Why is detecting deafness in children so very important?
Do you know that a baby starts hearing while still a foetus in the mother’s womb? It is crucial to understand that speech and hearing are intricately interconnected in children. Actually, the first few years are crucial to development of communication skills in babies. Children learn and develop their speaking skills by copying those around them. If they can’t hear properly, they won’t learn to speak properly either. Therefore, if a newborn baby or a toddler suffers from any kind of hearing impairment, it can have a drastic and long lasting negative impact on their speech and communication skills for an entire lifetime. Ergo! You need to ensure that your baby’s hearing is in good shape at the earliest.
There are certain age-related hearing and speech milestones that your child should follow:
- Birth to 3 months – Your baby startles when loud noises occur, gets pacified and soothed when spoken to, makes cooing sounds, and has different crying sounds to express different needs.
- 4 to 6 months – Your baby makes babbling noises, follows a sound’s direction with eyes, gives response when you change your voice tone, appears to listen to music, and shows displeasure and eagerness through sounds.
- 7 to12 months – Your baby utters one or two words, is able to recognize a few common items by name, tries to copy different speech sounds, and turns to look in the direction of sounds.
- 1to 2 years – Your toddler is able to speak two words together, can follow simple commands, is learning to speak more and more new words every month, and can point out objects in picture book when you name them.
- 2 to 3 years - Your child is able to obey 2-step orders, comprehends different meanings, has words for most things in his environment, and those around him can understand his speech.
- 3 to 4 years – Your child is able to answer why/where/who/what questions, is able to talk in sentences containing four or more words, can converse comfortably without repeating words/ syllables, and watches TV at the same sound level as the rest of the family.
- 4 to 5 years- Your child understands short stories, listens attentively, answers simple question easily, has voice clarity at par with other children, speaks out detailed sentences, and is able to make correct sounds most of the time.
Unfortunately, it is not really possible for parents to ascertain that their child has hearing impairment before the child turns at least 8 to 12 months old. Equally unfortunately, it also means that a large and critical chunk of a hearing-impaired child’s communication development duration is lost.
Do you know that in most developed nations have newborn hearing screening programmes in place whereby every newborn child is given an audiological assessment prior to discharge from the hospital? Any infant found suffering from hearing impairment gets referred to ENT specialists for further evaluation and intervention to start a corrective regimen at the earliest. Sadly, such a system is still not in place in India and scores of newborns with hearing impairment go undetected till much later.
Children can suffer from deafness due to many reasons. These could be present from the time of the birth or could have arisen later.
Conditions affecting children from birth that can cause deafness:
- Inheritance of malfunctioning genes from parents
- Presence of Down’s Syndrome or Goldenhar’s Syndrome with hearing loss as one of the many syndromic disabilities
- Infection received in the womb such as rubella (German measles), cytomegalovirus, or herpes simplex virus
- Blood’s Rh factor related complications
- Premature birth
- Diabetes in mother
- Toxaemia during pregnancy
- Anoxia or lack of oxygen
Post-birth conditions in children that can cause deafness at any age:
- Ear infections (otitis media)
- Ototoxic medicines that damage the auditory system
- Infectious diseases such as encephalitis, meningitis, measles, chickenpox, mumps, or influenza
- Head injury or trauma to ear
- Exposure to loud noises
- Foreign bodies in ear
- Earwax compaction
- In rare cases, deafness could be caused by cancers
Do some babies have a higher risk of developing deafness and need to especially undergo hearing screening at the earliest?
Yes, some babies are more at risk than other babies. Get your baby checked for deafness if the baby:
- Has a family history of permanent hearing loss
- Is born premature or has a birth weight of less than 2 kg
- Has low Apgar scores (numbers assigned at birth that reflect the newborn's health status)
- Required post-birth ventilator support for breathing for more than 10 days
- Was in neo-natal intensive care unit (NICU) for more than 5 days
- Had severe jaundice after birth
- Suffers from hydrocephalus (fluid accumulation in brain)
- Suffered meningitis
- Has received exposure to ototoxic medications that can cause damage to the ear
- The mother suffered some illness (e.g. rubella) during pregnancy
Hearing tests are specialized assessments that require professionals trained in diagnostic hearing testing techniques and auditory rehabilitation of adults and children. They are called audiologists. Nevertheless, as hearing tests for children need special diagnostic equipment and set up along with advanced training, not every audiologist is able to test hearing of children.
Yes, it is absolutely possible to conduct hearing tests, whatever the age of the child. However, the type of testing will vary from child to child depending on their age / level of development. Some hearing evaluations employ interactive games to engage the child, some other do not need any behavioural response from them.
Some children are not able to cooperate as they are simply either too young or have delayed development issues such as mental retardation. For such children, trained audiologists have two different types of tests that do not require their cooperation.
Here is a brief look at both these evaluations:
Auditory Brainstem Response (ABR) test - This hearing test assesses the integrity of the auditory system from the ear to the brainstem. It is conducted by attaching 4-5 electrodes to the child's head. Then different sounds are offered to the child’s ear through small earphones. In response to these stimuli, the hearing nerve starts showing activity and sound impulses move up to the brain. As the inner ear converts sound signals to electrical ones to send forth to the brain through the auditory nerve, the electrodes are able to record this activity and display it onscreen in waveforms. The child is then exposed to various levels of different sounds, and assessing the waveforms on screen, the audiologist can assess the child’s lowest hearing threshold.
Otoacoustic Emission (OAE) Test - This test measures acoustic response shown by the cochlea or the inner ear by placing a tiny probe containing a microphone and a speaker into the child’s ear that measures the response of the inner ear to a sound stimulus. It is usually performed as an initial assessment or as a supplementary one to the ABR test.
Cooperative and alert infants or toddlers between the ages of 5 to 30 months are usually assessed for hearing through a test called the Visual Reinforcement Audiometry (VRA).
Older children between the age group of 3-5 years of age are assessed through a technique called Play Audiometry that is suitable for kids capable of handling slightly more complicated tasks.
The imperative first step is to assess the child’s hearing and pinpoint the condition that’s responsible for its loss. If the cause is treatable through surgical intervention, the ENT surgeon undertakes it. For example, if the deafness is due to a condition called the secretory otitis media, the surgeon will conduct a surgery called myringotomy grommet to restore hearing.
On the other hand, if the underlying condition is incurable, rehabilitation is the next step that needs to be taken at the earliest. First, hearing assessments are carried out and then based on the result, hearing aids may be prescribed. Hearing aids amplify the sounds around the child to make him or her hear what they have been missing and thus provide the stimuli to their growth as well as speech and language development.
However, not all children are suitable for hearing aids. Some children with higher severities or hearing loss configurations may require other types of technological assistance such as the BAHA hearing system or a cochlear implant.
These alternatives can be used along with speech therapy, special education, and FM (frequency modulated) or IR (infrared) systems to provide superior access to auditory information in afflicted children.
A cochlear implant is an electronic device that is partially implanted surgically into the cochlea which is the hearing organ of the inner ear. The remaining part of the device consisting of microphone, processor, and transmitter has to be worn externally. This cochlear implant uses electrical current to stimulate the remaining hearing nerve fibres by bypassing defective cochlear parts.
Cochlear implants are best suited for children with severe to profound affliction (hearing loss in both ears, >70 dB/ poor speech discrimination, < 50% correct on a sentence recognition test) that hearing aids are not able to improve much. Suitability for cochlear implant requires complete evaluation including hearing tests along with a CT or MRI scan of the ear.
Cochlear implants can be given to children as young as 6 months old. However, first it has to be ruled out that the child will not receive equivalent hearing gain from hearing aids. Therefore there is a preceding trial lasting 3 to 6 months in which hearing aids are installed in both ears and intensive auditory training is also given to ensure that cochlear implant is the only viable option.