Transcript Electrophysiological

Electrophysiological
Measures of the
Auditory System
Perry C. Hanavan, Au.D.
Audiologist
Electrophysiological Tests
• Immittance
• Evoked Potential
• Otoacoustic Emissions
First
• Observations
– Appearance of person, age, gender, unusual
characteristics
– Patient information, case history, selfassessment, other clinical data
– Otoscopic exam
Electrophysiologic Triage Trio
• Tympanogram
• Acoustic Reflex
• Otoacoustic Emissions
Triage Trio
Tympanogram
Type A
Acoustic Reflexes
Normal
OAE
Normal
Normal peripheral
and lower brainstem
function (possible
APD) normal hearing
Tympanogram
Type A
Acoustic Reflexes
Normal Range
Normative Data
OAE
Absent or
Depressed
Cochlear loss, outer
hair cell loss, ABR
normal, hearing aids
beneficial
OAE
Present
Auditory
Neuropathy/
Auditory
Dys-synchrony
OAE
Absent
Severe or profound
inner ear loss
(occasionally
otosclerosis)
OAE
Absent
Conductive or
mixed loss (possible
severe/profound
loss)
Tympanogram
Type A
Tympanogram
Type A
Tympanogram
Not Type A
Acoustic Reflexes
Absent or Elevated
Acoustic Reflexes
Absent
Acoustic Reflexes
Absent
Immittance
•
•
•
•
Ear Canal Volume (ECV or PVT)
Tympanometry
Static Compliance
Acoustic Reflex, Decay, & Latency
Ear Canal Volume
• Measure at +200 mmH20
• Provides measure of volume of external
ear canal
• Volumes based on age
• Volumes greater than 2.5 mmH2O (adult)
or 2.0 (child) suggest:
– Perforation or
– Patent PE tube
Tympanometry
• Objective
measure of
the function of
the TM and
middle ear
• 5 or 6 basic
shapes
Which type tympanogram indicates normal
middle ear function?
A. A
B. B lo
C. C
D. Ad
E. As
F. Ap
Tympanogram Types
Type A Tympanogram
OE
ME
IE
AN
CNS
Type AD Tympanogram
OE
ME
IE
AN
CNS
Type AS Tympanogram
OE
ME
IE
AN
CNS
Type BLow Tympanogram
OE
ME
IE
AN
CNS
Type BHi Tympanogram
OE
ME
IE
AN
CNS
Type C Tympanogram
OE
ME
IE
AN
CNS
Type AP Tympanogram
OE
ME
IE
AN
CNS
Static Compliance (Peak
Compliance)
Static Compliance – SC
Ear Canal Volume – ECV
Middle Ear Volume – MEV
Peak Volume – PV
OE
Ear Canal Volume
(ECV)
ME
Volume
(Static Compliance)
OE and ME
Volume
(Peak Volume)
SC = PV – ECV
The ECV reflects the volume in the ear
canal as the ECV measure is often
made at +200 in which the TM is very
stiff reflecting most of the acoustic
energy (acoustic energy is not
absorbed by middle ear)
The PV reflects the ear canal volume AND
the middle ear volume as the measure
is made where the tympanogram peaks
or in other words, the measure is made
where the TM is most compliant or
mobile; thus it is assumed that the PV
represents the volume of the OE and
the ME.
Thus, the SC, or PV minus the ECV,
represents the ME volume
The normal range for our equipment
ranges from .25 to 2.5
Static Immitance
• The terms peak compliance (ml, cc or cm3) and peak
static acoustic admittance (mmho) can be used
interchangeably when using a 226Hz probe tone.
• Most references use the term static admittance (SA)
when reporting results.
• In the most recent edition of Katz et al 2009, there is a
comprehensive list of large scale studies that reported
normative ranges for peak SA.
• Summarizing across these studies, the 90% range for a
normal tympanogram is .2 to 1.8.
Shanks, J., & Shohet, J (2009). Tympanometry in clinical practice. In J. Katz, L.
Medwetsky, R. Burkard, & L. Hood (Eds.), Handbook of clinical audiology (6th ed.)
(pp. 157-188). Baltimore: Lippincott, Williams & Wilkins.
Static Compliance
(Peak Compliance)
Acceptable Range by Age
0.9
1.8
Flaccid: disarticulation,
flaccid TM, etc.
Normal mobility
0.2
0.3
Child
Adult
Stiff: otosclerosis, fluid,
tympanosclerosis, etc.
Tympanometric Width
Normative Cutoff Values (if larger, abnormal)
Infant:
1 – 10 yr olds:
Adults:
235 daPa
200 daPa
235 daPa
ART
Abnormal ART
Recruitment
• ART – AC PT =< 60
indicates recruitment
– (cochlear
pathology)
Reflex Decay
Bekesy vs. Gold
• Bekesy
–
–
–
–
Passive
Broadly tuned
Studied dead cochlea
Awarded Nobel Prize
• Gold
–
–
–
–
Active
Fine tuned
Studied live responses
Went on as an
astronomer
Otoacoustic Emissions
• David Kemp disovered
OAEs
• Acoustic energy produced
by the cochlea and
recorded in the external
auditory canal
• Most likely energy produced
by outer hair motility and
possibly outer hair cell cilia
• Objective test
– DPOAE
– TEOAE
DPOAE
DPOAE
Evoked Potentials
•
•
•
•
EcochG
ABR
Middle Latency
Late Response
OAE & ABR Screen
ABR Wave
I Auditory Nerve
II Auditory Nerve
III Cochlear Nuclei
Interwave
Latencies
IV SOC
V ???
Absolute
Latencies
ABR Supra-aural Phone Data
Add .9 to Absolute values when using insert phones
Newborn ABR Latency Data
Auditory Processing
• Dichotic Sentence
Identification
– Dichotic sentence testing is a
binaural separation test
procedure used to determine
levels of auditory maturation,
hemispheric dominance for
language, and to identify
disordered or damaged
central auditory pathways.
– The advantage of testing
binaural separation with both
word and sentence stimuli is
to compare findings obtained
with both simple and more
complex linguistic levels of
auditory stimuli.
Dichotic Sentence Identification
• The DSI test uses 6 of the same sentences as the
SSI-ICM test but presents 1 sentence to each ear
simultaneously at 50-dB SL, and the participant is
asked to select from a printed list which 2 sentences
were heard.
• Fifer et al showed that the test is resistant to the
effects of SNHL below 50 dB HL.
• The DSI test is administered in both a free and a
directed mode.
• In the directed mode, only the sentence heard in test
ear is noted, whereas in the free mode, the
sentences heard in both ears are reported.
• Five presentations are used if the score is 100%;
otherwise, another 5 sentences per ear are
administered.
• Scores are better in the directed mode than in the
free mode, and the right ear scores are normally
higher in adults than the left ear scores, presumably
due to age related corpus callosum dysfunction.
• Normal scores are 80% correct and above.
Pediatric Speech Intelligibility
(Closed Set)(Recorded)
• PSI
– Both monosyllabic words
and sentences recorded in
quiet and with competition.
– Employs color plates with
pictures of animals (animals
used to avoid ethnic biases)
which represent either the
sentences or the words.
– Investigates peripheral and
auditory processing
disorders.
BKB-SIN (Adults)
BKB-SIN (Children)
Fig 8-1
ECV= .5
ECV= .6
Fig 8-2
ECV= .9
ECV= 1.3
Fig 8-3
Fig 8-4
Fig 8-5
Fig 8-6
Fig 8-7
Fig 8-8
Fig 8-12
Fig 8-14
Fig 8-15