Conductive Hearing Loss Overview

Conductive Hearing Loss

• Hearing loss is a result of a problem with the outer or middle ear.
• Sound waves may not reach the inner ear, or not reach the inner ear with sufficient intensity.
• If a person can hear, but the sound is muffled, this could indicate conductive hearing loss.
• Examples of conductive hearing loss include:
  • Otosclerosis.
  • Otitis Media.

Otosclerosis

• Otosclerosis is a condition that disrupts the movement of the bones in the middle ear.
• The condition causes gradual and significant hearing loss that is usually progressive.
• Otosclerosis is more common in women and there is a familial link to the condition.
• Otosclerosis can be treated using either a surgical procedure known as Stapedectomy or Hearing Aids.
• In severe cases, a Cochlear Implant may be necessary.

Otitis Media

• Otitis Media is an inflammation of the middle ear cavity.
• This inflammation is often accompanied by fluid build-up and sometimes the tympanic membrane is intact.
• Otitis Media may be asymptomatic.
• Diagnosis is based on an external visual exam, otoscopy and tympanometry.

Sensorineural Hearing Loss

• Affects the inner ear, the auditory nerve, or both.
• Sound signals may not reach the brain properly.
• This results in distorted or muffled sound.

Prevalence of SNHL in Children

• Approximately 1 in 1,000 live births are diagnosed with SNHL.
• No risk factor is established for approximately 40% of children diagnosed with hearing loss.
• Approximately 9.3% of school-aged children experience bilateral hearing loss, and 11.3% experience unilateral hearing loss.
• Only 0.8% of children with bilateral hearing loss and 0.9% of children with unilateral hearing loss have hearing loss greater than 26db.

Prevalence of SNHL in Adults

• SNHL is one of the most common chronic health problems.
• Approximately 1 in 10 Australians experience SNHL.
• SNHL is strongly associated with functional decline and depression.
• 11% of adults experience bilateral higher frequency hearing loss, and 4.6% experience bilateral lower frequency hearing loss.
• There are strong associations with age, with hearing loss increasing with age.

Causes of SNHL: Congenital

• Genetic transmission accounts for approximately 50% of cases.
• Approximately 30% of cases are syndrome-related.
• Over 400 syndromes are associated with hearing loss.

Causes of SNHL: Syndromes with Hearing Loss

• Waardenburg Syndrome: Approximately 70% of cases experience bilateral sensorineural hearing loss
• Usher Syndrome: Causes hearing loss, retinal degeneration, and associated abnormalities.
• Goldenhar Syndrome: Results in ear abnormalities within the oculo-auriculo-vertebral spectrum.
• Down Syndrome: Hearing loss of all types is reported in 66% of cases, and middle ear fluid accumulation is reported in 60-80% of cases.

Causes of SNHL: Environmental

• Prenatal:
  • Maternal infections in the first trimester, including:
    • Congenital rubella syndrome: Hearing loss, microcephaly, IUGR, and meningoencephalitis.
    • Congenital syphilis: Hearing loss due to abnormalities of the cochlea
    • Cytomegalovirus: Varying degrees of hearing loss.
  • Fetal Alcohol Syndrome and other use of ototoxic agents.
• Perinatal:
  • Trauma (e.g., forceps damage), infection or anoxia.
  • Jaundice.
  • Low birth weight.
  • Preterm births account for 0.7-1.5% of cases.
• Post-natal:
  • Prolonged administration and/or high doses of ototoxic drugs.
  • Infectious diseases, including:
    • Meningitis.
    • Mumps.
    • Measles.
    • Encephalitis.

Noise-Induced Hearing Loss

• Long-term exposure to occupational or social noise.
• Gradual onset.
• Outcome depends on:
  • Intensity.
  • Duration.
  • Frequency.
  • Susceptibility of the person
• Damage more likely to occur in the outer cells.

Presbycusis

• Age-related degeneration of the inner ear.
• Bilateral and progressive
• Onset around age 50, but more rapid for men than women.
• 40% of people in Western countries over the age of 75 experience presbycusis.

Ménière's Disease

• Affects the membranous inner ear.
• Characterized by fluctuating hearing loss and tinnitus.
• Symptoms include:
  • Vertigo.
  • Aural fullness and/or tinnitus.
• Typically, the onset occurs between the ages of 40 and 50, although cases have been reported in children.
• There is a familial trend associated with the condition.

Head Trauma

• Overt fracture of the temporal bone can cause a cochlea fracture.
• May be accompanied by conductive loss resulting from:
  • Fracture of ossicles.
  • Tympanic membrane rupture.
• The facial nerve may also be affected in 20-40% of cases.

Effects of Hearing Loss

• Exacerbated by demanding situations where attention is needed for:
  • Auditory input.
  • Visual input.
  • Cognitive processes.
• Loss of visual and gestural cues for scaffolding comprehension.
• Psychological implications including:
  • Shame and embarrassment.
  • Denial.
  • Loss of autonomy.
  • Depression.
  • Anxiety.
  • Frustration.

Mitigating the Effects of Hearing Loss in Clinical Interactions

• Speak loud and clear and encourage others to do so.
• Provide counseling and support to patients.
• Advise families on communication strategies for interacting with patients.
• Implement appropriate communication strategies.