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Global Developmental Delay Evaluation: Evidence-based Approach

CaseThe parents of a 9-month old boy are concerned because he is unable to sit without support, does not

actively reach for objects, and coos but does not babble. How would you evaluate this patient?

Definitions

1. Significant developmental delay: defined as performance at least 2 SDs below the age-appropriatemean in at least one of the following categories on the Denver Developmental Scale: gross/fine

motor, speech/language, cognition, social/personal, and activities of daily living.

a. Isolated delay in social/language development is characteristic of autism spectrum disorders orhearing loss.

b.

Isolated delay in motor development is characteristic of cerebral palsy (a static encephalopathy)or myopathy.

2. Global developmental delay (GDD): a subset of DD defined as significant delay (by at least 2 SDs) intwo or more developmental categories.

a. Note that the term GDD is usually reserved for children 5 y.o, when MR severity is quantifiable with IQ testing.

Introduction

Developmental disabilities are relatively common in children, with a 5-10% prevalence. GDD is

estimated to be prevalent in 1-3% children < 5 y.o, and it is estimated that between 40,000 - 120,000

children born each year in the U.S. and Canada will manifest GDD. There are many possible causes for

the clinical picture of GDD and some causes are treatable. Therefore, early recognition and diagnosis is

important. In addition, some of the etiologies are genetically transmitted and may affect future family

members. An underlying etiology can be identified in approx 25% of cases of developmental delay, with

higher rates (50%) in GDD and motor delays, and lower rates (

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loss of speech and purposeful hand use, deceleration of head growth/microcephaly, seizures,

ataxia, autistic behavior, and stereotypic hand movements.

22q11 deletion syndrome, i.e. DiGeorge syndrome and velocardiofacial syndrome - typicalfeatures may include abnormal facies, cleft lip/palate, cardiac defects, recurrent infections due

to lack of thymus, and hypocalcemia from hypoparathyroidism.

Prader-Willi and Angelman syndromes Neurocutaneous syndromes, i.e. neurofibromatosis type I, tuberous sclerosis Leukodystrophy

2. Acquired causes:a. Prenatal or perinatal causes:

Exposure to teratogens or toxins (tobacco, alcohol, illicit drugs) Intrapartum asphyxia Prematurity Congenital infections

Congenital hypothyroidism - normally picked up on newborn screening. Birth trauma Intracranial hemorrhage

b. Postnatal causes: Infection (meningitis, encephalitis) Cranial trauma Environmental causes, i.e. poor nutrition, family stress, child abuse or neglect, severe

poverty

**Note that low-level lead poisoning is NOT associated with GDD although it may causesome cognitive deficits

Initial evaluation of GDD

1. History:a. Obtain a comprehensive family history

Ask about specific examples of neurologic disorders (i.e. epilepsy, mental retardation), anyhistory of miscarriages or infant deaths, and any consanguinity in family.

b. Construct a pedigree of at least 3 generationsc. Obtain an accurate prenatal and birth history

Include questions about: pregnancy complications; maternal medical conditions; maternaluse of medications, alcohol, tobacco, and illicit drug use during pregnancy; preterm or term

labor; any complications during delivery; Apgar scores; duration of postnatal hospital stay.d. Postnatal medical history

Any hospitalizations, surgeries, medical conditions, current medication use; any seizures orfeeding difficulties

e. Social historyf. Developmental history

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Assess the childs developmental progress in each of the Denver Developmental Scalecategories

Specifically ask about any loss of milestones or developmental regression (could suggestneurodegenerative or metabolic disorder)

Also ask specifically about the presence of any autistic features, i.e. poor eye contact,repetitive behaviors, or lack of appropriate social interaction.

Ask about any co-existing behaviors, such as epilepsy, sleep disturbances, behavioralproblems, and feeding difficulties.

2. Physical exam:a. Weight and height (also look at growth charts) - for growth deficiencyb. Head circumference - for microcephaly or macrocephalyc. Look for dysmorphic features - i.e. coarse facies, low-set ears, upslanting palpebral fissuresd. Skin exam - for neurocutaneous lesions such as cafe-au-lait spots (neurofibromatosis) or

hypopigmented ash leaf spots (tuberous sclerosis); findings over the spine/lower back can

suggest spinal dysraphism

e. Abdominal exam - for HSM (seen in storage disorders)f. Neurologic exam - for reflexes, tone, symmetry, strengthg. Also observe the childs spontaneous interaction with the environment and exploration of play

opportunities

3. Testing: (according to guidelines from the American Academy of Neurology and Child NeurologySociety)

a. Cytogenetic testing (high-resolution karyotyping) - routine testing is recommended even ifdysmorphic and specific syndrome features are absent.

b. Fragile X testing (FMR1 triplet repeat analysis) - recommended for both males and females,especially if there is a family history of developmental delay.

7 specific findings on history and exam increase diagnostic yield for Fragile X testingsignificantly:

1) Family hx of mental retardation2) Long jaw or high forehead3) Large or protuberant ears4) Hyperextensible joints5) Soft palmar skin6) Large testes7) Initial shyness followed by extreme verbosity

c.

Rett syndrome testing (testing for MECP2 gene deletion) - should be considered in females withunexplained moderate to severe mental retardation.

d. Fluorescence In Situ Hybridization (FISH) to assess for subtelomeric abnormalities - may beconsidered in children with unexplained moderate or severe developmental delay.

e. Metabolic screening - routine screening is NOT indicated unless newborn screening was notperformed, the results of the newborn screen are unavailable, or there are historical or PE

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findings that suggest a metabolic disorder (i.e. consanguinity in family, family history of child

loss, developmental regression, coarse facies, HSM).

f. Neuroimaging - recommended in the initial evaluation of GDD, esp if physical findings arepresent (i.e. microcephaly, focal motor findings). If available, MRI is preferred to CT scan.

g. EEG - only indicated if there is clinical evidence of seizures or epilepsy.h. Lead screening - only indicated if child has known identifiable risk factors for excessive lead

exposure (low SES, housing built before 1950, developmentally delayed with oral affinity,

children whose parents are exposed).

i. Thyroid screening - only indicated if newborn screening was not performed or there aresystemic features suggestive of thyroid dysfunction.

j. Hearing and vision testing - recommended for all children with GDD, as they are more likely tohave deficits than healthy kids, and these sensory deficits are likely to confound the picture of

GDD.

k. Autism or language disorder screening***Summary Chart from American Academy of Neurology Practice Parameter:

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Treatment

1. Treat underlying cause of GDD if possible (i.e. thyroid hormone for congenital hypothyroidism)2. Enroll child in Early Intervention program3. Develop an individual family service plan (IFSP) if child is