CSCD 4301 Final: Audiology Exam 3

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Temple University
Communication Sciences and Disorders
CSCD 4301

REVIEW – Principles of Audiology Exam 3 Interpretation of tymps, select auditory disorders, screening for hearing impairment, genetics, and behavioral hearing testing for infants and children Kramer: Chapter 8 (to page 236), 9, 10 Kramer Workbook – corresponding pages to Chapters 8, 9 and 10 Interpretation of tympanometry, Select Disorders, Screening, Genetics 1. Immittance – refers to tymps, reflexes, gradient, pressure, etc. • Non-behavioral testing • Shows conductive pathologies “objective” – but some tester error is always possible Impedance: opposition to the energy flow • High impedance = greater opposition to the flow of energy • Complex sum of mass reactance, stiffness reactance and friction (measured in ohms) Admittance: ability to transfer energy • High admittance = greater flow of energy • Determined by measuring how the SPL of the probe tone changes with applied pressure or due to the middle ear reflex in response to a reflex eliciting tone (acoustic reflexes) • Probe tone = 226 Hz at 85 dB SPL High admittance system = low impendance (vice versa) 1) Is the middle ear system compliant? Where does it move best?* (peak pressure) 2) Normal results = normal compliance at 0 daPa (atmospheric pressure) 3) Normal results = no middle ear problem, NOT normal hearing 4) Abnormal = conductive problem (NOT conductive hearing loss) * Peak air pressure on tympanogram matches the air pressure in the middle ear Negative pressure – there is a vacuum in the middle ear Positive pressure – the eardrum is bulging outward Tympanometry Measures how well energy flows through the system the system is the middle ear Admittance – ability to transfer energy • height on tympanogram, y axis (admittance and compliance used interchangeably) Peak Pressure – reflects pressure inside the middle ear cavity, x axis (ranges +200 to – 400 daPa) Volume – measures volume of space between eartip and the eardrum Small volume – cerumen Large volume – could be TM perforation, PE tube Note: volume cannot be seen on this tympanogram (See page 229 for the difference between “compensated” tymp (the one here, where the extreme points at either end go to zero 0 ml), and uncompensated. Normal (type A) • Peak admittance: 0 daPa • Systematic reduction at higher and lower pressures • Tympanometric peak pressure: pressure where tympanogram peak occurs • Admittance at +200 = volume of the ear canal (Peak Vec) • Overall peak (Peak Y): may include the admittance of both the outer and middle era • Admittance of middle ear (Ytm): difference in admittance between Peak y and Vec • Peak shape with the Ytm and the TPP within the normal range • Occurs in normal functioning middle ears • Can be found in some ears with otosclerosis or disarticulation of the ossicular chain Compensated Tympanogram: automatically removes the admittance due to the ear canal and displa only the admittance of th e middle ear 2 Reduced admittance (Type As): characteristic peak shape with the TPP in the normal range • Lower Ytm than the lower end of the normal range • Shallow • Suggests reduced movement of the tympanic membrane • May be seen in some cases of otosclerosis and some cases of otitis media • Likely to have air bone gaps High admittance (Type As or Add): • Type As: hypocompliant o peak shape with the TPP in the normal range o Ytm higher than upper end of normal range o Highly mobile tympanic membrane o Seen in some cases of disarticulation of ossicular chain or cases of thinned tympanic membranes resulting from previous middle ear infection • Type Add: hypercompliant o Extremely high Ytm: admittance may go off the chart o Highly suggestive of a disarticulation of the ossicular chain o Usually have air bone gap (conductive hearing loss) Normal admittance (compliance) at atmospheric or ambient pressure Middle ear system has normal mobility, with normal pressure (peak is at 0 ml) Hypocompliance (conductive problem - type B) - Low admittance or compliance, ≤ .2 ml - Flat with NO pressure peak - Occurs with middle ear fluid (otitis media), and with TM perforation or impacted cerumen - must make sure flat tympanogram is not due to poor placement or poor operation of the probe assembly - May or may not have air bone gaps o Normal Vec = air bone gaps o Large Vec = small perforation or PE tube. Likely to not have air bone gaps o Low Vec = foreign object or impacted cerumen. Have small air bone gap Eustachian tube dysfunction (type C): 3 - Normal admittance, negative pressure o Negative pressure may be normal due to temporary condition from sniffling or subsequent recent airplane flight - Shows there is a vacuum, or negative air space in the middle ear - Usually not have air bone gaps Tympanogram Types: - A: peak between +100 and -200 daPa, normal - As: peak but shallow: stiff: otosclerosis - Ad: peak off scale: floppy, disarticulation - B: no peak, flat, effusion - C: peak beyond -200 daPa, negative pressure Interpreting Impedance Results • Looks at flexibility (compliance) of eardrum to changing air pressures • Indicates how effective sound is transmitted into the middle ear • Allows us to view function of Eustachian tube, upper auditory pathways and reflex contraction from the middle ear muscles Which one is most highly correlated with hearing loss? Type C Acoustic Reflex Threshold: an involuntary contration that occurs in the middle ear in response to high-intensity sound stimuli or when the person starts to vocalize • Performed right after tympanogram • BILATERAL RESPONSE • Loud tone  one ear = contraction of the stapedius muscles in BOTH ears o Contraction alters transmission of sound through ossicular chain o Changes middle ear immittance • Abnormalities of cochlea, 8 cranial nerve, lower brainstem and/or 7 th cranial nerve may influence the ability to record an acoustic reflex • Reflex eliciting tones: 500, 1000, 2000 Hz o Mainly 1000 • Ipsilateral reflex: when the reflex elciting tone is presented to the same ear where the admittance is measured • Contralateral acoustic reflex: reflex eliciting tone is presented ot the opposite ear form where the admittance is being measured • dB HL below stapedius reflex threshold = no measurable change in admittance 4 • High dB HL of reflex eliciting tone  stapedius contral = admittance decreases o Downward deflection in the recording Normal reflexes – 85 dB SPL for normal hearing or hearing loss • Tone must be at least 70 dB HL to produce a measurable reflex • NORMAL RANGE: 75 – 90 dB HL o ART for broadband noise: 20 dB lower than for tones o MAX LEVEL: 115 dB HL • Testing lower than 70 dB HL = good for determining if any deflections are present due to artifacts • Testing above 105 caused tinnitus and additional hearing loss Abnormal (elevated or absent) for • Severe to profound hearing loss • Conductive problem (as with a flat tympanogram): acoustic reflex absent (instrument will not be able to record admittance change • Paralysis of cranial nerve VII (facial nerve) o 7 nerve problem is distal to stapedial branc: ART = normal o 7 nerve problem is proximal to spedial branch: ART = absent • Conductive hearing loss: o ABG > 30 dB with reflex eliciting tone = absent ART o ABG <30 dB = ART measurable between 100 and 115 Where would you see an acoustic reflex in a person who has severe to profound hearing loss? Cochlear. ART elicited at sensation level of less than 60 dB Otoacoustic Emissions (OAEs): low-intensity acoustic vibrations measured in the ear canal with a sensitive microphone • Emissions from a noormally functioning cochlea predominanly move OHC enhancing virabtions of basilar membrane  emission travel outward  middle ear ossicles - vibrate tympanic membrane  produce OAEs in ear canal Transient Eviked otoacousti Emissions: evoked by the presentation of a series of brief transients (clicks) • Broad frequency spectrum  stimulate wide portion of the basilar membrane Auditory Brainstem Response: one of a series of auditory evoked responses that can be measured from the neural pathways of the auditory system using small disk electrodes placed on the surface of the ehad Frequently occurring disorders 5 Ch 9, PPT, Blackboard file (review), videos on BB 1 2 Outer Ear Feature Hearing loss tympanometry Microtia Small, partial pinna, missing None – unless there is aural atresia lobe Normal tymp (type A) – unless Often occurs with atresia atresia Aural atresia Complete or incomplete Moderate conductive hearing loss congenital closure of the ear canal Middle Ear Feature Hearing loss, tympanometry Otitis media Middle ear inflammation Conductive or mixed hearing loss May start with Eustachian Acute, with effusion, chronic serous tube dysfunction), then develop into otitis media TM perforation Sensorineural hearing loss Inner Ear Feature Hearing loss, Tympanometry Noise-induced Acquired disorder. Noise exposure Sensorineural – degree hearing loss Ototoxic drugs, vestibulotoxic drugs depends on: type and (antibiotics, chemo, oxycontin, intensity of noise, spectral aspirin) Accidents composition of the noise, duration of exposure, rest between exposures, individual susceptibility Auditory Air and bone = 5-10 dB (no neuropathy significant ABG) Nerve may not process sound normally Presbycusis Decline in thresholds
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