Hearing loss in children can be congenital (present at birth) or acquired after birth and is becoming even more prevalent with approximately 5 in every 1,000 children being diagnosed with some type of hearing loss between ages 3-17. Hearing loss can often go undetected until a child is 2 years of age or older, which can have a serious effect on speech and language development. In fact, research indicates that children whose hearing loss is detected and treated before 6 months of age have far better outcomes than those treated after the age of 6 months.
Because the most crucial time period for language development is between birth and age 3, undetected hearing loss can have drastic implications on a child’s speech. For this reason, newborn hearing screenings are now conducted in all hospitals across the U.S., which has resulted in hearing loss being identified at younger ages than ever before.
Types of Hearing Loss in Children
Hearing loss in children can be categorized as:
- Central hearing loss: Occurs when the brain has difficulty processing information
- Peripheral hearing loss: Most common category of hearing loss which encompasses any loss associated with structural problems of the ear
Types of peripheral hearing loss include:
- Conductive: Common type of hearing loss in children, usually temporary and treatable, which is caused by blockage of sound transmission to the inner ear, often due to middle ear infections
- Sensorineural: Often permanent hearing loss which occurs due to damage or structural problems involving the cochlea (portion of the inner ear comprised of hair cells that convert vibrations into messages)
- Mixed: Hearing loss involving both conductive and sensorineural causes
Hearing loss can be measured by how much sound can be heard without any additional means of amplification. Degrees of hearing loss are:
Hearing loss is also classified by when it occurs, either congenital (present at birth) or acquired (occurring sometime after birth).
Congenital Hearing Loss
Congenital hearing loss can be brought on by either genetic (hereditary) or non-genetic factors. Over 50% of all hearing loss in children can be traced to genetic factors, although some cases do not manifest until later in a child’s life.
Genetic factors that can cause congenital hearing loss are classified as:
- Autosomal dominant hearing loss: Occurs when one parent who carries the dominant hearing loss gene (and often has some form of hearing loss) passes the gene to the child
- Autosomal recessive hearing loss: Occurs when two parents (who typically have no hearing loss) carry the recessive hearing loss gene and it is passed to the child
- X-linked hearing loss: Occurs when a mother carries the recessive hearing loss gene on the sex chromosome, which can then only be passed on to male children
Some genetic syndromes may also be characterized by hearing loss, including:
- Usher syndrome
- Down syndrome
- Treacher Collins syndrome
- Alport syndrome
- Crouzon syndrome
- Waardenburg syndrome
Congenital hearing loss may also be a result of non-genetic, or non-hereditary, factors, such as:
- Premature birth
- Complications during birth
- Intrauterine infections, such as herpes simplex virus, rubella (German measles), cytomegalovirus (CMV), or toxoplasmosis
- Anoxia (lack of oxygen)
- Brain or nervous system disorder
- Complication involving Rh factor in the blood
- Maternal diabetes
- Prenatal toxemia
- Prenatal drug or alcohol abuse
- Prenatal use of ototoxic medication
Acquired Hearing Loss in Children
Acquired hearing loss in children can present any time after birth and may be caused by an injury, disease, or other ear condition.
Common causes of acquired hearing loss are:
- Otitis media (ear infection): Often causes mild, temporary hearing loss, but if infection is recurring, the eardrum, auditory nerve, or bones within the ear can become damaged, causing permanent, sensorineural hearing loss
- Perforated eardrum
- Ototoxic medication
- Noise exposure
- Head injury
- Progressive diseases (such as Meniere’s or otosclerosis)
- Certain infections (such as measles, mumps, whooping cough, meningitis, and encephalitis)
Symptoms of Hearing Loss in Children
Hearing loss can often be difficult to recognize, especially in young children who have not yet begun to talk. Initial and regular hearing screenings are crucial in detecting both congenital and acquired hearing loss since problems with hearing can arise at any time. Being aware of specific developmental milestones will allow you to identify if your child may need additional hearing evaluation.
Typical normal hearing milestones to look for include:
- Birth to 4 months: Startles or jumps at loud noises, recognizes or quiets with parent’s voice
- 4 to 9 months: Turns head toward noises or voices, makes musical or babbling sounds, smiles when spoken to, understands hand motions (such as waving bye-bye)
- 9 to 15 months: Repeats simple sounds, responds when name is called, understands basic requests, uses voice to get attention
- 15 months to 2 years: Names common objects, shows interest in songs or stories, points to body parts when asked, uses simple words often
While all children develop at their own pace, monitoring your child’s behaviors based on these guidelines is a good way to identify if a hearing problem may exist. Pre-school aged children and older tend to display certain common behaviors if hearing loss is present.
Signs that your child may have hearing loss can include:
- Unresponsive when name is called
- Difficulty understanding people
- Reacting inappropriately to questions due to misunderstanding
- Learning difficulties
- Language delays or speech that is hard to understand
- Sits close to or turns up T.V.
- Watches others, then imitates their actions
- Says “what?” frequently
- Unable to hear well on phone
- Watches person talking intently (lip reads)
If your child is not displaying a majority of developmental milestones or is exhibiting signs of hearing loss, you should contact your doctor for further evaluation.
Evaluating Hearing Loss in Children
Hearing loss evaluation will depend on the child’s overall health, development, and age. Congenital hearing loss is often identified during the newborn hearing screening at the hospital. Hearing loss cases that emerge later can be detected during behavioral tests (often conducted by an audiologist), such as conventional audiometry test, visual reinforcement audiometry (VRA), or a conditioned play audiometry (CPA). These tests measure the child’s response to sounds by requiring a behavioral response from the child.
Children who are too young or are unable to be evaluated with a behavioral test can be physiologically tested.
Auditory Brainstem Response (ABR) Test/Brainstem Auditory Evoked Response (BAER) Test
Auditory brainstem response (ABR) test, also called brainstem auditory evoked response (BAER) test, is a diagnostic test which measures how the brain processes sound in order to diagnose hearing loss, as well as nervous system disorders. During the ABR test, brainwaves are recorded as they respond to a series of clicking sounds played through small earphones placed in the ears. Electrodes placed on the scalp and earlobes measure brain activity and reaction of the hearing nerve in response to sounds. ABR/BAER testing is a painless, objective, and reliable tool for diagnosing hearing loss in children.
Depending on the age of the child, sedation may be required, as it is important that the patient remain relatively still during the hearing evaluation. Older children may simply lay down on a recliner or in a bed during the test.
Auditory brainstem response testing evaluates:
- Auditory nerves
- Hearing pathways
As the ABR test is conducted, seven wave forms are generated on a graph. Your audiologist will evaluate the distance between wave peaks and height of waves in order to determine hearing abnormalities.
ABR testing can be used for:
- Screening newborns with risk of hearing loss
- Identifying hearing loss in infants and small children
- Evaluating hearing loss in patients who may otherwise be difficult to test, such as developmentally delayed
- Evaluating patients with possible retrocochlear pathology or Meniere’s disease
ABR testing can also help diagnose nervous system and brain disorders or damage.
Other tests which can be used to determine or measure hearing loss in children include:
- Auditory steady state response (ASSR) test: Hearing test, done in conjunction with the ABR test, in which a computer measures brain response to sound passing into the ear canals
- Otoacoustic emissions (OAE) test: Short hearing test in which a microphone placed in the ear canal records response signals emitted from the outer hair cells within the inner ear
- Central auditory evoked potential (CAEP) test: Hearing test, similar to ABR testing in the use of earphones and electrodes, that identifies proper functioning of the pathways between the brainstem and auditory cortex
- Middle ear muscle reflex (MEMR) or acoustic reflex test: Measures and records the ear’s response to sounds by sending loud noises into the ears to evoke a reflex
- Tympanometry: Tests eardrum movement rather than hearing to identify middle ear problems (such as fluid behind the eardrum or perforated eardrum) through the use of air pressure and soft sounds sent into the ear canal
Treating Hearing Loss in Children
Treatment for hearing loss in children will depend on the type, severity, and cause of the hearing loss. Oftentimes, conductive hearing loss can be corrected by treating the ear infections and alleviating the buildup of fluid in the ears. Sometimes surgery is required to correct more serious cases of conductive hearing loss to ensure that the problem is not recurring.
Sensorineural hearing loss, which is generally permanent, can be treated by enhancing sound through technological means, such as:
- Hearing aids: Many advancements have been made to hearing assistance devices which allow for more sound to be heard and to keep them in place and even discreet for young children.
- Cochlear implants: The auditory nerve is stimulated by a surgically implanted device and sound is sent directly to the hearing nerve. Cochlear implants are typically recommended for patients over 12 months of age with profound hearing loss who are unable to benefit from using hearing aids.
- FM system (auditory trainer): Amplification is achieved through an assistive listening device primarily used in classrooms or venues with excessive background noise. The speaker wears a small microphone that transmits the sound directly to the hearing aid or cochlear implant.
Children with hearing loss can often benefit from speech therapy, and for those with significant loss, sign language and lip reading can be taught as an additional means of communication. Even those patients whose hearing loss is corrected may need some type of language therapy to help them overcome any speech delays caused by the previous inability to hear.
Preventing Hearing Loss in Children
While hearing loss often cannot be prevented, there are steps that can be taken to lessen the risk that your child develops hearing loss:
- Get good prenatal care and follow your doctor’s instructions
- Seek proper medical treatment for ear infections
- Minimize or avoid prolonged exposure to loud noise
- Use ear protection when loud noise exposure is unavoidable
A child’s hearing can be damaged by prolonged exposure to everyday sounds that may not seem overly loud, such as:
- Lawn equipment
- Loud vehicles, such as farm equipment, snowmobiles, or recreational vehicles
- Loud music
Your doctor can advise you on what noise levels are safe for your child’s hearing. If your child is exhibiting signs of hearing loss or you are concerned about your child’s hearing, contact our office for an evaluation.