What is Otosclerosis?
The middle ear has 3 ossicles or the ossicular chain comprising of the malleus, the incus bone and the stapes bone.
Otosclerosis is a disease in which mature lamellar bone is removed by osteoclasts and replaced by woven bone of greater thickness, cellularity and vascularity.
There is commonly a fixation in the Incudo stapedial joint which fails or reduces the sound conduction resulting in deafness.
What are the causes of otosclerosis?
Aetiology and incidence of otosclerosis are:
- Age: Common in the second and third decade
- Race: Common in whites than blacks
- Sex: Male to female ratio is 3:2
- Pregnancy: Otosclerosis commonly increases post pregnancy. 1 in 24 pregnant females develop the disease
Other causative therories:
- Theory of metabolic disorders
- Infective theory
- Traumatic theory
- Theory of vascular diseases
What are the types of otosclerisis?
Different types of otosclerosis are:
- Stapedial otosclerosis: Occurs due to fixation of anterior part of the stapes footplate
- Cochlear otosclerosis: Here the new bone formation involves the bony capsule of the labyrinth causing sensorineural hearing loss.
How is otosclerosis graded?
Histopathological grading of otosclerosis:
- Acute active stage: Vascular phase of the disease also called Otospongiosis
- Intermediate stage
- Chronic inactive stage: Higher presence of mineralized bone with mosaic appearance.
What are the clinical features of otosclerosis?
- Deafness: The deafness is usually bilateral occurring between the third and fifth decade. Audiometry shows a typical conductive hearing loss at 2000 Hz called Caharts notch. An Impedance audiometry confirms the ossicular fixation
- Tinnitus: It is an indication of sensorineural which is seen in patients having this disease sine a long period
- Vertigo: These attacks are usually transient as a result of toxic enzymes
- The tympanic membrane shows a reddish glow, called Schwartz sign (Rising sun sign).
What is the treatment for otosclerosis?
- Medical line of treatment: Oral sodium fluoride therapy can be given 50 mg daily depending on the tolerance level of the patient. However, this therapy is usually for medically unfit patients and results are unreliable.
- Surgical treatment: Stapedectomy – Replacement of the fixed stapes suprastructure by a Teflon piston. Titanium prosthesis can also be used. However these days only the stapes suprastructure is removed keeping the footplate intact. A piston is inserted after perforating this footplate. This is also called Stapedotomy. Surgical treatment has immediate improvement on table and post operative recovery is usually fast.