audiology exam 2 - inner ear anatomy, pathologies, audiologic measurement, case history

vestibule

first part of inner ear

transduction point of inner ear

Organ of Corti (hair cells)

base

bottom end of cochlea close to oval window

apex

top of cochlea

cochlea position

by bony shelf

helicotrema

narrow channel where scala vestibuli and tympani are connected

scala tympani

bottom channel where perilymph fluid exits down

scala media

middle channel that houses O of C

scala vestibuli

top channel where perilymph fluid goes up

basilar membrane

floor of scala media

tectorial membrane

roof of O of C

Reisner's membrane

floor of scala vestibuli

perilymph

fluid that fills scala vestibuli and tympani

endolymph

fluid that fills scala media

Organ of Corti

final sense organ of hearing; transduces fluid energy to electrical

modiolous

central bony core around which cochlear structures wind

stria vascularis

area of rich blood supply provides support

stiff base

responds to high frequencies

elastic apex

responds to low frequencies

tonotopic organization of basilar membrane

base resonates w/ higher frequencies and apex w/ lower

outer hair cells

3 rows

inner hair cells

1 row

transducer

hair cells in O of C converts fluid energy to electrical

purpose of O of C attaching at 1 end

allows for movement to generate shearing motion and stimulate nerves

afferent fibers

sensory nerves that carry info towards brain

efferent fibers

motor nerves that carry info away from brain

nuclei

neural waystations of info transfer along central nervous pathway

central nervous pathway

signal transfer along SLIM: superior olives, lateral lemniscus, inferior colliculus, medial geniculate nucleus

outside fibers of auditory nerve

fibers from near base (high frequencies)

inside fibers of auditory nerve

fibers from near apex (low frequencies)

spiral ganglion

group of neurons in modiolus

endogenous examples

blockage, growths, genetic disposition, aging

cerumenosis

blockage by cerumen

cochlea

nerve structure that is the end organ of hearing

syndrome

constellation of physical and mental characteristics

Waardenburg syndrome

moderate bilateral SNHL, different colored eyes, wide top of nose, non pigmented part of hair

Down syndrome

trisomy 21, intellectual disability, short stature, flat facial profile, dysplasia of pinna, enlargement of tongue, Chronic Eustachian tube dysfunction, mixed hearing loss

enlargement of tongue

articulation issues

dysplasia of pinna

atypical placement of cells/growth/development

Chronic Eustachian Tube Dysfunction causes

many ear infections

microtia

small outer ear

atresia

no opening of ear canal to pinna

anotia

absence of external ear and canal

ear pit

small groove may indicate developmental anomaly

cerumen impaction

cerumen completely blocks off ear canal

neoplasm

new abnormal tissue growth

tympanic membrane perforation

tear in TM

tympanic membrane perforation cause

buildup of pressure from fluid after infection, trauma

tympanic membrane perforation treatment

surgical patch

otitis media

infection and swelling of middle ear

otitis media risk population

kids, Down Syndrome, Native Americans, smoking families

pressure equalizing tubes

span TM to replace Eustachian tube function

aurius dominus

right ear

aurius sinister

left ear

otitis media treatment

antimicrobial medications ex. amoxicillin

otosclerosis

bone growth around stapes that limits movement of ossicles

otosclerosis treatment

stapedectomy

Carhart's notch

decreased sensitivity @ 2000 Hz

stapedectomy

surgery for prosthetic stapes

cholesteatoma

layers of skin that grow out of innermost layer of TM after chronic OM

ossicular disarticulation/discontinuity

ossicles not connected the way they should be

audiometer adjustment

down 10 up 5

red earphone

on the right

blue earphone

on the left

test frequencies

250-8000 Hz

indicator of conductive hearing loss

threshold better for inner ear

effusion

escape of fluid into tissue/cavity

sterous

thin, watery, sterile fluid (no infection)

purulent

effusion containing pus (infected)

acute

21 days or less

chronic

8 weeks or more

recurrent

3 or more episodes in 6 months

prenatal

before birth

perinatal

during birth

postnatal

after birth

TORCH list

list of potential conditions related to hearing loss

anoxia

lack of oxygen

noise induced hearing loss (NIHL)

damages hair cells and eventually nerve fibers

noise notch

dip @ 4000 Hz w/ recovery @ 8000 Hz from NIHL

ototoxicity

ear poisoning from drugs

quinine

antimalarial drug that contributes to hearing loss

aspirin

high doses can cause tinnitus and hearing loss

endolymphatic hydro drops

overproduction of endolymph on the scala media

Meniere's disease characteristics

endolymphatic hydro drops, vertigo, severe spinning, tinnitus, fluctuating SNHL, feeling of fullness

presbycusis

decline in hearing part of aging process

stria vascularis

area rich in blood supply that nourishes O of C

presbycusis site of lesion

degeneration of hair cells, O of C, central auditory processing

SLIM

superior olives, lateral lemniscus, inferior colliculus, medial geniculate nucleus

central auditory pathology characteristic

speech recognition performance poor compared to hearing thresholds

acoustic neuroma

tumor growing out of 8th cranial nerve

acoustic neuroma characteristics

unsteadiness, poor speech understanding

acoustic neuroma treatment

MRI, Gamma knife radiosurgery, surgery

multiple sclerosis

demyelination of nerves that can slow inner ear nerve impulses

normal audiogram threshold

25 dB

behavioral measures of hearing

require some voluntary behavior

parts of case history

nature of past/present hearing problems, family history, noise exposure, amplification use, medical problems, children only birth and development,

otoscopy

use otoscope to examine ear visually

hearing threshold

lowest level of response 50 percent of time

audiogram axis

frequency/dB HL

audiometer

measures hearing thresholds