3. Normal child development, hearing and vision (Illustrated Textbook of Pediatrics) Flashcards
Influence of heredity
and environment
The four functional areas of child
development and their core features.
Developmental milestones
Median age
Limit age
Chronological age, physical growth and developmental skills usually evolve hand in hand. Just as there are normal ranges for changes in body size with age, so there are ranges over which new skills are acquired. Important developmental stages are called developmental milestones.
When considering developmental milestones:
• the median age is the age when half of a standard population of children achieve that level; it serves as a guide to when stages of development are likely to be reached but does not tell us if the child’s skills are outside the normal range.
• limit ages are the age by which the developmental milestones should have been achieved. Limit ages are usually two standard deviations (SDs) from the mean. They are more useful as a guide to whether a child’s development is normal than the median ages. Failure to meet limit ages gives guidance for action regarding more detailed assessment, investigation or intervention.
The difference between median and limit ages is shown
by considering the age range for the developmental
milestone of walking unsupported. The percentage of
children who take their first steps unsupported is:
- 25% by 11 months
- 50% by 12 months
- 75% by 13 months
- 90% by 15 months
- 97.5% by 18 months.
The median age is 12 months and is a guide to the common pattern to expect, although the age range is wide. The limit age is 18 months (2 SDs from the mean). Of those not achieving the limit age, many will be normal late walkers, but a proportion will have an underlying problem, such as cerebral palsy, a primary muscle disorder or global developmental delay. A few may be understimulated from social deprivation. Hence any child who is not walking by 18 months of age should be assessed and examined. Thus 18 months can be set as a ‘limit age’ for children not walking. Setting the limit age earlier may allow earlier identification of problems, but will also increase the number of children labelled as ‘delayed’ who are in fact normal.
Variation in the pattern
of development
There is variation in the pattern of development
between children. Taking motor development as an
example, normal motor development is the progression
from immobility to walking, but not all children
do so in the same way. While most achieve mobility
by crawling (83%), some bottom-shuffle and others
become mobile with their abdomen on the floor,
so-called commando crawling or creeping (Fig. 3.3). A
very few just stand up and walk. The locomotor pattern
(crawling, creeping, shuffling and just standing up)
determines the age of sitting, standing and walking.
Primitive reflexes
Moro
Grasp
Rooting
Stepping response
Asymmetrical tonic neck reflex
Sucking reflex
Moro – sudden
extension of the head
causes symmetrical
extension, then flexion
of the arms
Grasp – flexion of
fingers when an object
is placed in the palm
Rooting – head turns to
the stimulus when
touched near the mouth
Stepping response
– stepping movements
when held vertically and
dorsum of feet touch a
surface
Asymmetrical tonic
neck reflex – lying
supine, the infant adopts
an outstretched arm to
the side to which the
head is turned
Sucking reflex – child
sucks when nipple/teat
placed in their mouth
(automatic feeding
action)
Postural reflexes
Labyrinthine righting
Postural support
Lateral propping
Parachute
Labyrinthine righting
– head moves in
opposite direction to
which the body is tilted
Postural support
– when held upright,
legs take weight and
baby may push up
(bounce)
Lateral propping – in
sitting, the arm extends
on the side to which the
child falls as a saving
mechanism
Parachute – when
suspended face down,
the baby’s arms extend
as though to save
himself
Gross motor development (median ages)
Newborn (2)
6-8 weeks
6-8 months
8-9 months
10 months
12 months
15 months
Vision and fine motor (median ages)
6 weeks
4 months
4-6 months
7 months
10 months
16-18 months
14 months - 4 years
2-5 years
Hearing, speech and language (median ages)
Newborn
3-4 months
7 months
7-10 months
12 months
18 months
20-24 months
2,5 - 3 years
Social, emotional and behavioural development (median ages)
6 weeks
6-8 months
10-12 months
12 months
18 months
18-24 months
2 years
2,5 - 3 years
Developmental milestones by median age (Summary)
Newborn - 7 mo - 1 yr - 15-18 mo - 2,5 yrs
Gross motor
Vision and fine motor
Hearing, speech, and language
Social, emotional, and behavioural
Hearing screening of newborn infants
Early detection and treatment of hearing impairment
improves the outcome for speech and language and
behaviour. In order to detect hearing impairment in the
newborn period, hearing can be tested by:
• otoacoustic emission (OAE; Fig. 3.9a) – an earphone
produces a sound which evokes an echo or
emission from the ear if cochlear function is normal
• auditory brainstem response (ABR) audiometry
(Fig. 3.9b) – computer analysis of
electroencephalogram waveforms evoked in
response to a series of auditory stimuli.
Distraction testing
Used for infants in the age of…
This was the mainstay of hearing screening but has
been replaced by universal neonatal screening. It is
now only used as a screening test for infants at 7–9
months of age who have not had newborn screening
or cannot tolerate or cooperate with more complex
testing. The test relies on the baby locating and
turning appropriately towards sounds, but before
the child develops the ability for object permanence,
that is, the ability to remember that an assessor is
standing behind them even without seeing them.
High-frequency and low-frequency sounds are
presented out of the infant’s field of vision. Testing
is unreliable if not carried out by properly trained
staff, because it can be difficult to identify hearingimpaired
infants as they are particularly adept at using
non-auditory cues.
Visual reinforcement audiometry
Useful in infants between the ages of…
Also used in older children with…
This is particularly useful to assess hearing impairment
in infants between 10 and 18 months of age, although
it can be used between the ages of 6 months and 3
years. It is also used in some older children with learning
disability. Hearing thresholds are established using
visual rewards (illumination of toys) to reinforce the
child’s head turn to stimuli of different frequencies.
Localisation of the stimuli is not necessary and insert
earphones may be used to obtain ear-specific information,
thus making it more useful than free field tests
such as distraction and performance testing.
Performance and speech
discrimination testing
Between the ages of…
Also for older children with…
Performance testing using high-frequency and lowfrequency
stimuli and speech discrimination testing using miniature toys can be used for children with suspected hearing loss at 18 months to 4 years of age
or for older children with learning disabilities.
Hearing checklist for parents
Vision
Visual acuity from birth…
Visual acuity is low at birth but gradually
increases to normal adult levels by about 5
years of age.
