Definition:
Hearing loss is a decreased ability to hear. There are two main categories of hearing loss:

Conductive hearing loss - due to something interfering with the sound passing to the inner ear

Sensorineural hearing loss – due to damage to:

1. The major organ in the ear responsible for hearing (the cochlea)
2. The major nerve pathway and/or area of the brain responsible for hearing

Causes:
Causes of conductive hearing loss include:

Impacted ear wax
Fluid in the middle ear
Stiff bones in the middle ear (otosclerosis)
Injury
Tumors

Causes of sensorineural hearing loss include:

Excess noise
Aging
Exposure to toxic substances, including such drugs as:
Streptomycin
Gentamicin
Chemotherapy drugs
Diuretics
Steroids
Heart medicines
Anesthetics
Quinine
Aspirin-containing drugs
Acoustic neuroma
Cardiovascular disease
Multiple sclerosis
Viruses (measles, mumps, adenovirus, rubella)
History of meningitis or syphilis

Risk Factors
A risk factor is something that increases your chance of getting a disease or condition. Risk factors for hearing loss include:

Smoking and exposure to second-hand smoke
Aging
Meniere's disease
Not receiving all recommended immunizations
Repeated or poorly treated ear infections
Exposure to loud noise, music, or machinery
Use of certain antibiotics and chemotherapy drugs
Diseases that may result in blocked blood flow, including atherosclerosis, problems with blood clots, and collagen vascular diseases

Symptoms may include:

Decreased ability to hear any of the following:
Higher pitched sounds
Lower pitched sounds
All sounds
Speech when there is background noise
Dizziness
Ringing sounds in the ears
Problems with balance
In children, hearing loss may cause difficulty learning to speak

Diagnosis: The doctor will ask about your symptoms and medical history, and perform a physical exam. Tests may include:

• Weber Test - a tuning fork is sounded and placed on your forehead or teeth. This can help distinguish conductive from sensorineural hearing loss.
• Rinne Test - a tuning fork is sounded and placed in front and then behind of the ear. This can help distinguish conductive from sensorineural hearing loss.
• Audiometric Tests - these involve listening to tones in a soundproof room, and reporting whether you hear them or not.
• Tympanometry - measures the pressure in the middle ear and examines the middle ear's response to pressure waves.
• CT Scan of the Head – a type of x-ray that uses a computer to make pictures of the inside of the head. This may be done to check for a tumor or bone injury.
• Brain Stem Auditory Evoked Responses - electrodes are attached to the scalp and used to measure the electrical response of the brain to sound.
• Electrocochleography - tests the cochlea and auditory nerve

Treatment may include:

Earwax Removal
This is probably the simplest, easiest treatment for hearing loss.

Hearing Aids
There are many types. Digital technology has created tiny devices that cause little distortion.

Assist Devices
One example is the FM trainer. With this device, a person speaks into a microphone. The sound is then transmitted by radio waves directly to the earphone set worn on your ear. This can be particularly helpful if you have trouble hearing speech when there is background noise. FM trainers can also help children with hearing loss to understand their teachers.

Cochlear Implant
This device is surgically implanted. It directly stimulates part of the brain, and uses a tiny computer microprocessor to sort out incoming sound.

Treating Other Medical Illnesses
When hearing loss is caused by other medical conditions, it may be possible to improve hearing by treating those conditions.

Discontinuing or Changing Medications
If your hearing loss may be caused or worsened by a medication, talk to your doctor about stopping that particular drug, or changing to a drug that doesn't affect hearing.

Prevention
To help prevent hearing loss:

Stop smoking
Adequately treat ear infections
Get all appropriate immunizations
Treat all medical conditions
Avoid exposure to excess noise
Use adequate ear protection when using noisy equipment

Organizations:

American Academy of Otolaryngology - Head and Neck Surgery, Inc.

American Speech-Language-Hearing Association

SOURCES:

Current Medical Diagnosis and Treatment. Lange Medical Books; 2001.

Ferri's Clinical Advisor. Mosby; 2000.

Family Practice Sourcebook. Mosby; 2000.

The Little Black Book of Primary Care. Blackwell Science; 1999.

Last reviewed April 2003 by Reena Karani, MD

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.

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