Sensorineural Hearing Loss in Children

Definition

Hearing loss due to the failure of the inner ear to turn sound vibrations into nerve impulses for transmission to the brain. It can be moderate, severe or profound and can affect one or both sides.

Incidence

About one child in a thousand has significant sensorineural hearing loss.

Causes

Children may be born deaf or develop deafness suddenly or gradually. There are many causes. These include:

• Unknown
• Inherited with or without other abnormalities (a syndrome)
• Inherited with or without a family history
• Infection - Before birth, eg, rubella and cytomegalovirus. After birth, eg, childhood measles, mumps, chicken pox and bacterial meningitis
• Injuries - major head injuries
• Metabolic - often associated with major problems in early life such as jaundice or lack of oxygen
• In association with very low birth weight/extreme prematurity
• Psychogenic

Signs & Symptoms

The symptoms of sensorineural hearing loss will depend on the severity of the loss and the age at which it develops. The main symptom is lack of appropriate responsiveness to sound including voices and environmental sounds. Severely affected children will show no responsiveness to sound at all but deaf infants are often very visually alert and can appear to respond to sound when they are in fact responding to visual stimuli. Less severely affected children may turn the TV on loud, mishear or suffer educationally. Speech development may suffer in children with impaired hearing. Severely affected children may have no speech development although they may vocalise. Less severely affected children may have delayed speech development or tend to mispronounce. One sided hearing loss seldom produces major problems although there can be direction of hearing difficulty or problems in background noises.

Tests

The type of hearing test depends upon the age of the child:

Behavioural tests rely on the child making a repeatable response to sounds produced by the tester eg looking round when a rattle is shaken from behind. The degree of sophistication of the test depends on the child's developmental status. These tests are not reliable much before the age of eight months.

Electrophysiological tests test electrical activity in the auditory system. In general they can be performed at any age but require special equipment and have technical limitations.

If severe and profound hearing loss are not detected and treated in the early years of life, there is a risk that the child will never develop speech (deaf and dumb) it is therefore important to detect severe and profound deafness as young as possible so that help can be given. There is a wide geographical variation in the arrangements for this. The long term aim is to develop a system in which the whole population is screened using electrophysiological tests for hearing loss in the early weeks of life.

Other tests may be needed in some cases of sensorineural deafness. These may include tests of the heart, kidneys, eyes, blood tests for infection, genetic tests and scanning of the ears.

Treatment

Sensorineural deafness is permanent and there is no curative treatment. Few children are totally deaf however and the focus of treatment is to maximise the use of the child's residual hearing and to promote the development of communication and language.

Medical

No drug treatment helps sensorineural hearing loss.

Hearing aids

These are fitted as soon as the hearing loss is detected and usually to both ears although there can be some difficulty fitting them to the very youngest babies.

Surgical

Cochlear implantation is appropriate for some children who do not have a g