rest of what is on the midterm Flashcards
normal length and diameter of Eustachian tube
31-38mm long and 2-3mm in diameter
how is the eustachian tube in children different from adults?
- it is shorter in children
- more horizontal and less angulated
- the bony portion is relatively longer and wider in diameter
normally ET is ______ at rest
closed
muscle that causes active dilation of the ET
tensor veli palitini
muscle which assists in active dilation and provides support
levator veli palitini
muscle of the ET with undefined function (control pressure in the ME)
salpingopharngeus, it is located at the end of the ET
muscle of the ET not thought to play a role in ET function
tensor tympani muscle
physiologic functions of the ET
1) ventilation of the middle ear- through repeated opening
2) drainage of middle ear secretions via mucociliary transport system
3) protection from excessive nasopharyngeal secretions
ET dysfunction
failure of the et to open when swallowing which prevents pressure equalization and creates an optimal condition for the development of OME
5 causes of ET dysfunction
1) mechanical obstruction (intrensic or extrinsic)
2) functional obstruction (common in infants; poor tensor veli palatini muscle function)
3) temporary (acute upper respiratory tract infection-utri)
4) intermittent (allergies)
5) permanent/craniofacial defects (cleft palate, orofacial malformations)
more causes of ETD
ET function changes with age
- ascending in aircraft= high ME pressure which sucks nasopharyngeal secretions into ME
- descent in aircraft or scuba= negative ME pressure; stagnation of secretions in the ME
otorrhea
occurs when there is a reflux of nasopharyngeal secretions into ET; caused by TM perforation or after mastoid surgery
what happens when valsalva is performed
breaks the negative pressure in the ME and clears effusion
politzerization
inflates the middle ear by blowing air up nose and swallowing at the same time; same effect as valsalva
two types of tymps with intact TM
1) normal ET function would have intact TM and normal TPP
2) ET dysfunction and intact TM would have abnormally negative TPP
perforated TM
tymps are flat with large volume
when to do ETF tests?
if there is abnormal MEP
*ask pt to swallow and repeat tymp; if swallowing does not work, perform ETF tests
photoelectric technique of examining ET
measure light transmitted through ET by putting a light in by ET opening and measuring in the EAC
ET catheterization method of examining ET
- normal blowing= patent ET
- whistling sound= partial blockage of ET
- no sound = complete obstruction of ET
- bubbling sounds = middle ear catarrh
causes of Patulous ET
- alteration of anatomic components
- chronic ME diseases
- radiation therapy
- hormonal contraceptive pills
- pregnancy
- fatigue and stress
- weight loss
patulous ET treatment
- reassurance
- weight gain
- injection of meds
purpose of multifrequency tymps
to use 2+ probe frequencies to meausure Ya or Ba/Ga characteristics across a broad spectral range
normal control of middle ear
- stiffness controlled at a frequency below the RF
* mass controlled at a frequency above the RF
effect of otosclerosis on Ya tymp
- ear is stiffness controlled over a wider range of frequencies
- an increase in RF
- Y vector will be recorded in the lower quadrant
effect of ossicular discontinuity
- mass controlled at a lower frequency range
* decrease in RF compared to normal
what is the purpose of multifrequency tymps?
to determine if the ME is mechanically normal by determining the
1) RF of the middle ear
2) the B/G pattern
* ***we want to know if the middle ear is not normal if the ME is charaterized by a high or low RF
resonant frequency
the frequency where Bm=Bc (susceptance from mass= susceptance from compliance/spring
normal resonant frequency values
- using Ba measures: 800-1200Hz
- —-normal middle ear RF is 1000Hz, but the range of normal is very wide thus it can be difficult to use the RF to diagnose ME pathology
- using Ya measures: 800-2000Hz
how to determine RF
you want to use an array of tymps and see the change in tymp shape as a function of the probe frequency
- *look at:
1) admittance tymp (Y)
2) susceptance tymp (B)
3) phase angle
how to identify the RF
again use an array of tymps (as frequency increases, the shape of the component progresses from single peaked to notched)
RF on an admittance (Y) tymp
the RF is the lowest frequency at which the Ya tymp notches, the disadvantage of this is because the Ya tymp is a combo of B and G tymps which leads to an error in notching
RF on a susceptance (B) tymp
the RF is the lowest frequency at which the B tymp notches
* the center of the notch is below the negative tail of the tymp and is at 0daPa?
RF based off of phase angle
the RF is the frequency where the phase angle is =0 degrees
*this is found by sweeping frequencies from 500-2000HZ while holding the pressure in the ear canal constant, the phase angles are then plotted as a function of frequency (this is of little value and have unreliable measures due to artifacts
interpretation of number of peaks based of the Vanhuyse Model
1B1G and 3B1G=stiffness
3B3G and 5B3G=mass
Ya vector between 90-45 degrees
1B1G; ME is stiffness dominated
Ya vector between 45-0 degrees
3B1G; Ya is calculated at the center of the notch; ME is stiffness dominated
Ya vector between 0- negative 45 degrees
3B3G; ME is mass controlled
Ya vector between negative45 and negative 90 degrees
5B3G; Ba tymp develops a 2nd notch; ME is mass controlled
vanhuyse types that may be seen with ME pathology
- B tymp with more than 5 extrema
- G tymp with more than 3 extrema
- abnormal notch width
- -if the distance b/t the outermost B extrema is greater than 75daPa for a 3B pattern or greater than 100 daPa fro a 5B3G pattern
how B and G should look at lower frequencies
- @ low freq up to 452:
- —B&G single peaked
- —B is higher than g
- Above 452:
- —B&G amplitudes are = (cross)
- Around 565 &678:
- —expect B to notch -B falls below G
the higher the probe frequency, the ______ _______ the patterns
more complex (the greater the # of extrema)
pressure sweeping from _______ to _______ will result in less complex tymps
positive to negative
two most commonly used probe freq
226Hz and 678Hz
*many are beginning to include 1000Hz as a third freq
sweep of pressure
recommend
frequency of the probe is held constant and the pressure is varied (uses the conventional method to acquire tymp but also uses additional frequencies)
**lower RF
***good if you expect a stiffness-related pathology
sweep of frequency
frequency of the probe is varied while pressure is held constant
- higher RF
- *faster if a # of tymps must be collected
- *preferable for infants and children if 2-3 tymps are needed
- **preferable in cases of mass related pathology
high impedance pathology
higher freq tymps are important to reveal impedance changes in some stages of OME
low impedance conditions
a pt with a history of TM atrophy
- 226 Hz tymp is type Ad
- multifrequency tymp to exclude the possibility of ossicular disarticulation
- **with ossicular disarticulation, patterns occur at low frequencies
disadvantages of high frequency tymps in identifying mass pathology of ME
1) not commonly used
2) senstitivity as diagnostic test for otosclerosis is not high
3) multiple pathological conditions may coexist and obscure the true cause of hearing loss
* the more lateral and less significant pathological condition dominates the tymp
limitations to multifrequency tymps that Wideband helps overcome
can only measure to 2000Hz max, but this is not representative of all the frequencies we measure in tone tests
who developed energy refelctance (ER) and energy absorbance (EA) tymps
douglas H Keefe
equiptment for WBER and WBA measures
- mimosa’s middle ear power analyzer (wbMEPA)
* research system from Interacoustics
WBA/WBR
wide band reflectance and wide band absorbance
*these measurements are not pressurozed
WBT
wide band tympanometry
*pressurized
WB acoustic reflex
wide band AR
*can be recorded at a lower level so they are less painful/invasive than normal reflexes
*mean of 13 dB lower than clinical reflex threshold
(72dB as opposed to 85dB for typical threshold)
what does power reflectance measure?
middle ear inefficiency
*normal ear the acoustic power/energy is absorbed by the cochlea
what does power absorbance measure?
middle ear efficiency
*the transmission of sound
is refelctance tymp affected by ear canal properties?
no, pressure is not used and so the ear canal is not distorted and the stimulus (chirp from 125-10700HZ is measured in how much is reflected from the TM
energy reflectance equation
energy reflectance= reflected power/incident power
- if all energy is reflected. ER=1
- if all energy is passed into middle ear ER=0
wideband reflectance
power reflected as a function of frequency; expect low frequencies to be reflected more and speech frequencies to be reflected the least
why use reflectance?
- without pressurization there is greater reliability in infant ears to control for the effect of canal wall distensibility
- insensitive to probe location in the ear canal
- potentially greater sensitivity to ME function and disorders than tympanometry
- frequency-domain (measuring reflectance as a function of frequency): simple interpretation of efficiency of ME
how is reflectance measured
data acquisition using computer averaging techniques in sec. reflectance of each click is averaged
*chirp of 82 msec? but she said 32 chirps/sec?
clinical applications of energy reflectance/Energy absorbance
- newborn hearing screening: reduce false positives also also differentiate between middle ear and sensorineural loss if oae’s are failed
- middle ear disorders:
- acoustic reflex measure (less loud)
normative reflectance data
varies by frequency:
- <1000Hz is high reflectance
- 2000-4000Hz is low reflectance
reflectance pattern for those with TM perforation
lower energy reflectance across frequencies (makes sense because everything can get into the middle ear)
reflectance pattern for those with otosclerosis
higher than normal energy reflectance (ER) at frequencies under 1000Hz
reflectance pattern for those with ossicular discontinuity
deep, low frequency notch (low reflectance in low tones)
reflectance pattern for those with down syndrome
have low reflectacne for high frequencies when reflectance normally is high again
variables affecting ER
1) age- babies have less reflectance b/c they have more mass; they are more driven towards high frequencies
2) gender
3) ethnicity
energy absorbance equation
energy absorbance (EA)= 1-ER *this is because ER is a ratio
WBA without pressurization
wide band absorbance
* will be mirror image of energy reflectance off the x-axis (will go up instead of down)
WBA with pressurization
wide band tympanometry
*3D graph showing tymps at each frequency as well as absorbance at each pressure
effect of age on WBT
no significant difference between groups?
(presumably this is as long at they are <6mo
ER/EA advantages
provides info about the power transfer to the middle ear across a broad frequency range
- uses signal averaging (32 clicks?)
- improved microphone sensitivity: more sensitive to middle ear pathology and acoustic reflex threshold
the three primary acoustic reflex characteristics
- the presence or absence of the reflex
- the reflex threshold
- reflex decay
stapedial (acoustic) reflex
reflexive contraction of the middle ear muscles in response to an intense sound
- stapedius and tensor tempani muscle
- *measured using immittance techniques (how much the contractions lowered the admittance
origin
point of attachment of a muscle on a stationary bone
insertion
point of attachment of a muscle on a moving bone
tensor tympani muscle
origin: wall of the ET
insertion: manubrium of the malleus
innervation: V nerve
* contraction occurs mainly by tactile stimulation (not acoustic)
* contraction pulls the malleus inwards tightening the TM and increasing Za
non-acoustic reflexes
non-acoustic reflex arc depends on where the stin is stimulated
*trigeminal (V), facial (VII), glossopharyngeal (IX), and vagus (X) nerves send info to the reticular formation which controls muscle tone and piosture, communicates and activates the VII motor nucleus, activating the stapedius muscle
stapedius muscle
origin: around the facial canal in the pyramid (posterior wall of the ME)
insertion: head of the stapes
innervation: stapedial branch of the facial (VII) nerve
smallest muscle in the body (6mm long and 5mm^2 wide)
*contracts by acoustic and nonacoustic stimulation
*contraction pulls stapes down and out of the oval window increasing Za (bilateral response)
**acoustic is auditory reflex
**a tactile response results from stimulation around the pinna
both of the middle ear muscles do this
stiffen the ME transmission system and increase the impedance
three theories for the importance of the ME muscle reflexes
1) protection theory= protect cochlea from damage from loud sounds (low freq)
2) interference prevention= separate signal and noise
* **nonacoustic reflex response to chewing, talking, head movement serving to attenuate low freq body noise allowing high freq sensitivity to remain unchanged
3) desensitization= unimportant sounds such as eating, talking, yelling, and internal sounds
right contra with probe reference
probe in the right ear, stimulus in the left (clinic)
right contra with stimulus reference
stimulus in the right ear, probe in the left (Kaf)
four neuron ipsi pathway
primary pathway:
1) cochlea to ventral cochlear nucleus
2) VCN to superior olivary complex
3) SOC to VII motor nucleus
4) VII to stapedius muscle
three neuron ipsi pathway
secondary pathway/ fewer fibers:
1) cochlea to ventral cochlear nucleus
2) VCN to VII motor nucleus
3) VII to stapedius muscle
primary contra pathway
1) cochlea to ventral cochlear nucleus
2) vcn to medial soc on the contra side
3) soc to facial nerve nucleus
3) facial nerve VII to contralateral stapedius muscle
secondary contra pathway
1) cochlea to ventral cochlear nucleus
2) VCN to ipsi soc
3) soc crossover to Facial nerve neclues
3) facial nerve to stapedius
to have an acoustic reflex, all these must work
- middle ear and conchea
- VIII nerve afferent
- brainstem neurons (CN and SOC)
- facial nerve
- stapedius muscle
how to determine site of pathological involvement with reflexes
the comparison of ipsi and contra responses
threshold to know that what you are seeing is a reflex
0.02-0.03 deflection; reflexes should be done at TPP, and an airtight seal is very important
normal range for reflex thresholds
70-100dB HL with an 85 dB HL mean for tones
- 20dB less for BBN
- normally thresholds are present for stimulus levels 70-80dB SL (in other words above the hearing threshold for that test frequency)
difference in dB between ipsi and contra thresholds
contra thresholds are 3-5dB higher than ipsi with the exception of 2000Hz. (note: ears should be symmetric; in other words there should be less than a 10dB difference between right and left contra, and less then a 10dB difference between right and left ipsi
effect of age on ART
no effect with tones, art increases with advancing age ( must be louder)
non-acoustic reflex
tactile; is larger than the acoustic reflex, can interfere with accurate ART with a wiggly child
monophasic response (for ART)
increase in Za
biphasic response for (ART)
decrease in Za at the onset of the response, the increase in Za
- momentary contraction of the stapedius
- changes the coupling between the stapedius footplate and cochlear fluid
- stiffness pathology such as early otosclerosis, Cogan’s syndrome, stapes fixation (elasticity changes in the stapes and annular ligament associated with fixation of the footplate)
- **normally may occur in healthy ears when using high frequency tones (600-700Hz)
when not to do reflex testing
- severe recruitment
- hyperacusis
- tinnitus
what is acoustic reflex decay
admittance (Ya) measured over time
- measures the ability of the stapedius muscle to maintain sustained contraction
- also called adaptation
- decline in acoustic reflex contraction for a sustained acoustic activating signal
how to present AR decay
at 500 and 1000Hz
- normals no not show decay at these frequencies but everyone decays at 2000 and 4000Hz
- stimulus is 10dB above ART
- present for 10 seconds duration
reflex half-life
the time required for the response magnitude to decline to 1/2 (decay half-life of 10 seconds or less is a positive sign for a retrocochlear lesion
AR latency
how long it takes for the AR to occur after the stimulus is presented
- aka the time interval between the onset of an intense sound and onset of ME muscle contraction
- delay is measured from the onset of the stimulus until the beginning of the reflex response
- **the point at which the AR magnitude rises from baseline to 10% of its eventual max amplitude
ARLT stands for
Acoustic Reflex Latency Test
normal latency at 500,hz 1000, 2000, and 4000
500=102.8ms 1000=101.9ms 2000=127.7ms 4000=147.3ms *these would be seen with normal, cochlear HL, and cortical lesion?
long latency for ARLT
anything over 200ms
*this shows retrocochlear pathology
when is ARLT most effective?
when both ipsi and contra measurements were made
*both absolute latency and ILD were considered
ARLT advantages
a valid, cost-effective, simple clinical procedure
*requires only minor modifications of tympanometers
ARLT limitations
- age effect
- averaging techniques
- test-retest reliability
