What Are the Causes of Hearing Loss?
Hearing loss refers to a decrease in sensitivity to sounds that are audible to those with normal hearing. Hearing loss can also be described as a breakdown in the ear which affects the brain's ability to identify sounds. There are several types of hearing loss, and numerous possible causes. Hearing loss is often described by the location of where the loss occurs, the degree of hearing loss, and the configuration or what sounds are affected.
Conductive Hearing Loss
A conductive hearing loss is due to the sound signal is not being directed properly to the inner ear. This can occur in the outer or middle ear. This type of hearing loss is not typically a complete deafness, but a reduction in the loudness of sounds. Conductive hearing loss can be present at birth (or congenital) or can be acquired during a person’s lifetime. Causes include:
- Ear wax blockage
- Foreign body in the ear canal
- Fluid in the middle ear space
- Disruption in the bones of the middle ear
- Outer ear infection (such as “swimmers ear”)
- Middle ear infection
- Cholesteotoma, (an abnormal, non-cancerous growth of skin cells)
- Benign tumor (such as a vestibular schwannoma)
- Otosclerosis (an abnormal growth of bony tissue in the middle ear)
- Perforated ear drum
- Eustachian tube dysfunction
- Congenital conductive malformation such as an absence of the external auditory canal
This type of hearing loss is most likely to be treated by means of medication or surgery, and will often require a referral to an ENT physician. Treatments may include antibiotics, OTC decongestants, surgical intervention such as myringotomy and placement of PE tubes, use of osseointegrated hearing devices, or traditional hearing devices.
Sensorineural Hearing Loss
A sensorineural hearing loss occurs in the inner ear, or along the auditory pathway as sound signals travel to the brain. Without extensive testing, it is difficult to pinpoint whether the loss is in the cochlea (the inner ear) or in the auditory nerves between the ear and brain pathway. Causes of sensorineural hearing loss include:
- Excessive exposure to loud noise (greater than 85 dB)
- Ototoxic drugs (these include some antibiotics, ED drugs, and combinations of certain drugs with loop diuretics)
- Head trauma
- Autoimmune inner ear disease
- Meniere’s disease
- Benign tumor (acoustic neuroma)
- Viral or bacterial diseases (measles, mumps, meningitis, rubella, herpes)
- Genetic syndromes (Ushers Syndrome, Down Syndrome, Waardenburg Syndrome)
- Uncontrolled blood sugar
- High blood pressure
- Heart or vascular problems
- Kidney disease
- Large vestibular aqueduct
- Superior canal dehiscence syndrome
Sensorineural hearing loss can be treated medically, where there is an underlying cause such as disease or tumor. Most noise-induced or inherited losses are treated through traditional hearing amplification and auditory rehabilitation.
Auditory Processing Disorders
Some hearing loss occurs not in the middle or inner ear, but in the pathway to the brain or in the processing areas of the brain responsible for hearing and language. The causes of these types of hearing disorders are more elusive, but can occur due to
- Developmental disorders
- Head trauma
Treatment for auditory processing disorders may include listening therapy, use of assistive listening devices, and/or various forms of hearing amplification.