CHAPTER 32

Normal Development and Developmental Surveillance, Screening, and Evaluation

Geeta Grover, MD, FAAP, and Jeanne Anne Carriere, PhD

Development refers to the acquisition of functional skills during childhood. Monitoring the growth and development of children is an integral part of the assessment of pediatric patients. Recording the acquisition of developmental milestones provides a systematic approach by which to observe the progress of children over time. For ease of monitoring, these developmental milestones may be divided into 5 major domains or areas: gross motor, fine motor, language, social-emotional, and cognitive.

Four principles apply to all aspects of development. First, motor development is a continuous process that proceeds in the cephalocaudal direction and parallels neuronal myelination; therefore, developmental milestones reflect the maturation of the nervous system. Second, the sequence of development is the same in all children, but the rate of development may vary from child to child; for example, all children must walk before they run, but the age at which a child walks or runs varies from child to child. Third, the rate of attainment of milestones in 1 area may not parallel that in another. Fourth, certain primitive reflexes must be lost before corresponding voluntary movements can be attained (eg, the asymmetric tonic neck reflex must disappear before a child can roll over).

Pathophysiology

Development is influenced by biologic and environmental factors. Biologic factors, such as genetics, preterm birth, exposure to drugs in utero, or the presence of chronic disease, may place a child at increased risk for developmental problems and delays. Environmental factors that influence development include parental attitudes and actions, sociodemographic factors, and cultural and societal influences. The quality of parental stimulation may influence the rate of acquisition of certain skills, especially cognitive and language abilities in preschool-age children. Poverty and other socioeconomic factors may make it difficult for parents to provide their children with an optimal environment for growth and development. For example, research has found significant disparities in vocabulary and language processing between infants from families of higher– and lower–socioeconomic status (SES) as early as 18 months. Children from families of higher SES tend to have larger vocabularies at 2 years of age and score higher on language and cognition testing in elementary school. Processing speed is critical to language and cognitive development, because the faster children process (ie, understand) a word they have heard, the more cognitive energy they can put into other parts of communication. Fortunately, regardless of SES, parents who consistently engage in language-rich activities with their infants and young children can help their children learn more quickly.

Development in Newborns and Infants

Normal, full-term newborns enter the world capable of responding to visual, auditory, olfactory, oral, and tactile stimuli. They can be quieted and can even soothe themselves. Newborns can signal needs (eg, crying when hungry or wet), but they have a limited ability to respond to caregivers, primarily exhibiting disorganized and seemingly purposeless movements when stimulated. The newborn’s reflexive generalized symmetric movements (eg, arm waving and kicking) in response to environmental stimuli are eventually replaced by cortically mediated voluntary actions in older infants and children. Additionally, in newborns, certain primitive reflexes can be elicited by appropriate peripheral stimuli. Eventually, primitive reflexes are replaced by reactions that allow children to maintain postural stability in response to a variety of sensory inputs (ie, proprioceptive, visual, vestibular).

Primitive reflexes are mediated by the brain stem; they are involuntary motor responses that are elicited by appropriate peripheral stimuli and are present at birth but disappear during the first 6 months after birth. Normal motor development seems to be related to the suppression of these reflexes (Figure 32.1). Persistence or reappearance of these reflexes may indicate the presence of brain damage. Postural reactions, which are ultimately smoothly integrated into adult motor function (Figure 32.1), appear between 2 and 9 months of age. Postural reactions help maintain the orientation of the body in space and the interrelationship of 1 body part to another. The 3 major categories of postural reactions are righting, protection, and equilibrium.

The profile generated by combining primitive reflexes and postural reactions can be used to monitor the course of normal development and identify cases of problematic development. Persistence of primitive reflexes or failure of development of postural reactions can signal developmental problems. Authorities estimate that more than 70 primitive reflexes and postural reactions exist. Researchers do not agree on which of these reflexes or reactions are the most useful in the monitoring of development. The 7 most commonly used primitive reflexes are described in Box 32.1, and select postural reactions are presented in Box 32.2.

Figure 32.1. Primitive reflex profile.

Reprinted with permission from Capute AJ, Accardo PJ, Vining EP, Rubenstein JE, Harryman S. Primitive Reflex Profile. Baltimore, MD: University Park Press; 1978:10.

Normal Development

A developmental assessment should include an evaluation of milestones in each of the 5 major domains. Gross motor skills are overall movements of large muscles (eg, sitting, walking, running). Fine motor skills involve use of the small muscles of the hands, the ability to manipulate small objects, and eye-hand coordination. Language skills involve hearing and include understanding and use of language as well as nonverbal communication skills. Social-emotional skills involve attachment, socialization, and the ability to regulate emotions. Cognitive skills involve the ability to use higher mental processes, including comprehension, memory, problem-solving skills, critical thinking, and logical reasoning.

Table 32.1 outlines the normal pattern of development for each of these domains. The table lists the average age of attainment of these skills as well as the normal ranges as available. Development is an orderly and sequential process, and children must proceed through several stages before any given milestone is attained. Therefore, the physician should document not only what a child can do but how the child does it. For example, to sit without support, children first achieve head control. Several stages later they can sit in a “tripod” position with arms extended in front for support, and finally, they sit with the head steady and back straight without support (Figure 32.2).

Gross Motor Skills

During the first year after birth, the ultimate goal of gross motor development is walking. The first developmental skill toward this goal is head control; by 4 months of age there should be no head lag when a child is pulled to sitting from a supine position. By 6 months of age, children can sit without support for a few seconds. At 9 to 10 months of age, children can pull themselves to a standing position, and by 12 to 18 months of age, they can walk. Children then learn to run, use stairs, hop on 1 foot, and skip— in that order.

Fine Motor

Development of the 2-finger pincer grasp is the major goal of fine motor development during the first year (Figure 32.3). The hands primarily remain in a fisted position until 3 months of age. Infants also discover the midline at this age, and shortly thereafter they may play with their hands in the midline. At age 4 months, children begin reaching for desired objects; by 6 months of age, they can transfer an object from 1 hand to the other. By 7 months, they have a 3-finger pincer grasp, and by 9 to 10 months, they have developed the 2-finger grasp, which allows them to manipulate small objects, such as raisins. By 14 months, they begin to scribble, and by 3 to 5 years, they can copy geometric shapes. Children with early preference for the use of 1 hand over another, especially before approximately 18 months of age, should be assessed for the presence of paresis or other neuromuscular problems. Handedness may manifest by 3 years but often is not firmly established until 4 to 5 years of age.

Language Skills

The development of normal speech and language skills is discussed in Chapter 33.

Social-Emotional Skills

These skills enable children to interact and respond to the surrounding world. Deficits in the development of age-appropriate social skills/social relatedness (eg, social orienting, social referencing, joint attention, pretend play) are a defining feature of autism spectrum disorder (ASD; see Chapter 132). For children on this spectrum, the development of social skills is characteristically “out of sync” with their overall level of functioning. Joint attention is the inclination to share enjoyment, interests, or achievement with other people, and like other developmental skills, it seems to manifest in graduated stages. Early skills include reciprocal smiling at the sight of a familiar person, followed by later emerging skills, such as the ability to isolate one’s index finger and point with a coordinated gaze by 12 to 15 months of age. Lack of joint attention is a core deficit of ASD.

Cognitive Skills

These abilities allow children to think, reason, problem-solve, and understand the surrounding environment. Information processing theories address how individuals acquire, interpret, and remember information and how these abilities develop. Cognitive development involves gradual changes in these processes. Infants are born with some sensory and perceptual capabilities. Newborns are drawn to both novel and social stimuli, especially from their caregiver; these stimuli support further sensory and perception development as well as social and language development. As children develop, their attention span increases, they more efficiently process information, and they are better able to plan and direct their actions toward goals. Additionally, their knowledge base grows and becomes more integrated. These developments allow them to be more efficient learners as they age.

A child’s perception and understanding of the world, including the understanding of pain, disease, and illness, are guided by the child’s stage of cognitive development. The concept of object permanence or object constancy, the realization that objects may exist even if they cannot be seen, develops at approximately 7 to 9 months of age. The understanding of time comes much later. Children develop the concept of “today” at 24 months of age, “tomorrow” at 30 months, and “yesterday” at 36 months.

Figure 32.2. Stages in the development of sitting. A, Head control. B, “Tripod sitting.” C, Head steady and back straight without support.

Figure 32.3. Development of the pincer grasp. A, Rake (4 months). B, Inferior pincer grasp (7 months). C, Fine pincer grasp (9–12 months).

^a Detailed language milestones are presented in Chapter 33, Table 33.1.

^b For play and social pragmatic milestones, refer to Chapter 33.

^c Cognitive milestones adapted from constructivist theories of Jean Piaget, Lev Vygotsky, and information processing theorists.

Developmental Delay

Children are said to be developmentally delayed if they do not reach developmental milestones within the expected age range. The age ranges for these milestones are broad because of the wide variation among typically developing children. Children with global developmental delays have delays in multiple domains. Children can also have a specific delay in 1 area, such as expressive language or gross motor. Development across domains is often intertwined. Delays in 1 area can affect development in other domains. For example, a child with an expressive language delay may also demonstrate delays in social development because of limited communicative interaction with peers.

Differential Diagnosis

Three factors are involved in the differential diagnosis of children with developmental delays: determination of the area or areas of development in which delay is apparent; if motor delay is evident, determination of whether the condition is progressive or nonprogressive; and assessment for whether developmental milestones previously achieved are lost or if age-appropriate milestones were achieved at all.

The child with an early history of normal development who subsequently experiences a slowing of developmental progression, often associated with cognitive delays or seizures, may have a metabolic defect. The child who attains developmental milestones and subsequently loses them may have a neurodegenerative disease (eg, multiple sclerosis, adrenoleukodystrophy) or a lesion of the spinal cord or brain. The presence of habitual rhythmic body movements (eg, body rocking, head banging) may be a sign of a pervasive developmental disorder, such as ASD.

Cerebral palsy, the classic example of nonprogressive motor abnormality, is a form of static encephalopathy that is characterized by abnormal movement and posture. The type of cerebral palsy depends on which area of the brain is injured. Spastic cerebral palsy, which is the most common type, is secondary to upper motor neuron injury. The ataxic form of the disease is related to lesions of the cerebellum or its pathways. Dyskinetic cerebral palsy manifests as uncontrolled and purposeless movements that often result from a basal ganglia lesion (eg, athetosis after bilirubin deposition in the basal ganglia). Onset of symptoms is in infancy or early childhood. The key factor in making the diagnosis is establishing that the motor deficits are static and not progressing.

Evaluation

When evaluating children for possible delays in development, it is important to remember that a great deal of variation exists in the age of attainment of milestones. Additionally, the rate of acquisition of milestones in 1 area of development may not parallel that in another. Routine and ongoing assessment of a child’s level of development at all periodic health maintenance visits through observation, history, physical examination, and screening tests allows the physician to form a longitudinal view of the child. The physician is thus able to identify and differentiate true deficits and delays from temporary setbacks.

History

Evaluation of children for suspected delays in development includes a complete history (Box 32.3). Family history of birth defects, childhood deaths, intellectual disability, speech delay, learning disability, and known genetic conditions (eg, fragile X syndrome) should be obtained. Perinatal factors that place children at high risk for developmental difficulties include a history of maternal drug or alcohol use during pregnancy, preterm birth of the child, and congenital infections. Preterm infants are at increased risk for developmental, behavioral, and learning disorders compared with children born at term. Although no formal guideline exists about the specific duration of time that gestational age correction should be performed for preterm infants for attainment of developmental milestone relative to term infants, most experts recommend correcting for preterm status for the first 24 months after birth. Other historical risk factors for developmental delay include history of seizures, sepsis, or meningitis; exposure to lead or other toxins; and poor feeding or growth. Environmental factors, such as stressful home conditions, history of abuse or neglect, and lack of stimulation, may also contribute to delayed development.

Physical Examination

Height and weight should be checked. Abnormal growth (ie, height or weight <5th percentile or head circumference <5th percentile or >90th percentile) may be a marker for developmental delay. The presence of congenital anomalies (eg, cataracts, hypertelorism, spina bifida) or neurocutaneous lesions (eg, café au lait spots) may be suggestive of chromosomal anomalies or other genetic diseases. Neuromuscular examination should emphasize age-appropriate milestones. Abnormalities in muscle tone (eg, hypotonia, hypertonia), bulk, or strength may be clues to the presence of neuromuscular disease (eg, muscular dystrophy), cerebral palsy, or Down syndrome.

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