ENT - Otosclerosis Flashcards
What is otosclerosis?
Remodelling of the small bones in the middle ear, leading to conductive hearing loss
Presents before 40, more common in women
What factors contribute to the development of otosclerosis?
Environmental and genetic factors
Inherited in autosomal dominant pattern, no specific mutations identified
What is the role of the stapes in hearing?
Transmits vibrations from the oval window to the cochlea, converting them into action potentials
How does otosclerosis affect the stapes?
It causes stiffening and fixation at the base of the stapes where it attaches to the oval window, preventing effective sound transmission
Causes conductive hearing loss
What is the typical presentation of a patient with otosclerosis?
- Patient under 40 years
- Unilateral or bilateral hearing loss and tinnitus
Which type of sounds are affected more by otosclerosis?
Lower-pitched sounds are affected more than higher-pitched sounds
What is the effect of otosclerosis on a patient’s perception of their voice?
Patients may perceive their voice as being loud compared to the environment, can cause patient to talk more quietly
How can the TM appear suspected otosclerosis?
Can appear normal
What do Weber’s & Rinne’s test indicate in bilateral otosclerosis?
Weber’s
The sound is heard equally in both ears
Rinne’s
Conductive hearing loss, air conduction worse than bone
What investigations are used for otosclerosis?
Audiometry
Conductive hearing loss pattern with air conduction readings greater than 20 dB
Investigation of choice
Tympanometry
Generally reduced admittance
TM stiff and non-compliant, does not absorb sound, reflects most of it back
High-resolution CT
Detects boney changes, not always needed
What are the management options for otosclerosis?
Conservative with hearing aids
Surgical (stapedectomy or stapedotomy)
What does a stapedectomy involve?
Removing the entire stapes bone and replacing it with a prosthesis
Prosthesis attaches to oval window, hooks around incus, works the same way as the stapes
What is the difference between stapedectomy and stapedotomy?
Stapedectomy removes the entire stapes, while stapedotomy removes part of the stapes and leaves the base attached
