Nikki and Joanna's Deck Flashcards
What is included in the peripheral auditory system?
- outer ear to auditory nerve
What is included in the central auditory system?
-cochlear nucleus to auditory cortex
How many total nerve fibers are make up the auditory nerve?
50k
- 30,000 hearing (cochlear)
- 20,000 balance (vest)
Explain the two cores of the auditory nerve…
name the turns and their frequencies
Outer core- basal turn- high frequency
Inner core- apical turn- low frequency
Where does the auditory exit
IAM (Internal auditory meatus)
Where does the auditory nerve terminate?
The Ponto-medullary Junction (between the pons and medula)
What are the two nuclei of the cochlear nucleus?
Dorsal-ascending branch of auditory nerve terminates
Ventral-descending branch of auditory nerve terminates
What does the cochlear nucleus connect with
SOC (Superior Olivary Complex) and VNLL (Ventral Nucleus of Lateral Lemnisucs
What are the two primary nuclei of the Superior Olivary Complex
Medial Superior Olive (MSO) high
Lateral Superior Olive (LSO) low
What type of input does the SOC receive from the CN (cochlear nucleus)
ipsi (same side) and contra (opposite side)
SOC is the first site for what kind of interaction
Binaural
What is Binaural interaction
Processing information from both sides
What are two responsibilities of the SOC
Localization and Stapedial reflex function
What does ACSLIM stand for?
A-Auditory Nerve C-Cochlear Nucleus S-Superior Olivary Complex L-Lateral Lemniscus I-Inferior Colliculus M-Medial Geniculate Body
What does ipsilateral mean
same side
What does contralateral mean
opposite side
Give an example of a contralateral connection
left body controlled by right brain
What does auditory nerve make initial connection with
cochlear nucleus
What are the two nuclei of the Lateral Lemniscus
Dorsal - responds to low freq.
Ventral - responds to high freq.
What is another name for nuclei of Lateral Lemnisucs
Upper Pontine
What is another name for Superior Olivary Complex
Mid Pontine Nuclei
Where does the nuclei of lateral lemniscus receive most of its contralateral fibers from
CN and SOC
What is another name for Inferior Colliculus (IC)
Mid-brain nuclei
What kind of center is the IC
Major Binaural Center
Where does the IC receive most of its ipsi and contra fibers from
SOC and VNLL (ventral nucleus of lateral lemniscus)
The IC connects with what through what tract
Medial geniculate body–brachium
Name the three nuclei of the Medial Geniculate Body
Dorsal, Ventral, Medial
What is another name for Medial Geniculate Body
Thalamic Nuclei
What is the VMGB(Ventral medial geniculate body) sensitive to
HF acoustic stimuli
What is auditory radiation
When auditory fibers from the MGB fan out to the auditory cortex
What is another name for the auditory cortex
Heschl’s Gyrus
Where is the auditory cortex located
In the temporal lobe
What kind of fibers does the auditory cortex receive
Auditory radiation fibers
What are the three important cortical areas that the auditory fibers from the MGB radiate
Primary Auditory Area
Association/Wernicke’s Area/#22
Insula
What is included in the vasuclar anatomy
Brainstem and cortex
What portion of the brain makes up the ACA (Anterior cerebral artery)
Medial 3/4ths
What portion of the brain makes up the MCA (Middle Cerebral artery)
Lateral 3/4ths
What areas are included in the lateral 3/4ths of the brain
Heschl’s gyrus, Insula and Parietal areas
Two types of Intracranial Tumors
Intrinsic/Intra-axial
Extrinsic/Extra-axial
Intrinsic/Intra-axial tumors located…
inside the brain tissue (glial cells)
Extrinsic/Extra-axial tumors located…
outside the brain tissue (meningeal layers and nerve roots) Ex: acoustinc schwannomas
What does ABR stand for
Auditory Brainstem responses
What is an ABR
an objective test for hearing assessment
When can an ABR be obtained
any age
What is needed to perform an ABR
Three electrodes
-on top of head
-behind each ear
Clicks
What do the clicks of an ABR produce
- synchronous AP
- clear ABR recording
- information about he hearing status between 1000-4000Hz
Explain where each of the five major waves of an ABR come from
1&2-auditory nerve
3-cochlear nucleus
4-SOC
5-lateral lemniscus
What are the markers for an ABR waveform
latency and amplitude
what is latency of an ABR
Time of onset of each ABR waveform
Where does absolute latency occur for the 1,3,5 waveforms
between 60-70dBHL
What are the normal values for the 1,3,5 ABR waves
1st-2msec
3rd-4 msec
5th-6 msec
what are the normal relative interpeak latency values for the ABR waves
I-III, III-V: 2 msec
I-V: 4msec
Describe the results of an ABR if a cochlear lesion or conductive hearing loss occurs in the patient
absolute latencies are prolonged and abnormal
interpeak latencies are NORMAL
what are the results of an ABR if a neural lesion occurs in a patiente
absolute latencies are prolonged and abnormal
interpeak latencies are ABNORMAL
what does EOAE stand for
Evoked Otoacoustic Emissions
what are EOAE’s
low-level sounds produced in the cochlea to an evoking stimulus
recorded from the external ear canal using a sensitive low noise microphone
what are the most common types of EOAE’s
Transient Evoked OAEs
Distortion Product OAEs
What are TEOAEs obtained from
brief stimuli
clicks
tone burst
what are DPOAEs obtained from
pairs of puretones
cubic DP is most prominent and investigated
Clinical Applications of EOAEs
- screening for HI-newborns
- Evaluating cochlear OHC function
- monitoring changes in cochlear function
- evaluation interaction between two ears
- by stimulating the efferent system
What is another name for the efferent system
olivocochlear bundle
What does OCB stand for
Olivocochlear bundle
Describe the LOCB
20% uncrossed
unmyelinated
originates from LSO
innervated by auditory nerve dendrite below IHC
Describe the MOCB
80% crossed
myelinated
originates from MSO
innervated by base of OHC
What happens when the MOCB is stimulated
decreases in:
- endolymphatic potential
- hari-cell potential
- discharge rates of afferent neurons
What happens when the LOCB is stimulated
- no change in endolymphatic or cochlear microphonic potential
- decrease in discharge rate of afferent neurons
what is a noninvasive method to evaluate the OCB
EOAE’s
What are the nonpathological variables affecting EOAEs
probe fit internal/external noise floor ear differences age gender suppression effects of the OCB
Average TEOAEs for Newborns
18-20dBSPL
Average TEOAEs for Males and Females
Male-8-13dBSPL
Female-10-15dBSPL
Suppression Effect of TEOAEs equation
TEOAE quiet-TEOAE noisy=suppression effect
13dBSPL-10dBSPL=3dBSPL
normal level suppression effect=
normal functioning efferent system
below normal level suppression effect=
inefficient efferent system (difficulty hearing in noise)
what is presbycusis
difficulty hearing in noise due to aging
difficulty hearing in noise for children
auditory processing disorder
Audiometric Selection Criteria
- 20 dB HL or less
- normal tymps
- SD in quiet of 90% or more
negative history criteria
- ototoxic drug treatment
- noise exposure
- middle ear disease
What is the function of an ALD
to help with difficulty hearing in noise
what is an ALD
assistive listening device
three examples of an ALD
- personal pocket amplifier
- personal FM auditory trainer
- bluetooth streaming device streamed to hearing aid
Help hearing loss in noise besides ALD
- Counseling
- Preferential seating
- Reduce noise in background
- Slow down rate of speech
Localization (Central Auditory Processing Skills)
ability to localize where sounds come from and turn head towards them
Speech understanding in noise (CAP skill)
ability to pay attention despite background noise
Auditory Closure (CAP skill)
filling in gaps when not heard
Auditory memory (CAP skill)
to remember things auditorally
Temporal aspects of speech (CAP skill)
Prosody-music
Intonation-monotone
Binaural integration (CAP skill)
auditory information comes in both sides
Binaural separation (CAP skill)
ability to separate auditory info in each ear and decide which to pay attention to
Following directions (CAP skill)
remember later instructions but not beginning ones
the dorsal portion of the lateral lemniscus responds to
low frequency sounds
the ventral portion of the lateral lemniscus responds to
high frequency sounds
superior olivary complex is responsible for
localization
ABR WAVE IV
stapedial reflex function
Neural fibers from medial geniculate body radiate to…
primary auditory area
insula
wierneckes area
which site of binaural interaction happens at the inferior colliculus
second site
what is the lateral surface of the brain supplied by
middle cerebral artery
why is the ABR an objective test
because the patient is passive and you have to interpret results
stimulation of the MOCB results in what
a decrease in the cochlearmicrophonic and summating potential
How do you overcome the Hz restriction in an ABR
using puretones to get specific frequency above and below 1000-4000Hz
where does ABR wave 5 originate from
lateral lemniscus
what is a useful metric that can be used clinically
latency of ABR
why would OAEs be absent in a patient
conductive hearing loss
why would newborns fail OAEs immediately after birth
fluid in the ear or earwax build up
what are EOAEs used for
hearing loss in infants
evaluate cochlear and OHC function
monitor changes in cochlear function over time
at what age is the suppression effect significantly lower
age 60+
what kind of patients benefit from ALDs
patients with CAPD (Central Auditory Processing Disorders)
what temporal aspects of speech are affected in patients with CAPD
prosidy
intonation
rhythm
what is needed to pass OAE screening
minimum 6dB higher than background noise
what results from a lesion in the primary auditory cortex
ABR normal
why are ABRs normal with a lesion in primary auditory cortex
ABR checks integrity of auditory pathways only up to lateral lemniscus
