Hearing loss and deafness

Hearing loss and deafness 150 150 Tony Guo

Hearing loss and deafness

 

Causes of hearing loss

  • External ear
    • Impacted cerumen
    • Foreign bodies
    • External otitis
  • Middle ear
    • Otitis media
    • Serous otitis
    • Otosclerosis
    • Tympanic membrane trauma
    • Cholesteatoma
    • Acoustic neuroma
  • Inner ear
    • Ménière’s disease
    • Noise-induced hearing loss
    • Presbycusis
    • Ototoxicity

 

Types of hearing loss

  • Conductive hearing loss 
    • Sound transmission to inner ear impaired
      • Patients actually hear better in noisy environments
      • Patient often speaks softly
      • Identify and treat cause
      • Suggest hearing aid
    • Caused by 
      • Otitis media with effusion
      • Impacted cerumen
      • Perforation of TM
      • Otosclerosis
      • Narrowing of the external auditory canal
  • Sensorineural hearing loss  
    • Results in ability to hear sound but  inability to understand speech
      • Can lead to misunderstanding by others 
      • Hearing aids make sounds louder but not clearer
    • Caused by
      • Impairment of the inner ear
      • Vestibulocochlear nerve (CN VIII) damage
      • Congenital and hereditary factors
      • Noise trauma
      • Aging (presbycusis)
      • Meniere’s disease
    • Ototoxic drugs
      • Aspirin
      • NSAIDs
      • Antibiotics
      • Loop diuretics
      • Chemotherapy drugs
  • Mixed hearing loss
    • Central and functional hearing loss
      • Deafness in other family members often present
      • Can be psychologically or emotionally related
      • Sudden hearing loss
        • Sudden deafness
          • Unexplained, rapid loss of hearing
          • Usually affects just one ear
          • Medical emergency
      • Tinnitus
        • Perception of noise without an actual source of sound 
        • “Ringing in the ears”
        • May be first symptom of hearing loss
          • Most commonly caused by noise
          • More than 200 drugs cause tinnitus

      Classifications of hearing loss

      Decibel (dB) loss
      0-15  Normal hearing
      16-25  Slight hearing loss
      26-40  Mild impairment
      41-55  Moderate impairment
      56-70  Moderately severe impairment
      71-90  Severe impairment
      >90  Profound deafness*

      Clinical manifestations

      • Early signs of hearing loss often go unnoticed by patient
      • Pressure by others is a significant factor in whether help is sought
      • The unseen handicap
      • Understanding should be validated in patient teaching interactions
      • Obtain interpreter assistance
      • Ineffective communication and interaction can be frustrating for both patient and caregiver(s)
        • Withdrawal, suspicion, loss of self-esteem and insecurity are common psycho-emotional complications with advancing hearing loss

      Interprofessional Management

      Nursing Assessment

      • Health Promotion
        • Ototoxic substances—drugs
        • Ototoxic substances—industrial chemicals
          • Toluene, carbon disulfide, mercury
        • Monitoring is important
        • Discontinuing drug may be indicated
      • Assistive devices and techniques
        • Hearing aids
          • Fit by a specialist
          • Provide amplification, sound lateralization, speech discrimination
          • Require a motivated, capable user for optimum success
        • Speech reading
          • Lip reading
          • Visual cues associated with speech facilitates understanding for 40% of
            spoken words
        • Sign language 
          • For those with profound impairment
          • Sign language is not universal
          • American sign language (ASL) is used in the United States and in English-speaking areas of Canada
        • Amplification devices
        • Alerting systems
        • Texting systems
        • Closed caption
        • Specially trained dogs
      • Implantable hearing device or aid
        • Fully implantable
          • Nothing externally visible
        • Partially implantable
          • Have an external component worn behind or in the ear
      • Cochlear implant
        • For severe to profound sensorineural hearing loss in one or both ears
        • Ideal candidates became deaf after acquiring speech and language
        • Provides sound
        • Improves lip-reading ability
        • Enables monitoring own speech volume
        • Decreases feelings of isolation
      Nonverbal Aids Verbal Aids
      Draw attention with hand movements. Speak normally and slowly.
      Have speaker’s face in good light. Do not overexaggerate facial expressions.
      Avoid covering mouth or face with hands. Do not overenunciate.
      Avoid chewing, eating, smoking while talking. Use simple sentences.
      Maintain eye contact. Rephrase sentence. Use different words.
      Avoid distracting environments. Write name or difficult words.
      Avoid careless expression that the patient may misinterpret. Do not shout.
      Use touch. Speak in normal voice directly into better ear.
      Move close to better ear.
      Avoid light behind speaker.

      Otosclerosis

      • The most common cause of bilateral hearing loss in young adults
        • Tympanum takes on a reddish blush (Schwartz’s sign)
        • Poor air conduction
        • Treated with medications that slow bone resorption, hearing aids, and surgery

      Presbycusis

      • Hearing loss associated with aging
      Type Hearing change and prognosis
      Sensory
      Atrophy of auditory nerve, Loss of sensory hair cells Loss of high-pitched sounds. Little effect on speech understanding.

      Good response to sound amplification

      Neural
      Degenerative changes in cochlea and spinal ganglion Loss of speech discrimination.

      Amplified alone not sufficient

      Metabolic
      Atrophy of blood vessels in wall of cochlea with interruption of essential nutrient supply Uniform loss for all frequencies accompanied by recruitment.

      Good response to hearing aid

      Cochlear
      Stiffening of basilar membrane, which interferes with sound transmission in the cochlea Hearing loss increases from low to high frequencies. Speech discrimination affected with higher-frequency loss. Helped by appropriate forms of amplification

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