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W21 - 9530 > Week 5 - Otosclerosis > Flashcards

Week 5 - Otosclerosis Flashcards

1
Q

What is otosclerosis?

A
  • means “hardening of the ear”
  • metabolic bone disease of ossicles and otic capsule
  • fixation of the ossicles (stapes)
  • results in a conductive or mixed HL
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2
Q

Otosclerosis is altered body metabolism in the otic capsule resulting in cyclic _____ and deposition of bone

A

Reabsorption

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3
Q

T/F: abnormal bone from otosclerosis can also invade the cochlea causing sensorineural damage and a mixed loss

A

True

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4
Q

What are the two symptom-based classifications of otosclerosis?

A

Clinical
- symptomatic and presenting with combination of HL, tinnitus, and rarely vertigo

Histological
- asymptomatic, more common, and typically diagnosed postmortem

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5
Q

Besides the symptom-based classification, how else might otosclerosis be classified? What are the two categories of this system?

A

Site of Lesion Classification

  • based on the structure predominantly affected
  • losing utility since subtypes are on a continuum

Fenestral - stapes predominantly affected

Retrofenestral - cochlea predominantly affected

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6
Q

The prevalence of histologic otosclerosis is highest in which race?

A

Caucasian - 10%

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7
Q

Females are more often affected by clinical otosclerosis than males. When is the typical onset for the disease?

A

15-45 years

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8
Q

Name 3 possible factors implicated in the development of otosclerosis

A
  • hereditary
  • endocrine
  • metabolic
  • infectious (Measles)
  • autoimmune
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9
Q

Otosclerosis consists of an early phase an a late phase. Describe them

A

Early phase - otospongiosis = vascular spongy bone growth

Late phase - dense sclerotic bone in areas of earlier respiration and otospongiosis

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10
Q

Otosclerosis site of lesion is limited to the ___ capsule and stapes

A

Otic

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11
Q

What structures in the ME are usually affected by otosclerosis?

A

Oval window
Footplate
Annular Ligament
Round window (less frequent)

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12
Q

What does the cochlear dysfunction portion of otosclerosis consist of?

A

Invasion of membranous labyrinth

Atrophy of spiral ligament in lateral wall

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13
Q

T/F: Otosclerosis is invisible on high resolution CT scans

A

False

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14
Q

How does otosclerosis damage the cochlea?

A

Damage occurs via:

  1. Bony invasion of membranous labyrinth
  2. Enzymes produced in otosclerotic foci adjacent to lateral wall of cochlea infiltrate membranous labyrinth
    - disrupts cochlear fluid homeostasis
    - eventual degeneration of organ of corti
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15
Q

What case history and symptoms would we expect to see with otosclerosis?

A
  • progressive HL (conductive or mixed, SNHL, Carhart notch)
  • beginning unilateral, then possibly progressing to bilateral (80% of cases)
  • tinnitus (75%)
  • vestibular complaints (25%)
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16
Q

In most cases, the physical exam is limited in it’s usefulness, but what is one thing that may be visible with otosclerosis?

A

Schwartze sign - reddish discolouration of the TM d/t increased vascularity
(10% of cases)

17
Q

Is imaging usually required for otosclerotic diagnosis?

A

Not usually

  • audiology most useful
  • high res CT for surgical planning
18
Q

Describe the audiometric progression of otosclerosis

A

Variable

  • usually initial conductive HL in low freq
  • configuration flattens
  • increased conductive component in low freq and decline in BC for high freq
19
Q

What is Carhart’s notch?

A
  • 2 kHz dip for pure tone BC
  • Hallmark feature of otosclerosis
  • caused by reduction in BC activated ossicular motion affecting resonance
20
Q

Describe the audiometry of cochlear otosclerosis

A
  • mixed hearing loss initially
  • can advance rapidly
  • less common
21
Q

What type of imminance can we expect with otosclerosis?

A
  • type A or As tymps

- absent or unusual acoustic reflexes (e.g reverse, on-off, or diphasic)

22
Q

Which is the older method for stapes surgery: Stapedectomy or stapedotomy?

A

Stapedectomy

- stapes footplate is removed

23
Q

Describe how stapedotomy is different from stapedectomy

A

Stapedotomy is:

  • more commonly used now
  • keeps the footplate intact
  • results in less trauma to the oval window
  • and less possibility of damaging the inner ear
24
Q

What is the goal of stapes surgery?

A

To close the ABG

  • otosclerosis can recur and displace prosthesis
  • revision surgery may be required (may not fully restore hearing)
25
Q

What are some non-surgical interventions for patients with otosclerosis?

A

Medical:

  • fluoride (not effective)
  • bisphosphonate

Amplification:
- patients who do not want/are not fit for surgery

CI:
- advanced otosclerosis invading the cochlea causing SNHL

W21 - 9530 (6 decks)

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