What is conductive hearing loss?
This type of hearing loss can occur due to any condition which interferes with the conduction of sound reaching the cochlea.
What are the causes of conductive hearing loss?
Common causes of conductive hearing loss are as follows:
- Atresia of the external canal
- Congenital cholesteatoma
- Stapes fixation
- Malleus head fixation
- I. External ear
- Foreign body
- Acute inflammation
- Exostosis of ear canal
- Middle ear
- Tympanic membrane perforations
- Conditions having fluid in middle ear, hemotympanum, acute otitis media, secretory otitis media.
- Ossicular fixation
- Eustachian tube blockage
- Tumours of middle ear
How is conductive hearing loss diagnosed clinically?
Clinical assessment of hearing loss:
1) Tuning fork tests
- Rinne test: Bone conduction is better than air conduction in conductive hearing loss. It is also called Rinne negative. It is done with 256 Hz, 512 Hz and 1024 Hz tuning forks. 512 Hz tuning fork is most commonly used as it falls in the mid speech frequency and has minimum overtones and undertones.
- Webers test: It is done with 512Hz tuning fork. The sound lateralises to the worse affected ear in pure conductive hearing loss.
- Absolute bone conduction test: This test done to differentiate between conductive and sensorineural hearing loss.
- Pure tone audiometry: It is a qualitative and quantitative analysis of the patients hearing. It is also useful for medico-legal purposes.
- Impedance audiometry: Useful in intact tympanic membrane to know the cause of conductive hearing loss.
2) Routine radiological and blood investigations for fitness point of view.
What is the treatment for conductive hearing loss?
Most cases of conductive hearing loss can be managed by medical or surgical means.
Common surgical procedures include:
- Removal of canal obstruction
- Removal of fluid by myringotomy.
- Tympanoplasty for perforation of the eardrum or ossicular pathologies.
- Stapedectomy for otosclerosis.
- Mastoidectomy for cholesteatoma.
- Hearing aid for surgically unfit patients.