Definitions
Intellectual disability (ID) has replaced the older term mental retardation (MR), reflecting a more enlightened and progressive attitude toward individuals with disabilities. ID is characterized by significant limitations in intellectual functioning and in adaptive behavior that begin before age 18 years, and are expressed in conceptual, social, and practical adaptive skills. The impairments of ID extend beyond what is measured on a standardized test of intelligence, and must take into account the context of an individual’s typical environment and their cultural and linguistic backgrounds. Adaptive functioning includes 3 broad domains: conceptual, social, and practical. The conceptual domain involves academic competence, the acquisition of practical knowledge, and judgment in novel situations. The social domain involves awareness of others’ thoughts and feelings, empathy, friendships, and social judgment. The practical domain involves the ability to manage one’s own affairs, including school and work responsibilities, money management, and recreation ( Table 24.1 ). Although ID is a lifelong condition, it is recognized that “with appropriate personalized supports over a sustained period, the life functioning of the person with intellectual disability generally will improve.” In a long-term study comparing ID and non-ID siblings, those with mild ID (intelligence quotient [IQ] between 64 and 75) were just as likely to find stable employment, to have similar total family incomes, to have stable marriages, and to raise children as their siblings. However, they reported higher rates of psychologic distress and lower rates of participation in formal organizations. Table 24.2 provides descriptions of typical adult functioning in individuals with varying degrees of ID.
| Diagnostic Criteria |
| All 3 Criteria Must Be Met |
|
| Assumptions |
|
| Level | Mental Age as an Adult * | Adult Adaptation |
|---|---|---|
| Mild | 9-11 yr | Reads at 4th-5th grade level; simple multiplication/division; writes simple letters, lists; completes job applications; basic independent job skills (arrive on time, stay at task, interact with coworkers); uses public transportation, may qualify for driver’s license; keeps house, cooks using recipes |
| Moderate | 6-8 yr | Sight-word reading; copies information, e.g., address from card to job application; matches written number to number of items; recognizes time on clock; communicates; some independence in self-care; housekeeping with supervision or cue cards; meal preparation, can follow picture recipe cards; job skills learned with much repetition; uses public transportation with some supervision |
| Severe | 3-5 yr | Needs continuous support and supervision; may communicate wants and needs, sometimes with augmentative communication techniques |
| Profound | <3 yr | Limitations of self-care, continence, communication, and mobility; may need complete custodial or nursing care |
* International Statistical Classification of Diseases and Related Health Problems. 10th revision. World Health Organization; 2010.
The term developmental disability includes a diverse group of lifelong physical and mental impairments that negatively affect an individual’s ability to function as well as their peers. These conditions begin during childhood (before 22 years of age), and interfere with mobility, acquisition of self-care ability, communication skills, social skills, general learning ability, and independent living. The specific types of conditions and categories of disabilities vary widely. The National Institute for Child Health and Development (NICHD) includes the following conditions: neurologic disorders: cerebral palsy, muscular dystrophy, epilepsy, genetic syndromes, autism, and degenerative disorders; sensory disorders: blindness and deafness; metabolic disorders: phenylketonuria (PKU); and cognitive disorders: intellectual impairment, learning disabilities, and attention-deficit/hyperactivity disorder (ADHD). Developmental disabilities may be isolated, as in a child with impaired vision, or may be multiple, as in a child with delays in motor, cognitive, language, and social functioning. There may be considerable overlap in specific disorders in terms of the affected functions ( Fig. 24.1 ). In young children, developmental delays may result from a wide range of causes, including early environmental understimulation, chronic physical illness, neuromuscular disorders, central nervous system (CNS) abnormalities, genetic syndromes, etc. Some etiologies are fully or partly amenable to early educational and medical interventions, while others may lead to permanent intellectual impairment or progressive deterioration of functioning. Therefore, until a young child has had the benefit of early intervention services and he or she has matured to the point where formal cognitive, language, and adaptive measures are stable and predictive of future functioning, the descriptive term global developmental delay (GDD) is preferred.
Epidemiology
Intellectual Disability
(See Nelson Textbook of Pediatrics, p. 216.)
The overall prevalence of ID varies from 1-3%, depending on the criteria used and the age of the individual at the time of evaluation. For example, standardized tests of intelligence have a mean of 100 and standard deviation of 15 points. Statistically, 2.5% of individuals should have an IQ score below 2 standard deviations (70 points) and fit the cognitive criterion for ID. However, because the standard error of measurement is approximately 5 points, extending the IQ score upward to 75 points would almost double the prevalence of ID. This might be countered by secondary criteria involving deficits in adaptive behaviors, since many children with IQ scores in the mildly low range (55-70) will not qualify for a diagnosis of ID because they have adequate adaptive functioning.
Many studies have documented a higher rate of mild ID in economically disadvantaged children that stems from a few highly significant sociodemographic factors. In 1 study, approximately half of the excess prevalence of mild ID among African-American 10-year-old children in the mid-1980s was related to the mother’s level of education and her age at the time of delivery, birth order, sex of the child, and family’s income level.
Developmental Disability
(See Nelson Textbook of Pediatrics, p. 3412.)
Developmental disabilities affect approximately 1 in 6 children in the United States (13.8%). The prevalence rates vary by specific condition: Learning disabilities (7.66%) and ADHD (6.69%) are the most common, while ID, epilepsy, autism, deafness, cerebral palsy, and blindness each affect less than 1%. Boys have more than twice the prevalence of any developmental disability, and children insured by Medicaid have a nearly 2-fold higher prevalence of disability compared with those with private insurance. The overall prevalence of disability increased by 17% between 1997 and 2008, mostly due to a nearly 4-fold change in autism (from 0.19% to 0.74%). In addition, the prevalence of Down syndrome increased by 31% (from 0.09% to 0.12%). Table 24.3 lists the prevalences of selected conditions.
| Condition | Prevalence/100,000 | Comments |
|---|---|---|
| Cerebral palsy | 250-270 | Represents many causes |
| Significant hearing loss | 150 | In neonatal period |
| Down syndrome | 98-125 | Prevalence at birth |
| Fragile X syndrome | 117 | Predominantly in boys |
| Meningomyelocele | 60-100 | Prevalence at birth |
| Klinefelter syndrome | 100 | 15% have intelligence quotient (IQ) <80 |
| Fetal alcohol syndrome | 60-800 | Present at birth |
| Congenital HIV infection | 5-50 | Preventable with maternal and neonatal therapy |
| Blindness | 41-88 | At 10 yr of age |
| Infantile hydrocephalus | 64 | Prevalence at birth |
| Neurofibromatosis | 33 | 5% have intellectual disability |
| Trisomy 18 | 30 | Prevalence at birth |
| Trisomy 13 | 20 | Prevalence at birth |
| Turner syndrome | 20 | IQ may be normal |
| Prader-Willi syndrome | 13-20 | In childhood |
| Galactosemia | 14 | In infancy |
| Phenylketonuria | 6-12 | In infancy |
| Anophthalmia | 6 | Consider other anomalies |
| Rett syndrome | 4-5 | In girls 2-18 yr of age |
| Histidinemia | 3 | At birth |
| Acrocephalosyndactylia (Apert syndrome) | 1-2 | Present at birth |
Diagnosis
Identification of a specific cause for delayed development in a child is important and may provide insight into prognosis, recurrence risk, therapies, counseling, and linkage with a supportive group. From a community perspective, having a specific diagnosis for an affected individual helps in the development of treatment and prevention strategies. Identification of the child’s functional abilities, strengths and weaknesses, overall physical health, and environmental factors is critical for optimizing the child’s health, development, and functioning. In addition, the origin of developmental disability is not apparent in many children, or there may be multiple possible causal factors or multiple disabilities present. For example, 23% of children with developmental disabilities have 2 disabilities, and 6% have 3 or more. Even if a specific diagnosis cannot be made, early identification of developmental delay can lead to a program of early intervention or remediation that may improve the child’s ultimate functioning. To identify those disorders, which are amenable to intervention, an international consortium has developed both a web-based tool and a mobile application (app) to assist expert clinicians and general practitioners alike in the evaluation and management of children with ID ( http://www.treatable-id.org/ ).
Identification
Children who experience significant complications in the perinatal period or who are born with obvious congenital anomalies are at risk for developmental disabilities. In addition, newborn screening programs may identify children with rare but significant problems who require early treatments and interventions. Children with no apparent risk factors or obvious physical or neurologic symptoms may be identified through a process of surveillance and screening during routine child health care visits.
Developmental Risk Factors
Young children’s development may be adversely affected by biologic and/or sociocultural risk factors ( Table 24.4 ). Many risk factors can be graded according to severity (e.g., degree of prematurity, intracranial hemorrhage, intrauterine growth restriction), but it is often the cumulative effect of multiple factors that ultimately determines a child’s developmental outcome, even when 1 or more “severe” risks are present. For example, it has been shown that low 5-minute Apgar scores, in the absence of other symptoms of neonatal encephalopathy, correlate poorly with long-term neurologic dysfunction. Sociocultural risks also can have profound effects on development and may interact with biologic risk factors to create a greater effect than any single factor alone (so-called “double jeopardy”).
| Biologic | Sociocultural |
|---|---|
|
|
Developmental Protective Factors
During the process of developmental surveillance, the clinician should identify and acknowledge the influence of protective and supportive factors that may contribute to positive outcomes. For example, barring catastrophic circumstances, child-rearing conditions that support and enrich early development may compensate for biologic deficits. Sociocultural factors, such as small family size, higher level of parental education, and fewer changes in residence have a more powerful positive effect than many biologic risks and seem to be important predictors of developmental functioning beyond infancy. The brains of infants and young children are remarkably resilient and normal cognitive and language outcomes are often seen, even in the face of perinatal stroke or similar focal brain injuries. Neural plasticity also extends to situations of extreme environmental deprivation, providing interventions occur early enough. In addition, preschool early intervention programs that are designed to mitigate the factors that place children at risk for poor outcomes have been shown to have significant short- and long-term educational, behavioral, and economic benefits ( Table 24.5 ).
| Biologic | Sociocultural |
|---|---|
|
|
Screening for Specific Abnormalities
Deficits in vision, hearing, and language can have devastating effects on development; early intervention to ameliorate these problems can improve outcomes. All children should be screened on a regular basis for these conditions.
Visual Deficits
Children at high risk for development of deficits in vision (see Chapter 32 ) include those with strabismus (especially after 4 months of age), hydrocephalus, congenital infection, neonatal encephalopathy, congenital anomaly of the CNS, prematurity with overexposure to oxygen, and family history of a childhood onset of visual impairment. All neonates should routinely undergo an evaluation of their fundi for the presence of a red reflex, which can be obscured by cataract or tumor, as well as inspection of the globe, which may be affected by congenital glaucoma. Infants with nystagmus who do not follow visually by 3 months of age, who have dissociation between visual behavior and motor behavior, or whose parents express concern about their vision should undergo a formal ophthalmologic evaluation.
Preschool children should undergo periodic evaluations of extraocular movements to rule out strabismus and amblyopia; the evaluation should include visual inspection of the child’s eyes, the Hirschberg light test, and the cover-uncover test. As early in the child’s development as possible, specific tests of monocular and binocular vision such as Allen cards (3-5 years), the Snellen chart (>5 years), or the Titmus test (>4 years) should be performed.
Loss of Hearing
(See Nelson Textbook of Pediatrics, p. 3073.)
Early detection of hearing loss is critical for optimizing the language development of these children. Universal newborn hearing screening programs (UNHSP) have been in place since the 1990s to detect infants born with moderate, severe, or profound bilateral hearing impairment. More than 95% of all children born in the United States are screened for hearing loss shortly after birth. Although the prevalence of congenital deafness is low in the general population (1-3/1,000 infants), it is higher in infants who require neonatal intensive care services (2-4/100 infants). More than half of babies with permanent congenital hearing impairment do not have prospectively identifiable risk factors and would be missed without UNHSP. They would not receive hearing intervention within the 1st 6 months of life, a period that is critical for speech, language, and later learning development. Hearing loss can be acquired during infancy or childhood from infection (cytomegalovirus [CMV], meningitis), trauma (particularly basal skull and temporal bone fractures), ototoxic drugs (aminoglycosides, furosemide), or damaging noise levels. A number of genetic syndromes are associated with deafness (Waardenburg, Alport, Pendred, and Jervell and Lange-Nielsen) and progressive or late-onset hearing loss can occur in neurofibromatosis, Usher syndrome, Hunter syndrome, Friedreich ataxia, or Charcot-Marie-Tooth syndrome ( Table 24.6 ). The American Academy of Pediatrics (AAP) recommends that children with 1 or more “risk factors” should have hearing screening again at 24-30 months, even if they passed the newborn screening test. In addition, parental concern about hearing loss has a sensitivity of approximately 44%. If parents express concern about their child’s ability to hear and if the child has had recurrent episodes of otitis media, mastoiditis, or 1 of the perinatal or familial risk factors, a formal audiometric screening should be performed. Table 24.7 lists the latest acceptable age (“limit ages”) for the appearance of skills related to hearing; absence of these milestones may indicate a disorder of hearing. Deaf infants may smile, coo, and babble; however, their vocalizations usually cease after 8 months of age.
|
* Risk indicators that are of greater concern for delayed-onset hearing loss.
| Age (mo) † | Activity |
|---|---|
| 3 | Not startling to loud sounds |
| 6 | Not smiling to voice; not vocalizing |
| 9 | Does not localize speech or other sounds |
| 12 | Not babbling multiple sounds and syllables |
| 18 | No words |
| 24 | <50% of speech understandable |
* A child who does not demonstrate the activity by the stated age should have formal audiometry performed.
Speech and Language Disorders
(See Nelson Textbook of Pediatrics, p. 207.)
Disorders of speech and language development, prevalent in 3-20% of preschool children, are the most common reason for referral to early intervention programs and are correlated with subsequent learning problems. Speech refers to the mechanics of oral communication (sound production); language includes the understanding, processing, and production of communication (words). Speech problems may include articulation (pronunciation) deficits (phonologic or apraxic speech disorders), fluency disorders (stuttering), or unusual voice quality. Language delays may be confined to expression with normal receptive abilities, or may involve both expressive and receptive abilities. Language delays may be a feature of GDD/ID, autism spectrum disorders (ASDs), hearing impairment, or may be the result of an isolated disorder (specific language impairment).
Children with speech and language delays often experience emotional and social adjustment difficulties related to their inability to communicate effectively with parents and peers. In general, children with normal comprehension of language and normal nonverbal cognitive abilities have an excellent prognosis, while those with receptive delays are at risk for language-based learning disabilities (reading comprehension and writing disorders) ( Table 24.8 ).
| Refer for a Speech-Language Evaluation if: | ||
| At Age | Receptive | Expressive |
| 15 mo | Does not look/point at 5-10 objects/people named by a parent | Not using 3 words |
| 18 mo | Does not follow simple directions (“Get your shoes”) | Not using Mamma, Dadda, or other names |
| 24 mo | Does not point to pictures or body parts when they are named | Not using 25 words |
| 30 mo | Does not verbally respond or nod/shake head to questions | Not using unique 2-word phrases, including noun-verb combinations |
| 36 mo | Does not understand prepositions or action words; does not follow 2-step directions | Vocabulary <200 words; does not ask for things by name; echolalia to questions; regression of language after acquiring 2-word phrases |
Other Conditions
Prenatal and Newborn Screening Programs
Prenatal Screening
Prenatal screening has undergone significant changes with the advent of “next generation sequencing” (NGS) technologies. The traditional screening takes the form of biochemical and ultrasound tests, which may detect fetuses at high risk for chromosome anomalies and neural tube defects. In the 1st trimester (11-14 weeks’ gestation), measurement of maternal serum levels of human chorionic gonadotropin (hCG) and pregnancy-associated plasma protein A (PAPP-A), and a sonogram measurement of the fluid underneath the skin along the back of the fetus’ neck (nuchal translucency) may identify Down syndrome, trisomy 13, or trisomy 18. In the 2nd trimester (15-22 weeks’ gestation), a quad screen (α-fetoprotein, hCG, estriol, and inhibin A levels) may identify Down syndrome and neural tube defects (spina bifida, encephalocele). An abnormal result on these screenings is typically followed by high-resolution ultrasonography, chorionic villus sampling or amniocentesis, genetic testing (chomosome analysis or microarray), and genetic counseling. NGS technologies allow for noninvasive prenatal testing (NIPT) on maternal blood samples, also called cell-free fetal DNA prenatal testing. These technologies identify possible chromosomal and microdeletion disorders through maternal blood screening. If an abnormality is detected, a confirmatory test is still required through more invasive techniques such as amniocentesis. In addition, prenatal genetic carrier screening can be performed for a large number of disorders; at present, these are the only standard of care for individuals at high risk for certain genetic conditions (e.g., Tay-Sachs).
Newborn Screening
Uniform newborn screening has been highly successful in identifying children with rare but serious conditions who can benefit from early intervention. All 50 states, U.S. territories, and the U.S. military routinely test for inborn errors of metabolism (IEM), congenital hypothyroidism, congenital adrenal hyperplasia, severe T-cell immunodeficiency (SCID), cystic fibrosis, and hemoglobinopathies. Test samples should be collected between 24-48 hours of age, but results may be influenced by a variety of maternal and infant factors. For example, tests for congenital adrenal hyperplasia are sensitive to the weight of the infant and the use of steroids. Screening for hypothyroidism (thyroid-stimulating hormone [TSH]) may be falsely low in premature or low-birthweight infants. In addition, use of antibiotics and total parenteral nutrition (TPN) may interfere with interpretation of newborn metabolic screening tests. While all states screen for a “core panel” of 29 conditions, they vary in testing for other conditions. An additional 26 conditions have been recommended for inclusion in the U.S. Health and Human Services Recommended Uniform Screening Panel. Normal newborn screening test results do not eliminate the possibility that a clinically symptomatic child could have 1 of the disorders in the state’s panel. Clinicians should familiarize themselves with the specific tests that are routinely performed in each state.
Identification of Children With Developmental Disabilities in Primary Health Care Settings
Not all developmentally disabling conditions can be identified at or shortly after birth through newborn screening programs. Many disorders may not manifest until children are preschool or school age, and some infrequent disorders cause regression or deterioration of function beginning at different ages. Therefore, identification of children with developmental disabilities is a continuous process that should take place throughout childhood.
Parents, caretakers, or teachers who have concerns about the child’s behavior or his or her failure to meet age-appropriate developmental expectations often identify children with developmental disabilities. In 1 study, 14% of parents waiting for well child visits had a concern about their child’s learning or cognition. Multiple studies have found parental concern to identify correctly 74-80% of preschool age children (0-6 years old) with cognitive delays, speech and language delays, and learning disabilities. Conversely, the absence of parental concern correctly identified 70-80% of children without a significant disability. Thus, reliance on parental concern alone as a means of identification (sensitivity and specificity) matches acceptable standards for more formal developmental screening tests. However, sole reliance on parental concerns will miss a substantial number of children with developmental concerns, especially those with more subtle disabilities, for a variety of reasons. Parents may be unaware of their child’s delays, they may lack the confidence to raise their concerns to the health care provider, or the provider may dismiss these concerns and not pursue further investigation. In particular, children without obvious physical impairments may not be identified until they enter a formal school program. Complicating matters further, children with developmental disabilities may experience significant behavioral or emotional difficulties that “mask” (or distract from) their underlying developmental difficulties.
Developmental Screening
Developmental screening involves the routine application of a brief standardized tool when there is no obvious concern. Developmental screening tests for use by health care providers have been available for several decades, but they are rarely administered by pediatricians, and generally lack sufficient sensitivity to identify subtle disorders while falsely identifying a significant number of nonaffected children. Instead, physicians are more likely to rely on their own clinical judgment, which detects fewer than 30% of children with significant developmental disabilities, or on informal and nonstandardized lists of developmental milestones. A more practical and widely accepted alternative is the use of parent-completed developmental questionnaires, such as the Ages and Stages Questionnaire (ASQ) or the Parents’ Evaluations of Developmental Status (PEDS) that can be scored by nonphysician staff and interpreted by the health care provider.
Developmental Surveillance
Developmental surveillance is a “flexible, continuous process whereby knowledgeable professionals perform skilled observations of children throughout all encounters during child health care.” The goal of developmental surveillance is to identify children who may benefit from further diagnostic evaluations and early intervention services. To be effective, surveillance requires clinicians to be knowledgeable about child development and to recognize both variations of and deviations from normal patterns. Identification of children in need of further evaluation is believed to be improved by incorporating into the process developmental risk factors based on the child’s medical history, family history, as well as social and environmental circumstances. Additionally, clinicians are encouraged to include the observations and impressions of preschool teachers, public health nurses, and other professionals involved in the child’s care.
The AAP recommends a combination of both developmental surveillance at every well child visit and standardized developmental screening at the 9-, 18-, and 30-month visits ( Fig. 24.2 ). At any point in this process, children who elicit concern about their development should be referred for further diagnostic evaluations and for early intervention and educational programs.
Comprehensive Developmental Assessment
Children identified with developmental delays should receive a comprehensive, multidisciplinary evaluation including assessments of neurodevelopmental, cognitive, and communication functioning. These assessments should focus on both the child’s strengths and functional abilities as well as on weaknesses and disabilities. Based on the findings from these evaluations, further subspecialty consultations (e.g., neurology, genetics, physical medicine and rehabilitation, ophthalmology, occupational and physical therapy, speech therapy) can be arranged, and a plan for specific laboratory investigations developed. The goals of the evaluations are to identify a specific etiologic diagnosis, prognosis, recurrence risk, and interventions to promote the child’s optimal development. Parents may also benefit from associating with a disease-specific support group.
Neurodevelopmental Pediatric Assessment
History
Pediatric evaluation of a child with GDD or ID consists of a complete history and physical examination. Schedule the evaluation as a separate visit with sufficient uninterrupted time (at least 45-60 minutes) to focus on issues related to the child’s behavior and development. Unless the child’s and family’s histories are well known to the provider, parents can be asked to complete detailed history questionnaires, developmental and behavioral rating scales, and to provide any additional information from outside sources (e.g., prior medical records, consultation reports, educational evaluations, etc.) prior to this visit that will contribute to assembling a complete record of the child’s care. Previsit preparation may help parents to refresh their memory regarding their child’s development and to focus their questions and concerns during the evaluation.
Many disabilities have their origin in the prenatal period, so the pregnancy and birth history are reviewed carefully for possible developmental risk factors ( Table 24.9 ). Difficulty in conception or history of recurrent pregnancy loss may suggest the presence of an inherited chromosome anomaly. Maternal illnesses (toxoplasmosis, other [syphilis, varicella-zoster, parvovirus B19], rubella, CMV, and herpes [TORCH] infections; HIV infection) preceding or continuing through pregnancy, or exposure to potentially harmful or teratogenic substances (tobacco, alcohol, illicit drugs, radiation exposure, or medications) should be noted. Other pregnancy complications such as intrauterine growth restriction (which may reflect chronic placental insufficiency, uterine anatomic abnormality, or fetal genetic anomaly); bleeding (especially in the 3rd trimester), which can be caused by placenta previa; placental abruption; or hemolysis, elevated liver enzymes, and low platelets (HELLP) syndrome; hypertension (especially leading to eclampsia); complications of maternal diabetes; or limited prenatal care may be associated with poor fetal outcomes. In the perinatal period, signs of fetal distress during labor (heart rate and movement abnormalities associated with uterine contractions), low Apgar scores, neonatal seizures, or the need for extensive neonatal resuscitation may be the result of acute fetal CNS injury or preexisting congenital abnormalities that first manifest at the time of birth. The method of delivery and the reason(s) for nonvaginal delivery may reflect on fetal status at the time of birth. Neonatal physical measurements (weight, length, and head circumference) when compared with gestational age are helpful in determining whether the child experienced intrauterine growth restriction. Severe medical complications in the neonatal period such as the presence of neonatal encephalopathy syndrome including seizures and multiorgan compromise, intraventricular hemorrhage, neonatal infections, prolonged requirement for mechanical ventilation, need for extracorporeal membrane oxygenation (ECMO), the presence of complex cardiac anomalies, and necrotizing enterocolitis may be associated with increased risk of developmental disabilities ( Table 24.10 ). Conversely, an infant who did not require care in a neonatal intensive care unit (NICU) or prolonged stay in the hospital following birth likely experienced no significant perinatal developmental risk factors. When available, reviewing medical records from the neonatal period may be helpful in clarifying what actually transpired at the time of the infant’s birth.
| Item | Possible Significance |
|---|---|
| Parental Concerns | Parents are quite accurate in identifying developmental problems |
| Current Levels of Developmental Functioning | Used to monitor child’s progress |
| Temperament | May interact with disability or be confused with developmental delay |
| Prenatal History | |
| Alcohol ingestion | Fetal alcohol syndrome; an index of caretaking risk |
| Illegal drug, toxin, medication exposure | Developmental toxin (e.g., phenytoin); may be an index of caretaking risk |
| Radiation exposure | Damage to the CNS |
| Nutrition | Inadequate fetal nutrition |
| Prenatal care | Index of the social situation |
| Injuries, hyperthermia | Damage to the CNS |
| Smoking | Possible CNS damage |
| HIV exposure | Congenital HIV infection |
| Maternal PKU | Maternal PKU effect |
| Maternal illness | Toxoplasmosis, rubella, CMV, HIV, herpesvirus infections |
| Perinatal History | |
| Gestational age, birthweight | Biologic risk from prematurity and small for gestational age |
| Labor and delivery | Hypoxia or index of abnormal prenatal development |
| Apgar scores | Hypoxia, cardiovascular impairment |
| Specific perinatal adverse events; see Table 24.10 | Increased risk for CNS damage |
| Neonatal History | |
| Illness: seizures, respiratory distress, hyperbilirubinemia, metabolic disorder; see also Table 24.10 . | Increased risk for CNS damage |
| Malformations | May represent syndrome associated with developmental delay |
| Family History | |
| Consanguinity | Autosomal recessive condition more likely |
| Mental functioning | Increased hereditary and environmental risks |
| Illnesses (e.g., metabolic disease) | Hereditary illness associated with developmental delay |
| Family member died young or unexpectedly | May suggest inborn errors of metabolism or storage disease |
| Family member requires special education | Hereditary causes of developmental delay |
| Social History | |
| Resources available (e.g., financial, social support) | Necessary to maximize child’s potential |
| Educational levels of parents | Family may need help to provide stimulation |
| Mental health problems | May exacerbate child’s conditions |
| High-risk behaviors (illicit drug use, sexual promiscuity) | Increased risk for congenital infection; index of caretaking risk |
| Other stressors (e.g., marital discord) | May exacerbate child’s conditions or compromise care |
| Other History | |
| Sex of the child | Important for X-linked conditions |
| Developmental milestones | Index of developmental delay, regression may indicate a progressive condition |
| Head injury | Even moderate trauma may be associated with developmental delay or learning disabilities |
| Serious infections (e.g., meningitis) | May be associated with developmental delay |
| Toxic exposure (e.g., lead) | May be associated with developmental delay |
| Physical growth | May indicate malnutrition; obesity, growth failure caused by genetic disorder |
| Recurrent otitis media | Associated with hearing loss and abnormal speech development |
| Visual and auditory functioning | Sensitive index of impairments in vision and hearing |
| Nutrition | Malnutrition during infancy may lead to delayed development |
| Chronic conditions such as renal or cyanotic cardiac | May be associated with delayed development |
| Item | Comment |
|---|---|
| Apgar scores | <3 at 5 min or <5 at 10 min, and HIE |
| Abnormal EEG | |
| Neonatal seizures | Hypoglycemia, hypoxia, intracranial hemorrhage, or infection confer high risk |
| Intracranial | Grade III or higher; PVL hemorrhage |
| Hydrocephalus | Especially with other anomalies, thin cortical mantle, or parenchymal lesions |
| Central nervous system | Seen on CT scan or ultrasonography system anomalies |
| Prematurity | <32 wk |
| Small for gestational age | <3rd percentile (intrauterine growth age retardation) |
| Dysmorphic | 3 or more minor or 1 or more major features |
| Chromosomal | Trisomies, fragile X, XO anomaly |
| Ventilation required | Longer than 2 wk |
| Small head | <3rd percentile circumference |
| Meningitis/encephalitis | Bacterial (group B streptococci, Escherichia coli ) Viral (herpes simplex) |
| Hypoglycemia | Symptomatic |
| Congenital infection | Cytomegalovirus, toxoplasmosis, syphilis, rubella, herpes simplex, varicella-zoster, HIV |
| Hyperbilirubinemia | Requiring exchange transfusions |
| Associated medical problems | Such as retinopathy of prematurity, heart disease, bronchopulmonary dysplasia, necrotizing enterocolitis |
The social and economic circumstances of the family may reveal factors that place the infant at risk for developmental disabilities. The clinician should ask about the highest educational levels achieved by both parents, marital status or stability of the parents’ relationship, parental mental health concerns, history of “high-risk behaviors” (illicit drug use), housing status, and presence of a parental support system (close friends and extended family members) to help with care of the infant.
The 1st weeks and months of life are a “transition period” for both the infant and the family. Children with developmental disabilities may begin to manifest symptoms in this period with difficulties nursing, excessive colic, poor weight gain, onset of seizures, or delayed achievement of motor milestones. Review of prior growth records may help differentiate between a congenital or acquired disorder. A history of recurrent illness, family/social or environmental stress, trauma (especially to the CNS), or epilepsy may be associated with poor development. True regression, the loss of previously acquired skills, should be distinguished from failure of development. Newly emerging skills may fluctuate until they are firmly established. In cases of true regression, multiple areas of functioning are affected and do not reemerge over time.
Ages of achievement of common milestones in motor, language, cognitive, and social development should be reviewed. Parents of infants and toddlers may have more accurate recollections of their child’s milestones than parents of older children. In some cases, parents may recall comparing their child’s milestones to another child’s (sibling, relative, neighbor), or may only recall their child’s “major” milestones, such as ages at which the child began walking independently, waving “bye-bye,” using 1st words, or talking in sentences.
A 3-generation family pedigree should be reviewed to identify other individuals with conditions similar to the child’s, developmental/learning disabilities, or early deaths. Consanguinity may increase the risk of a recessive disorder. A family’s ethnic ancestry may suggest potential etiology, since a number of conditions occur at increased frequency among certain ethnic groups (e.g., Tay-Sachs disease among Ashkenazi Jews).
Social and environmental factors such as parental physical or mental illness (including substance abuse), death of a close family member, divorce, domestic abuse, parental incarceration, multiple changes of dwelling, placement in foster care, or having a sibling with a serious chronic illness may have significant adverse effects on a child’s development.
It is important to know whether the child has received any type of educational or therapeutic interventions and the impact those programs have had on his or her behavior and development.
For young children, a description of their play interests, self-help skills, and social interactions with parents, peers, and caretakers/teachers may provide valuable information about the child’s level of overall development. A review of common activities of daily living (ADL), including dressing, eating, toileting, and motor skills, often provides insight about the integrity of the child’s cognitive, communication, and neuromotor development. School experiences, academic readiness skills, educational achievement, and behavior patterns at home and school often reflect the cognitive and language development of school-age children and adolescents.
Physical Examination
The physical examination should begin with observations of the general appearance of the child, including overall state of health, visual and auditory responsiveness to the surroundings, and interactions with parents. When the child is at rest, subtle abnormalities of body proportions and movement patterns may be observed. Careful attention should also be paid to physical measurements (length/height, weight, and head circumference ) with values plotted on standard reference curves. Both poor growth and excessive growth may be associated with metabolic disorders or genetic syndromes. Head circumference measurements may be abnormal (greater or less than 2 standard deviations [SD] from the mean) or disproportionate for body size (head circumference should correlate with length/height of the child). Although large or small head size may be associated with significant pathology, a benign form of familial micro- and macrocephaly may be ruled out if 1 or both parents share the same trait. Dysmorphic features may suggest a recognizable pattern of deformation or malformation ( Table 24.11 ) (see Chapter 25 ). If the child has an unusual appearance, biologic family members should be examined either directly or from photographs to determine any resemblance. Additionally, examining serial photographs of a child at different ages can help to identify “coarsening” of facial features due to a storage disease (mucopolysaccharidosis). Abnormalities of skin pigmentation may suggest the presence of a neurocutaneous disorder (phakomatosis) associated with developmental disability (neurofibromatosis, tuberous sclerosis, Sturge-Weber syndrome) (see Chapter 30 ). A Wood’s lamp examination may be helpful if a depigmented lesion is identified (ash-leaf spots in tuberous sclerosis). Measurements of facial features, such as inner canthal distance, palpebral fissure length, auricular size and position, and development of the philtrum and upper lip, may be associated with structural anomalies of craniofacial development caused by genetic or teratogenic exposure (fetal alcohol syndrome). The oral structures should be examined for the presence of cleft palate (velocardiofacial syndrome, Stickler syndrome), macroglossia (Beckwith-Wiedemann syndrome), or recessed jaw (Pierre-Robin sequence). Anomalies of the neck may indicate vertebral abnormalities (Klippel-Feil syndrome) or genetic disorders (Turner syndrome, Noonan syndrome, Down syndrome). Cardiac anomalies are associated with a large number of syndromes. The abdominal exam may reveal evidence of an enlarged liver (associated with glycogen storage diseases, sphingolipidoses, or mucopolysaccharidoses). Examination of the back should include the “forward bend test” for scoliosis, and the presence of dimpling or a hirsute area in the lower spine that could represent an occult form of spinal dysraphism (tethered cord or other spinal cord anomaly). Anomalies of the extremities (limb proportions, hands, feet, and nails) are associated with a wide range of birth defects and syndromes. The presence of multiple malformations may be an important key to identifying a specific developmental disorder or syndrome. Although minor physical anomalies may be associated with developmental delay, most children with minor anomalies develop normally ( Table 24.12 ).
| Item | Possible Significance |
|---|---|
| General appearance | May indicate significant delay in development or obvious syndrome |
| Stature | |
| Short stature | Malnutrition, many genetic syndromes are associated with short stature (e.g., Turner and Noonan syndromes) |
| Obesity | Prader-Willi syndrome |
| Large stature | Sotos syndrome |
| Head | |
| Macrocephaly | Alexander syndrome, Canavan disease, Sotos syndrome, gangliosidosis, hydrocephalus, mucopolysaccharidosis, subdural effusion |
| Microcephaly | Virtually any condition that can restrict brain growth (e.g., malnutrition, Angelman syndrome, de Lange syndrome, fetal alcohol effects) |
| Face | |
| Coarse, triangular, round, or flat face; hypotelorism or hypertelorism, slanted or short palpebral fissure; unusual nose, maxilla, and mandible | Specific measurements may provide clues to inherited, metabolic, or other diseases such as fetal alcohol syndrome, cri du chat (5p−) syndrome, or Williams syndrome |
| Eyes | |
| Prominent | Crouzon syndrome, Seckel syndrome, fragile X syndrome |
| Cataract | Galactosemia, Lowe syndrome, prenatal rubella, hypothyroidism |
| Cherry-red spot in macula | Gangliosidosis (GM 1 ), metachromatic leukodystrophy, mucolipidosis, Tay-Sachs disease, Niemann-Pick disease, Farber lipogranulomatosis, sialidosis type III |
| Chorioretinitis | Congenital infection with cytomegalovirus, toxoplasmosis, or rubella |
| Corneal cloudiness | Mucopolysaccharidosis types I and II, Lowe syndrome, congenital syphilis |
| Ears | |
| Low-set or malformed pinnae | Trisomies such as Down syndrome, Rubinstein-Taybi syndrome, CHARGE syndrome, cerebrooculofacioskeletal syndrome, fetal phenytoin effects |
| Hearing | Loss of acuity in mucopolysaccharidosis; hyperacusis in many encephalopathies |
| Heart | |
| Structural anomaly or hypertrophy | CHARGE syndrome, velocardiofacial syndrome, glycogenosis type II, fetal alcohol effects, mucopolysaccharidosis type I; chromosomal anomalies such as Down syndrome; maternal PKU; chronic cyanosis may impair cognitive development |
| Liver | |
| Hepatomegaly | Fructose intolerance, galactosemia, glycogenosis types I-IV, mucopolysaccharidosis types I and II, Niemann-Pick disease, Tay-Sachs disease, Zellweger syndrome, Gaucher disease, ceroid lipofuscinosis, gangliosidosis |
| Genitalia | |
| Macro-orchidism | Fragile X syndrome |
| Hypogenitalism | Prader-Willi syndrome, Klinefelter syndrome, CHARGE syndrome |
| Extremities | |
| Hands, feet, dermatoglyphics, and creases Joint contractures | May indicate a specific entity such as Rubinstein-Taybi syndrome or be associated with chromosomal anomaly Signs of muscle imbalance around the joints; e.g., with meningomyelocele, cerebral palsy, arthrogryposis, muscular dystrophy; also occurs with cartilaginous problems such as mucopolysaccharidosis |
| Skin | |
| Café-au-lait spots | Neurofibromatosis Tuberous sclerosis Chromosomal aneuploidy McCune-Albright syndrome Fanconi anemia Silver-Russell syndrome Ataxia telangiectasia Bloom syndrome Basal cell nevus syndrome Gaucher disease Chediak-Higashi syndrome Hunter syndrome Multiple endocrine neoplasia type 2b Bannayan-Riley-Ruvalcaba syndrome Maffucci syndrome |
| Seborrheic or eczematoid rash | Phenylketonuria, histiocytosis |
| Hemangiomas and telangiectasia | Sturge-Weber syndrome, Bloom syndrome, ataxia-telangiectasia |
| Hypopigmented macules, streaks, adenoma sebaceum | Tuberous sclerosis, hypomelanosis of Ito |
| Hair | |
| Hirsutism | de Lange syndrome, mucopolysaccharidosis, fetal phenytoin effects, cerebrooculofacioskeletal syndrome, trisomy 18 |
| Neurologic | |
| Asymmetry of strength and tone | Focal lesion, hemiplegic cerebral palsy |
| Hypotonia | Prader-Willi syndrome, Down syndrome, Angelman syndrome, gangliosidosis, early cerebral palsy, muscle disorders (dystrophy or myopathy) |
| Hypertonia | Neurodegenerative conditions involving white matter, cerebral palsy, trisomy 18 |
| Ataxia | Ataxia-telangiectasia, metachromatic leukodystrophy, Angelman syndrome |
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