pediatrics
Intellectual Disability
Diagnosis of Intellectual Disability
Prenatal testing Intelligence and developmental assessment Imaging of the central nervous system Genetic testing Prenatal testing can be done to determine whether the fetus has abnormalities, including genetic disorders, that predispose to intellectual disability. From birth on, Childhood Development , including cognitive ability, are routinely assessed at well-child visits. For suspected cases of intellectual disability, development and intelligence are assessed in greater detail, typically by early intervention or school staff. Establishing intellectual disability is followed by efforts to determine a cause, often including central nervous system (CNS) imaging and genetic and metabolic testing. Accurate determination of the cause may provide a developmental prognosis, suggest plans for educational and training programs, help in genetic counseling, and relieve parental guilt. Prenatal Genetic Counseling may help high-risk couples understand possible risks. If a child has intellectual disability, evaluation of the etiology can provide the family with appropriate risk information for future pregnancies. Preconception or Prenatal Carrier Testing of Parents None Amniocentesis or chorionic villus sampling Quad screen Ultrasonography Maternal serum alpha-fetoprotein Noninvasive prenatal screening Amniocentesis or The quad screen(ie, measurement of maternal levels of beta-hCG, unconjugated estriol, alpha-fetoprotein, and inhibin A) is recommended for most pregnant women to evaluate risk of Down syndrome, trisomy 18, spina bifida, or abdominal wall defects. Prenatal Ultrasonography may also identify CNS defects. Maternal serum alpha-fetoprotein is a helpful screen for neural tube defects, Down syndrome, and other abnormalities. Screening (NIPS) methods can be used to identify numerical chromosome abnormalities and have been used to identify some larger microdeletion syndromes such as 22q11 deletion. Standardized intelligence tests can measure subaverage intellectual ability but are subject to error, and results should be questioned when they do not match clinical findings; illness, motor or sensory impairments, language barriers, and/or cultural differences may hamper a child’s test performance. Such tests also have a middle-class bias but are generally reasonable in appraising intellectual ability in children, particularly in older ones. Developmental screening tests such as the Ages and Stages Questionnaire (ASQ) or the Parents’ Evaluation of Developmental Status (PEDS) provide gross assessments of development for young children and can be given by a physician or others. Such measures should be used only for screening and not as substitutes for standardized intelligence tests, which should be given by qualified psychologists. A neurodevelopmental assessment should be initiated as soon as developmental delays are suspected. A developmental pediatrician or pediatric neurologist should investigate all cases of Moderate to severe developmental delays Progressive disability Neuromuscular deterioration Suspected seizure disorders History (including perinatal, developmental, neurologic, and familial) may identify causes. (See also the2011 evidence report on genetic and metabolic testing on children with global developmental delayfrom the American Academy of Neurology and the Practice Committee of the Child Neurology Society.) Cranial imaging(eg, MRI) can show central nervous system malformations (as seen in neurodermatoses such as neurofibromatosis or tuberous sclerosis), treatable hydrocephalus, or more severe brain malformations such as schizencephaly. Genetic testsmay help identify disorders: Standard Diagnosis shows Down syndrome (trisomy 21) and other disorders of chromosome number. Diagnosis identifies copy number variants such as might be found in 5p- syndrome (5p minus syndrome or cri du chat syndrome) or DiGeorge syndrome (chromosome 22q deletion). Diagnosis identify Fragile X syndrome. Chromosomal microarray analysis is the preferred investigative tool; it can be used to identify specifically suspected syndromes and also when no specific syndrome is suspected. It affords opportunities for identifying otherwise unrecognized chromosome disruptions but requires parental testing to interpret positive findings. Genetic Diagnostic Technologies of the coding regions (whole exome sequencing) is a newer, more detailed method that may uncover additional causes of intellectual disability. (eg, failure to thrive, lethargy, vomiting, seizures, hypotonia, hepatosplenomegaly, coarse facial features, abnormal urinary odor, macroglossia) may suggest a Approach to the Patient With a Suspected Inherited Disorder of Metabolism . Isolated delays in sitting or walking (gross motor skills) and in pincer grasp, drawing, or writing (fine motor skills) may indicate a Specific laboratory tests are done depending on the suspected cause ( see Table: Tests for Some Causes of Intellectual Disability ). Visual and auditory assessments should be done at an early age, and screening for lead poisoning is often appropriate. 