Physiology and Disorders of the Ear

Acute Otitis Media

PP: bacterial infection of middle ear

E:
infants/children
S. Pneumoniae
H. Influenzae
Moraxella Catarrhalis
-S. Aureus
-group A Strep

RF:
eustachian tube obstruction/dysfunction
congestion
upper respiratory infection
immune dysfunction

CM:
otalgia (ear pain)
-TM intact→pain
-TM perforation→no pain
aural pressure
decreased hearing
fever (rare)

DX:
clinical→otoscopic exam:

• erythema (redness)

• decreased tympanic membrane mobility

• opaque tympanic membrane+loss of landmarks

• tympanic membrane→bulges outward

TX:

abx x5-7 days (severe→10 days)

• 1st line: amoxicillin

• amoxicillin-clavulanate (augmentin)

• cefuroxime

• cefpodoxime

recurrent sx→ENT referral

• prophylaxis→abx

• myringotomy+myringotomy tubes

pain

• NSAIDS

• tylenol

C:
acute mastoiditis
tympanic membrane perforation
chronic otitis media

Tympanic Membrane Perforation

PP: hole in tympanic membrane

E:
sequelae of acute otitis media
trauma

CM:
hearing loss
tinnitus
otalgia
ear canal drainage

TX:

NP:

• self-healing

• swimming/bathing→earplugs

• recurrent sx+not tx→ENT referral

MX:

• topical abx

• PO abx

C:
cholesteatoma
hearing loss

Chronic Otitis Media

PP: chronic infection of middle ear+mastoid

RF: recurrent acute otitis media→inflammation

E:
P. Aeruginosa
Proteus species
S. Aureus
mixed anaerobes

CM:
chronic prurulent otorrhea (fluid coming out of ear)
otalgia (during acute flares)
tympanic membrane perforation/retraction
conductive hearing loss

DX: clinical

TX:

NP:

• remove infected debris

• water exposure→earplugs

• TM performation→ENT referral→surgery

mandatory:

• surgery

• ENT referral

MX:

• exacerbations→topical abx drops

• chronic discharge→PO ciprofloxacin BID x 1-6 weeks

Mastoiditis

PP/E: untreated acute otitis media→bx infxn of mastoid bone

CM:
pain
postauricular cellulitis
spiking fever

DX:

CT scan:
deconstruction of bony septa→joining of mastoid air cells

TX:

NP:

• hospital admit

• myringotomy→culture+drainage

• tx fail→mastoidectomy

MX: IV cefazolin Q 6-8 hrs

C: spread of infection

Cholesteatoma

PP:
keratinized squamous epithelium trapped in middle ear space→chronic infection→erosion+destruction of structures in ear

E:
form of chronic otitis media
m/c→eustachian tube dysfunction

CM:
foul smelling discharge
hearing loss

DX:
clinical→otoscopic exam

• TM refraction pocket

• TM perforation+keratin debris/granulation tissue

TX: ENT referral→surgery

C:
spreads to surrounding structures→nerves
erosion of ossicle bones
spread to facial nerve
rare→intracranial spread

Otitis Externa

PP: infection of ear canal

RF:
water exposure (“swimmer’s ear”)
mechanical trauma

E:
pseudomonas
proteus
aspergillus

CM:
auricle manipulation/touching→otalgia (ear pain)
purulent exudate in ear canal
erythema+edema of ear canal skin
edema of ear canal
rare→erythema of lateral tympanic membrane

DX: clinical

TX:

NP:

Prophx:

• protect ear from moisture

• acidification with drying agent (50/50 isopropyl alcohol/white vinegar)

• avoid mechanical injury

MX→otic (ear) abx drops:

aminoglycosides

• streptomycin

• clindamycin

• gentamycin

• amikacin

fluoroquinolones

• ciprofloxacin

• ofloxacin

• moxifloxacin

C:
periauricular cellulitis
malignant otitis externa

Cerumen Impaction

PP: plug of ear wax in external auditory canal

RF: attempts at entering ear canal

E: self-induced

CM:
ear itching
discomfort
fullness
trouble hearing
tinnitus
dizziness

DX:
clincal→otoscopic exam

TX:

NP:
mechanical removal

• suction

• irrigation

MX:
detergent ear drops+irrigation

• 3% hydrogen peroxide ear drops+irrigation

• 6.5% carbamide peroxide ear drops+irrigation

Eustachian Tube Dysfunction

PP:
eustachian tube not ventilating properly→air trapped in middle ear becomes absorbed→negative pressure→fluid accumulation

RF/E:
eustachian tube lining edema
viral upper respiratory infections
seasonal allergies

CM:
aural fullness
discomfort with changes in barometric pressure
yawning/swallowing→popping/cracking sound→partially blocked

DX:
clinical→otoscopic exam

• retraction of tympanic membrane

• decreased mobility on pneumatic otoscopy

TX:
NP:

• autoinsufflation

• avoid air travel/rapid changes in altitude/underwater diving

persistent→ENT referral

• tympanostomy tube

• balloon dilation of eustachian tube

MX:

• systemic (PO)+intranasal decongestants

• allergies→intranasal corticosteroids

Serous Otitis Media

PP: eustachian tube dysfunction→negative middle ear pressure→ fluid in middle ear

E/RF:
child
upper respiratory tract infection (URI)
barotrauma
chronic allergic rhinitis
unilateral+persistent→must exclude nasopharyngeal carcinoma

CM:
asx
or
conductive hearing loss
aural fullness

DX:
clinical→otoscopic exam

• dull/hypomobile TM

• air bubbles in middle ear

• air fluid level

• impaired hearing

TX:
NP:

• “watch and wait” x6 weeks

• tx ET dysfxn

• persisting with tx→ENT referral→ventilating tube

MX:
controversial

• PO corticosteroids

• PO antibiotics

C:
hearing loss
progressing→acute otitis media

Conductive Hearing Loss

PP:
mechanical disruption of external auditory canal/middle ear→impaired conduction of sound

E:
impacted cerumen
eustachian tube dysfunction
stiffness
discontinuity

CM:
impaired air conduction→diminished hearing
increased bone conduction→pt. hears things as loud→soft speaking voice

DX:
audiologic testing
determination→CT scan

TX:

• hearing aids

• surgery→TM repair

C: depends on underlying etiology

Sensorineural Hearing Loss

PP:
problems in the organ of Corti/nerve pathways to the auditory cortex→inner ear or central auditory pathway deficit→gradual/sudden-onset diminished hearing

E:
m/c→aging/presbycusis
congenital
hereditary
consistent loud noise
meneire disease
ototoxicity
systemic disease (DM/autoimmune dx/paget’s/etc.)
stroke/trauma/idiopathic→medical emergency

CM:
sudden onset/gradual diminished hearing
sudden→sensoneurial hearing loss→medical emergency (idiopathic/stroke/trauma)

DX:
audiologic testing
determine defect→MRI

TX:
depends on underlying etiology

• inner ear deficits→cochlear implants

• idiopathic/sudden hearing loss→urgent corticosteroids

C: depends on etiology

Presbycusis

PP: age-related hearing loss→sensoneurial effects

RF:

• noise trauma

• mx

• genetics

E: 65+ y/o

CM:
hearing loss

• progressive

• symmetrical

• often high frequency

• may be subclinical

TX:

• prevent hearing loss

• auditory rehabilitation
  -m/c→hearing aid
  -cochlear implant

C: impact on quality of life

External Ear Anatomy

superficial to deep

1. ear lobe

2. pinna/auricle
   -outside of ear

3. external auditory meatus/external auditory canal
   -tube leading to middle ear

4. mastoid process
   -filled with mastoid air cells

Middle Ear Anatomy

superficial to deep

1. tympanic membrane
   -separates external ear from middle ear

2. tympanic cavity
   -chamber in temporal bone

3. eustachian tube
   -tube that leads from middle ear→nasopharynx

4. ossicles
   -malleus (hammer)
   -incus (anvil)
   -stapes (stirrup/spur)

Inner Ear Anatomy

cochlea

• spiral/snail-shell part

• fxn→hearing

vestibule

• middle part

• fxn→equilibrium

semicircular canals

• posterior→tubelike structures

• fxn→equilibrium

Cochlea Anatomy+Function

contains 3 chambers:

scala vestibuli+scala tympani

• osseous labyrinth
  -bony outer shell

• perilymph
  -fluid

cochlear duct/scala media

• membranous labyrinth

• endolymph
  -fluid→contains high K+ (potassium) content

organ of corti:

• inside cochlear duct

• contains hair cells+supporting cells

hair cells

• hearing receptors

function

1. impulses transmitted to cochlear nerve (CN8)

2. travel to auditory cortex in brain

Barotrauma of the Ear

PP: rapid altitude changes→middle ear can’t equalize barometric pressure

RF:

• poor ET fxn

• congenital→narrow

• acquired→mucosal edema

E:
ear damage from:

• scuba diving

• flying

• barometric pressure severity→scuba diving>flying

CM:

• barometric stress→pain or vertigo

DX: clinical

TX:

allergic congestion/URI→avoid scuba diving

• descend slowly

• equilibriate in stages

• pain in first 15 feet of diving→abort

• TM perforation→do not dive

flying

• descent→swallow/yawn/autoinsufflate frequently

• prophx→take several PO decongestants
  -pseudoephedrine

• 1 hr before landing→topical decongestant
  -phenylephrine

C:

• hemotypmanum

• perilymphatic fistula

• acute labyrinthe dysfxn

• decompression sickness

Otosclerosis

PP: progressive+abnormal growth of the bony otic capsule (bony labyrinth)→decreased hearing

E:

• damage to stapes footplate

• genetics

CM: progressive hearing loss
-conductive hearing loss

DX: CT scan

TX:

• hearing aid

• stapendectomy

C: cochlear otosclerosis→permanent sensorineural hearing loss