Hearing Loss Flashcards

1
Q

Anatomy of middle ear

A
  • Manubrium of malleus attached to tympanic membrane
  • Head of malleus articulates with incus
  • Footplate of stapes is attached to oval window
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2
Q

Types of hearing loss

A
  1. Conductive
    - from external ear canal to stapedial footplate
    - bone conduction preserved but air conduction diminished (air-bone gap)
  2. Sensorineural
    - from stapedial footplate onwards
    - both bone and air conduction diminished to same extent below normal hearing thresholds
  3. Mixed
    - both conductive and sensorineural hearing loss
    - both bone and air conduction below normal hearing thresholds with air-bone gap
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3
Q

Causes of conductive hearing loss

A

Problem disruption of acoustic energy reaching inner ear

External ear:
- Obstruction of ear canal by wax, foreign body, tumour, exostosis, atresia
- Otitis externa
- TM perforation or retraction

Middle ear: (all middle ear conditions)
- Acute otitis media
- Otitis media with effusion
- Chronic suppurative otitis media
- Cholesteatoma
- Otosclerosis
- Temporal bone trauma
- Ossicular malformation, fixation, dislocation

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4
Q

Causes of sensorineural hearing loss

A

Problem with cochlea/auditory nerve

Acquired:
- Noise-induced hearing loss: affects high frequencies
- Age-related hearing loss/presbycusis: affects high frequencies
- Infective/inflammatory: meningitis, labyrinthitis, mumps or measles, autoimmune
- Ototoxic drugs: aminoglycosides, frusemide, antimetabolities e.g. methotrexate
- Neurologic: acoustic neuroma, cerebellopontine angle tumour, Meniere’s disease
- Perilymph fistula
- Sudden onset SNHL

Congenital:
- Hereditary: syndromic or non-syndromic
- Teratogens
- Intrauterine TORCH infections
- Perinatal factors: Anoxia, Kernicterus, Prematurity

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5
Q

Congenital syndromic causes of SNHL

A

Hearing loss occurs with other syndromes:
1. Waardenburg syndrome (AD) → changes in pigmentation of skin, hair (white forelock), blue eyes
Melanocytes pathological, melanocytes are involved in middle ear
2. Treacher Collins syndrome → underdevelopment of facial bones
3. Branchio-oto-renal syndrome (AD)
→ Preauricular pits/tags
→ Renal anomalies
→ 2nd branchial arch abnormalities (neck discharging sinuses)

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6
Q

Presbycusis (age-related hearing loss)

A

Seen in elderly
Age related bilateral sensorineural hearing loss
Symmetrical
Commonly associated with tinnitus

*Normal rinne’s and weber’s test

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7
Q

Inner ear barotrauma

A

Sudden large change in ambient pressure when diving or flying
- Sensorineural hearing loss

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8
Q

Meniere’s disease

A

Associated with vertigo lasting for hours
Tinnitus
Aural fullness
SNHL that is episodic (12-24h)

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9
Q

Acoustic neuroma/Vestibular schwannoma

A

Benign tumour originating from vestibular portion of CN VIII (E.g., vestibular schwannoma)

Symptoms: Tinnitus, disequilibrium, dizziness, headaches, SNHL

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10
Q

Sudden sensorineural hearing loss

A

Sudden SNHL is acute unexplained hearing loss, usually unilateral, <72hours
- 3 days, 3 contiguous frequency, 30dB

Prognosis: Spontaneous improvement is common, can be idiopathic

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11
Q

Subjective hearing tests

A
  • Pure tone audiogram
    For kids:
  • Play audiogram
  • Visual reinforcement audiometry
  • Behavioural audiometry

*requires patients to cooperate

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12
Q

Objective hearing tests

A

Otoacoustic emission
- Measure movement of outer hair cells in inner ear
- Good for screening but not diagnosis

Auditory brainstem response audiometry
- Measure response in brainstem to stimulus
- Child needs to be sedated → Movement can interfere with potentials

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13
Q

Audiogram for sensorineural hearing loss

A
  • Air and bone conduction equally affected (<25dB)
  • Indicates pathology in inner ear
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14
Q

Audiogram for conductive hearing loss

A
  • Air conduction does worse than bone (air-bone gap typically > 20db)
  • Indicates pathology in outer/ middle ear
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15
Q

Audiogram for presbycusis

A
  • Ski-slope appearance
  • Bilateral SNHL worse at higher frequencies (hard to hear speech)
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16
Q

Audiogram for noise-induced hearing loss

A

Bilateral SNHL
Dips at 4000Hz air conduction and recovers at 6000Hz

17
Q

Screening for paediatric patient

A

Universal Newborn Hearing Screening (UNHS)
- Early identification and intervention for hearing loss is essential for normal speech, language and educational development

Aims
1. Screen by 1 month
- Otoacoustic emission (OAE)/ Auditory Brainstem Response Test (ABR)
- Done first few days of life

  1. Complete hearing evaluation by 3 months of age
    - Definitive test: Auditory brainstem response testing
  2. Commence rehabilitative efforts by 6 months of age
    - Hearing aids
18
Q

Management of adult hearing loss

A

Hearing aids
1. Conventional (air conduction) hearing aids
- Can treat both SNHL / CHL / Mixed HL
- Fitted by audiologist customized to hearing configuration
- Different fit / designs
- Connectivity to smartphone

  1. Bone Conduction hearing aids
    - Needs to have good bone conduction thresholds (<45dBHL-55dbHL)
    - Better results than AC hearing aids if air-bone gap is > 30dbHL
    - BAHA excellent connectivity to smart phones

Surgical treatment for CHL
1. Tympanoplasty / Ossiculoplasty
2. Bone conduction / middle ear implant surgery

Surgical Treatment for SNHL
1. Cochlear implant
Indications:
- Severe to profound bilateral sensorineural hearing loss
- Not getting benefit with hearing aids
- Alternative to non-verbal communication - Sign language Writing / text to speech devices

19
Q

What is a significant air bone gap to be considered conductive hearing loss?

A

> 10db across at least 2 readings

20
Q

Audiogram for otosclerosis

A

Dip in bone conduction at 2000hz aka Carhart’s notch due to immobilisation of stapes plate

21
Q

Causes of cortical hearing impairment

A

Problem with central auditory processing
- Central auditory processing disorder
- Cortical deafness

22
Q

Rinne test results interpretation

A

Air > Bone:
- Normal
- Symmetrical (loss)
- Predominantly SNHL

Bone > Air:
- Predominantly CHL

23
Q

Weber’s test results interpretation

A

Central
- Normal
- Symmetrical (loss)

Lateralises to affected ear
- Predominantly CHL

Lateralises to better ear
- Predominantly SNHL

24
Q

X & O in audiogram represents

A

air conduction

25
Q

< >, [ ] in audiogram represents

A

bone conduction

26
Q

Management for vestibular schwannoma

A
  • Small (<1.5cm): monitoring
  • Medium (1.5-2.5cm): radiation vs surgical excision
  • Large (>2.5cm): surgery preferred

Surgery
- Translabyrinthine vs retrosigmoid approach

27
Q

Paeds: Inheritance of non-syndromic hearing loss

A

Autosomal recessive most common

28
Q

Paeds: What gene mutation is involved in inheritance of non-syndromic hearing loss

A

Connexin-26 mutation

29
Q

Paeds: Management for congenital hearing loss

A

Auditory rehabilitation
- Early cochlear implantation

30
Q

TM perforation
- Ix
- Mx
- Cx

A

Ix:
Pure tone audiogram
Tympanogram

Type of hearing loss:
Conductive hearing loss

Mx:
Watch for 3 months
Treat infections with topical ciprofloxacin
Myringoplasty if recurrent infections

Cx:
Acute otitis media
Facial palsy
Ossicular erosion
Cholesteatoma

31
Q

Management of sudden sensorineural hearing loss

A

Oral prednisolone for 10-14 days
Oral prednisolone + hyperbaric O2 within 4 weeks
Intratympanic steroids (IT dexa) within 6 weeks

*salvage hearing loss within 2 weeks time frame

32
Q

Diagnostic criteria for sudden SNHL

A

3 days, 3 contiguous frequency, 30dB