmall or no wave
''·· II or Ill
High-frequency hear ng loss or
brainstem dysfunc ion
":. latency
)
~
I
l
II
'
'
n~
1)ndistinct wave V
Latency calculation
f'
(;,
pelayed wave V
no wave I
~)atency,
Peripheral or brainst~m
dysfunction?
!
'
j
:. '
,.
.~rominent
wave VI
Really wave V?
I
I
;'t
·'1
wave V
Really wave IV?
i,'t
~:ij
(Delayed wave 1-V
f,rlatency
Brainstem dysfunctio ?
;·
I
\i
I
r·~~hort wave 1- V
use an ear-canal electrode (~.g., TIPtrode)
use TM or n electrode
1
change stimulus polarity to rrrefaction
horizontal electrode array
use click versus a tone burst i
lower high-pass filter
increase the number of sweeps (averages)
·obtain audiogram
·
Perform an air- versus bone-conduction audiogram
bone-conduction ABR
immittance measures
increase intensity
decrease intensity
change polarity
ECochG electrode
horizontal electrode array
obtain audiogram
increase stimulus intensity
horizontal or noncephalic electrode array
change.stimulus polarity
'
TI or TM electrode
I
obtain audiogram
\
increase stimulus intensity
lower high-pass filter setting
raise low-pass filter setting
use noncephalic electrode arr . y
analyze latency-intensity function
rule out inadvertent ipsilateral' masking
multiple replications
change polarity
obtain audiogram
increase intensity
rule out crossover response (masking)
see wave I enhancement tech~iques above
I
document young age
lower stimulus intensity
\
use contralateral masking
I
use horizontal or noncephalic ~lectrode array
use contralateral and noncephalic electrode arrays
change stimulus intensity leveli
compare with waveform from other ear
rule out hypothermia
document young age
calculate interear latency difference
verify wave V identification (se~ techniques above)
use gender-matched normativ~ data
obtain audiogram
j
rule out high-frequency hearin~ loss
rule out hyperthermia
l
wave I delayed?
bifid wave I?
use gender- and age-matched normative data
verify wave V versus IV identification (above)
verify wave V identification
verify repeatability of wave V
is wave V too small or wave I too big or both?
verify inverting electrode site (s'!laller V/1 amplitude ratio with
TIPtrode versus earlobe or m~stoid electrode)
1
#
Brainstem dysfunctio .
~,latency
!;l·'
r/:
f1t
'Small wave V/1
f.;·
..,.amplitude ratio
Brainstem dysfunction?
I
1
c·
I
!;
I
t
I
1
?.
,~piked
247 '
.I
APPENDIX NORMATIVE DATA
633
,•
'TABLE A.&. A Simple Guideline for Remembering Important Response Parameters
fn Clinical Analysis of the ABR
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,I
' The number five (5) is a critical clue (see bold font).
a high click stimulus intensity, such as 85 dB nHl ...
'
•
·•
•
•
Wave V lat~ncy is normally about 5.5 ms
Wave V amplitude is about 0.5 J.LV (microvolts)
Upper end of the adult normal region for the wave 1-V latency interval is 4.50 ms
Upper end of the term neonate normal region for the wave 1-V latenty interval is 5.00 ms
TABLE A.4.
Normative Data for Auditory Brainstem Response (ABR) in 189 Adult
Subjects with Mean Age of 48 Years
ABR PARAMETER
NORMAL RANGE OF LATENCY (MS)
Wave 1-111 interval
Wave 1-V Interval
Males
Females
lnteraural latency difference for wave V
Rate-latency shift for wave V
(11/sec to 88/sec)
1.23 to 2.85
3.57 to 4.56
3.42 to 4.56
- 0.59 to 0.42
0.12 to 1.32
Adapted from Lightfoot, G. R. (1992). ABR screening for acoustic neuromata: the role of rateinduced latency shift measurements. British Journal of Audiology, 26, 217-227.
TABLE A.S.
Nontumor (Normative) Statistics for Auditory Brainstem Response (ABR) Wave Component
latency Parameters Used in Differentiation of Cochlear versus Eighth-Nerve Pathology in Adults
GROUP
ABR LATENCY
MEASURE (MS)
Absolute
I
Ill
v
Normal hearing (N = 786)
Cochlear
99%ile
Mean
Mean
1.65
3.80
5.64
(0.14)
(0.18)
(0.23)
1.97
4.22
6. 18
1.80
3.98
5.82
(0.23)
(0.24)
(0.27)
2.15
1.84
3.99
(0.14)
(0.14)
(0.20)
2.49
2.16
4.45
2.17
1.84
4.02
(0.18)
(0.16)
(0.24)
- 0.02
- 0.03
0.00
(0.08)
(0.10)
(0.11)
0.21
0.26
0.29
-0.01
- 0.03
- 0.03 .
(0.25)
(0.23)
(0.20)
- 0.01
0.00
0.00
(0.10)
(0.10)
(0.11)
0.25
0.25
0.28
- 0.02
0.01
-0.02
(0.16)
(0.14)
(0.18)
lnterwave
1- 111
111-V
1-V
interaural wave
I
Ill
v
lnteraural interwave
..
I-III
111-V
1- V
I
Adapted from Joseph, West, Thornton, & Hermann, 1987.
3
BOYS TOWN NATIONAL
INSTITUTE INFANT AND PEDIATRIC
AUDITORY BRAINSTEM RESPONSE
NORMATIVE DATA
Table B-1 Boys Town Auditory Brainstem
Response Normative Data (N=l120)
Measurement parameters (courtesty of
Michael P. Gore:a)
Stimulus Parameters
Type
Click
Duration
100 usee
Rate
13/sec
Polarity
Rarefaction
Intensity
20-80 dB nHL in
20 dB steps
Transducer
BeyerDT48
Acquistion Parameters
Amplification
100,000
Electrodes
Cz to ipsilateral
mastoid with
forehead ground.
Filter Settings
100-3000Hz
Notch Filter
None
Filter Slopes
6 dB/octave
Analysis Period
10.24 or 15.36
msec
Number of
1024; two
Sweeps
replications.
From: Hall, James W., Handbook ofAuditory
Evoked Responses Allyn and Bacon, Boston.
ABR Normative Data
Table B-2. ABR Latency and Amplitude values
for 80 dB HL Click Intensity Level in Newborns.
Table B-3. ABR Latency and Amplitude
Values as a function oflntensity Level in
Newborns.
Latency ~ msec)
CA(N)
I
v I-III III-V 1-V
33-34 (38)
Mean
1.78 7.05 2.86
2.41
5.27
SD
0.30 0.39 0.28
0.26
0.36
35-36 (150)
Mean
1.78 7.02 2.84
2.39
5.24
0.26 0.38 0.27
SD
0.25
0.36
37-38 (158)
Mean
1.74 6.94 2.80
2.34
5.17
SD
0.21 0.42 0.3 1
0.26
0.40
39-40 (111)
Mean
1.72 6.82 2.70
2.38
5.09
SD
0.23 0.38 0.27
0.25
0.36
41-42 (74)
Mean
1.69 6.69 2.74
2.24
5.00
SD
0.19 0.29 0.22
0.21
0.30
43-44 (35)
Mean
1.65 6.53 2.65
2.21
4.88
SD
0.15 0.32 0.26
0.21
0.3 1
Note: Reported by Gorga et al. (1987).
Measurement parameters: stimulus-Click, 0.1 msec,
80 dB Ill.. (110 dB peSPL), 13/sec, monaural, Beyer
DT48 earphone; acquisition - filters, 100-3000Hz;
amplification, 100,000; sweep, 1,024; analysis time,
15 msec; electrodes, Cz-Mi. CA=conceptional age in
weeks; N = number of infants.
Wave V latency msec
CA(N)
80d8 60dB 40d8 20dB
33-34 (38)
Mean
7.05
7.62
8.48 9.72
SD
0.49 0.56
0.39
0.41
35-36(150)
8.42 9.61
Mean
7.02
7.58
0.54 0.67
SD
0.38
0.43
37-38 (1 58)
Mean
6.94
7.45
8.29 9.57
0.5 1 0.74
0.42
0.44
SD
39-40(ll IT
8.11 9.36
Mean
6.82
7.30
SD
0.38
0.40
0.49 0.57
41-42 (74)
Mean
6.69
7.20
8.08 9.31
SD
0.29
0.29
0.35 0.54
43-44(35)
7.94 9.16
Mean
6.53
7.08
SD
0.32
0.33
0.51
0.53
Note: Reported by Gorga et al. (1987).
Measurement parameters: stimulus-click, 0.1
msec, 13/sec, monaural, Beyer DT48 earphone;
acquisition- filters, 100-3000 Hz; amplification,
100,000; sweeps, 1,024; analysis time, 15 msec;
electrodes, Cz-Mi. CA= conceptional age in
weeks; N = number of infants.
3
•
33-34 Weeks AFTER CONCEPTION
Intensity
(dB HL)
Peak I (ms)
Peak Ill (ms)
Peak V (ms)
Inter-peak 1-V
Mean
crSigma
Mean
crSigma
Mean
crSigma
Mean
crSigma
30
4.17
1.13
6.46
1.03
8.88
0 .97
4 .71
0 .98
40
3.59
0.97
6 .17
0 .63
8.51
0.77
4.92
0.78
50
3.21
0.88
5 .79
0 .64
8.19
0.56
4 .98
0.73
60
3.07
0.69
5.38
0 .84
7.76
0.87
4 .69
0.91
70
2.59
0 .84
5 .22
0 .79
7.49
0.56
4.90
0 .75
80
2 .26
0 .81
5 .01
0.74
7.38
0.72
5.13
0 .67
35-36 Weeks
Intensity
(dB HL)
Peak I (ms)
Peak Ill (ms)
Peak V (ms)
Inter-peak 1-V
Mean
crSigma
Mean
crSigma
Mean
crSigma
Mean
oSigma
30
4.06
0.95
6.58
0 .82
8.77
0.99
4.72
0 .87
40
3.57
0 .89
6.00
0 .71
8.51
0 .60
4.94
0.73
50
3 .18
0 .51
5.72
0 .84
8.11
0 .56
4.93
0.77
60
2.73
0.71
5.33
0.63
7.68
0.41
4.95
0 .52
70
2 .33
0 .68
4.97
0 .55
7.41
0.61
5.08
0.64
80
2.13
0.69
4.47
0.71
7.19
0.48
5.06
0.56
37-38 Weeks
Intensity
(dB HL)
Peak I (ms)
Mean
crSigma
Peak Ill (ms)
Peak V (ms)
Inter-peak 1-V
Mean
crSigma
Mean
crSigma
Mean
crSigma
30
3.78
1.04
6.31
0.78
8.39
0 .88
4.61
0.90
40
3.22
0 .78
5 .61
0 .66
7.95
0 .69
4.73
0.71
50
2.94
0.64
5.43
0 .73
7.65
0.72
4 .71
0 .68
60
70
2.47
0 .89
5.06
0.43
7.28
0 .55
4.70
0.71
2.24
0 .67
4.75
0.41
7.17
0.47
4 .93
0 .54
80
2.02
0 .53
4.61
0.47
7.01
0.48
4.99
0.48
39-40 Weeks
Intensity
(dB HL)
Peak I (ms)
Peak Ill (ms)
Peak V (ms)
Inter-peak 1-V
Mean
oSigma
Mean
crSigma
Mean
oSigma
Mean
crSigma
30
3 .59
0 .81
5 .79
0 .84
8 .03
0 .72
4.44
0 .69
40
3.06
0.87
5.36
0.74
7.65
0 .55
4 .59
0.66
50
60
2.65
2.38
0 .72
0.58
5.01
4.71
0 .59
0 .62
7.31
7.07
0 .53
0.49
4.66
4 .69
0.60
0.51
70
1.94
0 .51
4.57
0.44
6 .83
0.48
4 .89
0.46
80
1.79
0.59
4.26
0 .62
6 .72
0.40
4.93
0.59
SmartEP System Manual
50
s
2 months
Peak I (ms)
Peak Ill (ms)
Peak V (ms)
Inter-peak 1-V
Mean
crSigma
Mean
crSigma
Mean
crSigma
Mean
crSigma
30
' 40
3.11
0.62
7.58
7.23
0.31
4.47
4.51
0.52
0.41
0.39
0.45
0.48
2.72
5.64
5.18
50
2.35
0.44
4.85
0.37
6.91
0.34
4.56
0.37
60
70
2.14
4.64
0.35
6.69
0.34
4.27
0.41
6.51
0.30
0 .38
4.55
1.81
0.42
0.30
4.70
0.33
80
1.64
0.43
4.18
0.32
6.39
0.29
4 .75
0.36
Intensity
(dB HL)
0.46
6 months
Peak I (ms)
Peak Ill (ms)
Peak V (ms)
Mean
crSigma
Mean
Mean
30
2.86
0.61
5.08
0.50
40
50
60
2.49
2.28
1.93
0.48
0.41
0.31
4.93
4.75
4.46
0.37
0.37
0.40
70
80
1.79
'1.60
0.32
0.26
4.26
4.10
0.34
0.31
6.50
6.27
Intensity
(dB HL)
crSigma
crSigma
Inter-peak 1-V
Mean
crSigma
7.20
0.44
4.34
0.42
6.86
6.68
6.34
0.33
0.41
0.27
4 .37
4.40
4.41
0.43
0.36
0.30
0.31
0.21
4.71
4.67
0.26
0.28
12 Months
Intensity
(dB HL)
Peak I (ms)
Mean
crSigma
Peak Ill (ms)
Mean
crSigma
30
40
50
2.90
2.43
2.18
0.44
0.40
0.26
5.11
4.59
4.43
0.51
0.22
0.23
0.18
60
70
1.91
1.81
0.29
0.23
4.01
3.84
80
1.62
0.24
3.79
0 .29
0.32
Peak V (ms)
Mean
crSigma
Inter-peak 1-V
Mean
crSigma
7.09
6.62
4.19
4.19
0.47
0.37
6.47
0.39
0.36
0.21
4.29
0 .27
6.15
6.14
0.24
0.19
4.24
4.33
0.33
0 .23
5.93
0.17
4.31
0.19
Adult
Intensity
(dB HL)
Peak I (ms)
Peak Ill (ms)
Peak V (ms)
Inter-peak 1-V
Mean
crSigma
Mean
crSigma
Mean
crSigma
Mean
crSigma
30
40
50
60
2.83
2.46
2.23
1.88
0.36
0.31
0.34
0.27
5.00
4.55
4.49
4.11
0.31
0.26
0.18
0.20
6.69
6.29
6.12
5.81
0.29
0 .27
0.22
0.27
3.86
3.83
3.89
3.93
0.30
0.15
0.24
0.22
70
80
1.75
1.59
0.21
3.86
3.64
0.23
5.67
0.22
5.57
0.15
0.16
3.92
0.17
3.98
0 .25
SmartEP System Manual
0.24
51
,. .
ABR site of lesion protocol
Parameters to be lnsoected:
1.
2.
3.
4.
5.
6.
7.
8.
Absolute latencies
Interpeak latency intervals
Interaural latency differences
.,
Latency-intensity function
Stimulus rate change (compare WV at 7.7 cps to WV ~t 57.7 cps)
Amplitude ratios (Amp WVI Amp WI)
-~ :;
Waveform morphology (look for presence of all three {~a~es)
Replicability
. :.;
'..
Enhancement of Wave I
;,
•
•
•
•
•
•
,. .
Increase intensity
Decrease rate
-~
Compare rarefaction and condensation to distinguish CM from neural response (CM present> dB)
Use TM or TTM electrode (ECochG)
Use horizontal recording montage
If no WI use toneburst at frequency equal to the highP.~t frequency where hearing is symmetrical (+/- 10)
Norms for Normals at 75dB HL (+/- 2 SDsl (Should reolicate within
o.i msl
'
1.6 ms
Ill
3.6-3.7
v
5.6 (if wave V is less than or equal to .6ms consider ABR normal)
I-III
2 ms {8th nerve to lower BS)
111-V
2 Ms (Extra axial BS)
1-V
4 ms (Intra axial BS)(I-V between the ears should be within .4 ms)
V-V
within 0.2-0.4 ms (make sure at same intensity)
Amplitude
Amp V/Amp 1)-1
Rate
7.7 to 5.7 =.5ms (+/- .3 ms) {Increasing from 10/sec to 100/sec shift~ WV b~' 0.5ms) (synchrony and
~
recovery)
NHL norms (run normal hearing subjects to determine click threshold, th.e._average will then become OdB nhl
'*'Absolute latencies less important than interpeak and interaurallatencies '\.
Change in latency with increase or decrease in body temperature=.2ms/degr~ ~elsius away from 98.8
(
Do not need to use correction factors for asymmetrical loss if retrocochlec.r will be huge difference. Absolutes
'
may be a little off but the interpeaks must be WNLs or should consider ABNORMAL
-kwv slightly later in contra; WIV-V complex more spread apart in contra; no Wave I in contra
MS looks retro with prolonged interpeaks and.sometimes amp ratio abnormalities (MRI r/o tumor vs. tissue)
•
ABR site of lesion protocol
Filter
~~[ -
.:
.
30-3000Hz (If too noisy then switch to
···
1500Hz) (light_s out)
. .
.~
·~~
;~
~
•
•
.rl
100~3CJOOHz
or 30-
~
Epoch
0-10 or 0-12 msec for site df lesion
Rate
Start with 22.7 to find bestw~veform then compare 7.7 & 57.7 (.1
ms change in latency for ever-V 10 cps chtmge in rate) (7.7 to 57.7
expect WV to change by about .·s ms (Sq=/- .3) ·
(greater than 30 cps increases latency ar1d de'creases amplitude)
(31.1/sec and 11.1/sec)
Polarity
l
'
,
I
..
;
I
Adults start with condensation (positiv~1b'asilar membrane
down first; slightly better wave V) (raref_pction negative
pulse, earlier and larger wave· I)·
BC always use alternating polarity
~
Stimulus
100 uv Click
Intensity
Start at 75dbnhl, if poor waveform theriBSdB, if still bad try
different polarity, if still ba~ try 95 dB inJensity or slow rate to 7.7
cps. (Very high intensity ~ay invoke the acoustic reflex.)
Artifact Rejection
10 uv (up to 25 uv)
Sweeps
2000
;
I
.. .
J
Protocol ABR Site of Lesion:
-t •
•
•
•
•
•
•
(
•
•
•
•
•
Start with poorer ear at 85dB nHL wit~ condensation clic~ @27.7 cps
If WI and WV responses aren't clear change to rarefaction
Increase to 95dB
Change back to condensation at 95dB, then 100 dB
Then rarefaction at 100 dB
Slow rate to 7.7 cps
_
)
Try TB at last Hz where audio symmetrical within 10 dB (if WV latencies~of TBs are comparable the
patient is ok) 1"t3~ ~ ~
Replicate at 27.7 cps (should be within·o.l ms)
Change to 7.7 cps and replicate
Change to 57.7 (or 77.7 cps) look at WV
SWITCH to other ear and start at 57.7 cps and replicate
,. ,
Then 7. 7 cps and replicate
J
ADULT NORMS
~
<
Y
Wave
I
II
III
IV
v
VI
,_
•
--
~
•
--
•~
•
A
•
~
Absolute Latencies (msec)
Mean
SD
Mean+3 SD
1.7
0.15
2.2
2.8
0.17
3.3
3.9
0.19
4.5
0.24
5.1
5.8
5.7
0.25
6.5
7.3
0.29
8.2
-
-~
Waves
I-III
I-V
III-IV
III-V
IV-V
V-VI
~
•
•
...,
lntenvave Latencies
Mean+ 3 SD
Mean
SD
2.1
2.6
0.15
4.0
4.7
0.23
1.2
0.16
1.7
2.4
1.9
0.18
1.3
0.7
0.19
0.25
1.5
2.3
-
•
~
--«-
v-
--
-
-
Interear lnten,·aw Differences
Mean+ 3 SD
Mean
SD
0.37 (0.4)
0.10
0.09
0.43 (0.5)
0.13
0.10
0.54 (0.6)
0.14
0.12
0.43
0.10
0.11
0.57 (0.8)
0.14
0.15
0.79 (0.8)
0.22
0.19
Normal values for BAEPs obtained from 50 normal subjects (15 to 51 years old, mixed gender) at 10 clicks/sec. Square wave duration
was 0.1 msec, click intensity was 60 dB SL, constant polarity. Latencies were measured to the wave peak; where a peak was not well
defined, a midpoint of the wave was estimated. When waves IV and V were fused into a single peak, the latency was taken to the
point of final inflection before the negative limb of wave V, and this was recorded as wave V only. If either wave appeared as a
distinct step on the other, this step was taken as the wave peak.
From: Chiappa, Keith H., M.D., Evoked Potentials in Clinical Medicine
Second Edition, Raven Press, New York.
ABR Nonnative Data
2
Torie -Burst ABR Settings
Auditory Brainstem Responses are usually
acquired using click stimulation. However, click
stimulation distributes the energy of the sound
over the entire frequency spectrum and
provides no frequency specific information.
This specific information can be used to help
with hearing aid fitting and other types of
diagnosis.
Tone Bursts.
Exact Blackman.
500 Hz: 8000us
1000 Hz: 5000 us or 4000 us
2000 Hz: 5000 us or 4000 us
4000 Hz: 5000 us or 2000 us
8000 Hz: 5000 us or 1000 us.
None.
Masking:
27'. 7jsec or 39.1 ;sec. Slower
Rate:
rates are used to enhance wave
I. Rate should not be a multiple
of the line current (e.g. 60 Hz).
Condensation for 500Hz andjor
Polarity:
Alternating for all frequencies.
Transducers: Insert Earphones.
Intensity:
80 to 95 dB HL for Neurodiagnosis. 90 dB HL down to 0
dB HL for Threshold search.
30 - 1500 Hz (for Adult ABA
Filters:
and infant ABA).
Notch Filter:
OFF. ON if there is excessive
electrical line noise present.
Amplification: 1OOx
Analysis Time 25.6 milliseconds for 500 Hz
Window:
and 1000 Hz; 12.8 milliseconds
for all others.
2000 - 2048.
Sweeps:
Electrode
Ipsilateral or Contralateral Array.
Montage:
Notice that the latency of the response
increases as the intensity of stimulation is
decreased.
Stimulus:
Envelope:
Duration:
The following graph shows the relationship of
latency with respect to frequency. Note that
lower frequency tones have a higher latency
value than higher frequency tones, reason why
it is recommended to use a wider time window
at lower frequencies.
Tone Burst Analysis
A tone burst series used for threshold detection
is displayed in the following figure. The series
shown is for a 500 Hz tone presented using the
parameters outlined in the previous table.
INTEWGENT HEARING SYSTEMS
1-800-IHSYSTEMS- www.ihsys.com
SNSEP010a
Rev: 54066
lo