Childhood Deafness

There are two types of hearing loss: sensorineural and conductive. Although conductive hearing loss is more common, the majority of permanent childhood hearing impairment is sensorineural.

• Conductive hearing loss: affects 4% of all school children. Almost all cases are due to glue ear. Sounds perceived by the brain are diminished but are generally not distorted.
• Sensorineural hearing loss: affects 0.3% of all school children. Sounds perceived by the brain are both diminished and distorted. The degree of distortion is independent of the degree of hearing loss (e.g. a very mild hearing loss but very poor speech discrimination is possible).
• Mixed hearing loss has components of both conductive and sensorineural hearing loss.

• Mild deafness: 20-40 dB
• Moderate deafness: 41-70 dB
• Severe deafness: 71-95 dB
• Profound deafness: 95 dB

• Temporary deafness, due to eustachian tube blockage and middle ear infections, is common.
• Permanent hearing impairment affects approximately 1 per 1000 live births but 50-90% more children are diagnosed with permanent hearing impairment by the age of 9 years.¹
• Most sensorineural hearing loss in children is congenital or acquired perinatally, but may present at any age. Approximately 10-20% of all deafness is acquired postnatally, although some genetic causes of deafness result in hearing loss that begins during childhood or adolescence.

Risk factors

• Family history
• Infection: congenital (e.g. rubella), meningitis
• Ototoxic medications: in utero or postnatal
• Low birth weight, low birth apgar scores, prolonged mechanical ventilation
• Craniofacial anomalies or any syndrome associated with sensorineural hearing loss
• Severe neonatal hyperbilirubinaemia
• Head injury
• Neurodegenerative disorders
• Concern about hearing, speech, language or developmental delay

• Genetic causes (50%): may or may not be part of a recognised genetic syndrome, e.g. Turner's syndrome, Klinefelter syndrome.
• Intrauterine (8%): congenital infection, e.g. rubella, CMV, toxoplasmosis; maternal drugs, e.g. alcohol, cocaine, streptomycin.
• Perinatal causes (12%): examples include prematurity and/or low birth weight, birth asphyxia, severe hyperbilirubinaemia and sepsis.
• Postnatal causes (30%): childhood infections, e.g. meningitis, encephalitis, head injury.
• Unknown causes: 20-30% of deaf children have no definite known aetiology.

• Presentation of hearing loss is dependent on the degree and patient age at onset of the hearing loss, the threshold for suspicion of parents and health care providers, and the presence of other identifiable risk factors.
• Always take parents seriously if they suspect that their child is deaf.
• Children with congenital or perinatally acquired profound sensorineural hearing loss (>90 dB) may present by age 6-9 months,² whereas those with lesser degrees of hearing loss may present with minor speech impediments, language delay, behavioural problems or problems at school.
• Children with congenital hearing loss may have other physical stigmata.
• Children with conductive hearing loss should be assessed for serous otitis media and adenoidal hypertrophy, e.g. mouth breathing, persistent cough (post-nasal drip). Wax may be a cause of conductive hearing loss but this is not a common cause in children. Examination of the ear may reveal evidence of chronic infections (e.g. perforation or scarring of the tympanic membrane, cholesteatoma, fluid behind the tympanic membrane).

• The differential diagnosis of children presenting with language, behavioral or school difficulties should include hearing loss.
• Conductive hearing loss may be due to chronic serous otitis media, foreign body, wax.
• The precise aetiology of sensorineural hearing loss may be obvious (e.g. post meningitis) or remain uncertain.

• Screening hearing in newborn babies has been shown to be cost effective and early identification is associated with better language, speech, social and emotional development.¹
• The oto-acoustic emission test and automated auditory brainstem response screen are the two main tests used by the NHS Newborn Hearing Screening Programme.
• Hearing screening tests for all ages of childhood are covered in a separate article.

• Specific tests for hearing loss include auditory brainstem response (formally the Brainstem Audio-Evoked Response or the automated Auditory Brainstem Response), otoacoustic emissions and audiometry.
• Tympanometry
• MRI or CT scan: may be indicated in investigation of any underlying cause of hearing loss.
• Chromosomal studies may be of benefit in seeking particular genetic syndromes.

Management of moderate to profound permanent hearing impairment includes:

• Family support, advice and information
• Hearing aids: the early use of hearing aids (before 6 months of life) has a better outcome , e.g. in terms of speech and language development.³
• Communication support (spoken and/or signed), e.g.:
  • Auditory-oral approaches maintain that many deaf children can develop their listening skills and a spoken language. These approaches emphasise the use of hearing aids, radio aids and cochlear implants to maximise the hearing a deaf child may have.
  • Lip reading/speech reading.
  • British Sign Language is a visual language using hand shapes, facial expressions, gestures and body language to communicate. It is an independent and complete language with a unique vocabulary.
  • Sign bilingualism describes an approach that encourages the learning and using of two languages at the same time: a sign language and a spoken/written language.
  • Finger spelling: each letter of the alphabet is indicated by using the fingers and palm of the hand. It is used for spelling names, places, or for words that don't have a sign.
• Pre-school education support
• Special school education needs assessment and provision
• Cochlear implants
• Other devices, e.g. radio aids (the teacher wears a transmitter and the child with hearing loss wears a receiver).

Conductive hearing loss

• Conductive hearing loss: grommet insertion and/or adenoidectomy may be required. If the hearing loss continues, amplification with a hearing aid may be needed. Speech therapy may also be required.
• If otitis results in the destruction or fixation of the ossicles, surgery may help improve ossicular function.
• Cholesteatomas should be treated surgically.

May cause long term speech, language and behavioural problems.

• Conductive hearing loss: 50% of cases of glue ear resolve within 3 months and 95% within 1 year. Problems rarely persist beyond childhood.
• Early identification of permanent hearing loss is associated with better language, speech, social and emotional development.⁴

• Rubella immunisation programmes aiming at eradication.
• Early diagnosis and treatment of potential causes, e.g. meningitis.
• Cautious prescribing of medications for pregnant and possibly pregnant women as well as children.