Hearing Loss: Causes and Types
Hearing loss may be congenital or develop due to environmental or age-related factors. It is classified into three main categories based on the affected anatomical region:
Conductive Hearing Loss
Conductive hearing loss occurs due to an obstruction in the transmission of sound waves from the outer or middle ear to the inner ear. It is typically caused by mechanical problems in the outer or middle ear and is often treatable.
Causes of Conductive Hearing Loss
Outer Ear Causes:
- Earwax (cerumen)
- Foreign objects in the ear canal (e.g., beads, cotton swabs)
- Inflammation or tumors in the external auditory canal
- Congenital anomalies of the ear canal or auricle
Middle Ear Causes:
- Perforated eardrum
- Fluid accumulation in the middle ear (otitis media with effusion)
- Middle ear infections (chronic otitis media)
- Fixation or calcification of the ossicles (otosclerosis)
- Head trauma causing membrane rupture or ossicle damage
- Middle ear tumors
Treatment: Most cases of conductive hearing loss can be reversed with surgery, hearing aids, or medical treatment.
Sensorineural Hearing Loss
This type of hearing loss is due to damage in the inner ear or auditory nerve and is usually permanent. Even if sound reaches the inner ear, the damaged hair cells or auditory nerve fail to transmit adequate signals to the brain.
Causes of Sensorineural Hearing Loss:
Inner Ear Causes:
- Inner ear infections
- Viral infections (mumps, rubella, meningitis, etc.)
- Prolonged exposure to loud noise (noise-induced hearing loss)
- Ototoxic drugs (e.g., chemotherapy, certain antibiotics)
- Meniere’s disease (characterized by vertigo, tinnitus, and hearing loss)
- Age-related hearing loss (presbycusis)
Auditory Nerve Causes:
- Auditory nerve tumors (e.g., acoustic neuroma)
- Stroke or neurological disorders
- Systemic diseases (e.g., diabetes, thyroid disorders)
- Infections or toxic exposures during pregnancy
Treatment: Sensorineural hearing loss is usually permanent. Hearing aids or, in advanced cases, cochlear implants may help improve hearing.
Mixed Hearing Loss
This type of hearing loss involves both conductive and sensorineural components. It means there is a problem in the outer or middle ear along with a disorder in the inner ear or nervous system.
Causes of Mixed Hearing Loss:
Conditions that can cause both types of hearing loss:
- Chronic middle ear infections spreading to the inner ear
- Ear or head trauma
- Age-related hearing loss combined with ossicle fixation
- Cholesteatoma (a destructive and expanding growth in the middle ear)
Treatment: Medical or surgical treatment is first applied to address the conductive component. Then, hearing aids or cochlear implants are considered for further support.
Conclusion
Hearing loss responds better to treatment when diagnosed early. If you experience hearing loss, ringing in the ears, or a feeling of fullness, it is important to consult an ENT specialist for a comprehensive hearing evaluation.
Prof. Dr. Elif Aksoy
ENT Specialist – Hearing and Balance Disorders
