Assessment of hearing in children

•Hearing impairment in children is not uncommon

•2-4 per 1000 newborns will have permanent childhood hearing loss

•More common in low socioeconomic classes

Prior to implementation of universal newborn screening, testing was conducted only on infants who met the criteria of the high-risk register (HRR).

It was found that the HRR was not enough, given that as many as 50% of infants born with hearing loss have no known risk factors

Early identification and intervention can prevent severe psychosocial, educational, and linguistic problems .

Infants who are not identified before 6 months of age have delays in speech and language development. Intervention at or before 6 months of age allows a child with impaired hearing to develop normal speech and language, alongside his or her hearing peers.

Risk factors• Family History.Family History.• Craniofacial anomalies (low set ears, cleft (low set ears, cleft

palate).palate).• Birth weight < 1500 g.Birth weight < 1500 g.• High serum bilirubin concentration > 20 High serum bilirubin concentration > 20

mg/dl (potentially neurotoxic).mg/dl (potentially neurotoxic).• Meningitis.Meningitis.• Hypoxia.Hypoxia.• In utero infection such as cytomegalovirus,

rubella toxoplasmosis, or herpes• Prematurity.Prematurity.• Hydrocephalus.Hydrocephalus.

•Syndromes associated with progressive hearing loss such as neurofibromatosis, osteopetrosis, and Usher syndrome

•Neurodegenerative disorders, such as Hunter syndrome, or sensory motor neuropathies, such as Charcot-Marie-Tooth syndrome

•Head trauma•Recurrent or persistent otitis media with

effusion lasting for at least 3 months

Hearing testing :

• Behavioral tests Behavioral tests • Electro-physiological testsElectro-physiological tests

Behavioural tests are based on eliciting or Behavioural tests are based on eliciting or observing a change in behaviour in observing a change in behaviour in response to sound.response to sound.

• Behavioral observation audiometry (BOA).Behavioral observation audiometry (BOA).• Visual reinforcement orientation Visual reinforcement orientation

audiometry (VROA).audiometry (VROA).• Play audiometry Play audiometry • Pure Tone Audiometry.Pure Tone Audiometry.

Behavioral Tests Behavioral Tests

•A child of any age can be tested with the appropriate hearing test.

•The type of test utilized depends on the child's age in years or developmental level.

• Some hearing tests require no behavioral response from the child, while other tests utilize games that entice a child's interest. The key is to find the right test method for each child.

Behavioral observation audiometry (BOA)•noisemaker testing is carried out with

infants younger than seven months of age and with older children who cannot respond when they hear a sound.

•Behavioural responses include startling to loud noises and stirring from sleep in response to a sound. An assortment of noisemakers, such as crunching cellophane, tiny bells, are used and most can be classified as low, mid or high frequency sounds.

Behavioral observation audiometry (BOA) Normal Response :Normal Response : 1) Up to 4 months: auropalpebral reflex; ‘’wink reflex’ 1) Up to 4 months: auropalpebral reflex; ‘’wink reflex’

(eye widening or blinking, beginning of primitive head (eye widening or blinking, beginning of primitive head turn or arousal from sleep or sudden tightening of the turn or arousal from sleep or sudden tightening of the eyelids if he was asleep)eyelids if he was asleep)

2) 4-7 months :- localized to side (horizontal only).2) 4-7 months :- localized to side (horizontal only).

3) 7-9 months :- localized to side and indirectly below.3) 7-9 months :- localized to side and indirectly below.

4) 9-13 months :- localized to side and below.4) 9-13 months :- localized to side and below.

5) 13-16 months :- localizing to side and below and 5) 13-16 months :- localizing to side and below and indirectly above.indirectly above.

6) 16-24 months :- localizing all signals at any angle.6) 16-24 months :- localizing all signals at any angle.

BOA

The most common neonatal response to sudden sound is the auropalpebral reflex

No response ?!

If the child is not localizing an auditory signal this doesn’t always mean that there is hearing loss, it may mean :

•Lack of interest

•Mental impairment.

•Physical impairment.

•Delayed auditory maturation.

Other behavioral responses

• Moro or startle reflex: flexion of legs, Moro or startle reflex: flexion of legs, embracing of arms and a brief cry.embracing of arms and a brief cry.

• Cessation of ongoing activity.Cessation of ongoing activity.

• Limb movement.Limb movement.

• Facial grimacing.Facial grimacing.

• Breathing changes.Breathing changes.

Visual reinforcement orientation audiometry (VROA)

•Assess childern aged 7 mon- 3 year

•VROA involves the child turning towards the loudspeaker when a sound is presented.

•By altering the frequency and intensity of the sounds, it is possible to find out about the child's ability to hear sounds across a range of frequencies.

Play audiometry

•test the hearing of children >3 years of age.

•This is also used to test the child's hearing when hearing devices are worn.

•Play audiometry works the same way as pure tone audiometry (person indicates when they can hear a tone), except when the child hears a tone, they put a marble in a marble race, press a computer key or put a piece in a puzzle.

•Behavioral audiometry is not sufficiently sensitive or specific for use in a screening program.

Electro-physiological testsElectro-physiological tests

Physiological tests help determine which part Physiological tests help determine which part of the auditory system is involved in the of the auditory system is involved in the child's hearing loss. child's hearing loss.

Physiological tests measure a physical Physiological tests measure a physical response of a specific part of the auditory response of a specific part of the auditory system and system and require little or no co-require little or no co-operation from the child.operation from the child.

1.1. Oto-acoustic emission testing (OAE).Oto-acoustic emission testing (OAE).2.2. Brainstem evoked response audiometry Brainstem evoked response audiometry

(BERA) or Auditory Brainstem Response (BERA) or Auditory Brainstem Response (ABR).(ABR).

3.3. Electro-cochleography (ECochG or EcoG).Electro-cochleography (ECochG or EcoG).4.4. Tympanometry and acoustic reflex.Tympanometry and acoustic reflex.

Physiological Hearing Testing - OAE• This test can be done as a supplement to the

ABR or as an initial screen of hearing.

• An otoacoustic emission test measures an acoustic response produced by the inner ear (cochlea).

• gives an idea about how hair cells in the cochlea are working. They respond to sound by producing a very soft sound of their own called an oto-acoustic emission.

•OAEs are used to assess cochlear integrity and are physiologic measurements of the response of the outer hair cells to acoustic stimuli.

•They serve as a fast objective screening test for normal preneural cochlear function.

•To measure OAEs, a probe assembly is placed in the ear canal, tonal or click stimuli are delivered, and the OAE generated by the cochlea is measured with a microphone.

Limitations•OAEs are not a sufficient screening tool in

infants who are at risk for neural hearing loss (eg, auditory neuropathy/dyssynchrony).

•Any infant in the NICU or in the hospital for more than 5 days should undergo an ABR screening so that the presence of auditory neuropathy is not missed. Cochlear function, and therefore OAE measurements, are usually normal in infants and children with this type of hearing loss.

Auditory Brainstem Response (ABR) •ABR is an electrophysiologic measurement

that is used to assess auditory function from the eighth nerve through the auditory brainstem.

• ABR recordings are generally obtained by placing disposable surface electrodes on the forehead and on both mastoids. Responses are typically measured from the forehead to the ipsilateral mastoid. ABR waveforms are obtained in response to abrupt click stimuli delivered in rapid pulse trains through insert earphones.

• Most ABR systems compare an infant's waveform with that of a template developed from normative ABR infant data. A pass or fail response is determined from this comparison.

• The limitation of the ABR is the need for the child to be quiet and still. The electrical potential the computer is recording from the auditory nerve is very small. Any muscle movement, including something as small as an eye blink, can obliterate the hearing response; therefore, the infant or child must be sleeping during the test.

• Diagnostic ABR testing is generally not used in universal newborn hearing screening programs because of the length of the procedure, the cost, and the need for an audiologist to perform the test and interpret the results.

Limitations

ABR

•The results from an ABR and an OAE evaluation can predict the child's hearing, determine if there is a loss, determine the type of hearing loss, and help with decisions regarding intervention.

•Intervention can include medical treatment, surgery, or hearing aids and therapy.

Electro-cochleography (ECochG or EcoG)• performed in hospital, under anesthetic.

•It picks up the tiny electrical signals generated in the cochlea in response to sound.

•It provides information about the functioning of the cochlea and the start of the nerve pathway to the brain.

Tympanometry and acoustic reflex•give information about the middle ear

which is just behind the eardrum. •A tympanogram, which shows if the

eardrum is moving normally, may indicate a problem in the middle ear that can cause a conductive hearing loss.

•When a child has a normal tympanogram, it may be possible to test for the presence of a muscle reflex - acoustic reflex - in the middle ear. The absence of this reflex to different sounds gives information about the auditory system.

Physiological Hearing Testing.• Impedance audiometry: used to evaluate Impedance audiometry: used to evaluate

middle ear, it is sensitive in differentiating middle ear, it is sensitive in differentiating between normal and pathological middle earbetween normal and pathological middle earincludes: tympanometry + measuring middle includes: tympanometry + measuring middle ear pressure + physical volume test to ear pressure + physical volume test to evaluate the tympanic membrane.evaluate the tympanic membrane.

• Heart rate audiometry: increase in heart rate Heart rate audiometry: increase in heart rate following loud sounds, in neonates heart rate following loud sounds, in neonates heart rate increases during 2-6 seconds following the increases during 2-6 seconds following the stimulus.stimulus.

• Respiratory rate audiometry: increase Respiratory rate audiometry: increase respiratory rate following loud sounds.respiratory rate following loud sounds.

Approach • 1. History:1. History:Previous sibling of same condition, family hx, risk factors of Previous sibling of same condition, family hx, risk factors of

pregnancy, low birth weight.pregnancy, low birth weight.Ask the parents about their estimation of their child’s Ask the parents about their estimation of their child’s

hearing ability.hearing ability.

• 2. P.E:2. P.E:• Eyes: Nystagmus, Myopia, Lids, Lashes.Eyes: Nystagmus, Myopia, Lids, Lashes.• Neck: Masses, Sinuses, Thyroid.Neck: Masses, Sinuses, Thyroid.• Mouth: colour and form of teeth, tongue movement, soft Mouth: colour and form of teeth, tongue movement, soft

and hard palate (Cleft Palate, Submucosal defect, Bifid and hard palate (Cleft Palate, Submucosal defect, Bifid uvula).uvula).

• Nose: Choanal atresia or Stenosis.Nose: Choanal atresia or Stenosis.• Ear: Low set ears , External Ear, Middle Ear, Tympanic Ear: Low set ears , External Ear, Middle Ear, Tympanic

Membrane.Membrane.

Treatment: treat the cause Treatment: treat the cause

Follow-up testing

•Infants who do not pass an initial hearing screening at birth should return for follow-up testing within 1 month. This follow-up allows for multiple testing sessions, medical intervention, parent counseling, and appropriate amplification measures to be initiated before the age of 6 months.