Otosclerosis (Otospongiosis)

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Basics

Description

  • A primary bone dyscrasia involving the otic capsule
  • This is the leading cause of conductive hearing loss in adults.
  • There are two forms:
    • Histologic otosclerosis: asymptomatic form in which abnormal bone spares vital structures of the ear
    • Clinical otosclerosis: Abnormal spongy bone involves ossicular chain or other structures, leading to altered physiology.
  • System(s) affected: sensory, hearing

Epidemiology

Incidence
  • Predominant age
    • Clinical onset usually in early 20s
    • Peak incidence 3rd to 5th decade
  • Predominant gender: female > male (2:1)
Pregnancy Considerations
  • Progression may accelerate during pregnancy.
  • Some women first notice hearing loss at this time.

Prevalence
  • Histologic form: 4–8% among U.S. Caucasian population; 1% among African Americans
  • Clinical form: 0.3–0.4%

Etiology and Pathophysiology

Unknown; possible association with measles virus infection, hormonal factors, cytokine-related inflammation, fluoride metabolism, and oxidative stress

Genetics
  • 50–60% of those affected give positive family history.
  • Appears to be transmitted by autosomal dominant gene with variable expressivity

Risk Factors

Unknown, possibly measles virus infection

Commonly Associated Conditions

  • van der Hoeve syndrome (rare triad of osteogenesis imperfecta, blue sclera, and otospongiosis)
  • Tinnitus, usually low frequency

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Basics

Description

  • A primary bone dyscrasia involving the otic capsule
  • This is the leading cause of conductive hearing loss in adults.
  • There are two forms:
    • Histologic otosclerosis: asymptomatic form in which abnormal bone spares vital structures of the ear
    • Clinical otosclerosis: Abnormal spongy bone involves ossicular chain or other structures, leading to altered physiology.
  • System(s) affected: sensory, hearing

Epidemiology

Incidence
  • Predominant age
    • Clinical onset usually in early 20s
    • Peak incidence 3rd to 5th decade
  • Predominant gender: female > male (2:1)
Pregnancy Considerations
  • Progression may accelerate during pregnancy.
  • Some women first notice hearing loss at this time.

Prevalence
  • Histologic form: 4–8% among U.S. Caucasian population; 1% among African Americans
  • Clinical form: 0.3–0.4%

Etiology and Pathophysiology

Unknown; possible association with measles virus infection, hormonal factors, cytokine-related inflammation, fluoride metabolism, and oxidative stress

Genetics
  • 50–60% of those affected give positive family history.
  • Appears to be transmitted by autosomal dominant gene with variable expressivity

Risk Factors

Unknown, possibly measles virus infection

Commonly Associated Conditions

  • van der Hoeve syndrome (rare triad of osteogenesis imperfecta, blue sclera, and otospongiosis)
  • Tinnitus, usually low frequency

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