Otosclerosis

Otosclerosis is a localized hereditary disorder of
bone metabolism of otic capsule enchondral bone
that is characterized by disordered resorption and
deposition of bone
It was first identified and reported by Adam Politzer
The hallmark of the disease is stapes fixation with
resultant conductive hearing loss.

Clinical otosclerosis-
refers to lesions that affect the stapes,stapediovestibular joint or
round window membrane and thus cause conductive hearing
loss.
Cochlear otosclerosis
refers to lesions involving the cochlear endosteum without
affecting the stapes or the stapediovestibular joint, thus causing
pure sensorineural hearing loss, with no conductive element.
Histologic otosclerosis
 refers to histopathological lesions that do not affect the stapes,
stapediovestibular joint or cochlear endosteum, and thus remain
asymptomatic during life.

Biology of the Otic Capsule
The bone of the otic capsule is unique: it exhibits two main
features not found in other bones of the human skeleton:
1. Very low bone remodeling rate because of its special
OPG/RANK/RANK-L system.
2. It contains small regions of immature cartilaginous tissue
called the Globuli Interossei.

Classically, two histologic phases are described in otosclerosis:
1. active phase: (spongiosis)is characterized by increased
vascularity and increased bone turnover (‘Blue Mentle’)
2. stabilized phase: (sclerosis) consist of dense mineralized

 1.Fenestral
 2.Retrofenestral otosclerosis
The site of predilection is the fissula ante-
fenestram in front of the vestibule is 80–90%
of cases
Round window involvement is found
histologically in 40% of patients with
otosclerosis
In a clinico-radiological study, RW
otosclerosis was observed in 13% of patients
with conductive hearing loss

Hearing Loss
Progressive conductive hearing loss in an adult without
history of recurrent ear infections or head trauma and with
normal otoscopic examination.
Hearing loss is usually noticed when it reaches 15–25 dB.
Patients may describe improved hearing clarity in noisy
environments.This phenomenon is known as Paracusis of
Willis.

Vestibular symptoms-Dizziness- reported in almost
25–30%
correlated with the degree of sensorineural hearing impairment
Tinnitus-roaring or hissing sound in the majority of cases.

Otoscopy-
A normal, intact,mobile tympanic
membrane.
A ‘flamingo flush’ or Schwartz
sign, a red blush of the
tympanic membrane over the
promontory

Tuning Fork Tests-
Both Weber and Rinne tests must be performed
A negative Rinne’s test (1024 Hz tuning fork) on the affected ear
is an important finding
Indication for stapes surgery is generally based on 25–30 dB ABG
on pure tone audiometry

Air conduction-In the early stages, a gradually progressive
low-frequency conductive hearing loss is first seen.
The footplate with partial mobility maintains the capacity for the
transmission of the high frequencies.
The typical pattern of cochlear otosclerosis in the early stages
is the “cookie bite”pattern where the greatest degree of hearing
loss occurs in the midfrequency hearing range and is
characteristically a mixed hearing loss.

Bone Conduction-Stapes fixation is usually associated with
the presence of Carhart’s notch which is characterized by
elevation of bone conduction thresholds of approximately 5
dB at 500 Hz, 10 dB at 1000 Hz, 15 dB at 2000 Hz and 5 dB
at 4000 Hz.

The compliance in ears with
subsequently surgically confirmed
otosclerosis is less than normal but the
range is such that in an individual ear it
does not add to the diagnosis.
If there is any doubt about there being
otitis media with effusion as an
alternative diagnosis, tympanometry is
obviously then of value.

A new middle ear assessment technique that has enabled to
quantify the reflected, or the absorbed energy in the ear
canal across a wide range of frequencies typically between
250 and 8000 hz
Power absorbance (PA) is a ratio of absorbed power over the
incident power and varies between 0 and 1. A value of 0
means all sound energy has been reflected back and a value
of 1 means all sound energy has been absorbed by the
middle ear system

1.Measures over a large range of frequencies (250–8000 hz).
2.Very fast,taking only a couple of seconds to perform
3.The magnitude of the PA does not depend on the distance
between the probe tip and the eardrum and so the location of the
probe in the ear canal
4. Can be run at ambient pressure and does not require
pressurization of the ear canal

Generally,a stiffening pathology results in decreased absorbance
over a specific frequency range. For example, otosclerotic ears
demonstrate significantly increased reflectance between 400 Hz and
1000 Hz.

Two distinct patterns of abnormal stapedial
reflexes are seen in otosclerosis.
If footplate mobility has decreased but it is not
yet completely fixed, nearly all patients will
show a biphasic response, the so-called on-
off effect
 If the stapes is firmly fixed, no reflexes can
be elicited from the affected ear.

High-resolution CT (HRCT) scanning is able to detect
abnormal bone densities within the otic capsule
HRCT shows active otosclerosis as hypodense or lucent
areas within the otic capsule
Recommended if the diagnosis is in doubt, for example with
early-age onset or associated vertigo.
It is also of value if cochlear implantation is being
contemplated.

The Ante Fenestral Focus (AF)a hypodense focus situated
anterior to the vestibule in the fissula ante fenestram,more or less
extending to the footplate, is diagnostic for otosclerosis

Densitometry can also provide information about the
otospongiotic or sclerotic stage
A 0.5 mm thin-slice CT to measure the density of the otic
capsule

The fissula ante fenestram area, which provides quantitative
assessment of the disease and higher sensitivity.
Kutlar and colleagues found significantly lower density in
active otosclerosis compared with control ears (1131vs 2091
HU respectively; P<.05).

First, a correlation was found between the location of the
density change and the frequency topography of the
sensorineural hearing loss (SNHL), since densitometric
values were correlated with the bone conduction thresholds
for certain frequencies.
Second, hypodense spongiotic regions were found to be
consistent with a greater degree of SNHL, in contrast to
hyperdense sclerotic ones

1.Medical
2.Hearing aid
3.Bone-anchored hearing aids
4.Surgery

Sodium Fluride
Use sodium fluoride fluoride ion replace
hydroxyl radical form  stable fluorapatite
complex resist osteoclast activites
It also leads to increased calcium deposition
in otospongiotic foci
Decreased bone remodelling
Lower dose of 3 to 10 mg/d
Progressive cochlear component, 20 mg/d is
given for up to 2 years

Bisphosphonates-
These drugs interact with osteoclast
metabolism to induce osteoclast apoptosis,
therefore inhibiting bone resorption

Function: amplify acoustic signal from the outer ear, creating
a greater acoustic energy and improving the mechanical
transmission of sound through the middle ear into the inner
ear.
 Perception is of normal sounds but louder.
 Indications: patients with conductive and sensorineural
hearing loss greater than 25 dB
Disadvantages: ear canal irritation and infection.
Expensive and may require multiple adjustments.

Conventional hearing aids may play one of four distinct
roles-
1. As a primary treatment, hearing aids are a particularly
effective method of managing conductive hearing
impairments.
2.In combination with surgery in far advanced
otosclerosis,hearing aids may provide useful function not
obtainable with single modality therapy.
3. During post-stapedectomy rehabilitation with hearing aids
it is likely to be the sensorineural rather than conductive
hearing loss that is being rehabilitated.
4. As a 'rescue' treatment many years after surgery for
otosclerosis, hearing aids are likely to be needed frequently.

A specific benefit is that they do not produce the risk of a
dead ear that may result from stapedectomy
An only hearing ear with otosclerosis combined with difficulty
using a conventional aid, or a post-fenestration cavity
It combines the concept of osseointegration and bone
conduction transmission to aid hearing
BAHAs are mainly indicated for conductive and mixed
hearing loss as well as for single-sided deafness (SSD), and
are used both on adults and on children

It consists of a titanium fixture, abutment, and a sound processor.
The sound processor will convert sound energy to vibration,
transmitted via the abutment and the titanium fixture and then the
skull, directly to the functioning cochlea via bone conduction

1. Stapedotomy
2. Stapedectomy
3. Fisch’s Reversal Steps Stapedotomy
4. Laser stapes surgery
5. STAMP

1.Conductive hearing loss of at least 25 dB with a negative Rinne
at 512 Hz
2. Mixed hearing loss with favorable discrimination score
(Speech discrimination score should be more than 60%)
3.Patients with far advanced otosclerosis and severe to
profound hearing loss in the 90–100 dB range and no
measurable bone conduction

1.Only-hearing ear
2.Chronic otitis media or chronic otitis externa.
3.Presence of vertigo with a clinical evidence of labyrinthine hydrops
4. Unfavorable systemic medical conditions
5. Above 70 years old
6. During pregnancy.

 Surgeon and patient preference
 Local-infiltration of local anaesthetic(1% lidocaine) and dilute
adrenaline (1 : 30 000–1 : 100 000)
• Medical problems not allowing for general anesthesia
• Immediate feedback on hearing
• Can inform surgeon of vertigo
• Risk associated with general anesthesia
General
Complications and difficulties can be managed easily
Motionless operative field

A tympanomeatal flap is elevated from 7 o’clock to 12 o’clock

The chorda tympani nerve is
gently freed from any
mucosal folds
Posterosuperior bony
annulus is reduced with
curettes,drill or hammer

The stapes superstructure
should be gently palpated to
check for fixation of the footplate.
 The diagnosis is often clearer
after disarticulation of the
incudostapedial joint.

Incudostapedial joint- Separated with
joint knife
Mobility of ossicles is reassessed to
make sure the stapes is indeed fixed
and fixed malleus is not missed
Stapedius tendon now divided with a
laser,scissors or microhook

Divide the posterior crus with a
laser,crurotomy scissors or
diamond bur drill
If possible anterior crus should
also be divided prior to
removing stapes
Then SSS now removed

Distance between footplate and
undersurface of incus is measured
Range=3.75-4.75

Stapedotomy should be made at
junction of middle and inferior thirds of
central portion of footplate
The perforation should be slightly wider
than prosthesis If too tight,the hearing
will be reduced

 Seal
•Venous blood is applied to the oval window
• 3 ml syringe with 20 gauge suction tip
 Other Seals
• Fascia
• Perichondrium
• Vein
• Fat
• Gelfoam

A control hole is the graftmade in
footplate.
The whole footplate or more typically
the posterior third is removed with picks.
The defect is covered with a connective
tissue graft
The prosthesis placed on graft

 Prof Ugo Fisch described reversing the steps
of the stapedotomy procedure in order to
reduce complications relating both to the incus
(luxations / subluxations) and footplate
(subluxations / fractures / floating footplate)
 These complications are avoided by
performing the footplate hole and fixing the
prosthesis to the incus before removing the
stapes superstructure.

Palva was the first surgeon to use laser for the perforation of
the footplate
Laser is used in stapes surgery to divide the stapedius
tendon,divide the anterior and posterior crura, and perforate
the footplate
Laser in otosclerosis surgery decreases the risk of
postoperative SNHL because it traumatizes less the inner ear
Still there is no difference in postoperative vertigo rate and
air-bone gap closure when compared with standard
techniques

Advantages
1. Haemostatic properties especially in secondary stapes surgery
2. Increased precision that exceeds by far other handheld
instruments
3. Reduced risk of a floating footplate or losing footplate
fragments into the vestibule
4. No excessive perilymph mobilization by the ability to create a
precise fenestrum in the footplate thus minimizing the risk of
acoustic trauma
5. Can fenestrate a relatively mobile footplate without the risk of
depression of the footplate into the vestibule

 Normal mobility of the ossicular chain can be obtained
without a prosthesis by vaporizing the anterior crus and
making a linear stapedotomy across the anterior one third of
the footplate
In this procedure,the stapedius tendon and most of the
normal stapes remain intact.

Advantages=
Eliminating hyperacusis
Less invasive so it reduces inner ear trauma
Possible prosthesis problems are avoided
Postoperative barotrauma risk is minimized

Teflon and titanium are the most used materials
Only titanium, platinum and plastic prosthesis are compatible with
MRI -good biocompatibility
Advantage of titanium is the shape-memory that allows the use of a
clip attachment to the incus
0.6 mm piston-closing the ABG especially at low and mid
frequencies and predicted an air-bone gap of 8-dB to 12-dB
0.4 mm piston-higher frequencies and predicted an air bone gap of
15 dB to 20 dB.

1. Malleus Ankylosis
2. Overhanging Facial Nerve
3. Floating or Depressed Footplate
4.Round Window Otosclerosis
5. Persistent Stapedial Artery
6.Perilymph Gushers
7.Obliterative Otosclerosis of the Oval Window
8.Incidental Disarticulation of the Incus

Malleus fixation in association with otosclerosis is reportedly
between 1% and 10%
May follow a congenital anomaly or chronic infection of the
ear
Otosclerotic bone also have a high incidence of anterior
mallear ligament hyalinization

A preoperative CT is valuable to detect the pathology
When the malleus head is ankylosed to the wall or the roof of
the epitympanum, incus and head of the malleus should be
removed, and reconstruction should be done with a malleus
attachment prosthesis

Occurs in approximately 9% of stapes procedures
Laser fenestration should be avoided in these cases because
of the risk of facial nerve injury
When the facial nerve covers the large part of the footplate, a
stapedotomy should not be attempted

It results from the mechanical pressure applied to the stapes
footplate
The use of laser prevents this complication
The technique for safe removal of the floating footplate-
-Avoiding subluxation, is insertion of a small hook into the
cleft between the margin of the footplate and the oval
window
-Rotation of the hook 90° can bring it under the edge of the
footplate for extraction by tilting

Intraoperatively it is very difficult to
assess the severity of RW otosclerosis
even with the use of angled endoscopes
 As it is prone to regeneration, and the
procedure may violate the round window
membrane, causing sensorineural
hearing loss

Stage RW1 or RW2 otosclerosis do not have any
negative impact on the hearing outcome after stapes
surgery.
otosclerotic focus on the lateral border of
the RW (white arrow), persistent
air in the recess (small black arrow)
otosclerotic focus on the entire inferior RW
(white arrow) but normal RW membrane
(longblack arrow)

Stage RW3 only a partial closure of the ABG was obtained after stapedotomy
Stage RW4 otosclerosis: stapedotomy not only fails to close the ABG but also may
be associated to a postoperative deterioration of the bone conduction.

Found in 1 6.Out of 5000 cases
In most cases, the procedure should be aborted
In very rare occasions, if the posterior half of the footplate is
visible and could be easily approached
Titanium prosthesis is preferable because it transmits less
the pulsations of the artery.

 Axial CT of the temporal bone showing the aberrant stapedial artery (white arrows)
arising from the junction between the vertical and horizontal segments of the intra-
petrous internal carotid artery,

 Right ear otosclerosis with persistent stapedial artery (PSA). (a) the posterior half of the
footplate is visible (*) and could be accessible for fenestration. (b) fenestration was done in the
footplate (black arrow) using microdrill.

Occasionally, fenestration of the
footplate results in the free flow of fluid
from the vestibule into the middle ear
Occurs as a result of a defect in the
cribrosa area of the internal auditory
canal
Treated with soft tissue plugging and
prosthesis to maintain the soft tissue
sealer in place

Most patients will report some degree of dizziness
12–45% of patients,postoperative vestibular symptoms occur
after total stapedectomy
Opening duration of the vestibule during the surgery and the
various surgical manoeuvers (labyrinthine insult)

Use of corticosteroids is helpful
Persistent vertigo may be due to a depressed footplate
fragment into the vestibule or simply because of a long
prosthesis
Long lasting vertigo implies a surgical exploration to rule out
perilymphatic fistula

The overall incidence,in the hands of experienced surgeons,
is less than 1%
Post-stapedotomy SNHL can occur immediately or weeks to
months following the procedure
SNHL that occurs in the early postoperative period can be
attributed to the surgical trauma.

Surgical management for postoperative
SNHL is recommended as soon as the
Etiological diagnosis is made:
-A suspected perilymphatic fistula: the
diagnosis is mostly clinical.
-A very long prosthesis penetrating deeply
in the vestibule: CT is helpful
A granuloma formation: the diagnosis is
mostly clinical.
Despite a good surgical management,
the recovery of a post-stapedotomy
SNHL is always difficult to obtain.

Fluid leaks from the inner ear, leading to a disturbance of the
cochlear and vestibular function
A fluctuating SNHL, episodic unsteadiness, and tinnitus
Fistulas are associated to prosthesis dislocation
When demonstrated during revision, a new correct prosthesis
placement along with an adequate sealing with a connective
tissue of the oval window are performed.

Results from exuberant inflammatory reactive granulation
tissues in response to surgery and the inadvertent inclusion
of a foreign body
The incidence of reparative granuloma has been estimated to
be 0.1% after stapedectomy and 0.07% after stapedotomy
If a granuloma invades the vestibulum, symptoms of vertigo,
hearing loss, and tinnitus appear within 7–15 days after an
uneventful surgery

Unfortunately most cases result in a permanent
sensorineural hearing loss.
Management-
 Middle ear exoploration
 Removal of granulations and prosthesis
 Steroids and antibiotics

A clinical otosclerosis with an air conduction level of 85 db or
greater and non-measurable bone conduction levels
Lurato et al. Proposed even the term very far-advanced
otosclerosis for otosclerotic patients with non-measurable air
and bone conduction thresholds on a standard clinical
audiometer resulting in a blank audiogram

Manifested as a lucent area in the normally homogeneously
dense, otic capsule.

(1) Hearing aids without surgery
(2) Hearing aids with stapes surgery
(3) The direct acoustic cochlear stimulation implant
(4)Cochlear implantation

This device is of use in patients with mixed hearing loss where a
successful stapedotomy alone would not allow the patient to
manage without a hearing aid.
The device consists of an active middle ear implant attached to a
stapes prosthesis

The DACS allows direct acoustic
stimulation of the perilymph via
the stapes prosthesis.
Indications were a minimum
average bone-conduction of over
30 db and with an additional air–
bone gap of over 30 db

Castillo and colleagues revealed that CIs improved the hearing of
100% of the patients with advanced otosclerosis
Indications for primary cochlear implantation-
1. Pre-op speech discrimination<30%
2. More severe changes on CT scanning
3. Small air–bone gaps do worse with stapedotomy

Cochlear implantation improved speech recognition
significantly more than stapedotomy in their meta-analysis
study.
The study also reported that the quality of postoperative
speech recognition was similar between successful
stapedotomy and well-fitted hearing aids and cis.
In addition, the metaanalysis revealed that previously failed
stapedotomy did not affect the speech recognition of patients
with advanced otosclerosis who had been fitted with CIs

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