The Quality Standards Subcommittee of the AAN and the Practice Committee of the CNS have issued recommendations for the evaluation of the child with nonprogressive global developmental delay (GDD), based on a review of relevant literature and scheme of evidence classification. GDD affects 1% to 3% of children. Routine metabolic screening (blood gas, serum lactate and ammonia, serum amino acids and urine organic acids, T4 and TSH) gave yields of 1% and is not indicated as an initial test, except when universal newborn screening (UNS) was omitted or uncertain. Routine cytogenetic studies and molecular testing for fragile X mutation gave yields of 3.5% to 10% and are indicated, even when dysmorphic and specific syndrome features are absent. Additional genetic studies (including subtelomeric chromosomal rearrangements) may be indicated in children with a family history of GDD. Rett syndrome is considered in girls with unexplained moderate to severe delays. Serum lead levels are mandatory in children with identifiable risk factors of lead exposure or signs of intoxication. Thyroid studies are ordered only if clinically indicated or in the absence of newborn screening; the yield is near 0 in patients included in UNS; 4% if no UNS. EEG is recommended when symptoms suggest epilepsy or a specific epilepsy syndrome. Routine neuroimaging, preferably MRI, is recommended, particularly if the neurological examination is abnormal or the history suggests acquired CNS injury or risk of cerebral malformation. Routine visual and audiometric testing is recommended in all cases, and screening for autism or a language disorder should be considered. A specific etiology can be determined in the majority of children with GDD. In the absence of specific clinical features, a stepwise approach is recommended: MRI, cytogenetic screen/fragile X, metabolic tests, and genetic consultation. [1]

COMMENT. After a detailed history and examination, a consensus-based staged approach to the evaluation of the child with global developmental delay is suggested. The timing of this evaluation is often a problem, a subject that needs further study. State-based newborn screening programs will identify some metabolic disorders shortly after birth. All states screen for phenylketonuria and congenital hypothyroidism, and most screen for sickle cell disease and galactosemia [1]. Thirty two states require universal newborn hearing screening. All children with GDD should have auditory and visual testing. Based on diagnostic yield, the MRI (nonenhanced) had the highest yield (55%), and metabolic screening the lowest (1%). The Committee emphasizes that the report is meant as an educational service, and is not meant to exclude alternative individualized evaluations of GDD.