Types of Hearing Impairment
CONDUCTIVE HEARING LOSS
Conductive hearing loss usually results from conditions of the external or middle ear, although there are a few very unusual causes of inner ear-related conductive hearing loss. Perforations (holes) of the eardrum, wax, ear infection or inflammation, otosclerosis, and trauma are potential sources of conductive hearing loss. This type of hearing loss may be surgically correctable. Hearing aids are also very effective in these patients. The specific cause of a conductive hearing loss can be determined by a physician trained in the evaluation of the ear, such as an Ear Nose and Throat doctor (Otolaryngologist) or an otologist/neurotologist.
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SENSORINEURAL HEARING LOSS
Sensorineural hearing loss is a result of injury, inflammation, or aging of the inner ear, the hearing nerve, or the brain. The most common cause of hearing loss is presbycusis or age-related hearing loss. Many congenital and hereditary hearing losses are sensorineural. Other causes include trauma, noise exposure, idiopathic sudden hearing loss, Meniere’s disease, acoustic neuroma tumors, autoimmune inner ear disease, and Lyme’s disease. Sensorineural hearing loss includes a loss of loudness of sound and/or a decline in the understanding of speech. High pitched sounds are often lost first, followed by a gradual loss of low tones. This type of hearing loss may be sudden or slowly progressive.
Diagnosis of the specific cause of sensorineural hearing loss requires an examination by a qualified physician, high quality hearing testing, review of family and medical history, and possibly radiographic imaging such as MRI or CT scans. Many kinds of sensorineural hearing losses can be treated medically if a diagnosis is made in a timely manner. Surgery is generally not effective in returning normal hearing. Hearing aids are beneficial for most patients. New technology including implantable hearing aids and cochlear implantation are available for patients who do not do well with hearing aids.
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MIXED HEARING LOSS
Mixed hearing loss is a combination of conductive and sensorineural hearing loss. If is often a combination of two or more conditions of the ear. It should be evaluated by a physician, and may require a combination of treatments including surgery and/or hearing aids.
HEARING LOSS IN ONE EAR
A hearing loss isolated to one ear results in a unique but frustrating experience for the patient. Even a small hearing loss decreases a person’s ability to distinguish the direction of sound and understand speech in noisy backgrounds. More severe one-sided hearing loss will not only affect the hearing in the affected ear alone, it also results in significant difficulty of understanding speech in background noise, such as an office, a party, or even a restaurant. The patient will not be able to discriminate sound from the left side verses the right side. He may require face to face conversation and may even read lips in order to better communicate.
WHAT IS TINNITUS?
Tinnitus is noise in the ear or head. Tinnitus is often associated with hearing loss and results from the same mechanisms that cause hearing loss.
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HOW IS HEARING LOSS EVALUATED?
The evaluation of hearing loss includes a physical examination of the ear nose and throat. An otologist/neurotologist will examine the ears with a microscope to observe in detail the ear canal, the ear drum, and the status of the middle ear.
An audiologist (non-physician hearing care professional) will perform an audiogram (hearing test) which will include pure tone hearing levels and speech understanding. Tone hearing is tested through the air (air conduction) and through the mastoid bone (bone conduction). All three components of the audiogram are important in determining the type. For example, i f air and bone conduction thresholds are the same, the loss is sensorineural. If there is a difference between air and bone thresholds (an air-bone gap), the loss is conductive or mixed. Specific information is also important in making a diagnosis of the cause of the hearing loss. It is important for the audiogram to be personally reviewed by a physician.
It is important for every person with hearing loss to be evaluated by a physician experience in the evaluation and treatment of hearing loss, such as an otolaryngologist or otologist/neurotologist.
Several important signals should be brought to the prompt attention of a doctor including:
- Asymmetric hearing loss
- Progressive hearing loss
- Sudden hearing loss
- A painful or draining ear
- A lesion of the external ear
- Difficulty hearing despite a normal hearing test
- Tinnitus (head or ear noise)
- Dizziness, vertigo, or balance difficulty
- Excessive ear wax
- A medical history of cancer
- Pain with loud sounds