Assessment Of Hearing And Speech In Cerebral Palsy Children And Management
By department of Big Ears, KEM hospital, Pune
Hearing assessment is an integral part of evaluating a child with any speech and hearing problem. Hearing loss has the highest incidence rate for any paediatric disability and should be detected as early as possible. Population based surveys in 2003 in India using the WHO protocol estimated the prevalence of hearing impairment to be 6.3% of people suffering from significant auditory loss. The incidence of hearing disability in the past one year was reported to be 7 per 100 000 population.
Several risk factors for hearing impairment in infants and children are the same risk factors for a child to develop cerebral palsy. Cerebral palsy (CP) and hearing impairment may occur as a result of factors found:
- Prenatally (before birth): Anoxia (lack of oxygen), exposure to radiation, ototoxic medication (drugs that harm the foetus), genetic disorder, foetal stroke, and injury, infection of uterus or kidney, toxaemia, anaemia, Rh incompatibility, in-utero infection such as rubella.
- Perinatally (at the time of birth): Anoxia, Rh incompatibility, hyperbilirubinemia and injury.
- Postnatally (after birth): Anoxia, injury, infections such as toxoplasmosis and meningitis.
Thus it should come as no surprise that hearing impairment occurs more frequently among those with cerebral palsy than in the general population. Recent studies have shown that up to 15% of children with CP also suffer from a hearing loss.
Hearing problems are generally grouped into two types: Sensorineural and Conductive. Conductive hearing loss pertains to problems associated with the outer and the middle ear. Sensorineural hearing loss or permanent hearing loss pertains to problems associated with the inner ear and the auditory nerve. Both types of hearing loss may be present in a child with CP.
However, an infant or child diagnosed with permanent hearing impairment can have a devastating impact on the child’s acquisition of language and development of communication, which in turn can lead to poor literacy skills. It is also likely to affect other areas of development such as educational achievement, self esteem and long term employment opportunities as compared to a conductive hearing loss.
Thus early diagnosis of permanent childhood hearing impairment is very important. Early intervention can greatly improve the outcomes for both the child and the family. Therefore the importance of timely referral of children with suspected hearing loss for a full hearing assessment cannot be overemphasized. This can be accomplished by a screening and /or a diagnostic hearing assessment.
Hearing in children can be assessed at an extremely young age. A reasonable assessment of hearing is now possible in the newborns using objective tests such as:
- Otoacoustic emissions (OAE).
- Auditory Brainstem Response (ABR).
- Auditory Steady State Response (ASSR).
- Immittance Audiometry (Tympanometry with acoustic reflex testing).
Behavioural audiologic assessment includes:
- Behavioural Observation Audiometry (BOA) age range birth to 6 months.
- Visual Reinforcement Audiometry (VRA) age range 6 -24 months.
- Conditioned play audiometry age range 2.5 – 3.5 years
- Pure Tone Audiometry (Conventional PTA) age range 3.5 years and above.
- Speech Audiometry (which includes Speech reception threshold and Speech discrimination test) age range3.5 years and above.
A test battery approach is used consisting of a number of assessment tools to diagnose hearing impairment and identify the probable site of lesion. No single test can provide all that information. Since CP children lack motor control and are likely to have a high frequency sloping hearing loss (especially in the case of kernicterus where hearing may be better in some frequencies and poor in some) behavioural tests may sometimes be unreliable enabling an objective assessment of hearing. Hence a test battery approaches if of utmost importance.
Sloping hearing losses are generally difficult to identify by parents since the child’s response is better in some frequencies compared to other frequencies. In the case of transient tone abnormalities in CP children, hearing may improve with time and so regular monitoring of their auditory status is required. Hence in CP children hearing assessment should be carried out as a rule.
Language development in CP children can be enhanced by effectively using the residual hearing through adequate amplification such as hearing aids and cochlear implants.
Communication disorder in children with cerebral palsy refers to difficulty understanding what is spoken and putting words together to communicate ideas. Best time for a cerebral palsy (CP) child to learn is when they are young because the brain has effectively finished developing by the time child is 6 years old. If you wait too long, the brain is done growing and developing thus the process is harder. The earlier you teach a child, the easier it is.
In cerebral palsy children along with motor co-ordination problems there are feeding, swallowing and receptive-expressive difficulties. A comprehensive speech and language evaluation is necessary to rule out these difficulties followed with regular speech and language therapy.