Ear Flashcards
EAR ANATOMY
Describe the anatomy & function of the ear (including outer, middle & inner)
Outer
2x structures:
1. Auricle (pinna, concha, tragus)
2. External acoustic meatus/EAC (outer 1/3 cartillage, inner 2/3 bone) to TM
Nerves:
- Posterior/inferior- vagus
- Anterior/superior- CN3 (auricular temporal nerve)
Middle
TM to petrous temporal bone
3x structures:
1. Ossicles
- Malleus (handle TM- head incus)
- Incus
- Stapes (base oval window)
2. Eustachian tube (nasopharynx to middle ear antero-inferiorly)
3. Muscles
Limit amplitude of vibration w/ loud sounds- reflex
- Tensor tympanii (vagus)
- Stapaedius (facial)
Inner Ear
4x structures:
1. Bony & membranous (perilymph) labyrinth
2. Vestibule- equilibrium
3. Semicircular canals- equilibrium
4. Cochlea- sensory organ for hearing
EAR SYMPTOMS
Describe some manifestations of ear disorders and their causes
- Otalgia - otitis externa, referred pain (peritonsilar abscess, tonsilitis)
- Purulent otorrhoea- otitis externa, AOM with perforation, branchial cleft cyst, cholesteatoma
- Hearing loss- conductive (OME), sensorineural
- Swelling- cellulitis, peri-auricular abscess
- Vertigo- peripheral (labyrinthitis, perilymphatic fistula (trauma/congenital), cholesteatoma, BPPV, Menieres), central
- Nystagmus- vestibular
- Tinnitus- OME/eustachian tube dysfunction, pulsatile= AVM
HEARING TESTS
Describe the types of hearing assessments and what age group they are appropriate for.
0-3 months (up to 2yrs): Auditory Brainstem Response/ABR
- measures EEG brainstem response to clicking noise
- tests at 35dB
- pass or fail- 50% of fails have permanent HL
- A-ABR used in neonatal screening (mod-severe HL)
- can distinguish normal or conductive HL
> 6mo: Behavioral observed
- voice/tones are played in sound field, look for response
6mo-2yrs Visual re-inforced
- Turn head towards sound, paired with toy
2-5 yrs: Conditioned play
- Children learn to do task when sound plays- i.e stack blocks
>4yrs: Kendall Toy test
- Two toys infront of child, auditory prompt to grab one
>4-5yrs: Pure tone audiometry
- Audiometry at different frequencies/dBs to determine hearing threshold
- Tests both air and bone conduction
- Vertical axis: Db (loudness), logarithmic- conversation = 45dB
- Horizontal axis: Frequency (pitch) Hz
- Right = O, < (bone) Left = X, > (bone)
- Air bone gap = conductive hearing loss or mixed
- SNHL = both air = bone
Tympanometry
Assess membrane compliance = middle ear function
- TM compliance
- Ear canal volume (Y)
- Middle ear pressure (X)
1. Type A tympanometry - normal/most common- peaks at atmospheric pressure
2. Type B tympanometry- fluid or perforation (next most common)
3. Type C tympanometry- eustachian tube dysfunction (least common)
Pneumatic otoscopy
- Gold standard for OME
- Measures movement of drum
Acoustic reflectometry
- Measures reflection f sound from TM, if OME sound reflected will be louder (usually <50%)
Rare (any age) Otoacoustic Emissions
- Tests structures of hearing
- Measures potentials (spontaneous/evoked) of hair cells- when stimulated
- Cannot detect neuropathy
HEARING LOSS (OVERVIEW)
Outline the types/severity ratings of hearing loss and causes. What are some other investigations you might order and considerations for management
Hearing Loss
1/1000- mild-mod at birth
Severity: Mild = 20-30dB, Moderate 30-50 dB, Severe 50-70 dB, Profound >70
Types: Central, Sensorineural (peripheral), Conductive
- *Causes:**
- Congenital: genetic 50%, ⅓ syndromic, ⅔ non-syndromic
- Acquired: pre, peri & postnatal causes (see table)
Other Ix:
History, examination- height, weight, HC, ?dysmorphic, skin lesions, neuro
Pure tone audiometry & tympanometry (to characterise), vestibular function testing
- Genetic testing +/- metabolics, autoimmune screens
- Ophthalmology- acuity & fundoscopy
- CMV most common infection +/- TORCH
- ECG- (long QT/developmental delay- Jervell and Lange Nielsen syndrome)
- Urinalysis (haematuria- Alports) +/- renal U/S
- MRI- cochlea, intracranial lesions
Management
- Speech therapy
- Educational aids
- Alternative communication methods- Auslan, sign systems, gestures, written
- Hearing devices- aids, cochlear implant, BAHA, VTS device, assistive device
- Conductive HL: grommets
- SNHL: Cochlear implant (if >12mo, profound HL, failed hearing aids)
SENSORINEURAL HEARING LOSS (1)
Outline congenital/genetic causes of sensorineural hearing loss
- Structural
- Perilymphatic fistula
- Inner ear malformations
- Genetic (1/2,000 births)
Non-syndromic (2/3rds)
- 80% autosomal recessive
- Bilateral mod-profound SNHL
- GJB2 gene encoding connexin 26 (chromosome 13)- regulates K+ metabolism in cochlea
- 35delG mutation - Europeans
- 15% autosomal dominant (delayed/progressive)
- 2% X-linked recessive
- 1% Mitochondrial
Syndromic (1/3rd)
Chromosomal
- Trisomy 21/Down’s (mixed/SNHL)- narrow EAC, higher risk OME, ossicular abnormalities
Autosomal dominant
- Waardenburg syndrome 1 & 2
- white forelock, wide eyes, iris pigmentation changes
- Branchio-oto-renal syndrome
- external ear malformations/microtia, mixed HL, branchial malformations +/- renal malformations (less common)
- Treacher-Collins syndrome
- microtia/middle ear malformation= mixed HL
- cleft-palate
- CHARGE
- semicircular canal hypoplasia, variable/mixed HL
Autosomal recessive
- Pendred syndrome (thyroid)
- SNHL & goitre, hypothyroid or normal function, enlarged vestibular aqueduct
- Usher syndrome (eyes)
- SNHL, visual loss (retinal dystrophy)- tunnel vision/poor night-time acuity
- Jervell & Lange Neilsen syndrome (heart)
- Long QT, SNHL, arrythmias characterised by syncope/sudden death
- Alport syndrome (kidneys)
- Affects type IV collagen
- Nephritis, lens defect, progressive SNHL
Mitochondrial - often multisystem diseases
Unknown
- Goldenhaar (microtia, cleft lip, under-developed jaw, eyes, mouth, facial muscles)
- Hereditary neuropathies- Charcot-Marie-Tooth, Freidrich Ataxia
SENSORINEURAL HEARING LOSS (2)
Outline acquired causes of sensorineural hearing loss
- Intrauterine infections
- CMV most common
- Toxoplasmosis (prevent with pyrimethamine)
- Rubella
- Syphillis (delayed) - Perinatal insults
- Hypoxia
- Prematurity/ low BW (<1.5kg)
- Bacterial meningitis - Post-natal
- Infections (OM, labyrinthitis, meningitis)
- Ototoxic drugs (ABx- aminoglycosides, macrolides, vancomycin, tetracyclines, chemo- cisplatin, 5FU, bleomycin, salicylates)
- Trauma
- Metabolic bone disease (osteopetrosis)
- Neoplastic infiltrations, acoustic neuroma
- Noise exposure
- Hyperbilirubinemia
OTITIS EXTERNA
Define, then outline causes/risk factors, symptoms, diagnosis. treatment & complications
OTITIS EXTERNA
Infection/inflammation of external auditory canal
Risk factors
- Prolonged/excessive wetness- swimming, bathing, humidity
- Excessive dryness
Causes
- P. Aeruginosa
- Gram +ve & Gram -ve skin/ENT commensals (S. aureus, S. epidermidis, Proteus spp, Klebsiella spp.)
- Fungi- candida, aspergillus
- Atopic dermatitis, sebhorreic dermatitis, psoriasis, acne
Symptoms - clinical diagnosis
- Severe otalgia
- Otorrhoea (clear, purulent)
- Erythematous, swollen EAC
Treatment
- Topical antibiotics (ciprofloxacin drops & hydrocortisone)- 7 days
- Ear canal toilet- hydrogen peroxide, betadine, ear wick, ear spears
- IV antibiotics- flucloxacillin: 5 days- if cellulitis, piperacillin/tazobactam:14 days if systemic features, severe pain or failure of Rx
Complications (usually immunocomprimised, diabetics- rare)
- Nerve palsies (Bell’s)
- Vertigo
- SNHL
OTITIS MEDIA (1)
Define, then outline epidemiology, risk factors, causes & symptoms
Otitis media
Infection/inflammation of middle ear
- Acute
- Recurrent (3 in 6mo, 4 in 12mo)
- Chronic: effusion, perforation/suppurative (central/safe, atticoantral- unsafe, marginal & can lead to cholesteatoma)
Epidemiology
- 50% children experience before 12mo, 70% before 3 years, 75% by school age
- Peak incidence first 2 years of life
Risk factors
- Host: age <6-12mo, atopy, cleft palate/craniofacial deformities, immunocompromise, ATSI
- Environment: family member with AOM, daycare exposure, multiple siblings, smoking/air pollution, dummy use/bottle feeding
- Protective- breastfeeding
Causes
- 75% bacterial/other- S. Pneumoniae (35%), Haemophillus (25%), Moraxella (15%), S. Aureus, GAS
- 25% viral
Symptoms
- Ear pain
- Fever
- Decreased oral intake
- Vomiting
- Lethargy
OTITIS MEDIA (2)
Outline examination findings, diagnosis & natural history
Otitis media
Examination: bulging TM, hemorrhagic, injected or cloudy, +/- perforation
Diagnosis (clinical)
- History: acute onset symptoms/signs- ear pullinng/otalgia, otorrhoea, malaise, anorexia, fever
- Exam: Bulging TM, decreased movement on valsalva, air/fluid level, perforation
Natural history
- 80% resolves in 1-2 weeks without treatment (NNT 7)
- 70% will have effusion by 2 weeks
- OME- 60% resolve in 1 month, 90% by 3 months
- 2-7 days ABx reduces pain by 40%
OTITIS MEDIA (3)
Outline the course (recurrent, OME, chronic OME, suppuritive) & complications of otitis media
Otitis media
Examination: bulging TM, hemorrhagic, injected or cloudy, +/- perforation
Diagnosis (clinical)
- History: acute onset symptoms/signs- ear pullinng/otalgia, otorrhoea, malaise, anorexia, fever
- Exam: Bulging TM, decreased movement on valsalva, air/fluid level, perforation
- Pneumatic otoscopy (OME)
- Audiology & tympanometry (OME)
Natural history
- 80% resolves in 1-2 weeks without treatment (NNT 7)
- 2-7 days ABx reduces pain by 40%
Treatment
Analgesia
Antibiotics
- If well/no red flags- watch and wait for 48h
- If not improving high dose amoxicillin 30mg/kg BD → augmenting
- red flags: ATSI, immunocompromised, single hearing ear/cochlear implant, <6mo
Follow up
- Observe for hearing loss/language delays 3-6mo
Ear toilet/betadine or hydrogen peroxide washes if chronic suppuritive
Consider surgical management (grommets) if:
- Bilateral
- >3mo
- Symptomatic
- Risk factors
- Complex/co-morbidities
- At risk of S&L delay
Nb: no improvement in outcome, symptomatic relief, extrude 9-18mo
Complications
Localised
- TM perforation
- Persistent effusion → conductive HL
- Chronic OM ()
- Ossicular necrosis
- Cholesteatoma
- Mastoiditis
- Labyrinthitis
CNS
- Meningitis
- Brain abscess
- Venous sinus thrombosis
- Facial nerve palsy
Mastoiditis- define & detail clinical signs. Differentiate between acute & chronic, outline investigations, treatments and complications
Mastoiditis: inflammation or infection of mastoid air cells
Clinical signs: boggy, erythematous & tender swelling over mastoid bone. Ear protrusion. +/- OME/AOM
Acute: younger patients, complication of AOM, S.Pyrogenes/S.Pneumoniae
Chronic: older patients, P. Aeruginosa
Diagnosis
- Clinical
- CT Temporal bones to confirm- opacification (OME), bony erosion
Treatment
- IV ABx
- Myringotomy (incision to TM to drain fluid)
- Mastoidectomy (removal of infected mastoid air cells)
Complications
- Petrositis- irritation of CN5, eye pain
- Grandengio syndrome-eye pain, rectus paralysis & suppuritive OM
INNER EAR PATHOLOGY
Define, outline symptoms, course and treatment of:
- BPPV
- Otosclerosis
- Labyrinthitis/otitis interna
- Osteopetrosis
- *Benign paroxysmal positional vertigo (BPPV)**
- Recurrent episodes of brief disequilibrium
- Caused by particles forming/accumulating in semicircular canals (posterior most common)
- Attack- vertigo, frightened/off balance child, nystagmus, sweating, N&V <1 min, no altered consciousness
- Occur in clusters- several days, then remit for weeks
- Uncommon >5yrs
- Relationship with migraines (family history)
- Rx Hallpike Manouvre
- *Otosclerosis**
- Abnormal temporal bone growth- stapes fixes to oval window, leading to hearing loss (conductive → SNHL)
- Dizziness, tinnitus, hearing loss
- Diagnosed on hearing test or CT- cochlear nerve/ossicle danage
- Teenage white females most common
- Rx vitamin supplementation, hearing aids, stapedectomy
- *Labyrinthitis**
- Inflammation/infection of inner ear structures (viral > bacterial, i.e OME)- vestibule & cochlear
- Sudden onset dizziness, tinnitus, fatigue, hearing loss
- Causes hearing loss- 20% of children affected, conductive or SNHL
- Ossicular atrophy, cochlear degeneration, otosclerosis
- Rx: steroids in acute phase, vestibular rehabilitation (physio)
- *Osteopetrosis**
- Skeletal dysplasia (rare)
- Can lead to temporal bone/ossicular dysplasia → hearing
