Pediatric Aural Exam 1

What degree of hearing loss (aka “how much”) put children at risk for communication and learning delays?

Mild to moderate.

What domains/abilities are at risk? 

Hearing and speech perception, speech production, language skills, academic abilities, psychological and behavioral. 

Incidence: 3 in 1000 newborns will have HL at birth, this increases to ~6 per 1000 by school age. What are some reasons for this increase?

Late identification, late onset, or progressive hearing losses. 

Be familiar with common origins (i.e., etiology) of hearing loss:

Genetic 55% Of genetic HL, only about 30% are associated with a syndrome. Infection 25% (in utero or at birth), and know some risk factors for HL (see High Risk Register).  Family history, in utero infection, craniofacial anomalies, low birth rate, Hyperbulirubinemia, ototoxic medications, bacterial meningitis, low apgar score, mechanical ventilation 5+ days, syndromes w/HL.

Know the JCIH’s 1-3-6 rule/guidelines for Newborn Hearing Screening  

Screened no later than 1 month of age. 

Confirmatory audiological and medical eval no later than 3 months of age. 

Intervention ASAP but no later than 6 months of age. 

Know differences between Behavioral and Objective (aka Physiological) testing for screening and diagnosing hearing loss (HL). 

Behavioral testing relies on the patient's response to sound stimuli. It involves observing and interpreting the patient's behavioral reactions to sounds of varying frequencies and intensities.  Objective testing measures the physiological responses of the auditory system to sound stimuli. These responses are recorded using specialized equipment and do not require the patient's active participation.

Pure Tone Audiometry:

This involves presenting pure tones of different frequencies and intensities to the patient through headphones or insert earphones. The patient indicates when they hear the tones by raising their hand or pressing a button. Pure tone audiometry can be used across all ages, including children and adults.

Speech Audiometry:

Speech audiometry evaluates the patient's ability to understand speech. It involves presenting words or sentences at varying intensities to assess speech recognition thresholds and word recognition scores. Speech audiometry is commonly used in adults but can also be adapted for older children who can follow instructions.

Play Audiometry:

Play audiometry is specifically designed for young children. It uses age-appropriate games or activities to engage the child in responding to sound stimuli. This may include identifying sounds or placing objects in response to hearing specific sounds.

Auditory Brainstem Response (ABR):

ABR measures the electrical activity of the auditory nerve and brainstem in response to sound stimuli. Electrodes are placed on the patient's scalp, and sound stimuli are presented through earphones. ABR is commonly used for newborn hearing screening and in patients who are unable to participate in behavioral testing, such as infants or individuals with developmental disabilities.

Otoacoustic Emissions (OAEs):

OAEs measure the sounds produced by the inner ear in response to sound stimuli. A small probe is placed in the ear canal, and a series of clicks or tones are presented. OAEs are often used as a screening tool for hearing loss in newborns and infants.

Behavioral 

Behavioral testing can be used across various age groups, from infants to adults. However, specific techniques like play audiometry are more suitable for children who are developmentally able to participate in the activities.

Objective 

Objective testing techniques like ABR and OAEs are particularly useful for newborns, infants, and individuals who may have difficulty participating in or providing reliable responses during behavioral testing. However, they can also be used in older children and adults when necessary.

What is a threshold?

The lowest level of sound that can be heard 50% of the time.

What is an Air-Bone Gap?

An air-bone gap indicates a discrepancy between air conduction and bone conduction thresholds. Measure the air conduction threshold by testing with headphones or earphones. Measure the bone conduction threshold by using a bone oscillator on the mastoid bone.

What is the “speech banana”?

A speech banana is a banana-shaped range on an audiogram that covers the frequencies and decibels that are needed to understand speech. Contained within the speech banana are letters and letter combinations for these sounds.

Conductive:

obstruction or damage in either outer or middle ear that prevents sound entry 

• ~14% of newborns 

Sensorineural:

disturbance in the inner ear, eighth nerve, brain stem, midbrain, or auditory cortex 

~62% of newborns 

Mixed

combination of both 

Only ~8% of newborns Hearing Loss

Normal:

PTA is 19 dB HL or better

Mild

PTA is between 20 (or 16) and 40 dB HL

Moderate

PTA is between 41 and 70 dB HL

Severe

PTA is between 71 and 90 dB HL 

Profound

PTA is poorer than 90 dB HL

Autosomal dominant inheritance

In this case, only one of the child’s parents contains DNA with a mutation. 

• The parent with the mutation is considered heterozygous because their DNA has two copies of the same gene, one is mutated, and the other is not. 

• The mutation then has a 50/50 chance of being passed down to the child. 

Autosomal recessive inheritance 

For a child with this type of inheritance, both parents are carriers of a mutation. Meaning they have the gene for hearing loss, but it is suppressed by a non-mutated gene. 

The child then must obtain both mutated genes from each parent. There is a 25% chance of this occurring. 

X-linked inheritance

• This is a type of hearing loss caused by a mutation on an X chromosome. 

• Women have two X-chromosomes and if one is affected, it’s possible that the other 

chromosome can compensate. 

• Men have a X chromosome and a Y chromosome on their DNA making them more likely to suffer from this type of inheritance. 

Mitochondrial inheritance 

• The Mitochondria in our cells contains its own DNA! 

• Only the mitochondrial DNA from the mother can be passed down to the child because the sperm cells from the father do not contain DNA. 

• This type of inheritance is a common cause of genetic hearing loss in China! 

Know that cancer-fighting drugs used in Chemotherapy, like the commonly used Cisplatin, damage the hair cells of the cochlea resulting in permanent sensorineural HL for 50% or more of patients. Be able to justify why we would still rely on such an ototoxic drug. 

What is the dB range for everyday speech? What levels/sounds are likely to be harmful to hearing?

Conversational speech is typically from 50-70 dB spl  on average about 60 dB.

3 factors that put you at risk for NIHL.

1. How loud the noise is 

2. How close you are to the noise (distance to source) 

3. How long you hear the noise 

What type of hearing loss does otitis media result in?

Acquired Conductive

Acute OM

This is a middle ear infection that lasts less than 6 weeks 

Chronic OM

This is when there is a recurrence of ear infections causing inflammation of the middle ear and maybe a perforation. It lasts 3 months or longer

Otoacoustic Emissions (OAEs): 

Structures Assessed: OAEs measure the sounds generated by the cochlea, specifically the outer hair cells. When sound enters the cochlea, the outer hair cells vibrate, producing faint sounds called otoacoustic emissions. These emissions can be measured using a probe placed in the ear canal. 

Pros: 

• OAE testing is quick, non-invasive, and does not require patient cooperation. It is therefore suitable for newborn hearing screening and can be performed on infants and young children. 

• OAEs can detect cochlear outer hair cell dysfunction, which is associated with certain types of hearing loss, including mild sensorineural hearing loss. 

• It provides valuable information about cochlear function and can help differentiate between sensorineural and conductive hearing losses. 

Cons: 

• OAEs are unable to assess the auditory nerve or higher auditory pathways beyond the cochlea. 

• They may not be reliable in cases of severe or profound hearing loss, as the emissions may not be present or detectable. 

• OAEs cannot provide information about the degree or configuration of hearing loss, limiting their diagnostic utility in some cases. 

Auditory Brainstem Response (ABR): 

Structures Assessed: ABR measures the electrical activity of the auditory nerve and brainstem in response to sound stimuli. It evaluates the integrity and function of the auditory nerve and lower auditory pathways. 

Pros: 

• ABR can detect hearing loss at various levels of the auditory pathway, including the auditory nerve and brainstem. 

• It is particularly useful for diagnosing neural hearing loss, auditory neuropathy spectrum disorder (ANSD), and retrocochlear pathology. 

• ABR can be performed on individuals of all ages, including newborns and infants, and does not require active participation. 

Cons: 

• ABR testing typically requires electrode placement on the scalp, which may be uncomfortable for some patients, especially young children. 

• The test duration is longer compared to OAE testing, as it involves monitoring neural responses over time. 

• ABR may not provide detailed information about cochlear function or specific aspects of hearing loss, such as frequency-specific thresholds.