SLHS 340 Test 3

Otoacoustic Emissions (OAEs)

-Function of outer hair cells contracting

-Sound goes in and the microphone records OAEs(forward and back)

-Non linear

-Pre neural potentials generated by the cochlea

-NOT a hearing test

OAE's are ____ and _____

objective and non invasive

DPOAEs

Elicited by two pure tone frequencies where f2>f1 and creates an interaction within the cochlea producing a third tone

-largest DPOAE is at 2f1-f2

Where are DPOAEs absent?

-in individuals with sensorineural HL>55dB HL

-in individuals with conductive HL

Where CAN DPOAEs be present?

in individuals with neural/retrocochlear HL

TEOAEs

Elicited by a click stimulus with acoustic energy between 2000-5000Hz

-Last about 10msec

-faster than DPOAEs

Where are TEOAEs absent?

-in individuals with sensorineural HL>30dB HL

-in individuals with conductive HL

Where CAN TEOAEs be present?

in individuals with neural/retrocochlear HL

General Evoked OAE interpretation

-Use results to evaluate OHC function at specific freq.

-does not tell us DEGREE

-TPOAE better at 1000Hz

-DPOAEs better above 2000Hz

Clinical Application of OAEs

- Newborn screening

- Pediatric assessment

- Difficult to test individuals

- Functional hearing losses

- Monitor OHC function (from ototoxic medications)

- Interoperative monitoring (facial nerve)

Auditory evoked potentials

-Measuring of auditory neural function using various time windows

-Scalp electrodes on a persons head

-record electrical activity/neural function

Auditory Brainstem Response(ABR)

-Short latency response synonym

-Auditory neural activity generated within the 8th nerve and brainstem pathways in response to sound

-consist of 5-7 waves within 10msec of stimulus presentation

ABRs are ____ and ____

objective and noninvasive

ABR Waves represent

Cells within what structures are responding

ABR Wave I

8th nerve as it exits the cochlea

ABR Wave II

proximal portion of 8th nerve

ABR Wave III

Lateral side of cochlear nucleus, mostly ventral

ABR Wave IV

superior olivary complex

ABR Wave V

lateral lemniscus and inferior colliculus

Recording Parameters of ABR

-four electrode montages at vertex(high forehead), one on each ear lobe, and a ground

-stimulus clicks are most common

-through air conduction

ABR component measures

amplitude and latency

ABR Threshold estimation

reduce the presentation level until a measurable wave V is absent

ABR threshold measures

-Some consistency with behavioral thresholds

-Can quantify amount of hearing loss

-Poorer frequency specificity compared with pure-tones

-Affected by the integrity of the neural system

Middle Latency Response (MLR)

-Occur from 10-50ms after stimulus is presented

-represent neural activity from the thalamus and parts of auditory cortex

-early cortical=MLR

Long Latency Response

-Occur 50-250ms after stimulus presentation

-Represent neural activity from sylvian fissure and superior temporary plane of temporal lobe

ABR Conductive Pathology

prolongation of all waves but interpeak latencies will remain normal

ABR Cochlear Pathology

Decreased waveform morphology and prolonged waves at lower presentation level, and normal range a higher presentation level(just messy)

ABR Retro-Cochlear Pathology

-Only have wave 5 prolongation, absent waves, or prolonged interpeak latencies

-mass blocking the pathway from 8th nerve to cochlear nucleus

External Otitis

-Inflammation of EAC → viruses/fungus/bacteria

-Audiogram: Normal → just painful

-If canal swells & shuts = conductive

-If advanced it can lead to otorrhea (discharge)

artEsia

E = EAC ( closure or absence of EAC)

Audiogram: complete atresia = conductive hearing loss

aNOtia

NO pinna (absent pinna)

Can be fixed surgically (reconstructed)

MICROtia

micro = small (small/malformed pinna)

Doesn't have to affect hearing

Exostosis

-Bony growth

-No hearing loss unless fully occluded

-Kissing exostosis = conductive hearing loss

Stenosis

-Narrowing of ear canal

-Audiogram normal BUT takes less wax to occlude

-Common in individuals with Down syndrome

Occluding/Impacting Wax

-Relatively flat (low Vec), conductive hearing loss

-May have a flat tympanogram with absent acoustic reflexes → not enough energy reaching stapedius

Excessive wax

Tymp normal → pressure bypasses wax

Foreign object

-common in children

-Audiogram: no loss unless fully occluded

-Bugs most common in adults

Collapsing Ear Canal

-​​Occurs at any age, but is more prevalent in older adults

-Unilateral or bilateral

-May affect audiometric results

-Blocking frequencies from entering the ear canal

-Air bone gap in high frequencies

Otitis Media

-Inflammation or infection of the middle ear (eustachian tube dysfunction)

-Most common in children of 2 yrs (chronic ME infections)

-Otoscopy: vascularization/ fluid behind TM

-Audiogram: normal unless lots of fluid in the ME space = conductive

-Tymp: only ET → Type C BUT if virus takes over = Type B

-Acoustic reflexes = absent → fluid blocking ME movement

Serous otitis media

thin liquid free of bacteria

Something got sucked up in the Eustachian tube w/no bacteria

Secretory otitis media

thick liquid free of bacteria

Purulent or suppurative otitis media

fluid that contains cellular debris and bacteria

tympanoSClerosis

-SCar tissue, Stiffens TM (scar tissue from PE tubes)

-Audiogram: normal but enough plaque → mild conductive

-Tymp: low in amplitude b/c the TM stiff

Otosclerosis

-Growths of spongy bone around ossicular chain and stapes footplate

-Bilateral 90% of the time

-Tymp: Type As (stiff)

-Audiogram: can be rising OR flat

conductive hearing loss → no distortion

-Absent reflexes

-HAS a Carhart Notch = worsening of bone conduction thresholds by 10-15 dB at 2000 Hz

-Can have an effect on language development

Ankylosis

-Immobilizes the footplate at the oval window and can result in

-Type B→ immobilize the stapes causing it to be fixed.

Cholesteatoma

-Cyst filled with keratin that grows within middle ear (stinky)

= due to a result of chronic otitis media

-Audiogram: progressive conductive

-Tymp: shallow or flat depending on development

-Absent reflexes on affected side

-If mass grows enough sill restrict movement to the ossicles

-Movement restriction → Type As but if worsens (left untreated) Type B (go into inner ear = balance problem)

TM Perforations

-Audiogram: most cases mild conductive

-Tymp: high Vec (perforation causes a larger volume → no pressure seal)

-Acoustic reflexes = absent

Ossicular Discontinuity

-Middle ear bones are broken (trauma or disease)

-Audiogram: flat conductive hearing loss

-Tymp: high peak admittance

-Reflexes: absent on affected side

Meniere's Disease

-Pressure equalization problems within cochlea and semicircular canals

-Only true IE pathology

-Imbalance and vertigo is extreme

-Unilateral 90% of cases

-Audiogram: Fluctuating sensorineural b/c episodic

Low frequency loss → becomes flat over time

-Word Rec: poor

Roaring tinnitus

Shshshs (roaring) precursor to Meniere's episode

Low grumble

Debilitating Vertigo

Full blown episodes

Can last a couple of days

Labyrinthectomy

Complete cleaning out of the inner ear

Sudden Sensorineural Hearing Loss

-Hearing loss with sudden onset and no apparent cause

-Can be an indicator of tinnitus (unilateral)

-Audiogram: mild to profound hearing loss w/ poor word rec

-Slight in children

-Medication to help get hearing close to normal

Noise Induced Hearing Loss

-Probably normal middle ear

-Tymp: Type A

-Notch around 3000, 4000, or 6000 Hz

-Progressive high-frequency hearing loss

Presbycusis

Age-related hearing loss

More likely in men

Ototoxic Medication types

-Loop diuretics (Furosemide).

-Aminoglycosides (-mycin antibiotics)

-Some cancer medications (Cisplatin)

-Uses DPOAEs to monitor outer hair cell function during treatment (marker for change)

Head Trauma

-Cant be found in isolation

-Type and degree of hearing loss vary according to the nature of the injury

-Conductive, sensorineural, and mixed hearing losses are all possible

Vestibular Schwannoma

-Benign tumors arising from the Schwann cells of the vestibular branch of the VIIIth cranial nerve (mass growing on auditory meatus)

-Audiogram: Progressive unilateral high frequency

Word Rec: poor

-Acoustic Reflex Decay: stapedius can't be flexed for more than 10 seconds

-Either elevated or absent acoustic reflexes

-Tinnitus on affected side

Facial Nerve (VIIth) Disorders

-Generally not related to hearing loss but because the stapedius is innervated by the VIIth nerve, an audiologist may be asked to evaluate

-Facial nerve paralysis may lead to abnormal threshold measures

Bell's Palsy

-Facial nerve disorder

-7th cranial nerve damage

-Reflexes are absent

Auditory Neuropathy

-True inner hair cell pathology

-Normal hearing using pure tones but may show hearing loss

-Poor word recognition based on pure tones

-Normal, robust OAEs

-Absent or delayed ABRs

Brainstem or Cortical Pathology

-Often have normal peripheral hearing

-Speech perception problems

-Often normal in quiet

-Possibly abnormal in noise

-Normal OAEs

-Abnormal evoked potentials