Chapter 32 - Hearing Loss, Ototoxicity

Question 1

What does medical clearance for hearing aids mean?

Answer 1

Make sure to evaluate for other causes of HL other than presbycusis

Question 2

4 common ototoxic medications

Answer 2

Aminoglycosides/Vanc, platinum based chemo, loop diuretics (lasix, ethacrynic acid), salicylates/NSAIDs

Renal impairment increases ototoxicity for all these drugs that are renally excreted

Question 3

Top 4 causes of CHL

Answer 3

Cerumen impact
OME (most common in kids)
TM perf
Otosclerosis

Can also have FB in canal

Question 4

Top 3 causes of SNHL

Answer 4

Presbycusis
Noise exposure
Hereditary

Less common: trauma, ototoxicity, sudden idiopathic HL, autoimmune, Menieres, tumors, meningitis, viral labyrinthitis

Question 5

3 steps to eval/treat sudden SNHL

Answer 5

Audiogram
Steroid burst (oral) then taper or trans-tymp
MRI IAC to r/o acoustic neuroma

Question 6

When to get imaging for hearing loss

Answer 6

T-bone trauma
cholesteatoma
tumor (glomus, acoustic neuroma)
Children (especially prior to any surgery beyond PE tubes)

Question 7

Most common rads finding in pediatric SNHL

Answer 7

enlarged vestibular aqueduct

Question 8

Maximal amount of CHL, what it means if its over 50

Answer 8

Max is 60 d

Over 50 is likely ossicular chain abnl (ossicular chain disruption typically causes >50db HL)

Question 9

History items for eval of HL

Answer 9

lateral, duration, severity, progression
otalgia, tinnitus, otorrhea, vertigo, aural full
ototoxic meds, head trauma, FHx 
autoimmune
surgery

Question 10

TM compliance

Answer 10

Increased (Ad) - ossicular chain discontinuity

Decreased (As) - otosclerosis

Question 11

Age at which presbycusis typically starts

Answer 11

after 60

Question 12

Otoacoustic emissions vs auditory brainstem response

Answer 12

OAE: outer hair cell response to acoustic stimulation

ABR: CN VIII, CNS produce sounds in response to an acoustic stimulation, tests electrical conductivity of hearing signal up brainstem

Question 13

Incidence and risk factors for cong HL

Answer 13

1-3 per 1000
RF: FHx childhood-onset permanent HL, ToRCH (toxo, syph/parvo/varicella, rubella, CMV, herpes), NICU >48 hr, craniofacial abnl (esp pinna/EAC), syndromes
Also: BW <1500g, hypoxia, hyperilirubinemia, low APGAR, head trauma, ototoxic meds

Question 14

Hearing milestones to 2 years

Answer 14

0-3mo: startled by loud, calmed by familiar
6mo- localize
9mo- respond to name, mimic sounds
12mo- first words
18mo- follow simple commands
2yr- say 20+ words, put together 2-word sentence

Question 15

Which imaging to get for SNHL

Answer 15

Children- MRI or CT T bones for all SNHL

Adults- MRI IAC w/ contrast for sudden or suspect acoustic neuroma

Question 16

How aminoglycosides cause HL

Answer 16

damage vestibular and cochlear hair cells
Strepto and gentamicin vestib>cochlear
Opposite for neomycin, tobramycin

Question 17

How vancomycin causes HL

Answer 17

potentiates effect of aminoglycosides, doesn’t appear to be ototoxic on its own

Question 18

How cisplatin causes HL

Answer 18

damage outer hair cells

Question 19

How loop diuretics cause HL

Answer 19

stria vascularis damage

Question 20

How NSAIDs/aspirin cause HL

Answer 20

cochlear damage with high doses

Completely reversible with d/c drug, almost always

Question 21

How ototoxicities present, audiogram findings and how to tailor audiogram to this concern

Answer 21

tinnitus, then perceive hearing loss
Symmetric, high frequency first
Test pure tones and DPOE at 8-20 kHz, because first effects are seen at frequencies >8 kHz

Question 22

How to treat profound bilateral SNHL

Answer 22

here you can use a cochlear implant rather than hearing aid

Question 23

Options to treat unilateral SNHL

Answer 23

HA
contralateral routing of signals (CROS)
BAHA

Question 24

How CROS works

Answer 24

hearing aid on poorer hearing ear used as microphone

transmits sound to better hearing ear

Question 25

How BAHA works

Answer 25

turns sound energy into vibrational energy

vibration transmits through skull to the BETTER hearing ear

Question 26

Causes of sudden SNHL

Answer 26

Usually idiopathic

Rarely: acoustic neuroma, syphilis, lyme disease, vascular disease, autoimmune disease

Question 27

Treatment Suddent SNHL

Answer 27

oral burst
taper 10-14d, max dose 60mg/d
Or transtympanic

Question 28

Immune-mediated SNHL

Answer 28

bilateral, rapidly progressive
roaring tinnitus
Tx with high dose steroids (max 60mg/d 4wk), then taper
Immunomodulators for recurrent (MTX)

Question 29

How barometric trauma presents

Answer 29

usually pain due to INC middle ear pressure
Can lead to TM perf
Rarely, pressure change can lead to SNHL

Question 30

Hearing loss due to head trauma

Answer 30

SNHL due to T-bone fx through cochlea

CHL due to fx of ossicles or TM

Question 31

Hearing loss due to acoustic trauma: temporary or permanent?

Answer 31

Can be either

Question 32

Otosclerosis: present, cause, audiogram finding, treatment

Answer 32

fixation stapes footplate in oval window
due to abnormal bone remodeling
CHL uni or bilat
Carhart notch pattern (10-15 db DEC in BONE conduction at 2000 Hz)
Many cases hereditary
Tx stapedectomy or HA

Question 33

When to evaluate serous effusion with nasopharyngoscopy

Answer 33

Unilateral > 3mo or without preceding AOM

Any serous effusion associated with recurrent epistaxis, HA, vision change, painless neck mass

Question 34

Indications for PE tubes in kids

Answer 34

Effusion > 3mo with documented HL
Recurrent (3 in 6 mo, 4 in 12 mo)
Complicated AOM (meningitis, CN VII, mastoiditis)
Vestibular problems?

Question 35

How does SCC dehiscence lead to HL?

Answer 35

Also called layrinthine fistula
Creates a third window into inner ear (other than round/oval)
sound energy lost through fistula

Question 36

Signs of labyrinthine fistula on physical exam

Answer 36

Tullio - dizzy/nystagmus after loud sound

Hennebert- dizzy/nystag after valsalva or pneumatic otoscopy