Hearing Impairment in Children

Definition | Aetiology | Pathophysiology | Risk Factors | Signs and Symptoms | Investigations | Management | References

Definition

Hearing impairment refers to partial or complete inability to hear in one or both ears. It can range from mild to profound and can be present from birth (congenital) or develop later (acquired). Early diagnosis and intervention are crucial for children to develop normal speech and language skills.

Aetiology

Hearing impairment in children can be caused by a variety of factors, including:

• Genetic Causes: Inherited conditions, such as mutations in the GJB2 gene, account for about 50% of congenital hearing loss.
• Infections: Prenatal infections such as cytomegalovirus (CMV), rubella, or syphilis can cause congenital hearing impairment. Postnatal infections, like meningitis, mumps, or otitis media, can lead to acquired hearing loss.
• Prematurity: Preterm infants, especially those requiring neonatal intensive care and ventilation, are at increased risk.
• Noise Exposure: Prolonged exposure to loud noises can cause damage to the inner ear, leading to hearing loss.
• Ototoxic Medications: Certain drugs, such as aminoglycoside antibiotics or chemotherapy agents, can damage the hearing system.
• Trauma: Head injuries or damage to the ear can lead to hearing impairment.

Pathophysiology

Hearing impairment can occur due to problems in different parts of the auditory system:

• Conductive Hearing Loss: This type occurs when there is a problem in the outer or middle ear that prevents sound from being conducted to the inner ear. Common causes include ear infections (otitis media), earwax blockage, or fluid in the middle ear (glue ear).
• Sensorineural Hearing Loss: This occurs when there is damage to the inner ear (cochlea) or the auditory nerve. Causes include genetic factors, infections, or exposure to loud noises.
• Mixed Hearing Loss: This is a combination of conductive and sensorineural hearing loss.
• Auditory Neuropathy: In this condition, sound is detected by the ear, but the signals do not travel properly from the ear to the brain due to a problem with the auditory nerve.

Risk Factors

• Family history of hearing loss.
• Prematurity and low birth weight.
• Neonatal intensive care unit (NICU) stay, particularly with the use of mechanical ventilation.
• In utero infections such as CMV or rubella.
• Prolonged exposure to loud noises.
• Recurrent ear infections.
• Use of ototoxic medications.
• Head trauma.

Signs and Symptoms

Signs of hearing impairment can vary based on the child's age and the severity of the hearing loss. Common signs include:

• Infants:
  • No response to loud sounds.
  • Failure to turn towards sounds by 6 months of age.
  • No babbling or delayed speech development.
• Toddlers and older children:
  • Delayed speech and language development.
  • Difficulty following instructions.
  • Speaking loudly or frequently asking "What?" or "Huh?"
  • Not responding when called, particularly in noisy environments.
  • Frequent ear infections or complaints of ear pain.

Investigations

Hearing tests are essential for diagnosing the type and severity of hearing loss. Common investigations include:

• Newborn Hearing Screening: Universal newborn hearing screening is offered to detect hearing impairment shortly after birth. It typically involves otoacoustic emissions (OAE) and auditory brainstem response (ABR) testing.
• Visual Reinforcement Audiometry (VRA): Used in children aged 6 months to 2.5 years, this test evaluates the child’s response to sounds through headphones or speakers.
• Pure Tone Audiometry: For older children, this test measures hearing across different pitches and volumes.
• Tympanometry: This test evaluates the function of the middle ear and can detect problems such as fluid or eardrum perforation.
• Genetic Testing: If hearing loss is suspected to be genetic, genetic testing may be recommended to identify underlying causes.

Management

Management depends on the type and severity of hearing impairment:

Medical Management:

• Conductive Hearing Loss: Treating the underlying cause, such as ear infections or fluid build-up. Antibiotics or grommet insertion may be required for recurrent ear infections.
• Sensorineural Hearing Loss: There is no cure, but management includes the use of hearing aids or cochlear implants, depending on the severity of hearing loss.

Hearing Aids and Implants:

• Hearing Aids: These devices amplify sound and are commonly used for mild to moderate hearing loss.
• Cochlear Implants: These are recommended for children with severe to profound sensorineural hearing loss. The implant bypasses damaged parts of the ear and directly stimulates the auditory nerve.

Speech and Language Therapy:

Children with hearing impairment often require speech and language therapy to aid in communication development. Early intervention is crucial for developing speech, language, and social skills.

Educational Support:

Children with hearing impairment may need special educational support, including the use of hearing devices in the classroom, sign language, or a personalised educational plan (PEP).

Family Support and Counselling:

It is important to provide emotional support and counselling for both the child and their family to cope with the challenges of hearing impairment. Support groups and early intervention programmes can help families navigate the condition.

References

1. NHS (2023). Hearing Problems in Children. Available at: NHS Website
2. NICE (2024). Hearing Loss in Children: Diagnosis and Management Guidelines. Available at: NICE Guidance
3. British Medical Journal (BMJ) (2022). Paediatric Hearing Loss: Clinical Overview and Management. Available at: BMJ