Auditory Evoked Potentials: Selected Measures Lecture and Lab Bruce Edwards, Au.D. University of...
If you can't read please download the document
Auditory Evoked Potentials: Selected Measures Lecture and Lab Bruce Edwards, Au.D. University of Michigan Health System Michigan Audiology Coalition Meeting
Auditory Evoked Potentials: Selected Measures Lecture and Lab
Bruce Edwards, Au.D. University of Michigan Health System Michigan
Audiology Coalition Meeting E. Lansing, MI October 17, 2014
Slide 2
Intro to me Asst Director of Audiology & Electrophysiology,
UMHS 35 years of clinical experience evaluating patients with
auditory, vestibular, facial measures, >20 years in IOM includes
training staff, educating students and colleagues As CMU grad
student w/ two others, assembled an ABR device from components in
speech lab; recorded my ABR using huge loudspeaker & a tiny
oscilloscope with lots of manual switches Dont pass up
opportunities!
Slide 3
MAC: AEP Lecture [50 - 60 mins] Variety and uses of AEP Effects
upon AEP Quality control measures throughout Three case studies
Questions Hands-on /Demo lab thanks to Audiology Systems and to
Gordon Stowe for bringing equipment to demo; may need
volunteers-
Slide 4
Lab component [60 mins] Otometrics CHARTR ep IHS Smart EP IHS
baby simulator Biologic Nav Pro, neurodiagnostic two- channel;
possibly ASSR Audiology Systems Gordon Stowe
Slide 5
EPs used clinically Auditory brainstem response
Electrocochleography Cochlear microphonic Otoacoustic emissions, a
low-level sound emitted by the cochlea, so not an AEP Vestibular
evoked myogenic potentials Middle latency potentials Later latency
potentials
Slide 6
Quality Measures and AEP Recordings To achieve replicable and
valid clinical measures: Improve the SNR / Fsp (single-point F
ratio) / Fmp (multiple-point F ratio) Relax patient, patients
parents Have a goal for each encounter Calibrate yourself &
your methodology Be a skillful collaborator (work with patients,
deliver your results, plan next steps in a patient-centric
fashion)
Slide 7
Auditory Brainstem Response
http://tx.technion.ac.il/~eplab/EPs/sld002.htm Arguably the most
commonly-used form of AEP in Audiology: a far-field potential
recorded from the ascending auditory pathway Its versatility as a
measure of the neurologic auditory system is unmatched by other
measures
Slide 8
Generator sites for ABR
Slide 9
Auditory systems blood supply is crucial, two important systems
#1 Vertebrobasilar distribution: Cochlea, CN VIII Upper spinal cord
Medulla Cerebellum Pons Midbrain Temporal & occipital lobes
OAE, ECoG, ABR
Slide 10
Important systems #2 Internal Carotid: Most of the anatomical
area rostral to the brainstem Hippocampus (medial temporal lobe)
Cerebral hemispheres AMLR, Late Responses, P300, Mismatched
Negativity [MMN]
Slide 11
ECoG http://tx.technion.ac.il/~eplab/EPs/sld001.htm Generation
of SP, AP, CM requires inner and outer hair cells of basilar
membrane brush or push against tectorial membrane, with eventual
release of neurotransmitters to spiral ganglion neurons
Slide 12
Evoked Otoacoustic emissions -Transient OAE -Distortion product
OAE -Others are available but have been taken up by clinicians
given the relative ease of use and benefits derived by TE and DP
OAEs ILO http://www.mimosaacoustics.com /products/dpoae.html
Slide 13
Vestibular evoked myogenic potentials -A short latency response
in posterior neck muscles, or the eyes, in response to loud clicks
- This reflex arc for cVEMP includes ear, saccule, IVN, vestibular
nuclei, vestibulospinal tract, CN XI (accessory n.), SCM -Used to
determine the function of the utricle and saccule of the inner ears
otolith organ in patients with -VIII n. lesions that involve
inferior vestibular nerve (cVEMP) -suspected superior canal
dehiscence -Menieres disease
www.mayo.edu/mayo-edu-docs/mayo-clinic-audiology-
conference-documents/burkard-shepard-handout.pdf P1/13 P2 N1 /
23
Slide 14
Auditory Middle Latency Potentials Generators include
thalamocortical pathways, mesencephalic reticular formation,
inferior colliculus; Used to calculate lower freq hearing,
objectify complaints of tinnitus; response matures in adolescence,
sleep/sedation effects are seen in AMLR amplitudes Note 1) slow
negative-10 potential, precedes the AMLR Na, and 2) possible
influence of PAM on early AMLR components
www.tinnitusjournal.com/deta lhe_artigo.asp?id=478
www.audiologyonline.com/articles/good-
practices-in-auditory-brainstem-827
Slide 15
Auditory Late- latency Potentials Generators for later
responses include thalamic projections into the auditory cortex,
primary auditory cortex, supratemporal plane, tempoparietal
association complex, lateral frontal cortex Auditory processing
modulated by auditory experiences
http://tx.technion.ac.il/~eplab/EPs/sld004.htm
http://en.wikipedia.org/wiki/File:G ray685.png
http://theluciddreamsite.com/the- dorso-lateral-prefrontal-cortex-
and-lucid-dreaming.html
Slide 16
Selected uses for AEP Newborn hearing screening Followup
infants referred from EHDI Preoperative planning for intraoperative
neurophysiologic monitoring Confirmation of results of audiologic
assessments Screening for VIIIth nerve lesions Estimates of nerve
conduction in patients with systemic neurologic disease
Slide 17
Suggestions to maximize quality opportunities in clinical AEP
recordings Provide uncomplicated, jargon-free instructions for
patients or parents Be a facilitator of the appointment - use
clear, simple instructions and have the patient acknowledge -be
flexible and intuitive Consider the best stimulating and recording
parameters for the test that you will conduct; it will vary
depending on patient age and your intentions Importantly, have a
plan to reach a specific goal for each patient. Example: What is
the most important outcome for this encounter? Ex.: Averaged
responses at intensity levels less than admitted pure tone levels
Ex.: Preoperative responses used for IOM (or to confirm lack of
response from affected side)
Slide 18
Suggestions as you work with families As Mom goes, so goes
baby: Nothing will hurt your baby. I need your help during your
babys appointment. Parents often want to know if/how they can
assist Direct families to arrive hungry and sleepy; arrive before
appt if traveling a distance (during which newborn will sleep)
Parents should play with baby after arrival Complete skin prep of
electrode sites before feeding, sleeping If doing bone conduction
ABR, use pre-auricular or earlobe sites for inverting/reference
electrode (avoid a mastoid location)
Slide 19
EP orientation -Balanced impedances across leads are crucial
-Active / positive electrode on vertex (could be cervical neck to
increase the amplitude of ABR wave V) -Reference / negative
electrode placed at ear level mastoid, earlobe, pre-auricular skin
(for b/c ABR studies) -Ground on forehead or contralateral ear
Differential amplifier schematic used in common mode rejection:
signals common to two lines opposite in polarity cancel before
amplification and output
Slide 20
Environmental & drug effects on AEP Post-auricular muscle
artifact: reduce EMG, get patient comfortably positioned for ~30-90
min visit Electromagnetic energy in electrical lines & outlets
transmitted to instrumentation and/or recording electrode leads EKG
can average into averaged responses; so avoid placing ABR leads
across patients chest; pacemakers/defibrillators may make
recordings challenging In operating room (OR) or outpatient clinic
(OPC) Inhalational anesthetics (ex: isoflurane) cause
dose-dependent, predictable delay in waves III-V of ABR OR
Conscious sedatives (ex: chloral hydrate) with no known effects on
sensory nerve conduction; sedation is short lasting and
poorly-predicted; core body temp will induce IPL changes OPC
Slide 21
Three case studies of AEP #1 Hearing Threshold Estimation
(Audiologys bread & butter) #2 Preoperative Evaluation of
Auditory System in a patient with large, compressive mass #3
Intraoperative Neurophysiologic Monitoring: hearing preservation
attempt, vestibular schwannoma
Slide 22
#1 case study Hearing Threshold Estimation: KR Indications for
Procedure: 6 wk female born w/o incident or concerns at U-M Von
Voigtlander Women's Hospital; referred bilaterally for additional
testing in August Seen in f/u at the University of Michigan C. S.
Mott Children's Hospital for ABR evaluation of peripheral hearing
sensitivity no family history of hearing loss startles to loud
sounds at home, per parents no risk factors for progressive hearing
loss procedure was described in detail to the mother and
grandmother
Slide 23
Recognize the pattern?
www.google.com/images?hl=en&q=pictures+of+ABR+responses&gws_rd=ssl&sa=X&oi=image_result_group&ei
=6aAtVLbCEZCsyASMroHQBw&ved=0CBQQsAQ
Slide 24
#1 case study- Hearing Threshold Estimation: KR POVR: Point
Optimum Variance Ratio algorithm; pass > 3.5
Slide 25
#1 case study- Hearing Threshold Estimation: KR
Slide 26
Slide 27
#1 case study Hearing Threshold Estimation: KR Results Test and
Findings: DPOAE used to assess cochlear outer hair cell function
between 2000 and 6000 Hz bilaterally: OAE present bilaterally
ruling out mild sensorineural or neural hearing loss ABR: Recording
electrodes placed on forehead and ears; insert earphones used to
deliver click and 1 kHz tone-burst stimuli monaurally at various
intensities ABR waveforms document near-threshold Wave V responses
replicable down to 20 dBnHL in each ear suggesting normal
peripheral hearing in mid-to-high frequencies Impression: passed
follow-up evaluation bilaterally results discussed with mother and
grandmother, literature provided re: normal speech, language,
hearing development hearing should be reevaluated if needed
Slide 28
#2 case study ABR preop in pt. with large mass lesion in the
right CPA/IAC 40-something woman in 1st trimester of her pregnancy
Complained of quick- onset hearing loss, tinnitus right ear
Audiologic assessment reveals unilateral SNHL Note the word rec
score!
Slide 29
#2 case study Pt. BH with large mass lesion in the right
CPA/IAC; soon after the delivery:
Slide 30
#2 case study Pt. BH, large mass lesion in the right CPA/IAC;
soon after the delivery:
Slide 31
#2 case study Pt. BH with large mass lesion in the right
CPA/IAC; intraop ABRs: examine waveform at end
Slide 32
#2 case study ABR in pt. BH with large mass lesion OUTCOME
Preop Hearing Postop Hearing
Slide 33
#3 case study Pt. CG: vestibular schwannoma, planned hearing
preservation 1 yr c/o intermittent lightheadedness, NOS; delayed
surgery for ~ 6 months Neurologist ordered MRI Preop audio WNL, ABR
I-III, 3.6 msec, I-V @ 5.6 msec DP OAE intact bilaterally
Vestibular testing revealed right peripheral system weakness
Slide 34
#3 case study-patient CG with vestibular schwannoma, planned
hearing preservation
Slide 35
#3 case study-patient CG with vestibular schwannoma, planned
hearing preservation (note scale differences) Prior to closing (end
of case)Prior to incision (start of case)
Slide 36
#3 case study patient CG with vestibular schwannoma, undergoing
planned hearing preservation: OUTCOME Patient survived the
procedure without neurological complications Patients mass lesion
was completely removed Patients facial nerve function remained
intact, measured by triggered EMG measures (0.1 mA threshold) &
by patients postoperative function Patients hearing was preserved
per ABR throughout the case and by patient report after surgery;
post-op audio to be done
![Habituation of laser-evoked potentials by migraine phase ... · PDF fileHabituation of laser-evoked potentials by ... fibromyalgia [26] and cardiac syndrome X ... evoked magnetic fields,](https://img.pdfslide.us/doc/110x75/5a89cc0c7f8b9a7f398b6264/habituation-of-laser-evoked-potentials-by-migraine-phase-of-laser-evoked-potentials.jpg)
