Auditory brainstem response (ABR)

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Auditory brainstem response (ABR)
Approximately 1 of every 1000 children is born deaf. Many more are born with less severe degrees of hearing impairment, while others may acquire hearing loss during early childhood.
combination of technological advances in ABR and otoacoustic emissions (OAE) testing methods are used for evaluation of hearing in newborns.

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Auditory brainstem response (ABR)

  1. 1. Presented byDr. PANKAJ YADAVdrpankajyadav05@gmail.com1drpankajyadav05@gmail.com
  2. 2. ABR Test2drpankajyadav05@gmail.com
  3. 3.  Approximately 1 of every 1000 children is borndeaf. Many more are born with less severe degreesof hearing impairment, while others may acquirehearing loss during early childhood. combination of technological advances in ABR andotoacoustic emissions (OAE) testing methods areused for evaluation of hearing in newborns.3drpankajyadav05@gmail.com
  4. 4.  Automated auditory brainstem response (AABR)testing (eg, Algo-1 Plus) as an effective screeningtool in the evaluation of hearing in newborns, witha sensitivity of 100% and specificity of 96-98%. To screen for normal hearing, each ear may beevaluated independently, with a stimulus presentedat an intensity level of 35-40 dB nHL. Click-evoked ABR is highly correlated with hearingsensitivity in the frequency range from 1000-4000Hz.4drpankajyadav05@gmail.com
  5. 5.  1. Parental concern about hearing levels intheir child 2. Family history of hearing loss 3. Pre and post natal infections 4. Low birth weight babies 5. Hyperbilirubinemia 6. Cranio facial deformities 7. Head injury 8. Persistent otitis media 9. Exposure to ototoxic drugs5drpankajyadav05@gmail.com
  6. 6.  Auditory brainstem response (ABR) audiometry is aneurologic test of auditory brainstem function inresponse to auditory (click) stimuli. Brain stem evoked response audiometry, Auditory brain stem response, ABR audiometry, BAER (Brainstem auditory evoked responseaudiometry). First described by Jewett and Williston in 19716drpankajyadav05@gmail.com
  7. 7.  ABR audiometry refers to an evoked potential generatedby a brief click or tone pip transmitted from an acoustictransducer in the form of an insert earphone orheadphone. The elicited waveform response ismeasured by surface electrodes typically placed at thevertex of the scalp and ear lobes. The amplitude (microvoltage) of the signal is averagedand charted against the time (millisecond), much likean EEG. The waveform peaks are labeled I-VII. These waveforms normally occur within a 10-millisecondtime period after a click stimulus presented at highintensities (70-90 dB normal hearing level [nHL]).7drpankajyadav05@gmail.com
  8. 8.  Electrode Placement:Disposable electrodes are placed using the followingguideline for “Dual Channel System Configuration”: Red, Side A: Right Mastoids Red, Side B: Left Mastoid Black: Forehead below blue Blue: Forehead above black Impedance Testing: Before performing ABR testing, electrode impedances werechecked. Checking for Electrical Noise: Before beginning the test, it was checked to make sure theEEG activity, in the EEG and Amplifier window, was normalfor a relaxed state and that the signal did not containartifacts waveforms reflecting electrical noise.8drpankajyadav05@gmail.com
  9. 9. The following settings are used: Stimulus: 0.1 milliseconds Broadband Click Rate: 29.3/sec Polarity: Rarefaction Transducers: Insert Earphones Intensity: 90 dB HL down to 30 dB HL for thresholddetection (wave V) Filters: 100 – 3000 Hz Notch Filter: ON Amplification: 100x Runs: 2-4 Analysis Time Window: 12.8 milliseconds Sweeps: 2048 Electrode Montage: contra-lateral Array9drpankajyadav05@gmail.com
  10. 10.  Recording of ABR: The recordings were started from 70 dB intensity andthan successively increased or decreased as peridentification of wave V peak. Wave V was traced at successively lower intensities tofind out minimum intensity at which it is elicitedknown as “Hearing Threshold”. Both ipsi-lateral and contra-lateral recordings weremade for each ear. Multiple recordings were carried out at each intensityand were superimposed, to check the reproducibilityof the waves thus obtained. The median time taken for ABR 25 min including 10min of patient preparation.10drpankajyadav05@gmail.com
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  13. 13.  Wave I - The ABR wave I response is therepresentation of the compound auditory nerveaction potential in the distal portion of cranialnerve (CN) VIII from afferent activity of the CN VIIIfibers (first-order neurons) as they leave thecochlea and enter the internal auditory canal. Wave II - The ABR wave II is generated by theproximal VIII nerve as it enters the brain stem.13drpankajyadav05@gmail.com
  14. 14.  Wave III: The ABR wave III arises from second-orderneuron activity (beyond CN VIII) in or near thecochlear nucleus in the caudal portion of theauditory pons. Wave IV: The ABR wave IV, which often shares thesame peak with wave V, arise from pontine third-order neurons mostly located in the superiorolivary complex, but additional contributions maycome from the cochlear nucleus and nucleus oflateral lemniscus.14drpankajyadav05@gmail.com
  15. 15.  Wave V: reflects activity of multiple anatomicauditory structures. The ABR wave V is thecomponent analyzed most often in clinicalapplications of the ABR. Although some debateexists regarding the precise generation of wave V, itis believed to originate from the vicinity of theinferior colliculus. The second-order neuronactivity may additionally contribute in some way towave V. Wave VI and VII: Thalamic (medial geniculate body)and cortical region.15drpankajyadav05@gmail.com
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  17. 17. 1. Absolute latency interaural difference wave V(IT5) - Prolonged2. I-V interpeak interval interaural difference -Prolonged3. Absolute latency of wave V - Prolonged ascompared with normative data4. Absolute latencies and interpeak intervalslatencies I-III, I-V, III-V - Prolonged as comparedwith normative data5. Absent auditory brainstem response in theinvolved ear17drpankajyadav05@gmail.com
  18. 18.  1. It is an effective screening tool forevaluating cases of deafness due toretrocochlear pathology i.e. (Acousticschwannoma). 2. Used in screening newborns for deafness 3. Used for intraoperative monitoring ofcentral and peripheral nervous system 4. Monitoting patients in intensive care units 5. Diagnosing suspected demyelinationdisorders18drpankajyadav05@gmail.com
  19. 19. 1. 1. All waves are absent in severe hearing loss aswell as in a large acoustic neuroma.2. 2. A normal BERA response virtually rules out anacoustic neuroma; but doesn’t at all rule outintrinsic brainstem lesion or even non-acoustictumor of the CP angle e.g. Meningioma.19drpankajyadav05@gmail.com
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