Otosclerosis is a disease affecting the bone of the middle ear that causes conductive or mixed hearing loss. It involves abnormal bone remodeling in the inner ear capsule, most commonly at the stapes footplate, causing stapes fixation and hearing loss. Symptoms include progressive hearing loss beginning in young adults. Diagnosis is made through audiometry showing air-bone gaps and absent acoustic reflexes. Treatment involves stapedectomy or stapedotomy surgery to remove the stapes and replace it with a prosthesis to reestablish sound conduction.

1. OTOSCLEROSIS
Dr Harjitpal Singh
Assistant Professor(ENT),
Dr RKGMC, Hamirpur

2. INTRODUCTION
• Disease of altered bone metabolism unique to the human
temporal bone.
• Localized hereditary disorder affecting enchondral bone of the
otic capsule characterised by disordered resorption and
deposition of bone.
• Remodelled bone bridges the stapediovestibular joint 
impedes sound transmission  Conductive hearing loss.
• Bone remodelling extends into the cochlea  Sensorineural
hearing loss.

3. 6
Membranous Labyrinth

5. HISTORY
• VALSALVA – Early 18th century – ankylosed stapes by
ossification of it’s ligament
• Von Troltsch – In 1869 - Named the final inactive stage –
Otosclerosis
• Siebenmann – In 1912 – Designated the active hyperemic stage
“Otospongiosis”
• Politzer – Recognized otosclerosis as a primary bone disease

6. DEVELOPMENTAL ANATOMY
LABYRINTH – 3 PARTS :
1. MEMBRANOUS / OTIC / ENDOLYMPHATIC LABYRINTH : Utricle,
saccule, cochlear duct (scala media), semicircular ducts,
endolymphatic duct and sac
2. PERILYMPHATIC / PERIOTIC LABYRINTH : Vestibule, scala tympani,
scala vestibule, perilymphatic spaces of semicircular and
endolymphatic ducts
3. BONY LABYRINTH / OTIC CAPSULE

7. DEVELOPMENTAL ANATOMY(cont)
• OTIC CAPSULE : Ossifies by 14 ossification centres
 First centre – 16 weeks – region of cochlea
 Last centre – 20-21 weeks – posterolateral region of posterior
semicircular canal
• Three layers of bone from ossified otic capsule :
1.Outer periosteal layer
2.Inner endosteal layer
3.Enchondral layer – consisting of intrachondral and
endochondral bone

9. PATHOGENESIS
• Normal otic capsule – low remodelling rate – 2%
• Otosclerosis – Abnormal bone remodelling in the endochondral layer
• GLOBULI INTEROSSEI – Embryonic cartilage rests – sites of
predilection
• Immature bone laid – continued remodelling occurs – prominent
osteoblastic involvement – OTOSPONGIOSIS
• Maturation of the lesion into a sclerotic, dense, irregularly woven and
poorly vascularised bone - OTOSCLEROSIS

10. PATHOGENESIS(cont)
• Most common site of predilection : FISSULA ANTE FENESTRUM
– focus anterior to stapes footplate  Stapes fixation
• Other sites :
Round window niche
Cochlear apex
Less frequently – walls of internal auditory canal, around
cochlear aqueduct, semicircular canals

11. PATHOGENESIS(cont)
GROSS APPEARANCE :
Active, spongiotic lesions – rich vascularisation and hyperemic
overlying mucosa  red discolouration of promontory 
SCHWARTZE SIGN
Mature focus of otosclerosis – white, well demarcated lesion

12. HISTOLOGY
Immature active lesions – numerous vascular spaces with
osteoblasts and precursors. Extracellular substance is
increased – stains blue with hematoxylin-eosin stain 
BLUE MANTLE – First histologic sign
Mature lesions – Less vascular spaces, laying of more bone and
fibrillar substance. Stains red with hematoxylin-eosin stain

14. ETIOLOGY
GENETIC PREDISPOSITION :
Autosomal dominant pattern with incomplete penetrance of 20
to 40 %
50% of cases – positive family history
Eight loci associated with otosclerosis : OTSC1 – 8
Significant association with COL1A1 gene – codes for type I
collagen
VAN DER HOEVE syndrome : Triad of osteogenesis imperfecta
(COL1A1 gene), otosclerosis and blue sclera

15. ETIOLOGY(cont)
• RACE : Whites more than blacks. Common in Indians. Rare amongst
Chinese and Japanese
• SEX : More common in females. India – predominant in males
• AGE OF ONSET : Between 20 and 30 years.
• HORMONAL FACTORS : In females, deafness worsens during
pregnancy and menopause

16. ETIOLOGY(cont)
• VIRAL INFECTION : Evidence of possible persistent measles infection.
Ultrastructural and immunohistochemical evidence of measles
like structures and antigenicity in active otosclerotic lesions
• Measles RNA in fresh footplate specimens of otosclerosis
• Elevated levels of antimeasles antibodies in the perilymph of
patients undergoing stapedectomy

17. TYPES OF OTOSCLEROSIS
1. STAPEDIAL : Causing stapes fixation and conductive hearing
loss – most common
2. COCHLEAR : Involves region of round window – liberation of
toxins  Sensorineural hearing loss
3. HISTOLOGIC : Remains asymptomatic

18. STAPEDIAL OTOSCLEROSIS
1. ANTERIOR FOCUS : In front of the oval window – Fissula ante fenestra
2. POSTERIOR FOCUS : Behind the oval window
3. CIRCUMFERENTIAL : Around the margin of stapes footplate
4. BISCUIT TYPE : In the footplate but annular ligament free
5. OBLITERATIVE TYPE : Completely obliterates the oval window niche

19. STAPEDIAL OTOSCLEROSIS(cont)

20. COCHLEAR OTOSCLEROSIS
• It is defined as the presence of an otosclerotic lesion in the capsule of
the cochlea, clinically characterised by sensorineural type of
deafness probably due to liberation of toxic materials into the inner
ear fluid.
• Cochlear otosclerosis involves region of round window or other areas in
the otic capsule.
• It may be associated with stapedial fixation when it is known as
combined or mixed otosclerosis.
• The diagnosis of pure cochlear otosclerosis without the involvement of
stapes can be suspected in any patient who has developed bilateral
progressive sensorineural deafness in early adult life.

21. HISTOLOGIC OTOSCLEROSIS
This type of otosclerosis remains asymptomatic and causes neither
conductive nor sensorineural hearing loss.

22. OTOSCLEROSIS - SYMPTOMS
• HEARING LOSS : Painless, progressive, often bilateral
• AGE : Patient presents in 3rd or 4th decade of life
• POSITIVE FAMILY HISTORY of hearing loss
• PARACUSIS WILLISI : Patient hears better in noisy surroundings
• TINNITUS : More common in cochlear type
• VESTIBULAR SYMPTOMS : 10 – 30% of the patients. Dizziness,
unsteadiness – potential coexistence of otosclerosis and
Meniere’s disease

23. OTOSCLEROSIS - SIGNS
• OTOSCOPY : Normal mobile tympanic membrane. (2% of patients with
chronic otitis media – may have otosclerosis – additive component)
• SCHWARTZE SIGN : Vascular blush on the promontory seen through the
tympanic membrane
• TUNING FORK TESTS : 256, 512, 1024 Hz
1.Rinne – Negative
2.Weber – Lateralised to the ear with greater conductive loss
3.Absolute Bone Conduction – May be normal.
Reduced in cochlear type

24. AUDIOLOGICAL EVALUATION
• PURE TONE AUDIOMETRY
• TYMPANOMETRY
• ACOUSTIC REFLEX

25. PURE TONE AUDIOMETRY
• Complete audiometry – air and bone conduction thresholds,
speech discrimination scores – essential
• Characterizes the severity of the disease
• Shows loss of air conduction, more for lower frequencies.
• Conductive, mixed or rarely pure sensorineural hearing loss may be
present
• Maximal conductive loss – 55 to 60 dB
• Conductive loss > 60 dB – suspicion of ossicular discontinuity

26. PURE TONE AUDIOMETRY(cont)
• Depression of bone conduction threshold at 2000 Hz –
CARHART’S NOTCH-- It disappears after successful stapedectomy.
• Decrease in bone conduction thresholds:
5 dB at 500 Hz
10 dB at 1000 Hz
15 dB at 2000 Hz
5 dB at 4000 Hz

28. AIR – BONE GAP :
Early in the disease , typical air-bone gap greatest in the
lower frequencies
More advanced ankylosis – loss equalizes across frequencies

29. TYMPANOMETRY
Normal in early cases.
Curve of ossicular stiffness – As – later

30. ACOUSTIC REFLEX

31. 24
ACOUSTIC REFLEX(cont)
• Measure of movement of stapes at stimulus
• Reflex is absent in otosclerosis
 Progressive changes in the configuration of the acoustic reflex
with stapedial fixation:
A:-Healthy reflex with a sustained change in compliance as long
as stimulus is on.
B:-Diphasic reflex with on-off pattern. Seen in cases of early
otosclerotic fixation.
C:-Absent acoustic reflex

32. DIFFERENTIAL DIAGNOSIS
• Ossicular discontinuity
• Congenital stapes fixation
• Attic fixation of malleus head
• Paget’s disease
• Serous otitis media
• Osteogenesis imperfecta

33. TREATMENT
• NON SURGICAL :
 Sodium fluoride : Was believed to slow the progression of the
disease. No evidence to support use of sodium fluoride in
otosclerosis
 Hearing aids .
• SURGICAL:
 Stapedectomy
 Stapedotomy
 Stapes mobilization
 Lempert’s fenestration operation
STAPES SURGERY

34. SURGERY FOR OTOSCLEROSIS
INDICATIONS :
Air-bone gap of 25 dB or more at frequencies of 250 Hz to 1000 Hz
Rinne negative at 512 Hz
Speech discrimination minimum 60%
Bilateral involvement – Worse ear operated first. Patient preference in
case of symmetric loss

35. SURGERY FOR OTOSCLEROSIS(cont)
CONTRAINDICATIONS:
• Infected middle ear or external ear
• Perforation of the tympanic membrane
• Active disease
• Only hearing ear
• Patients with vestibular symptoms – to rule out Meniere’s disease
• Professions requiring intact vestibular system – Athletes, divers,
frequent fliers
• Industrial workers – work in noisy surroundings – vulnerable to
occupational sensorineural hearing loss
• Pregnancy

36. SURGERY FOR OTOSCLEROSIS(cont)
ANAESTHESIA:
• Patient’s and surgeon’s preference
• LOCAL ANAESTHESIA :
Saves time
Intra-operative vestibular stimulation: patient can report &
prevents excessive inner ear irritation
• GENERAL ANAESTHESIA :
Assurance against pain and head movement
No increased risk of vestibular stimulation

37. SURGERY FOR OTOSCLEROSIS(cont)
1.Permeatal incision is made from the 6 O’clock to 12 O’clock position, 6 mm lateral
to the tympanic annulus at the centre. The tympanomeatal flap is elevated
2. Exposure of stapes area. This may require removal of posterosuperior
bony overhang of the canal.
3. Removal of stapes superstructure.
4. Creation of a hole in the stapes footplate (stapedotomy) or removal of a part of
footplate (stapedectomy).
5. Placement of prosthesis.
6. Repositioning the tympanomeatal flap.

39. PROSTHESIS

41. PROSTHESIS(cont)
• Correct length of the prosthesis is the measured distance of the medial
side of the incus to the opening in the footplate plus 0.25 mm
• An additional 0.25 mm is added – if bending of prosthesis is anticipated
• Ascertain sufficient opening of the loop of the prosthesis
• Prosthesis grasped by its loop with alligator forceps and placed on the
incus and fenestra in one movement
• Tightening of the loop around the incus done with a crimper – at the
narrowest area of the long process

44. TOTAL STAPEDECTOMY
• Performed in certain situations :
Floating footplate
Comminuted fracture of the footplate
Footplate inadvertently removed during suprastructure
dislocation through anterior crus attachment
Revision surgeries
Instruments required to create a small fenestra are lacking

47. COMPARISON
STAPEDECTOMY
• Better low frequency hearing gain
• Maybe the only method technically
possible
STAPEDOTOMY
• Better high frequency hearing gain
• Lower incidence of :
1.Perilymph fistula
2.SNHL
3.Lateralization of graft
4.Postoperative vertigo
5.Less labyrinthine trauma

48. SURGERY FOR OTOSCLEROSIS(cont)
• Stapes mobilization: It is no longer done these days as it gives
temporary results; refixation being quite common
• Lempert’s fenestration operation: It is almost outdated now.
Here an alternative window is created in the lateral
semicircular canal to function for the obliterated oval
window. It has the disadvantage of a postoperative mastoid
cavity and an inherent hearing loss of 25 dB which cannot be
corrected.

49. POST-OPERATIVE CARE
Can be discharged few hours after the surgery with instructions :
Keep the ear dry
Avoid strenuous physical activities
Avoid nose blowing ; Sneeze with an open mouth
Air travel permissible after a couple of days
Oral antibiotics continued for a week

50. COMPLICATIONS
INTRAOPERATIVE :
• TEARS IN THE TYMPANOMEATAL FLAP : Repaired by placement of
a medially placed tragal perichondrium or fascia graft
• SUBLUXATION OF INCUS :
Complete procedure with incus attachment prosthesis
Abort and give time for the incus to reattach to the malleus
Complete disarticulation – remove incus and use malleus
attachment prosthesis

51. COMPLICATIONS(cont)
• OTOSCLEROSIS OF THE ROUND WINDOW :
Complete obliteration associated with conductive hearing loss.
Attempts at removing  Sensorineural hearing loss – hence contraindicated
• OBLITERATIVE OTOSCLEROSIS OF OVAL WINDOW :
Saucerizing the obliterated niche and thinning the obstructing bone.
Fenestration made with a 0.7 mm diamond burr
• PERSISTENT STAPEDIAL ARTERY :
 Incidence – 1 in 5000 to 10000 ears.
 Occupies anterior half of the footplate – fenestration in posterior half.
 Cannot be safely coagulated with bipolar cautery or laser.

52. COMPLICATIONS(cont)
• MALLEUS ANKYLOSIS :
Corrected by removing the incus and head of malleus and
reconstruction with malleus attachment prosthesis
• PERILYMPH GUSHERS AND OOZERS :
Rapid drainage of inner ear fluids  sensorineural hearing loss
Fenestra is packed with tissue graft, vein graft or perichondrium
Preoperative lumbar drain placement and lowering
cerebrospinal fluid pressure – in suspected cases

53. COMPLICATIONS(cont)
• FLOATING / DEPRESSED FOOTPLATE :
Fenestration may be made with laser
A small bur hole created inferior to the annular ligament
and the footplate elevated with a small hook
Opening sealed with a tissue graft and appropriately sized
prosthesis placed
If footplate is depressed into the vestibule, should not be
extracted

54. COMPLICATIONS(cont)
• Exposed, overhanging Facial Nerve
• FACIAL PALSY :
Immediate : Local anaesthesia, intraoperative trauma to nerve
Delayed : Incidence 0.5%. Appears 5 to 20 days after surgery and
resolves within 1 or 2 months
• CHORDA TYMPANI DYSFUNCTION :
Injury – hypoguesia and dysguesia ; atrophy of fungiform papillae in
the denervated area
A stretched nerve causes more disturbing symptoms than a severed nerve

55. COMPLICATIONS(cont)
• OTITIS MEDIA :
In immediate postoperative period : High risk of suppurative
labyrinthitis and meningitis.
Treatment : Removal of ear canal packing
Admission and broad spectrum antibiotics
Steroids to minimize inner ear damage

56. COMPLICATIONS(cont)
• VERTIGO :
During surgery, immediate post – op or delayed onset
Immediate : Insult to membranous labyrinth, pneumolabyrinth,
chemical irritation by blood
Delayed : Benign paroxysmal positional vertigo, perilymphatic
fistula

57. COMPLICATIONS(cont)
• REPARATIVE GRANULOMA :
Mass of exuberant granulation tissue developing in reaction to
surgery or foreign body
5th to 15th day of surgery – signs and symptoms of labyrinthitis
Otoscopy : Oedema and hyperemia of skin flaps and tympanic
membrane
Audiometry : Mixed hearing loss and decreased speech
discrimination
Immediate re-exploration – granulation tissue and prosthesis
removed, fenestra sealed with tissue graft. Post-op steroids.

58. COMPLICATIONS(cont)
• PERILYMPHATIC FISTULA :
PRIMARY : At the end of stapedectomy
SECONDARY : Develops months or years later
Rates significantly lower following stapedotomy
Symptoms : Persistent or fluctuating hearing impairment, vertigo
and disequilibrium, aural fullness, meningitis
Positive fistula test
Treatment : Re-exploration and defect closure

59. COMPLICATIONS(cont)
• SENSORINEURAL HEARING LOSS :
Early : Surgical trauma
Delayed : Perilymphatic fistula

60. COMPLICATIONS(cont)
• CONDUCTIVE HEARING LOSS :
IMMEDIATE :
1.Malfunctioning prosthesis
2.Unrecognized malleus fixation
3.Unrecognized round window obliteration
4.Middle ear effusion
5.Unrecognized semicircular canal dehiscence

61. COMPLICATIONS(cont)
• CONDUCTIVE HEARING LOSS :
DELAYED :
1.Erosion of the incus at site of prosthesis attachment
2.Malpositioned prosthesis
3.Bony or fibrous regrowth at the oval window area
4.Round window obliteration

62. REVISION STAPES SURGERY
• More challenging
• Higher incidence of complications
• Lower success rates

63. INDICATIONS
• Immediate or delayed postoperative conductive hearing loss of
atleast 20 dB in speech frequencies
• Dizziness and unsteadiness – Excessively long prosthesis
• Symptoms of perilymphatic fistula

64. FINDINGS AT REVISION EXPLORATION
• Prosthesis malfunction at the incus
• Prosthesis displacement from the oval window
• Intact footplate
• Short prosthesis
• Malleus fixation
Laser helpful in revision surgeries – Divide adhesions, mucosal
folds, soft tissue surrounding the prosthesis in oval window

65. THANKS