1. OTOSCLEROSIS

2. ANATOMY OF LABYRINTH
 Otic capsule
It is the bony labyrinth and consists of 3 layers-
endosteal, enchondral, periosteal
 Otic labyrinth
The endolymphatic/membranous labyrinth. Consists of
utricle, saccule, cochlea, Semicircular canals,
endolymphatic duct and sac.
 Periotic labyrinth
The perilymphatic labyrinth. Surrounds the otic labyrinth
and is filled with perilymph. Consists of vestibule,
scala vestibula, scala tympani and perilymphatic
space around semicircular canals and periotic duct

5. DEFINITION
 Otosclerosis, or Otospongiosis is a primary disease
of the bony labyrinth. One or more foci of irregularly
laid spongy bone replace part of normally dense
enchondral layer of bony otic capsule.
 Most often, otosclerotic focus involves the stapes
region leading to stapes fixation and conductive
deafness.

6. ETIOLOGY
The exact cause is unknown but many factors have
been proposed:
 Anatomical basis- Areas of cartilage rests in the
bony labyrinth which due to certain non-specific
changes are activated to form a new spongy bone.
One such area is the fissula ante fenestrum lying in
front of the oval window- site of predeliction for
stapedial type of otosclerosis

7.  Heredity- 50% show positive family history.
Autosomal dominant trait with incomplete
penetrance and variable expressivity
 Race- Caucasians most commonly affected
 Age of onset-Hearing loss starts between 20-40
yrs. Rare before age of 10 and after 40.
 Endocrine- Pregnancy, increased deafness during
menopause
 Associated with osteogenesis imperfecta, viral
infection (measles virus- Paget’s disease)

8. TYPES OF OTOSCLEROSIS
1. Stapedial Otosclerosis
 Anterior Focus
 Most common, at fissula ante fenestram
 Posterior Focus
 Lesion spreading from posterior oval window to annular
ligament
 Circumferential
 Lesion flows across the ligament totally obliterating the
annular ligament
 Biscuit type
 Lesion replacing entire footplate, but no involvement of
annular ligament leading to a solid footplate
 Obliterative
 Completely obliterates the oval window

10. 2. Cochlear Otosclerosis
Involves region of round window or other areas of
otic capsule and may cause sensineural hearing
loss due to liberation of toxic chemicals into inner
ear fluid
3. Histologic Otosclerosis
Remains asymptomatic. No deafness.

11. PATHOLOGY
 Gross
Otosclerotic lesion appears chalky white, greyish or
yellow. If red in colour indicates active and rapidly
progressive otosclerotic focus.

12.  Microscopically
Divided in two phases:
 Early spongiotic phase (otospongiosis)
 Osteocytes, histiocytes, osteoclasts
 Active reabsorption of bone
 Stains blue (blue mantles) on using H&E stain
 Dilated vessels (Schwartze’s sign)
 Late or Sclerotic phase
 Formation of new bone in resorption areas
 New bone is dense and sclerotic
 Stains red on using H&E stain
 Starts in endochondral bone then involves endosteal &
periosteal layers and membranous labyrinth as disease
progress

13. SYMPTOMS
 Hearing loss- insidious, painless and progressive.
Often bilateral conductive type.
 Paracusis Willisii- Hears better in noisy than quiet
surroundings
 Tinnitus- more common in cochlear type
 Vertigo- uncommon
 Speech- monotonous, well modulated, soft speech

14. SIGNS
 Schwartze sign; red hue occasionally seen over
promontory through tympanic membrane. Indicative
of active focus with increased vascularity
 Eustachian tube function is normal

15.  Tuning fork tests
 Negative Rinne (BC>AC): First for 256Hz then
512Hz and when stapes fixation complete; for 1024
Hz.
 Weber test : will be lateralized to the ear with
greater conductive loss.
 ABC normal, may be decreased in cochlear
otosclerosis with sensineural loss

16.  Audiometry
 Pure Tone Audiometry
 Loss of air conduction at lower frequencies
 Bone conduction normal, sometimes shows a dip at
2000 Hz (Cahart’s notch) which disappears after
successful surgery.
 Speech Audiometry
 Normal discrimination score except in those with
cochlear involvement.

18.  Tympanometry- Normal in early cases but later
shows curve of ossicular stiffness. Stapedial reflex
absent when stapes is fixed

19. TREATMENT
 Medical: No treatment for curing otosclerosis.
Sodium fluoride has been tried to hasten maturity of
active focus., not recommended.
 Surgical: Stapedectomy/stapedotomy with
placement of prosthesis is the treatment of choice
 Hearing aid

20. Selection criteria
 Hearing threshold is 30dB or worse
 AB gap at least 15dB
 Rinne’s negative for 256 Hz and 512 Hz
 Speech Discrimination Score is 60% or more

21. Contraindications
 Only hearing ear
 Meniere’s disease
 Occupation such as athletes, frequent air travellers,
construction workers, divers
 Experience frequent change in pressure
 Works in noisy surrounding
 Otitis externa
 Perforated TM
 Young children
 Poor state of health

22.  Prosthesis
 Teflon piston
 Stainless steel piston
 Platinum Teflon piston
 Titanium Teflon piston

23. STEPS OF STAPEDECTOMY
1. Meatal incision and elevation of tympanomeatal
flap
2. Exposure of stapes area. This may require
removal of posterosuperior bony overhang of
canal
3. Removal of stapes superstructure
4. Creation of a hole in the footplate of the stapes
(stapedotomy) or removal of part of footplate
(stapedectomy)
5. Placement of prosthesis
6. Repositioning of tympanomeatal flap

25. COMPLICATIONS OF STAPEDECTOMY
1. Tear of tympanomeatal flap and perforation of TM
2. Injury to chorda tympani with taste disturbance
3. Incus dislocation
4. Injury to facial nerve
5. Vertigo
6. Perilymph fistula/granuloma
7. Conductive loss- short, loose or displacement of
prosthesis, incus erosion (late)
8. Sensineural hearing loss- intraoperative trama,
labyrinthitis, perilymph fistula
9. Dead ear

26. Thank you