Otoslerosis

  • Otosclerosis is characterized by abnormal removal of mature dense otic capsule bone by osteoclasts, and replacement with the woven bone of greater thickness, cellularity, and vascularity.
  • When disease involves the annular ligament of the oval window and stapes footplate, a conductive hearing loss (CHL) occurs which is slowly progressive, usually bilateral and asymmetric. 
  • The hallmark of bone conduction thresholds in otosclerosis is the Carhart notch which is as a result from the disruption of normal ossicular resonance, approximately at 2000 Hz. One of the earliest signs of otosclerosis is an abnormal acoustic reflex.
  • Carharts notch
  • Bone conduction is normal in otosclerosis.
  • In some cases there is a dip in bone conduction curve which is maximum at 2000 Hz / 2 KHZ called as Carharts notch.
Carharts notch is seen only in bone conduction curve.
  • It disappears after successful stapedectomy/stapedotomy.
  • Hormonal influences during pregnancy might cause a more rapid progression in women, bringing them to clinical attention.
  • While otosclerosis may potentially involve any part of the bony labyrinth, it carries a distinct predilection for the region near the anterior border of the oval window (fissula ante fenestram).
Otosclerosis is caused by immobility of the stapes.
  • Its most distinctive feature is conductive hearing loss, but sensorineural hearing loss and vertigo are also common; 
  • tinnitus is infrequent due to Cochlear Otosclerosis,increased vascularity in lesion or conductive deafness
  • Paracusis Willis refers to improved hearing with background noise. It is seen in patients with otosclerosis.
  • Otosclerosis is suggested by a positive family history(50% have family history)
  • a tendency toward onset at an earlier age, 
  • the presence of conductive hearing loss, or bilateral symmetric auditory impairment.
  • Females are more commonly affected than males. 
  • Whites are affected more than negroes.
  • Age = most common between 20-30 years and is rare before 10 and after 40 years.
  • Deafness is increased by pregnancy, menopause, trauma and major operations.
  • Viruses like measles virus have also been associated with it.
  • Stapes footplate—Shows a rice grain / biscuit type appearance
  • Blue mantles are seen histopathologically.
Gene's Test
  • This test was earlier done to confirm the presence of otospongiosis.
  • In this test, BC (bone conduction) is tested and at the same time Siegle's speculum compresses the air in the meatus.
  • In normal individuals hearing is reduced after this; i.e. Gelles test is positive; but in stapes fixation, sound is not affected. i.e Gelles test is negative.
FINDINGS IN OTOSCLEROSIS
  • Symptoms of otosclerosis
  • Hearing loss :- Bilateral conductive deafness which is painless and progressive with insidious onset. In cochlear otosclerosis sensorineural hearing loss also occurs along with conductive deafness.
  1. Paracusis willissii :- An otosclerotic patient hears better in noisy than quiet surroundings.
  2. Tinnitus :- More common in cochlear otosclerosis.
  3. Speech :- Monotonous, well modulated soft speech.
  4. Vertigo :- is uncommon.
  5. Signs in otosclerosis
Tympanic membrane is quite normal and mobile.
  • In 10% of cases flamingo - pink blush is seen through the tympanic membrane called as Schwartz sign. It indicates active focus with increased vascularity.
  • Tuning fork tests in otosclerosis
  • As otosclerotic patients have conductive deafness, the tuning fork tests results will be as follows :?
Rinnes :- Negative
  • Webers :- Lateralized to the ear with greater conductive loss.
  • Absolute bone conduction (ABC) :- Normal (can be decreased in cochlear otosclerosis).
  • Gelles test :- No change in the hearing through bone conduction when air pressure of ear canal is increased by Siegle's speculum.
  • Audiometry in otosclerosis Audiometry is one of the important tools in evaluation of a patient of otosclerosis.Various audiometric tests are :?
1. Pure tone audiometry
  • Shows loss of air conduction, more for lower frequencies with characteristic rising pattern. Bone conduction is normal. However in some cases, there is a dip in bone conduction curve which is maximum at 2000 Hz (2 KHz) and is called the Carhart's notch.
2. Impedance audiometry
  • Impedance audiometry shows :-
Tympanometry
  • Patient with early disease may show type A tympanogram (because middle ear areation is not affected) Progressive stapes fixation results in classical As type tympanogram.
Acoustic (stapedial reflex)
  • It is one of the earliest sign of otosclerosis and precedes the development of airbone gap. In early stage, diphasic on-off pattern is seen in which there is a brief increase in compliance at the onset and at the termination, stimulus occurs. This is pathognomonic of otosclerosis. In later stage the reflex is absent.
  • Treatment with a combination of sodium fluoride, calcium gluconate, and vitamin D may be effective. If not, surgical stapedectomy/stapedotomy/fenestration should be considered.
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