hearing

Question 1

pars flaccida

Answer 1

weakest part of the ear drum -tympanic membrane

Question 2

mechanical sound deficit

Answer 2

conductive hearing loss

Question 3

sensory hearing loss

Answer 3

problem with sound conversion from mechanical to electrical signals = hair cells within cochlea

Question 4

central hearing loss

Answer 4

problems with auditory sound perception

occurs in the brain

Question 5

neural hearing loss

Answer 5

impaired electrical transmission = CH VIII damage

Question 6

causes of conductive hearing loss

Answer 6

ear canal lesions = wax, otitis externa
ear drum
middle ear = otitis media, ossicles

Question 7

tympanosclerosis

Answer 7

calcified plaque on ear drum (scar = normal)

can cause conductive hearing loss

Question 8

perforation of ear drum

Answer 8

conductive hearing loss

bumpy holes with exposed hair cells- cochlea exposed

Question 9

atelectasis

Answer 9

thinning of ear drum from retraction (negative pressure)

conductive hearing loss

Question 10

cholesteatoma

Answer 10

trapped squamous epithelium
erosion with local invasion
can cause intracranial and extra cranial complications
tx: requires surgery, 10% recurrence
conductive hearing loss = mechanical erosion of bones
sensorineural hearing loss = erosion into inner ear
coronal CT = gray area surrounding ear bones

Question 11

middle ear effusion

Answer 11

conductive hearing loss
bubble = fluid
honey-colored = infected
unilateral = common finding in nasopharyngeal tumors

Question 12

otitis media

Answer 12

middle ear conductive hearing loss
acute = PAINFUL
chronic = > 6 weeks - usually bilateral

Question 13

ossicle fixation

Answer 13

conductive hearing loss = bones can’t move properly to transmit signal

Question 14

ossicle erosion

Answer 14

conductive hearing loss

Question 15

ossicle dislocation

Answer 15

incudomalleolar dislocation = gap between bones

conductive hearing loss

Question 16

fracture of temporal bone

Answer 16

conductive hearing loss

Question 17

sensorineural hearing loss

Answer 17

nerve injury
Webber test = localizes to normal ear
Rinne test = normal (air conduction > bone conduction) = but both are decreased in affected ear

Question 18

ototoxic exposures

Answer 18

sensorineural hearing loss
chmotherapeutic drugs = Cisplatin, carboplatin, vincristine, bleomycin
antibiotics = aminoglycosides (genamycin), vancomycin, biaxin, chloramphenicol
heavy metals = mercury, lead, arsenic, gold
loop diuretics
high dose opiates

Question 19

acousitc neuroma

Answer 19

vestibular Schwannoma = neoplasm - benign growth of Schwann cells
cerebellopontine angle and into internal auditory canal
unilateral sensorineural hearing loss, tinnitus, variable dizziness
dx: MRI T1 with contrast

Question 20

genetic sensorineural hearing loss

Answer 20

non-syndromic = hearing ONLY = connexic-26

Question 21

connexin 26 mutation

Answer 21

autosomal recessive
causes sensorineural hearing loss
Gene = GJB-2 = gap junction protein important for cell ion exchange
tx: hearing airs, cochlear implant

Question 22

syndromic sensorineural hearing loss

Answer 22

usher’s syndrome
pendred’s syndrome
alport’s syndrome
waardenberg;s syndrome

Question 23

Usher’s syndrome

Answer 23

sensory hearing loss and vision loss due to retinitis pigments
leading cause of deaf-blindness
autosomal recessive
usually bilateral visual loss in 10 years

Question 24

Pendred’s syndrome

Answer 24

hearing loss and thyroid disfunction
peroxidase defect - autosomal recessive
Sx: goiter, thyroid hormone deficiency, progressive

Question 25

Alport's Syndrome

Answer 25

Type IV collagen defect kidney failure in teens X-linked (usually males)

Question 26

Waardenberg's Syndrome

Answer 26

``` defect in neural crest development dystopia canthorum = wide set eyes white forelock autosomal dominant sensorineural hearing loss ```

Question 27

tonotopic arrangement frequencies

Answer 27

frequency map - pitch representation in space = starts in cochlea and continues to cortex base of cochlea = high frequencies - caudal cortex apex of cochlea = low frequencies = rostral cortex

Question 28

frequency tuning

Answer 28

each hair cell corresponds to a characteristic frequency

Question 29

spacial representation of complex sounds

Answer 29

right and left auditory cortex have hemispheric specialization left cortex = speech right cortex = music, environmental noises

Question 30

sound localization

Answer 30

horizontal = inter aural time delay and inter aural level differences vertical (elevation) = shape of pinna

Question 31

inter aural time delay

Answer 31

delay lines = horizontal localization of low frequency sound extra time required for sound to reach other ear detect phase differences between ears

Question 32

time delay pathway

Answer 32

cochlear nerve --> medial superior olive --> ipsilateral lateral lemniscus --> inferior colliculus

Question 33

inter aural level differences

Answer 33

horizontal localization of higher frequencies (2kHz - 20 kHz) compares volumes of sound from both ears stimulation of Right CN VIII --> excitatory input to ipsilateral (Right) lateral superior olive (LSO) and inhibitory input to contralateral (Left) superior olive vis medial nucleus of trapezoid body (MNTB)

Question 34

vertical localization of sound

Answer 34

spectral notches of pinna (shape)

Question 35

tinnitus

Answer 35

perceived tone despite absence of sound stimulus constant buzzing in ears chronic = perception of sound from CNS acute = ototoxic drug, concert

Question 36

bones of the middle ear

Answer 36

maleous - connects to tympanic membrane incus stapes - connects to cochlea