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  1. Definition:
    It is a hereditary localized disease of the bony labyrinth characterized by alternating phases of bone resorption and formation- Here the normal dense enchondral layer of the bony otic capule gets replaced by irregularly laid spongy bones. It is a progressive disease.

Extra Edge. Most common site of involvement in stapedial otosclerosis is located at the anterior edge of oval window in the area of fissula ante fenestrum.

  1. Features:
    1. Autosomal dominant
    2. Hereditary : 15%
    3. Male: Female = 1:2
    4. Age group affected = 15-45 years (deafness manifests usually at 20-30 yrs of age)
    5. Puberty
    6. Races:
      1. White > Negros
      2. More in the Caucasians
    7. Site of affection:
      1. Fissula ante fenestrum (Most common site of otosclerosis) : 80-90%
      2. Fossula post fenestrum (region is anterior to the oval window)
    8. 70-85% cases have bilateral involvement of the ear



  1. Anterior focus
  2. Posterior focus
  3. Lobster - clawtype
  4. Biscuit type
  5. Circumferential type
  6. Obliterative type (footplate and the stapedial crura cannot be identified)

Fig: Type of stapedial otosclerosis. A. Anterior focus. B. Posterior focus. C. Circumferential. D. Biscuit type (thick plate). E. Obliterative.

  1. Histopathology
    Features: Blue Mantles
    (Remodeled bone with blood vessels around)
    1. Metabolic theory
    2. Immune disorder
    3. Vascular disease
    4. Infection
    5. Trauma
    6. Anatomical/histological anamolie
  2. Clinical features:
    1. Symptoms
      1. Deafness: B/L. gradually increasing conductive hearing loss.
        1. Most frequently
        2. Paracusis willisi/Lombard effect (better hearing in noisy environment)
        3. Voice of the patient
          • ​​Quiet Voice
          • Low volume speech
      2. ​​Tinnitus: Indicator of sensorineural hearing loss.
      3. Vertigo: Due to the effect to toxic enzyme liberated by the otosclerotic foci on the vestibular labyrinth. Associated endolymphatic hydrops
        Note: In a young to middle aged lady with B/L hearing loss is usually cause is otosclerosis.
    2. Signs:
      1. Otoscopic examination: Normal tympanic membrane
        (10% flamingo pink blush is seen through the tympanic membrane )- Schwartz’s sign, because this is seen only during active stage of the disease.
      2. Tuning Fork Test:
        1. Rinnes:-ve
        2. Bing lest: No change in the bone conduction threshold
        3. Gelles Test: No change in the bone conduction threshold

Extra Edge. Gelle’s test compares intensity of bone-conducted tuning fork sound without and with raising pressure on the tympanic membrane with Siegel’s speculum. Normally, Gelle’s test is positive because intensity of hearing decreases when air pressure is raised in external auditory canal. In ossicular fixation or ossicular discontinuity, increased air pressure makes no changes in the sound intensity. (Gelle’s negative).

  1. Audiogram:
    1. Stapedial otosclerosis
      • ​​Initially;
        Rising audiogram (stiffiiess tilt)
      • Later:
        Flat curve with widened A- B gap
    2. Cochlear otosclerosis;
      • ​​Cookie-Bite Curve (greatest degree of hearing loss is in the mid–frequency range)​
Fig: Otosclerosis left ear. Note dip at 2000 Hz in bone conduction (Carhart’s notch).

Carhart’s notch at 2000 Hz (BC)-disappears with successful stapedectomy

Extra Edge. Carhart’s notch is seen in otosclerosis. Bone conduction curve shows maximum loss at 2000 Hz.

Extra Edge. Schwartz sign is a pink reflex, seen through intact tympanic membrane, in the area of oval window. It indicates active otosclerosis usually during pregnancy.

  1. Impedance audiometry will show AS type of tympanogram.
  1. Treatment:
    1. Medical therapy: Sodium flouride therapy Indication:
      1. Cochlear otosclerosis= Pt will have mixed hearing loss.
      2. Radiologically active focus= Best would be MRI.
      3. Patients with a positive schwartze sign= indicating active focus.
    2. Surgical treatment: when loss >30dB
      1. Stapedectomy
      2. Stapedotomy
      3. Fenestation surgery.
        In all the above mentioned surgeries, Argon or KTP laser can be used:
  2. ​​Belfast Rule:
    1. To assess whether stapedial surgery successful
    2. Postoperative air condition average over the speech frequencies should be close to 30 dB
      The interaural difference should be reduced to 15 dB
    3. Where NaF or surgery cannot be done, hearing aid remains the only option.
      Indomethicin, ipriflavone: also used in this management

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