This document discusses auditory brainstem response (ABR) testing. It describes the electrical potentials recorded along the auditory pathway in response to sensory stimuli. ABR testing can help evaluate neurological abnormalities of the auditory nerve and pathways, assist with cochlear implant development and hearing threshold estimation, and is used for newborn hearing screening and intra-operative monitoring. The document outlines the typical ABR waveforms and latencies observed, as well as clinical applications and limitations of ABR testing.

1. Dr Nzanzu Kikuhe & Ms Josephine Likichoru
ENT Department MAKERERE UNIVERSITY
Kampala, Uganda
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2.  Electrical signals in nervous system in response
sensory stimuli.
 Ongoing electrical activity in the brain and
recorded via electrodes placed on the scalp.
 Potentials recorded along the auditory path way
from VIII CN the auditory cortex
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3. Type of AEP Response Latency
Electrcochleography Early <2msec
Auditory Brainstem
response
Early < 10msec
Middle Latency response Middle 15 to 50msec
Auditory cortical
response
Late 75 to 200msec
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4.  First described by Jewitt and Willison (1971)
 Test of Response of auditory brainstem to
auditory (click) stimuli.
 Several anatomical sites along the brain stem.
 Characterized by 7 peaks
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6.  Wave I – distal portion of the IIIV CN
 Wave II- proximal portion
 Wave III- cochlear nucleus
 Wave IV- uncertain but may be from superior
olivary complex
 wave V is related to activity in the LL and inferior
colliculus
 Wave VI-medial geniculate body
 Wave VII-auditory cortex
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9. Latency
ms
I 1.58
III 3.73
V 5.55
I-III 2.17
I-V 3.99
 Latency:
 Values are outside
normal??
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10.  Neurological abnormalities of CN VIII and the
auditory pathways
 CI development
 Estimation of hearing threshold
 New born screening
 Intra-operative monitoring
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11.  Not direct test of hearing

 History
 Behavioral tests
 Tympanometry
 OAEs
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13. 13

14.  Assessment of middle
ear function
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15.  Give appointment to prepare yourself
 Patient preparation
 Equipment preparation
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16.  Recorded by attaching 3 or 4 electrodes to the
surface of the scalp.
 1 channel- 3 electrodes
 2 channel- 4 electrodes
-vertex
-each ear either on mastoid or ear lobe
( blue, active and red reference)
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17.  Sedation

 Subject lying supine with a pillow under his head.
 Room should be quite.
 Clean the scalp & apply electrode.
 Check the impedance.
 Select the ear in the stimulator
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21.  AC clicks used to estimate higher frequencies (2-
4KHZ)
 Low frequency tone bursts
 BC clicks

 Watch for wave V which is the most persistent
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24.  Normal (replicable wave V)
 Lowest level at which a clear response (CR)
 30dBnHL is considered satisfactory hearing
 One below CR
 Usually 10dB above PTA thresholds
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25.  Latencies will be prolonged
 Abnormality/Degradation of wave forms
 Absence
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26.  Conductive hearing
 Latencies are also prolonged
 Thresholds elevated ( above 30dBnHL), never absent
 BC ABR down to 15dBnHL or less
 But this has to be determined by tympanometry before
time
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27.  Thresholds may be high depending on degree of
hearing loss
 Latencies are prolonged at lower intensities but
normal at higher intensities
 Disappears below threshold
 Amplitude reduces as intensity reduces
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28.  History
 Tests done other than ABR
 ABR thresholds
 Conclusions
 Recommendations ( optional)
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29.  Depending on degree and type
 Hearing aids
 C I
 Other conditions may require surgery
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30.  Its stable and recorded within 10dB of true hearing
threshold
 High sensitivity and specificity >95% for threshold
estimation
 Not affected by sleep , sedation or anaesthesia
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31.  Limited frequency information
 Its affected by neural maturation
 Babies must sleep
 Time and space
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32.  Several clinical trials have shown ABR testing as
an effective screening tool in the evaluation of
hearing in newborns, with a sensitivity of 100%
and specificity of 96-98%.

 Latencies in new borns are usually longer and
keep changing with maturity
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33. 33

34. ◦ Eggermont, Jos J.; Burkard, Robert F.; Manuel Don
(2007). Auditory evoked potentials: basic principles
and clinical application. Hagerstwon, MD: Lippincott
Williams & Wilkins. ISBN 0-7817-5756-8. OCLC
70051359.
◦ Hall, James W. (2007). New handbook of auditory
evoked responses. Boston: Pearson. ISBN
0-205-36104-8. OCLC 71369649.
◦ Moore, Ernest J (1983). Bases of auditory brain stem
evoked responses. New York: Grune & Stratton. ISBN
0-8089-1465-0. OCLC 8451561.
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35. ◦ DeBonis, David A.; Donohue, Constance L.
(2007). Survey of Audiology: Fundamentals for
Audiologists and Health Professionals (2nd Edition).
Boston, Mass: Allyn & Bacon. ISBN 0-205-53195-4.
OCLC 123962954.
◦ Don M, Kwong B, Tanaka C, Brackmann D, Nelson R
(2005). "The stacked ABR: a sensitive and specific
screening tool for detecting small acoustic
tumors". Audiol. Neurootol. 10 (5): 274–
90. doi:10.1159/000086001. PMID 15925862.
◦ Prout, T (2007). "Asymmetrical low frequency hearing
loss and acoustic
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36. ◦ DeBonis, David A.; Donohue, Constance L.
(2007). Survey of Audiology: Fundamentals for
Audiologists and Health Professionals (2nd Edition).
Boston, Mass: Allyn & Bacon. ISBN 0-205-53195-
4. OCLC 123962954.
◦ Don M, Kwong B, Tanaka C, Brackmann D, Nelson R
(2005). "The stacked ABR: a sensitive and specific
screening tool for detecting small acoustic
tumors". Audiol. Neurootol. 10 (5): 274–90. Cortical
reorganization in children with cochlear implants. Brain
Research .
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