Any child whose development is delayed or disordered needs assessment to determine the cause and management. Neurodevelopmental problems present at all ages, with an increasing number now recognised antenatally (Table 4.1). Many are identified in the neonatal period because of abnormal neurology or dysmorphic features. During infancy and early childhood, problems often present at an age when a specific area of development is most rapid and prominent, i.e. motor problems during the first 18 months of age, speech and language problems between 18 months and 3 years and social and communication disorders between 2 and 4 years. Abnormal development may be caused not only by neurodevelopmental problems (Table 4.2) but also by ill health or if the child’s physical or psychological needs are not met.

When performing a clinical examination on a young child with a developmental problem:

Many examination findings can be predicted from observation of functional skills.

Many parental concerns about their child’s development are found to be variations of the norm, in which case the parents should be reassured. If in doubt, observe the child’s progress over a period of time.

Abnormal development – key concepts

The terminology can be confusing, but:

• Delay – implies slow acquisition of all skills (global delay) or of one particular field or area of skill (specific delay), particularly in relation to developmental problems in the 0–5 years age group

• Learning difficulty – used in relation to children of school age and may be cognitive, physical, both or relate to specific functional skills

• Disorder – maldevelopment of a skill.

The following are agreed definitions:

• Impairment – loss or abnormality of physiological function or anatomical structure

• Disability – any restriction or lack of ability due to the impairment

• Disadvantage – this results from the disability, and limits or prevents fulfilment of a normal role. It is situationally specific; a child with a learning disability may for example be a good skier or enjoy swimming.

The term ‘handicap’ is now discouraged as it can imply a person deserves pity. Difficulty and disability are often used interchangeably, but difficulty is used particularly in an educational context.

The pattern of abnormal development (global or specific) can be categorised as (Fig. 4.1):

• slow but steady

• plateau effect

• showing regression.

The severity can be categorised as:

• mild

• moderate

• severe

• profound.

Other features of developmental delay are:

• The gap between normal and abnormal development becomes greater with increasing age and therefore becomes more apparent over time (Fig. 4.2).

• It may be the presentation of a wide variety of underlying conditions (Table 4.2).

• The site and severity of brain damage influences the clinical outcome, i.e. whether there will be specific or global developmental delay, learning and/or physical disability.

• It may be genetic, with important implications for the family.

• There is a wide age band across which it can be normal to achieve a developmental skill. Limit ages denote beyond the normal range.

Summary

Abnormal development

• Incorporates global and specific delay or disorder, learning difficulty, impairment and disability

• Varies in pattern of progression and severity

• Becomes more apparent with age.

The choice of investigations to identify the cause is influenced by the child’s age, the history and clinical findings (Table 4.3). In some children, no cause can be identified even after extensive investigation.

Table 4.3

Investigations or assessment to consider for developmental delay

Cytogenetic	Chromosome karyotypea
	Fragile X analysisa
	DNA FISH analysis, e.g. for chromosome 7, 15, 22 deletions, CGH microarray (comparative genomic hybridisation), telomere screen
Metabolic	Thyroid function tests, liver function tests, bone chemistry, urea and electrolytes, plasma amino acidsa
	Creatine kinase, blood lactate, VLCFA (very long chain fatty acids), ammonia, blood gases, white cell (lysosomal) enzymes, urine amino and organic acids, urine mucopolysaccharides (GAG) and oligosaccharide screen, urine reducing substances, lead levels, urate, ferritin, biotinidase
	Maternal amino acids for raised phenylalanine
Infection	Congenital infection screen
Imaging	Cranial ultrasound in newborn
	CT and MRI brain scans
	Skeletal survey, bone age
Neurophysiology	EEG (for seizures and can be specific for some progressive neurological disorders and syndromes)
	Nerve conduction studies, EMG, VEP (visual evoked potentials), ERG (electroretinogram)
Histopathology/histochemistry	Nerve and muscle biopsy
Other	Hearinga
	Visiona
	Clinical genetics
	Cognitive assessment
	Therapy assessment – physiotherapy, occupational therapy and speech and language therapy
	Child psychiatry
	Dietician
	Nursery/school reports

^aBasic screening tests.

Abnormal motor development

This may present as delay in acquisition of motor skills, e.g. head control, rolling, sitting, standing, walking or as problems with balance, an abnormal gait, asymmetry of hand use, involuntary movements or rarely loss of motor skills. Concern about motor development usually presents between 3 months and 2 years of age when acquisition of motor skills is occurring most rapidly. Examination may reveal underlying abnormal motor signs.

Causes of abnormal motor development include:

• central motor deficit e.g. cerebral palsy

• congenital myopathy/primary muscle disease

• spinal cord lesions, e.g. spina bifida

• global developmental delay, as in many syndromes or of unidentified cause.

As hand dominance is not acquired until 1–2 years or later, asymmetry of motor skills during the first year of life is always abnormal and may suggest an underlying hemiplegia.

Late walking (>18 months old) may be caused by any of the above but also needs to be differentiated from children who display the normal locomotor variants of bottom-shuffling or commando crawling (see Ch. 3), where walking occurs later than with crawlers.

Concern about abnormal motor development needs assessment by a neurodevelopmental paediatrician and physiotherapist. Ongoing physiotherapy input and subsequent involvement of an occupational therapist is likely to be needed.

Cerebral palsy (CP)

Cerebral palsy may be defined as an abnormality of movement and posture, causing activity limitation attributed to non-progressive disturbances that occurred in the developing fetal or infant brain. The motor disorders of CP are often accompanied by disturbances of cognition, communication, perception, sensation, behaviour and seizure disorder and secondary musculoskeletal problems. Although the lesion is non-progressive, the clinical manifestations emerge over time, reflecting the balance between normal and abnormal cerebral maturation. Cerebral palsy is the most common cause of motor impairment in children, affecting about 2 per 1000 live births. The term is usually used for brain injuries occurring up to the age of 2 years. After this age, it is more appropriate to use acquired brain injury as the diagnosis. Although the underlying cause is static, the resulting motor disorder may evolve, giving the impression of deterioration. The diagnosis for each child should formulate: the distribution of the motor disorder, the movement type, the cause and any associated impairment.

Causes

About 80% of cerebral palsy is antenatal in origin due to vascular occlusion, cortical migration disorders or structural maldevelopment of the brain during gestation. Some of these problems are linked to gene deletions. Other antenatal causes are genetic syndromes and congenital infection.

Only about 10% of cases are thought to be due to hypoxic-ischaemic injury during delivery and this proportion has remained relatively constant over the last decade. About 10% are postnatal in origin.

Preterm infants are especially vulnerable to brain damage from periventricular leucomalacia (PVL) secondary to ischaemia and/or severe intraventricular haemorrhage. The rise in survival of extremely preterm infants has been accompanied by an increase in survivors with cerebral palsy, although the number of such children is relatively small.

Postnatal causes are meningitis/encephalitis/encephalopathy, head trauma from accidental or non-accidental injury, symptomatic hypoglycaemia, hydrocephalus and hyperbilirubinaemia.

MRI brain scans may assist in identifying the cause of the cerebral palsy but a scan is not necessary to make the diagnosis.

Clinical presentation

Many children who develop cerebral palsy will have been identified as being at risk in the neonatal period. Early features of cerebral palsy are as follows:

• Abnormal limb and/or trunk posture and tone in infancy with delayed motor milestones (Fig. 4.3); may be accompanied by slowing of head growth

• Feeding difficulties, with oromotor incoordination, slow feeding, gagging and vomiting

• Abnormal gait once walking is achieved

• Asymmetric hand function before 12 months of age.

In CP, primitive reflexes, which facilitate the emergence of normal patterns of movement and which need to disappear for motor development to progress, may persist and become obligatory (see Ch. 3).

The diagnosis is made by clinical examination, with particular attention to assessment of posture and the pattern of tone in the limbs and trunk, hand function and gait. There are three main clinical subtypes: spastic (90%), dyskinetic (6%) and ataxic (4%). A mixed pattern may occur. Functional ability is described using the Gross Motor Function Classification System (Table 4.4).

Table 4.4

Gross Motor Function Classification System (GMFCS)

Level I	Walks without limitations
Level II	Walks with limitations
Level III	Walks using a handheld mobility device
Level IV	Self-mobility with limitations; may use powered mobility
Level V	Transported in a manual wheelchair

See http://www.canchild.ca/en/measures/gmfcs.asp for further details (accessed January 2011).

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