What causes minimal hearing loss?
Ear infection or otitis media is the most frequent cause of minimal hearing loss in children. It is an inflammation in the middle ear that usually causes fluctuating hearing loss averaging 21-40dB. However, many children are born with minimal hearing loss caused by problems in the inner ear. Because these hearing losses are mild they may go undiagnosed in the early years but they can cause significant problems educationally if they are not addressed.
This diagnosis is often missed and many children with hearing loss due to otitis media will pass a school screening test. Children with learning disabilities frequently have histories of chronic middle ear infection (4-5 episodes over a 6-12 month period), causing reduced hearing over a significant part of the school year.
What causes hearing loss?
About 50 percent of deafness is hereditary . Genetic hearing loss is not necessarily passed from parent to child, but may appear in other family members. More than 90 percent of the parents of deaf children are hearing people. Most hereditary hearing loss is recessive so both parents need to be carriers. Each parent carries a single copy of a deafness-causing mutation . The carrier rate in the general population for a recessive deafness-causing GJB2 mutation is about one in 33.
Other factors that can cause hearing loss include accidents and injuries, constant high noise levels that eventually cause severe damage to the nerves of the ear, illness or infection, and drugs which adversely effect the organ of hearing. Rubella or other viral infections contracted by the pregnant mother may cause deafness in an unborn child. A problem during the birth process such as a cutoff in the supply of oxygen may affect hearing. Hearing loss may also be part of the aging process in older people and is more likely to be mild. In many cases there may be no clear reason for hearing loss and the cause may never be determined.
Is hearing loss permanent? Can it be corrected?
In order to understand the different types of hearing loss it is important to know something about how normal hearing occurs. Sound waves traveling through air are funneled into the external ear canal which makes the eardrum with its attached ear bones (maleus=hammer, incus=anvil, stapes=stirrup) vibrate within the air-filled middle ear. This is the ears' conduction system. The piston-like movement of the three bones and eardrum stimulates a fluid wave in the liquid-filled inner ear. The movement of the inner ear fluid bends microscopic nerve endings called hair cells that are the ears' sensory structures. There are 30,000 hair cells and when they are bent by the movement of the fluid they work like a switch turning on an electrical current that travels through the nerve of hearing to the central auditory centers in the brain.
Conductive hearing loss: caused by a problem affecting the conduction system. Examples are excessive wax blocking the external ear canal, fluid in the middle ear preventing the eardrum from vibrating, or a disruption or fixation of the bones in the middle ear. Many conductive hearing losses can be treated and eliminated with medication or surgery. If a problem in the middle ear cannot be corrected, hearing aids and other assistive devices may be helpful.
Sensorineural hearing loss: caused by a problem in the inner ear hair cells (sensory loss) or auditory nerve (neural loss). Some or all of the hair cells in the cochlea may be damaged or absent. It is also possible that the auditory nerve from the cochlea to the brain may be damaged, incompletely formed, or there may be problems with transmission of sound across the auditory nerve. Infrequently, the auditory nerve may have a tumor growing in it which is generally benign (acoustic neuroma).This type of loss is not reversible. Most people with sensorineural hearing loss benefit from hearing aids. If the hearing loss is severe or profound, a cochlear implant may be recommended. A cochlear implant can be thought of as a very strong hearing aid which is surgically implanted. Sensorineural hearing loss can be stable, can fluctuate or be progressive and can even worsen as children get older. It is important to monitor children's hearing to determine the stability of their hearing loss. Young children should be tested at least twice yearly. Older children should be tested annually. Your child should always be retested if you suspect a change in his/her hearing ability.
Mixed hearing loss : a combination of conductive and sensorineural losses
What is an audiologist?
An audiologist is a professional with a Masters or Doctoral degree who diagnoses, treats, and manages individuals with hearing loss or balance problems. Audiologists have special training in the prevention, identification, assessment and non-medical treatment of hearing disorders. Audiologists receive professional certification and licensure and are the most qualified professionals to perform hearing tests, refer patients for medical treatment and provide hearing rehabilitation services including hearing aids.
Audiologists determine appropriate treatment through a complete medical history and a variety of specialized hearing and balance tests. Based on the diagnosis, the audiologist presents treatment options to patients with hearing impairment or balance problems. Audiologists dispense and fit hearing aids as part of a comprehensive treatment program. They refer patients to physicians when the hearing or balance problem requires medical or surgical evaluation or treatment.
What is a speech-language pathologist and how do they help child with hearing loss?
Speech-language pathologists work with a team that can include parents, audiologists, psychologists, social workers, classroom teachers, special education teachers, guidance counselors, and physicians to provide comprehensive language and speech assessments for children. These services help children with communication skills, cognitive abilities and social interaction. Services provided by speech-language pathologists include memory retraining, cognitive skills, language development, and efforts to improve abstract thinking. These services can help children overcome their disabilities, gain self-esteem, and lead productive and meaningful lives.
From the Children's Hearing Website
http://childrenshearing.org/custom/hearing_loss.html
