Otosclerosis / Otospongiosis

OTOSCLEROSIS or OTOSPONGIOSIS
  • Disease of bony labyrinth where spongy bone replaces normal enchondral layer of bony otic capsule
  • Most often the otosclerotic focus involves stapes, leading to stapes fixation and CHL
Etiology
Family history present, Autosomal dominant
  • Common in Indians
  • Females affected twice more than males.
  • But in India males are more affected
  • Age 20-30 yrs
  • May be initiated or made worse by pregnancy, menopause, after an accident or a major operation
  • Van der hoeve syndrome- triad of Osteogenesis imperfecta, Blue sclera and Otosclerosis
Types
  • Stapedial otosclerosis causing stapes fixation and CHL is the most common variety
  • Fissula ante fenestrum - in front of oval window is the site of predilection (anterior focus)
  • Cochlear otosclerosis – causes SNHL, Otosclerosis tinnitus
Microscopic
  • Immature focus – vascular spaces, osteoclasts, osteoblasts & fibrous tissue – stains blue on HE staining (Blue mantles of Manasse)
  • Mature focus – less vascular with lot of fibrous tissue and few osteoblasts – stains red on HE staining
Symptoms and Signs
  1.  Hearing loss – painless progressive bilateral CHL
  2.  Paracusis willisi - hears better in noisy surroundings
  3.  Tinnitus, Vertigo, Monotonous soft speech
  4.  Tympanic Membrane – normal and mobile
  5.  Schwartz sign – reddish hue seen on the promontory through TM, which indicates active focus
  6. TFTs- negative Rinne, Weber lateralized to the ear with greater hearing loss
  7. The tympanogram is Type AS
  • In some cases a dip in the bone conduction curve appear at 2000Hz which disappears after successful stapedectomy (Carhart's notch)
  • Bezold's triad – absolute negative Rinne's, raised lower tone limit, prolonged bone conduction
  • Gene’s test and Gelle's test identifies Otosclerosis
Treatment
  • Medical - Sodium fluoride
  • acts by inhibiting proteolytic enzymes in cochlea, 
  • indicated in patients with positive schwartz sign, 
  • contraindicated in chronic nephritis
  • Surgical: Stapedectomy/ Stapedotomy with a placement of prosthesis - treatment of choice
The prosthesis used in the surgical treatment are
  • Teflon (M/C used)
  • Stainless steel
  • Platinum                 — All are MRI compatible
  • Gold
  • Titanium

The prosthesis is placed between the long process of incus and foot plate of stapes
Exam Question
  • Most often the otosclerotic focus involves stapes, leading to stapes fixation and CHL
  • Family history present, Autosomal dominant
  • Age 20-30 yrs
  • Females affected twice more than males.
  • Stapedial otosclerosis causing stapes fixation and CHL is the most common variety
  • Cochlear otosclerosis – causes SNHL, Otosclerosis tinnitus
  • Fissula ante fenestrum - in front of oval window is the site of predilection (anterior focus)
  • Hearing loss – painless progressive bilateral CHL
  • Paracusis willisi - hears better in noisy surroundings
  • Membrane – normal and mobile
  • Schwartz sign – reddish hue seen on the promontory through TM, which indicates active focus
  • TFTs- negative Rinne, Weber lateralized to the ear with greater hearing loss
  • The tympanogram is Type AS
  • In some cases a dip in the bone conduction curve appear at 2000Hz which disappears after successful stapedectomy (Carhart's notch)
  • Gene’s test and Gelle's test identifies Otosclerosis
  • The prosthesis used in the surgical treatment are Teflon (M/C used)
Don't Forget to Solve all the previous Year Question asked on Otosclerosis / Otospongiosis