DEVELOPMENTAL DELAY
Developmental status of a child is usually measured and expressed either as Developmental age, i.e. the age for which expected milestones have been achieved or as developmental quotient (DQ) derived by dividing developmental age (DA) by chronological age (CA) and multiplied by 100 (DQ = DA/CA? 100).
DQ is an absolute value and not a percentage.Developmental delay (DD) refers to the significant delay in achieving developmental milestones in any one or more of the following domains: (a) gross and fine motor, (b) social-personal, (c) cognition, (d) speech and language, and (e) activities of daily living, as compared to peers, i.e. a performance of less than 2 SD for the age- appropriate norms. A DQ of less than 70 is also considered as developmental delay.
This term is reserved only for children below 5 years of age, in whom formal intelligence quotient (IQ) testing is not possible. The term 'Intellectual disability' is used in older children (Ch 3.6).
Types: Developmental delay may be further classified as:
a. Global developmental delay (GDD), when two or more domains are affected, and
b. Development dissociation, when the delay is limited to only one domain or is disproportionately more in one domain as compared to others. DA or DQ should always be measured in different domains separately, to identify developmental dissociation, if any.
Developmental deviance, i.e. differences in the sequence of achieving different milestones in one or more domain may be innocent or sinister, e.g. some infants may not creep before they start walking and should not be construed as abnormal.
Developmental regression, refers to the loss of previously acquired milestones, usually suggestive of a neurodegenerative disorder.
Etiology of DD is identifiable only in ~70% cases and common causes include genetic disorders, intrauterine infections, e.g.
congenital rubella syndrome, perinatal hypoxia at the time of birth and postnatal insults to developing brain till 2 years of life. Emotional deprivation may also lead to DD, specially in social domain while hearing impairment is the commonest cause of delay in language development (Table 3.7).Diagnostic approach for a child with suspected DD aims to-(a) confirm the presence of DD vis a vis individual variations and deviance, (b) differentiate global DD from developmental dissociation, deviance or regression, (c) identify the cause of DD, if possible, and (d) search for presence of co-morbidities, if any.
Early detection of developmental delay involves a step-wise approach:
a. Informal developmental surveillance of all children during all health-care visits;
b. Formal development screening of all children at scheduled intervals;
c. Formal developmental assessment of children with abnormal screening results.
Step I. Informal developmental surveillance, discussed earlier (Ch 2.7) is a continuous and informal process
TABLE 3.7: Causes of developmental delay
• Idiopathic (30%)
• Familial
• Genetic disorders:
- Chromosomal: Down syndrome, Fragile X syndrome
- Inborn errors of metabolism: Phenylketonuria
- Mitochondrial disorders
• Fetal brain injury:
- Congenital brain malformations
- Intrauterine infections, e.g. CRS
- Teratogens: Alcohol, phenytoin
- Obstetric complications
• Perinatal brain injury:
- Prematurity and/or low birth weight
- Birth asphyxia and birth injuries
- Metabolic: Hypoglycemia, kernicterus
• Postnatal brain injury (in first 2 years):
- Infections: Meningitis, encephalitis
- Head injury
- Endocrinal: Hypothyroidism
- Prolonged hypoxia: Seizures, ALTS
- Toxic: Lead poisoning
- Metabolic: Hypoglycemia
• Environmental:
- Emotional deprivation
- Visual/hearing disability
ALTS: Acute life threatening events
to assess the development of a child during regular health check-up/immunization visits by asking the developmental history from mother, observing his/her behavior in the clinic and examination to elicit common age-appropriate milestones.
A developmental delay may exist when the child fails to achieve developmental milestones at the expected age, despite adjustments for individual variations. However, the purpose of this surveillance is not to draw a line between normal and abnormal, but to identify high-risk children, who need referral for formal assessment.Mother and child protection (MCP) card also includes a check-list of red-flag signs for delayed development for different ages, which can also be used by field health workers to identify a high-risk child, who need referral for further assessment (Table 2.12).
Step II. Formal developmental screening involves use of validated and locally appropriate screening tools to identify high-risk children who needs detailed developmental assessment.
IAP recommends that—
a. All children should be screened by these screening tools at the age of 9-12 months, 18-24 months and at school entry, coinciding with immunization visits, and
b. High-risk children should also be additionally screened at 4-6 months.
Many screening tests are available for this purpose, including widely used Denver developmental screening
TABLE 3.8: Referral criteria for formal developmental assessment
• Delayed development on informal surveillance
• Delayed development on formal screening
• Family h/o delayed development/intellectual disability
• Neuromuscular or neuroregression disorders
• Presence of dysmorphic features/physical stigmata (Table 3.9)
• Presence of vision or hearing disabilities
• Abnormal neuroimaging findings
DD: Developmental delay, ID: Intellectual disability
test (DDST), or locally developed Phatak's Baroda development screening test or Trivandrum development screening test, discussed in Ch 2.7.
However, these screening tests should not be used to assign development quotient/intelligence quotient or to declare the developmental delay but only to identify high-risk children for formal assessment.
Step III: Formal development assessment tests: Developmental delay is a shattering diagnosis for parents and should not be made without formal assessment.
Table 3.8 enlists high-risk children for developmental delay, who must be referred for formal developmental assessment, including those identified on informal surveillance or screening tests.Formal developmental assessment tests must be administered only by trained personals, usually developmental pediatricians or clinical psychologists. Many such tests are available and the choice depends on the age of the child, expected area of developmental abnormality and familiarity of the assessor with the test.
Bayley scale of infant development (BSID-IV) for children aged 16 months to 42 months and its Indian version- developmental assessment scale of Indian infants (DASII) for children aged 0-30 months, are commonly used in India to confirm the presence and severity of developmental delay in young children.
Other domain-specific tests are also available, e.g. Vineland adaptive behavior scale II for personal-social domain and clinical linguistic/auditory milestone scale (CLAMS) for language skills.
Step IV. Assessment of a child with confirmed DD on formal developmental assessment tests needs a detailed history, clinical examination, relevant investigations and developmental evaluations to arrive at an etiological diagnosis, to identify the line of further management, predict the expected outcome and parental counselling. Important components of this assessment include—
a. Detailed history, with special reference to similar family history (pedigree analysis), consanguinity, adverse antenatal or perinatal events and behavioural problems, e.g. attention-deficit.
b. Review of the development record to distinguish between- (a) delay from birth or later, (b) global developmental
delay from developmental dissociation, (c) developmental delay and developmental regression, and (d) non-progressive delay and progressive worsening.
Presence of developmental dissociation (selective delay in one or two domains) narrows the diagnostic possibilities, e.g. hearing impairment for speech/ language domain, vision/hearing impairment for personal-social domain, neuromuscular disorders for motor domain, etc.
Similarly, a non-progressive global delay indicates cerebral palsy, whereas a deviancy or regression in social and communication domains may indicate autism spectrum disorder.c. Physical examination with special reference to anthropometry, physical stigmata (Table 3.9), vision/hearing problems and neurological signs. Ophthalmoscopic examination is highly informative in etiological diagnosis of developmental delay, e.g. presence of chorioretinitis in intrauterine infections, cherry-red spot in neurodegenerative disorders, papilledema in hydrocephalus, etc.
d. Relevant investigations, depending on suspected etiology, mainly include cytogenetic, biochemical and neuroimaging tests (Table 3.10).
e. Family screening: Once a genetic diagnosis is firmly established in the index case, parents and siblings should be screened for assessing the risk of recurrence and genetic counselling.
Management: Except for few causes, e.g. hypothyroidism, phenylketonuria and lead intoxication, majority of the disorders with developmental delay have no pharmacological cure and management primarily aims
TABLE 3.9: Common physical stigmata in developmental delay
• Size : Tall/short stature, obesity, failure to thrive
• Head: Microcephaly, hydrocephalus
• Eyes : Slanting eyes, microphthalmia, cataract
• Ears : Deformed or low-set ears
• Face : Coarse facies, retro-/prognathia
• Mouth : Cleft lip/palate, macroglossia
• Hair : Sparse, kinky, light-colored
• Neck : Short or webbed neck
• Limb : BrachyVarachnodactyly, poly-∕syndactyly
• Skin : Cafe-au-lait spots, adenoma sebaceum
• Genitals : Hypogonadism, hypospadias to achieve maximum functional independence and eliminate function-limiting factors, e.g. vision/hearing impairment or seizures.
Management and rehabilitation program of each child needs to be individualized, according to their needs and potential. A multidisciplinary team approach is essential in these cases, involving following interventions:
a. Physiotherapy and occupational therapy for neuromuscular dysfunctions.
b. Management of associated deficits, e.g. hearing, vision and speech delay, seizures, etc.
c. Psychotherapy or behavioral modification.
d. Schooling, preferably in a regular school, as far as possible.
e. Parental support and counselling
Parental counselling is an essential component of the management of development delay to help them understand the:
a. cause of developmental delay.
b. goals of diagnostic and therapeutic interventions,
c. anticipatory course and expected long-term outcome,
d. strengths of the child, and
e. potential to prevent recurrence in subsequent children.
Managing a child with developmental delay is often a frustrating task for parents, who should be counselled in clear and compassionate manner but without kindling unrealistic expectations.