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

• Hearing loss – painless progressive bilateral CHL
• Paracusis willisi – hears better in noisy surroundings
• Tinnitus, Vertigo, Monotonous soft speech
• Tympanic 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)
• 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)