Hard Hearing

Hearing mechanism
1. Cochlea
  1. Scala vestibuli
  2. Scala media
    1. Tectorial membrane
    2. Basilar membrane
      1. organ of Corti
        hair cells
        excited by basilar membrane vibration
        binding of short and long cilia
        influx of cations from scala media
        hair cell membrane depolarization
        cochlea stimulated
        signal carried to primary auditory area in cortex
        hearing loss
        Trauma
        Earwax buildup
        Loud sounds
  3. Scala tympani
2. sound waves conducted to tympanic membrane
  1. vibration of ossciles
    1. fluid moves in scala media
Infections
1. Otitis externa
  1. Acute, subacute, chronic
  2. Necrotizing
    1. extends to deeper tissue
    2. immunocompromised adult patients
    3. causes cellulitis, osteomyelitis
2. Otitis media
  1. due to bacterial infection
    1. Streptococcus pneumoniae
      1. Haemophilus influenzae
    2. Mastoiditis
    3. Labyrinthinitis
    4. Facial nerve palsy
3. purulent discharge
Otorrhea
1. Trauma
  1. bloody discharge
    1. chronic infection
  2. clear, watery discharge
    1. CSF
  3. mucoid discharge
    1. perforated tympanic membrane
2. Tumors
3. Foreign body
Tinnitus
1. high-pitched ringing
  1. pressure on CNVIII
  2. Inner ear fluid increased pressure
2. Subjective
  1. only audible to person with it
3. Objective
  1. heard by examiner
  2. from aneurysm
Aural polyps
1. benign growth in ear canal or middle ear
  1. Foreign object, tumor, inflammation
  2. otalgia, otorrhea, bleeding, hearing loss
Cholesteatoma
1. Congenital
  1. embryological cell remnants in middle ear
2. Primary acquired
  1. tympanic membrane retraction
3. Secondary acquired
  1. tympanic membrane injury
4. painless otorrhea, progressive hearing loss
Vertigo
1. sensation of moving environment
2. Peripheral: inner ear issue
  1. Benign paroxysmal positional vertigo
  2. Meniere's disease
  3. Vestibular neuritis
3. Central: brain issue
  1. Migraine, TBI, stroke

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