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Otosclerosis

Introduction

Otosclerosis. This is one of the commonest causes of hearing loss in young adults. It is inherited as an autosomal dominant trait with variable penetrance.  50% have a family history.

It has a prevalence of 0.5-2% with a female to male 2:1.

Pathology

Bone deposition occurs around the stapes footplate. This reduces the movement of the stapes, thereby reducing transmission to the cochlea. Eventually the stapes can become fixed causing severe conductive hearing loss.

In most cases just the stapes which is affected. However, otosclerosis can also affect the bony aspect of the cochlea and its nerve cells causing sensorineural hearing loss.

 

Otosclerosis

Symptoms

  • Usually appears in early adult life
  • Hearing loss – usually conductive
  • 85% are bilateral
  • Paracusis is common: when hearing is improved when in a lot of background noise.
  • Exacerbated by pregnancy, menstruation and menopause
  • Usually conductive hearing loss
  • 75% have tinnitus
  • Mild transient vertigo 

 

 

    Diagnosis

    • Diagnosis is mainly clinical, on examination the following may be present: progressive conductive hearing loss, a normal tympanic membrane, and no evidence of middle ear inflammation
    • 10% have Schwartz's sign – a pink tinge to the tympanic membrane
    • Audiometry with masked bone conduction shows a dip at 2kHz (Cahart's notch)
    • Imaging is not usually used for uncomplicated conductive hearing loss. However for those with sensorineural/mixed hearing loss, diagnosis may be complex. In such cases, high-resolution CT is often used

     

     

      Treatment

      • Fluoride may inhibit sclerotic progression
      • Hearing aids
      • Stapedectomy: involves removing a portion of the adherent stapes and replacing it with an implant. This technique is effective in 90% of cases
      • Microdrill and CO2 laser Stapedotomy: this involving making a hole in the stapes footplate and inserting a piston-like prosthesis. This procedure has a similar efficacy as Stapedectomy  
      • For severe disease a cochlear implant may be used

       

      References

      • Burton M, Leighton S, Robson A, Russell J (2000).  Hall and Colman’s Diseases of the Ear, Nose and Throat. Churchill Livingstone. Chapter 26 pp. 177-181
      • Drake-Lee A (1996) Clinical Otorhinolaryngology. Churchill Livingstone. Chapter 22 pp. 246-249
      • Lissauer T, Clayden G (2007). Illustrated Textbook of Paediatrics. Mosby Elsevier.  Chapter 16 pp.262-263
      • Roland N.J, McRae R.D.R, McCombe A.W (2001). Key topics in Otolaryngology Second Edition. BIOS Scientific Publishers Limited. pp 330-335
      • Image from: Geneva Foundation for Medical Education and Research. Accessed on 18/07/2011: http://www.gfmer.ch/genetic_diseases_v2/gendis_detail_list.php?cat3=1086

       

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