Otosclerosis - School of Medicine

Otosclerosis

Jason A. Showmaker MD
James Denneny MD

Objectives

Preoperative Assessment
Intraoperative Decision

Making
Postoperative Care and

Expectations

Historical Perspective

 1860

 Toynbee describes fixation of stapes with hearing loss

 1893

 Politzer coins the term otosclerosis

 1956

 Shea describes the footplate fenestration procedure

Epidemiology

 Prevalence varies

 Autosomal dominant, variable penetrance
 Lowest in Asians, Africans, and Native Americans
 Highest in Scandinavian region
 HL onset in 20s and progressive
 Affects women 2/3 and men 1/3

 Cadavers

 Otosclerosis seen in 7-10% of temporal bones

Histopathology

 Bone resorbed by osteoclasts and replaced by
osteocytes with new bone formation which is highly
vascular

 Lesions appear at Fissula ante fenestrum and
spread anteriorly typically

 Involvement of stapes footplate = conductive loss
 Involvement of cochlear endosteum = sensory loss

 Inflammatory mediators damage Organ of Corti and
spiral ligament

 Both = mixed loss

Mechanism – Conductive Loss

Cummings Ch 144.

Mechanism – Sensorineural Loss

Cummings Ch 144.

Histology

Inventory of House Ear Institute Temporal Bone
Laboratory

What type of hearing loss?

Inventory of House Ear Institute Temporal Bone
Laboratory

What type of hearing loss?

Inventory of House Ear Institute Temporal Bone
Laboratory

What type of hearing loss?

Inventory of House Ear Institute Temporal Bone
Laboratory

What type of hearing loss?

Conductive

Inventory of House Ear Institute Temporal Bone
Laboratory

What type of hearing loss?

Cummings Ch 144.

What type of hearing loss?

Cummings Ch 144.

What type of hearing loss?

What type of hearing loss?

Mixed

Inventory of House Ear Institute Temporal Bone
Laboratory

Purely cochlear otosclerosis
Sensorineural hearing loss only

Inventory of House Ear Institute Temporal Bone
Laboratory

Case 1 – Preoperative Assessment

 52 year old female with “bad hearing”

 Onset – Noticed in twenties
 Progressively worse over time
 Pregnancy?
 Paracussis of Willis

 Hear better when talking or in noisy environment

 Family history of surgically corrected hearing loss

Case 1 – Preoperative Assessment

 Physical Examination

 Otomicroscopy

 No middle ear effusion
 No tympanic membrane perforation
 Red blush on the promontory

 Tuning Fork

 Weber 512Hz – lateralizes to right ear

 Rinne 512 Hz – AD: BC>AC

 Rinne 1024 Hz – AD: BC>AC

Tuning forks

 Weber

 Lateralization when there is a ____ dB discrepancy
between ears

 Answer: 5 dB

 Rinne – flip consistent with _____dB CHL

 512 Hz: 15-20 dB loss

 1024 Hz: >30 dB loss

Tympanometry

 What findings would you expect?

Acoustic Reflexes

Acoustic Reflexes

Acoustic Reflexes

Acoustic Reflexes

Acoustic Reflexes

Pure Tone Audiometry

 “Specific and distinctive patterns of test results change in
predictable ways with the progression of the disease”

 M.T. Hannley

 Provides frequency specific information
 Shows disease severity

Early Stage Otosclerosis

 Increased stiffness

 Reduced effectiveness of transmission of low
frequencies

 Resonant frequency of the middle ear is raised
 Pt notices at 25 dB

 “Stiffness Tilt”

Footplate fixation

 Footplate fixation and mass effect occurs
 Stabilization of low frequency loss and progression

of high frequency loss
 Maximum air-bone gap across all frequencies

limited to 60-65 dB
 Slope flattens

Carhart Notch

 Hallmark of otosclerosis
 Elevation of bone conduction thresholds of:

 5 dB at 500 Hz
 10 dB at 1000 Hz
 15 dB at 2000 Hz
 5 dB at 4000 Hz

Carhart Notch

 Hallmark of otosclerosis
 Elevation of bone conduction thresholds of:

 5 dB at 500 Hz
 10 dB at 1000 Hz
 15 dB at 2000 Hz
 5 dB at 4000 Hz

Carhart Notch

 Hallmark of otosclerosis
 Elevation of bone conduction thresholds of:

 5 dB at 500 Hz
 10 dB at 1000 Hz
 15 dB at 2000 Hz
 5 dB at 4000 Hz

 Altered ossicular resonance
 Mechanical artifact- not a true
indication of cochlear function

*Overclosure

Carhart Notch

 Hallmark of otosclerosis
 Elevation of bone conduction thresholds of:

 5 dB at 500 Hz
 10 dB at 1000 Hz
 15 dB at 2000 Hz
 5 dB at 4000 Hz

 Altered ossicular resonance
 Mechanical artifact- not a true
indication of cochlear function

*Overclosure

As disease progresses…

 The audiogram changes in predictable ways

Stapes fixation and cochlear disease

 More common with advancing than pure CHL
 High frequencies most sensitive to cochlear otosclerosis

Speech Audiometry

 Purely conductive otosclerosis

 SRT should agree with the pure-tone average (500,
1000, and 2000) within +/- 6 dB

 Discrimination scores 90-100%

 Cochlear otosclerosis

 Word discrimination affected by the high frequency
losses

 Poor discrimination scores predict worse outcome with
surgery

Basic Audiometric Findings

 Normal middle ear pressure
 Slowly progressive conductive HL with gap closure

at 2000 Hz
 Acoustic Reflexes absent

Case 1 Diagnosis/Discussion

 Otosclerosis

 Hearing aid vs surgery

 Dizziness
 Adjustment period postop
 Facial nerve weakness – not really
 Further hearing loss - <2%
 Total hearing loss - <1%
 Taste disturbances - temporary

Stapedectomy vs Stapedotomy



















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