JC97 (ENT) - Common ear diseases and hearing loss Flashcards
Anatomical structures involved in conductive vs sensorineural deafness
Conductive:
External ear - Eardrum - Ossicles
Sensorineural:
Cochlea - Auditory nerve - Brainstem
Ddx Conductive deafness
Sound cannot be transmitted to inner ear, e.g. mechanical blockage:
Middle ear: Eardrum perforation Ossicular chain problem Chronic infection (ossicular joint erosion) Iatrogenic damage Otosclerosis (foot plate of stapes) Tumor Middle ear fluid effusion
External ear canal: congenital meatal stenosis/ meatal atresia/ microtia/ deformities e.g. cauliflower ear
Otitis externa
Wax impaction
Foreign body obstruction
Ddx sensorineural deafness
in children and adults
Children:
Born profoundly deaf, genetic
Neonatal (e.g. uncontrolled neonatal jaundice)
Adult:
Meningitis
Noise (occupation: long exposure damages hair cell)
Inner ear dysplasia/ deficient inner ear
Damage to inner ear: Ear/ head trauma Drug-induced, e.g. TB drugs (injection of gentamicin) Chronic ear infection Cochlear otosclerosis Radiotherapy
Clinical assessment of hearing loss
Thresholds assessed
Pure tone audiogram (PTA)
Air conduction (AC) threshold - softest sound heard through external auditory canal
Bone conduction (BC) threshold - Vibrator on skull, usually mastoid process
Quantify severities of hearing loss in dB
Effect of deafness on daily life
Mild: 20-40dB (e.g. cannot hear bird sing)
Moderate: 40-70dB
Severe: 70-90dB
Profound hearing loss: >90dB (e.g. cannot hear dog bark)
Childhood onset: Poor development of speech and language, education
Adult: Poor communication for social, occupational activities. Socioeconomic and safety concerns
Ddx malformations and diseases at the auricle of external ear
Congenital malformations:
- Preauricular sinus
- Accessory auricle
- Bat ear (most common)
- Microtia, Meatal atresia
Disease:
- Pinna keloid
- Perichondritis
- Herpes zoster vesicles
- Pinna carcinoma: SCC and BCC
- Haematoma auris
- Cauliflower ear
Preauricular sinus
- Pathogenesis
- Complications
Hole (sinus opening) in anterior pinna
Due to improper fusion of 6 auditory hillocks during embryonic development of auricle
Cx: Discharge and infection
Accessory auricle
Pathogenesis
Effect on hearing
improper fusion of 6 auditory hillocks during embryonic development of auricle
No effect on hearing
Effect on cosmesis, may be removed
Microtia and meatal atresia
Describe malformation
Effect on hearing
Severe deformity of pinna (external ear) increases the likelihood of deformity in middle ear
meatal atresia = no opening to middle ear at all = likely conductive deafness
Pinna keloid
Cause
Effect
Due to trauma (common esp in young ladies/ gentlemen with ear piercing at cartilage)
Infection = pinna keloid
2 infections of the auricle/ pinna of external ear
Perichondritis - infection of the cartilage of pinna
Herpes zoster vesicles: Reactivation of varicella zoster
Herpes zoster vesicles on pinna of external ear
- Cause
- Major complications
Reactivation of varicella zoster
Ramsay Hunt Syndrome:
- Vesicles on pinnae/ external auditory canal
- Sensorineural hearing loss and peripheral vertigo
- Facial paralysis
Haematoma auris
- Cause
- Complication
Cause:
- Trauma causes blood to pool under perichondrium
- Swelling of pinna causes loss of curvature
Complication:
- Cartilage without blood supply from perichondrium»_space; cartilage necrosis and permanent deformity
Cauliflower ear
- Cause
- Effect on hearing
severely deformed pinna due to repeated trauma, delayed treatment
Traumatic pinna deprived of blood supply becomes necrotic
No effect on hearing, just cosmesis
Ddx lesions in the external ear canal
- Otitis externa
- Impacted wax
- Foreign body obstruction
- Osteoradionecrosis
- Aural polyp
- Squamous cell carcinoma (skin cancer)
- Metastatic tumor from parotid gland
Impacted ear wax
- Physiological production of ear wax
- Effect on hearing
Wax = normal secretion with antiseptic property, normally pushed out spontaneously by pars tensa epithelium
Infected wax can exacerbate impaction
Conductive deafness
Foreign body obstruction in external ear canal
- Common objects
- Treatment for insect obstruction
cotton wool, plastic beads, tissue paper, Lego, earring, batteries
Treatment for insect: pour oil to suffocate it before removal
Osteoradionecrosis of external ear canal
- Most common cause
- Effect on hearing
Very common after H&N irradiation due to NPC
Necrosis of soft tissue and bone complicated by infection, discharge,
Hearing loss; Conductive, sensorineural, mixed
Otitis externa
- Common causative pathogens
- Common anatomical location affected
- Triggers/ predisposing factors
Pathogen:
- Staphylococcus aureus (from skin)
- Fungal
Anatomical extent:
- Diffuse (from skin infection)
- Localized Furunculosis at cartilaginous part of EAC
Triggers for S. aureus: Narrow ear canal (congenital, trauma) Skin disease, e.g. eczema Diabetes mellitus Humidity (“Singapore Ear”) Impacted ear wax Foreign body Water (swimming, shower) Abrasion (scratching, pricking)
Trigger for fungal: overuse of antibiotic eardrops
Otitis externa
Presentation
Pain, discharge, NO hearing loss
Note: external ear diseases seldom is the sole cause of hearing problem
(unless totally impacted wax)
E.g. otorrhoea + conductive deafness = ook for middle ear problems
Otitis externa
Treatment options
Local cleansing (remove wax/ foreign body, suction clearance)
Keep away from moisture (not to swim for 2-3 weeks)
Local antibiotic eardrops against Staphylococcus (e.g. cloxacillin, cephalexin); Antifungals
Correct causes: small meatus, osteoma
Ddx middle ear lsions
Infection:
Acute otitis media and chronic suppurative otitis media
Otitis media with effusion (blocked Eustachian tube)
Trauma:
Traumatic perforation
Hemotympanum
Tumor:
Glomus tumor
Facial nerve neuroma
Congenital Cholesteatoma
Benign tympanosclerosis
Acute otitis media
- Source of infection
- Causative pathogens
- S/S
Ascending infection from nasopharynx via eustachian tube
Causative pathogens:
- Most viral
- Bacterial: Strep. pneumoniae, H. influenzae, Moraxella catarrhalis
S/S: Pain Conductive deafness Constitutional symptoms (fever) No otorrhea unless eardrum perforated (late stage) (cf CSOM)
Chronic suppurative ototis media
Source of infection
Causative pathogens
S/S
Source:
- Severe acute otitis media (ascending infection from nasopharynx)
- Trauma: mechanical, iatrogenic, barotrauma, blast injury
- Over-use of antibiotic eardrops causing fungal CSOM
Causative pathogens: Mixed organisms: Staphylococcus aureus Pseudomonas aeruginosa Escherichia coli Bacteroides fragilis Fungus: aspergillosis, candidiasis Tuberculosis
S/S:
Recurrent otorrhoea +/- suppuration
Conductive/ mixed hearing loss
Acute otitis media
First line investigation and typical findings
Otoscopy:
Redness, congested vessels on eardrum
Usually: middle ear still filled with air
Late stage: filled with pus
Chronic suppurative otitis media (CSOM)
First- line investigation and typical findings
1) Otoscopic exam:
- Persistent, non-healing eardrum perforation
Active CSOM:
- Perforation, discharge, hearing loss»_space; Ear swab and bacteria culture**
Inactive CSOM:
- Perforation without discharge»_space; no need for bacteria culture
2) Audiological assessment: Pure tone audiogram
Define the types of eardrum perforation in chronic suppurative otitis media
Centra (safe) vs Marginal (unsafe) perforation
Central/ Safe:
- aka Tubotympanic perforation
- At pars tensa
- More common
Marginal Unsafe:
- akak attic perforation/ atticoantral perforation
- At rim/ pars flaccida
- Higher risk of complications e.g. facial nerve palsy, inner ear damage
- Associated with Cholesteatoma
Acute otitis media
Treatment options
Oral antibiotics
- Against Gram- positive bacteria: amoxicillin, erythromycin, co-trimoxazole, cefuroxime
Supportive treatment for pain, fever
Drainage myringotomy (refractory/ late stage): drain pus under GA to relieve symptoms and send for culture
Chronic suppurative otitis media
Treatment options for safe and unsafe CSOM
Local cleansing, ear mopping (remove wax/ foreign body,
suction clearance)
Broad-spectrum antibiotic eardrops (e.g. cephalosporin)
Safe CSOM: Tympanoplasty ,Hearing aid
- Hearing improvement and prevent otorrhoea
Unsafe CSOM: Compulsory mastoidectomy (remove cholesteatoma)
- remove posterior canal and prevent further complications
Intracranial complications of Chronic suppurative otitis media
Extradural abscess
Subdural abscess
Meningitis
Brain abscess – temporal lobe, cerebellum
Sigmoid sinus thrombophlebitis
Otitic hydrocephalus
Extracranial complications of Chronic suppurative otitis media
Facial nerve palsy (CN VII superior to oval window)
Ossicular chain erosion - more conductive deafness
Inner ear damage:
- Labyrinthitis (spread to inner ear) = mixed HL/ total deafness
- Lateral semicircular canal (LSCC) fistula (superior to oval window)
Subcutaneous/ subperiosteal abscess
Otitis media with effusion
First-line investigation
Pathogenesis
Otoscopy: intact eardrum but air-fluid level behind, suggesting effusion in middle ear cavity
Pathology:
o Eustachian tube normally opens during swallowing/ Valsalva’s maneuver
o Obstruction in Eustachian tube due to effusion»_space; hearing loss (conductive/ mixed)
Causes of otitis media with effusion/ Eustachian tube blockage
Mechanical:
- Enlarged adenoid/ adenoid hypertrophy (children)
- NPC (adult)
Poor mucociliary clearance in the ET tube
- Infection
- Rhinitis
- Post-irradiation in H&N cancer
ET tube dysfunction
- Cleft palate (difficulty opening ET)
- Post-op iatrogenic damage
Traumatic perforation of eardrum
First-line investigation
Prognosis
Management
Investigation:
- Otoscopy
Prognosis:
- Natural healing in 3-4 weeks if clean and without infections
Management:
- Clean and dry
- Do not clean blood to introduce infections
- Follow-up hearing loss assessment
Haemotympanum
Causes
Effect on hearing
Prognosis
Causes:
Trauma to ear
Temporal bone fracture
Hearing: Conductive hearing loss
Prognosis: self-limiting
Glomus tumor
Cause
Hearing loss
Vascular tumor in middle ear
Conductive hearing loss or mixed in advanced stage (involve inner ear)
Ddx inner ear lesions
- Acoustic neuroma at cerebellopontine angle
- Temporal bone fracture
Complications of acoustic neuroma
Which nerve does it arise from?
3 components in CN VIII – 2 vestibular nerves + 1 auditory nerve:
o Acoustic neuroma usually arises from vestibular part of nerve
Benign (does not metastasize)
Complications:
Compression on auditory nerve - Sensorineural hearing loss
Compression on CN V - CN V palsy
Compression on low cranial nerves (IX, X, XI, XII) - low cranial nerves palsy
Compression on cerebellum - cerebellar problem
Temporal bone fracture
Complications
Conductive deafness, e.g. blood in middle ear (haemotympanum), perforated eardrum, fracture line through ossicle chain
Sensorineural deafness: fracture line damages through cochlea
Facial nerve palsy (may be affected by inflammation/ swelling/ fracture)
Hearing rehabilitation options
Reconstruction of sound conducting mechanism – middle ear surgery:
o Eardrum perforation repair (tympanoplasty for safe CSOM)
o Ossicular chain surgery
Hearing aids
Cochlea implants
Types of hearing aids
o BW (body worn) – wire, headphone o BTE (behind the ear) o ITE (in the ear) o ITC (in the canal) – less obvious o CIC (completely in the canal) o Meatal atresia no ear canal need direct bone conduction at skull
Cochlear implant
- Indications
- Surgery mechanism
Bilateral profound sensorineural hearing loss (total deaf; no matter how
much amplification)
No additional benefit from appropriately-fitted hearing aid
Mechanism of cochlear implant
surgery:
All structures are defective in patient so need to stimulate nerve directly
Electrode leads to cochlea
Wear external switch processor signal sent to device to directly stimulates
cochlea
info transmitted through CN VIII (auditory nerve) to brain (auditory cortex)
