Q4 LONG ANSWER 10M ★ High-yield

Define Approach to a Child with Developmental Delay. Describe its aetiology, causes, investigations and management.

Pediatrics · Final Professional

Developmental delay is a significant lag (usually > 2 SD below the mean, or DQ < 70) in achieving milestones in one or more developmental domains.
Global Developmental Delay (GDD) denotes delay in ≥ 2 of the four domains in a child under 5 years.
Beyond 5 years, once cognition can be formally tested, the term intellectual disability is used.

Pattern	Likely area involved
Isolated motor delay	Cerebral palsy, neuromuscular disease, spina bifida
Isolated speech/language delay	Hearing loss, autism, oromotor problem, environmental deprivation
Global delay	Genetic/metabolic, perinatal insult, congenital infection, hypothyroidism
Regression (loss of skills)	Neurodegenerative / inborn errors of metabolism — always pathological

Chromosomal — Down syndrome, fragile-X syndrome, microdeletions.
Genetic / metabolic — inborn errors of metabolism; neurocutaneous syndromes.
Structural — neural tube defects, cerebral malformations, congenital hydrocephalus.
Congenital infections (torch); teratogens (alcohol — fetal alcohol syndrome); maternal illness.

CNS infections (meningitis, encephalitis); head trauma; hypoxic insults (near-drowning).
Hypothyroidism; severe undernutrition; iron deficiency; lead poisoning.
Severe psychosocial deprivation / neglect; uncontrolled epilepsy.

Antenatal — infections, drugs / alcohol, maternal illness.
Perinatal — asphyxia, prematurity, jaundice, NICU stay.
Developmental history — age of attainment of milestones and any regression.
Nutrition, immunisation, seizures; family history & consanguinity; prior sibling deaths.

Anthropometry including head circumference (micro- / macrocephaly).
Dysmorphology — facies, ears, palate, hands, genitalia.
Skin (neurocutaneous markers) — café-au-lait macules, ash-leaf spots, port-wine stain.
Full neurological exam — tone, power, deep reflexes, persistence of primitive reflexes, posture, gait.
Vision & hearing; organomegaly (storage disorders); cardiac exam; eye (cataract, cherry-red spot, KF ring).

Condition	Pointers
Cerebral palsy	Motor delay, abnormal tone, persistent primitive reflexes, history of asphyxia/prematurity
Down syndrome	Hypotonia, upslanting eyes, flat facies, single palmar crease, cardiac defect
Congenital hypothyroidism	Lethargy, feeding difficulty, constipation, large tongue, umbilical hernia, prolonged jaundice
Autism spectrum disorder	Poor eye contact/social reciprocity, language delay, repetitive behaviour, normal motor
Fragile-X	Long face, large ears, macro-orchidism, intellectual disability (commonest inherited cause)

Vision & hearing (BERA) in every child — especially with speech delay.
Thyroid function; CBC; and a metabolic screen (blood gas, ammonia, lactate, urine metabolic screen) if regression / consanguinity.
Karyotype / chromosomal microarray; Fragile-X testing; targeted genetic & metabolic tests.
Neuroimaging (MRI brain) for microcephaly, focal deficits, regression or seizures.
EEG if seizures are suspected; serum creatine kinase for isolated motor delay (muscular dystrophy).

Treat the treatable — thyroxine for hypothyroidism, correct hearing/vision, nutrition, treat seizures & infections.
Early intervention & therapy — physiotherapy, occupational therapy, speech therapy, special education.
Family counselling & support; genetic counselling; disability certification and rehabilitation services.
Regular follow-up to monitor progress and detect associated problems (epilepsy, behaviour, contractures).

Outcome depends on the cause, severity and timeliness of intervention.
Treatable causes (hypothyroidism, hearing loss, nutritional) do well if corrected early; genetic/structural causes and those with regression carry a guarded prognosis.
Early intervention during the period of maximal brain plasticity markedly improves functional outcomes.

The most important red flag in developmental assessment is understanding why the loss of a skill the child once possessed is fundamentally different from — and far more serious than — simply being slow to acquire it.
A child with static developmental delay (from cerebral palsy, birth asphyxia, a chromosomal disorder, or intellectual disability) develops slowly — but they keep going forwards.
They may sit late and walk late, but they do not UNSIT or UNWALK.
The underlying insult is a fixed, non-progressive one.
But a child who could sit and can no longer sit; who could speak and has stopped speaking; who could walk and now falls — has regression.
And regression means that something is actively destroying the nervous system right now.
The causes are a short and grave list: neurodegenerative disorders, inborn errors of metabolism (many of which are treatable if caught — which is why they must be sought urgently), brain tumours, hydrocephalus, subacute sclerosing panencephalitis (a late complication of measles — important in India), and severe epilepsy syndromes.
Hence: regression demands urgent, thorough investigation — never reassurance.

A rule that transforms outcomes is understanding why every child with delayed speech must have their hearing tested — before anything else, and however unlikely deafness may seem.
Language is learned by hearing it: a child who cannot hear cannot acquire speech, however normal their intelligence and however loving their family.
Hearing loss is the commonest cause of isolated speech delay — and, crucially, it is invisible: the child looks entirely normal, responds to visual cues, and parents (and doctors) commonly conclude that they are simply 'a late talker' or 'stubborn' or 'lazy'.
Meanwhile the critical period for language acquisition is passing.
And this matters enormously, because the condition is treatable: a hearing aid or a cochlear implant, fitted early, allows normal language development — whereas a diagnosis made at four or five years leaves permanent language and educational impairment.
Hence: universal newborn hearing screening where available; and, in any child with speech delay, a formal audiological assessment (BERA/OAE) — not merely a clapped hand behind the head, which the child will feel and see.
Delay in speech may also indicate autism, intellectual disability, or a specific language disorder.

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