Approach to the child with global developmental delay
Definition for global developmental delay (GDD)
  • GDD is operationally defined as significant delay in 2 or more developmental domains.
  • The developmental domains are
    • Gross motor
    • Vision and fine motor
    • Speech, hearing and language
    • Personal/social
  • Significant delay is defined as performance or ability of 2 standard deviations or more below the mean on accepted norm-referenced developmental testing i.e. Denver Developmental Screening Test
Definition for other forms of developmental delay
  • Motor delay is defined as significant delay in gross and/or fine motor skills with appropriate performances in other developmental domains.
  • In developmental language disorders, the significant delay is restricted to speech and language skills with normal performance in other developmental domains.
  • In autistic spectrum disorders, there are observed qualitative defects in social skills, communication (verbal and non-verbal) and restrictive/repetitive patterns of behaviour.
Objectives of assessment of the child with GDD
  • Confirm the presence of developmental delay
  • Categorize the developmental domains affected
  • Establish etiologic diagnosis for the delay
  • Manage any associated medical complications
Work-up towards establishing the diagnosis
  • Detailed directed history
  • Physical examination
  • Ancillary evaluations
  • Laboratory investigations
Detailed directed history
1. HISTORY OF DEVELOPMENTAL MILESTONES
  • History of developmental milestones in all domains
  • Present developmental abilities
  • Any actual loss or regression of previously acquired skills
If positive à progressive encephalopathy as opposed to static encephalopathy
2. FAMILY HISTORY
  • Consanguinity
  • Other affected family members
  • Early post-natal deaths of other siblings
3. PREGNANCY (PRENATAL EVENTS)
  • Intra-uterine difficulties
  • Use of drugs or alcohol
  • Toxin or infection exposure
  • Previous miscarriage or stillbirth
4. PERINATAL EVENTS
  • Timing of delivery: prematurity
  • Obstetric complications
  • Birth weight: low BW, small for gestation
  • APGAR scores
  • Signs of possible hypoxic-ischaemic encephalopathy
i.e. poor sucking, irritability, obtundation, seizures
5. NEONATAL COMPLICATIONS
  • Intra-ventricular haemorrhage
  • Sepsis/meningitis
  • Hypoxia from respiratory complications
  • Severe hyperbilirubinaemia
6. SOCIAL HISTORY
  • Mentally retarded parents
  • Single or teenage parent } Delay could be due to
  • Child abuse } parental neglect
Physical examination
1. GENERAL EXAMINATION
  • Major congenital anomalies i.e. spina bifida, CHD
  • Dysmorphic features or minor congenital anomalies
  • FTT
  • Neurocutaneous stigmata
  • Visceral abnormalities i.e. hepatosplenomegaly
  • Skeletal abnormalities i.e. dwarfism
2. EXAMINATION OF THE HEAD
  • OFC: microcephaly or macrocephaly
  • Comparison with previous OFC
  • Head shape
  • Fontanelles and sutures
3. NEUROLOGICAL EXAMINATION
  • Neurological signs i.e. hypotonia, hypertonia
  • Persistence of primitive reflexes or abnormal postures
  • Focal motor findings
  • Involuntary movements
  • Encephalopathic states
Ancillary evaluations
1. VISUAL ASSESSMENT
  • Vision screening
  • Full ophthalmologic examination
2. AUDIOMETRIC ASSESSMENT
  • Behavioural audiometry
  • Brainstem audiometry evoked response if above is not possible

3. FORMAL PSYCHOMETRIC ASSESSMENT (FOR IQ)
4. PSYCHOLOGICAL EVALUATION OF PATIENT AND FAMILY
Laboratory investigations
1. CYTOGENETIC ANALYSIS FOR CHROMOSOMAL ANOMALIES
  • Higher yield when there are dysmorphic features
  • May need testing for subtelomeric rearrangements in the presence of family history of developmental delay or mental retardation.
2. MOLECULAR ANALYSIS FOR FRAGILE X SYNDROME

3. NEURO-IMAGING (MRI PREFERABLE TO CT SCAN)
  • Higher yield when there are asymmetric neurological findings or abnormal OFC
4. SCREEN FOR METABOLIC DISORDERS
  • Higher yield in the presence of history of
    • Parental consanguinity of affected sibling
    • Multiple organ involvement
    • Developmental regression
  • Usually includes
    • Urine organic acid screen
    • Serum amino acids (quantitative)
    • Serum lactate
    • Serum ammonia
    • Capillary/arterial blood gas
5. THYROID FUNCTION TEST
  • If not screened previously in the newborn protocol
  • If clinically indicated
6. OTHER LABORATORY INVESTIGATIONS TO BE CONSIDERED
  • EEG
    • For the diagnosis of treatable electroclinical syndromes such as (a) Landau Kleffner syndrome (electrical status epilepticus during slow-wave sleep) and (b) severe myoclonic epilepsy
  • Serum creatinine phosphokinase
    • If suspecting muscular dystrophy
  • EMG or NCS
    • If other neuromuscular disorders are strongly suspected
  • Lysosomal enzyme analysis, urine mucopolysaccharides and very-long-chain fatty acids may be needed, especially if there exists potential treatment or genetic counselling.
Common diagnoses following evaluation of the child with GDD
  • Cerebral dysgenesis (17%)
  • Hypoxic-ischaemic encephalopathy (10%)
  • Chromosomal anomalies (10%)
  • Toxin exposure – alcohol or cocaine(8%)
  • Metabolic disorders (5%)
  • Neuromuscular disorders (3%)
  • Neurocutaneous syndromes (3%)
  • Other genetic or dysmorphic syndromes (3%)
  • Epileptic syndromes (3%)
Importance of establishing the diagnosis
  • Specific therapeutic interventions if possible (for some neurometabolic disorders)
  • General medical management
  • Prognosis and long-term outcome
  • Genetic counselling for future risks
Follow-up
  • Review results of previous investigations
  • Referral for appropriate rehabilitation services and/or developmental programmes
  • If no diagnosis ascertained yet, to re-assess developmental progress and consider
    • Further metabolic testing as the need arises
    • The possibility of progressive encephalopathy
  • Sometimes diagnosis may become apparent with time especially for dysmorphic syndromes