Chapter 32 - Hearing Loss, Ototoxicity Flashcards
What does medical clearance for hearing aids mean?
Make sure to evaluate for other causes of HL other than presbycusis
4 common ototoxic medications
Aminoglycosides/Vanc, platinum based chemo, loop diuretics (lasix, ethacrynic acid), salicylates/NSAIDs
Renal impairment increases ototoxicity for all these drugs that are renally excreted
Top 4 causes of CHL
Cerumen impact
OME (most common in kids)
TM perf
Otosclerosis
Can also have FB in canal
Top 3 causes of SNHL
Presbycusis
Noise exposure
Hereditary
Less common: trauma, ototoxicity, sudden idiopathic HL, autoimmune, Menieres, tumors, meningitis, viral labyrinthitis
3 steps to eval/treat sudden SNHL
Audiogram
Steroid burst (oral) then taper or trans-tymp
MRI IAC to r/o acoustic neuroma
When to get imaging for hearing loss
T-bone trauma
cholesteatoma
tumor (glomus, acoustic neuroma)
Children (especially prior to any surgery beyond PE tubes)
Most common rads finding in pediatric SNHL
enlarged vestibular aqueduct
Maximal amount of CHL, what it means if its over 50
Max is 60 d
Over 50 is likely ossicular chain abnl (ossicular chain disruption typically causes >50db HL)
History items for eval of HL
lateral, duration, severity, progression otalgia, tinnitus, otorrhea, vertigo, aural full ototoxic meds, head trauma, FHx autoimmune surgery
TM compliance
Increased (Ad) - ossicular chain discontinuity
Decreased (As) - otosclerosis
Age at which presbycusis typically starts
after 60
Otoacoustic emissions vs auditory brainstem response
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
Incidence and risk factors for cong HL
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
Hearing milestones to 2 years
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
Which imaging to get for SNHL
Children- MRI or CT T bones for all SNHL
Adults- MRI IAC w/ contrast for sudden or suspect acoustic neuroma
How aminoglycosides cause HL
damage vestibular and cochlear hair cells
Strepto and gentamicin vestib>cochlear
Opposite for neomycin, tobramycin
How vancomycin causes HL
potentiates effect of aminoglycosides, doesn’t appear to be ototoxic on its own
How cisplatin causes HL
damage outer hair cells
How loop diuretics cause HL
stria vascularis damage
How NSAIDs/aspirin cause HL
cochlear damage with high doses
Completely reversible with d/c drug, almost always
How ototoxicities present, audiogram findings and how to tailor audiogram to this concern
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
How to treat profound bilateral SNHL
here you can use a cochlear implant rather than hearing aid
Options to treat unilateral SNHL
HA
contralateral routing of signals (CROS)
BAHA
How CROS works
hearing aid on poorer hearing ear used as microphone
transmits sound to better hearing ear
How BAHA works
turns sound energy into vibrational energy
vibration transmits through skull to the BETTER hearing ear
Causes of sudden SNHL
Usually idiopathic
Rarely: acoustic neuroma, syphilis, lyme disease, vascular disease, autoimmune disease
Treatment Suddent SNHL
oral burst
taper 10-14d, max dose 60mg/d
Or transtympanic
Immune-mediated SNHL
bilateral, rapidly progressive
roaring tinnitus
Tx with high dose steroids (max 60mg/d 4wk), then taper
Immunomodulators for recurrent (MTX)
How barometric trauma presents
usually pain due to INC middle ear pressure
Can lead to TM perf
Rarely, pressure change can lead to SNHL
Hearing loss due to head trauma
SNHL due to T-bone fx through cochlea
CHL due to fx of ossicles or TM
Hearing loss due to acoustic trauma: temporary or permanent?
Can be either
Otosclerosis: present, cause, audiogram finding, treatment
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
When to evaluate serous effusion with nasopharyngoscopy
Unilateral > 3mo or without preceding AOM
Any serous effusion associated with recurrent epistaxis, HA, vision change, painless neck mass
Indications for PE tubes in kids
Effusion > 3mo with documented HL
Recurrent (3 in 6 mo, 4 in 12 mo)
Complicated AOM (meningitis, CN VII, mastoiditis)
Vestibular problems?
How does SCC dehiscence lead to HL?
Also called layrinthine fistula
Creates a third window into inner ear (other than round/oval)
sound energy lost through fistula
Signs of labyrinthine fistula on physical exam
Tullio - dizzy/nystagmus after loud sound
Hennebert- dizzy/nystag after valsalva or pneumatic otoscopy
