Otology

Question 1

Recognize conductive versus sensory hearing loss on an audiogram.

Answer 1

conductive hearing loss: bone conduction normal, air conduction abnormal (air bone gap)*****

Sensory hearing loss:
changes in pure tone threshold

Neural: changes in word recognition scores or clarity of hearing

Question 2

Audiogram

Answer 2

x axis: hearing level (decibel units; 0dB is the normal threshold for hearing a particular pitch)

y axis: different pitches using frequency of 250-8000Hz

Circles right ear
X left ear

Pure tone thesholds: represent the “sensory” or cochlear aspect of hearing function.

Word recognition score represents the ability to discriminate words at normal conversation loudness levels (neural aspect of hearing ability– 8th n. and central auditory pathways)

Sloping: low freq heard better
rising: lower freq heard worse.

Question 3

Conductive hearing loss

Answer 3

Involves disorders of the external ear canal, tympanic membrane, and middle ear ossicular chain that impair transmission of sound to cochlea

Question 4

Sensory hearing loss

Answer 4

Involves the sensory transduction apparatus within the cochlea.
Manifests with changes in pure tone hearing threshold.

Question 5

Neural hearing loss

Answer 5

Involves disorders of the 8th nerve and central auditory pathways.
Manifests as changes in word recognition scores or the clarity of hearing.

Question 6

Causes of Conductive Hearing Loss

Answer 6

Otitis media
TM perforation
Cholesteatoma
Otosclerosis
Congenital aural atresia

(With testing: normal bone conduction, abnormal air conduction= air bone gap)

Question 7

Causes of sensory hearing loss

Answer 7

Hair cell loss –most common pathology causing hearing loss –(presbycusis, noise trauma (acute vs chronic (industrial 80 dB 8 hr; 90dB, 4 hrs)), ototoxicity (aminoglycosides, cancer agents, macrolides, ASA, quinine, loop diuretics, hydrocodone, viagra), genetic factors (environ 25%, idiopathic 25%, genetic 50%–nonsyndromic vs syndromic 70%–most are aut recessive, with 50% of these in Connexin 26/GJB2 )
**non-syndromic mutations most common

Also: endolymphatic hydrops (expansion of the endolymphatic compartment of the inner ear. Assoc w/ recurrent vertigo, sensorineural heaing loss, tinnitus, and aural fullness referred to as Meneire’s Disease)

Also: loss of endocochlear potential due to systemic metabolic disorders (DM, hypothyr, renal failure, arteriosclerosis) impaired blood flow, immune dysfunc (lupus, cogans, sarcoidosis, granulomatosis, autoimm inner ear disease)(should be +80 mV for normal functioning of organ of corti, potential maintained by stria vascularis (pumps K ions into scala media)

Question 8

Presbycusis

Answer 8

Gradual, progressive bilateral hearing loss caused by degenerative physiologic changes assoc w/ aging.
Decreased hearing threshold sensitivity.
Decreased ability to understand supra-threshold speech.
Central auditory process impairment.

Question 9

Menerie’s disease

Answer 9

associated with endolymphatic hydrops, a cause of sensory hearing loss.

Question 10

Causes of Neural Hearing loss

Answer 10

8th nerve tumors (vestibular schwannoma/acoustic tumor)
Auditory neuropathy
Multiple Sclerosis

Hallmarks: asymmetry of hearing b/t two ears, reduced speech perception scores

Question 11

Mainstay of treatment for SNHL

Answer 11

hearing aids

others: implantable hearing aides (in devel), cochlear implants (stim to 8th nerve in cochlea) for infants >1 with profound HL and adults with progressive HL where conventional hearing aids are no longer effective. Speech and language training and assistive devices are good adjuncts

Question 12

Word recognition score more for…

Answer 12

more of a neural test (hair cell, 8th n, brain itself)