Bilateral hearing loss may affect professional life of a person. Hearing loss in children can impair normal development of speech & language, his emotional balance and academic & intellectual skills.
So every effort should be taken to know the Cause of hearing loss and effective management to Prevent further loss.
A brief account of Anatomy and Physiology of Hearing– How we hear to understand the causes of hearing loss.
Some Clinical Facts Related to Hearing Loss
- Most common cause of Conductive hearing loss is wax.
- Most common cause of progressive conductive loss in young adults and middle age is otosclerosis.
- Common cause of deafness in children is otitis media with effusion.
- Most common cause of deafness in elderly people is presbyacusis.
- Conductive hearing loss is largely preventable and can be managed by medicine/surgery.
- Sensorineural loss which can not be cured by medicines should be started with rehabilitation by hearing-aids.
Types of Hearing Loss
Hearing loss can be two types:
- ‘Conductive loss’ when something is hampering conduction of sound from external or middle ear to reach inner ear or nerves of hearing. It can be corrected with medicine and/or surgery.
- ‘Sensorineural loss’ When problem is in inner ear or auditory nerves (Same as one has weak eye-sight). Usually it is permanent and need rehabilitation in the form of hearing-aids or cochlear implants.
Causes of Conductive Deafness
Conductive deafness is caused by the failure of the sound waves to pass along the external and middle ear to the inner ear.
Causes in the External ear canal like
- Congenital atresia.
- Foreign body impaction.
- Inflammation like otitis externa.
- big furuncle.
- fungus mass.
- Tumors like exostosis and cancer.
Causes in the Middle ear
- Perforation of ear drum by trauma or infection.
- Acute and chronic otitis media and adhesions.
- Fluid or blood in the middle ear.
- Tumour in the middle ear.
- Fixation of ossicles like otosclerosis.
- Disruption of ossicles by trauma or infection
Causes in the Eustachian tube
- Blockage of Eustachian tube by Inflammation, allergy, adenoids or tumors
Causes of Sensorineural Loss
Sensorineural loss can be sensory when it is because of problem in the inner ear (cochlea) or neural when problem is in the nerves of hearing (retrocochlear).
Cochlear Causes: Hearing Loss May Present Rrom Birth (Congenital) or May Develop Later In Life (Acquired)
- Infection like TORCHES to mother or intake of ototoxic drugs by mother during the first 3 months of pregnancy.
- Birth injury or hypoxia to neonate.
- Jaundice in new born.
- Old Age (presbiacusis).
- Trauma (head injury or noise trauma).
- Infection:Viral- measles, mumps and influenza. Or Bacterial- meningitis, typhoid, tuberculosis and syphilis.
- Endocrine and metabolic: Diabetes mellitus, Paget’s disease. And Hypothyroidism.
- Use of Ototoxic drugs: like aminoglycoside antibiotics (streptomycin, gentamicin, and neomycin), diuretics antimalarials (chloroquine, quinine), and cytotoxic drugs (cisplatin).
- Vascularcauses: spasm, hemorrhage or thrombosis of the internal auditory artery.
- Endolymphatic hydrops including Meniere’s disease.
Cochlear nerve lesions:
Tumors like acoustic neuroma.
Vascular insufficiency, tumors, multiple sclerosis, and epilepsy.
Management Depends On the Cause And Type of Hearing Loss
Management depends on the cause and type of hearing loss.
- Removal of obstruction of canal like impacted wax, foreign body, tumor, atresia.
- Medical or surgical management (by putting ventilation tubes or Grommet) of fluid in the middle ear.
- Treatment of middle ear infection.
- Removal of mass.
- Repair of ear drum perforation by cauterization or surgery.
- Stapedectomy surgery for fixation of stapes.
- Any cause in nose or throat should be managed by medicines or surgery.
Sensory neural loss:
- If it is sudden loss, spontaneous recovery may be expected. Vascular causes, viral infection and inner ear membrane rupture are possible causes, 10 to 15% may have underlying itiology so it is important to find out & treat like steroids for Immune mediated loss, surgery for tumour and for ototoxicity-stop the drug.
- Mostly chronic sensory-neural loss can not be cured and person is prescribed to wear hearing-aids. In bilateral severe to profound hearing loss cochlear implant (electronic device, a part is implanted under skin by surgery) may be successful.
- Auditory training is given to help at home, in the work place and in the society.