CHAPTER 10

The American Academy of Pediatrics (AAP) has established a policy for developmental surveillance and screening in the primary care setting that, when applied consistently, will identify children who are not meeting expected developmental milestones.1 This policy statement recommends that children who are identified by screening as being at risk receive a developmental evaluation to confirm a developmental diagnosis, a medical evaluation to investigate the etiology of the developmental condition, and a referral to initiate early intervention services. The AAP policy statement specifies that pediatric subspecialists, such as neurodevelopmental pediatricians, developmental-behavioral pediatricians, child neurologists, pediatric physiatrists, or child psychiatrists, can perform the diagnostic developmental evaluation for children who fail screening. However, 1 in 6 children in the United States has a developmental disability, and the prevalence of autism spectrum disorder (ASD), attention-deficit/hyperactivity disorder (ADHD), and other developmental delays has been increasing over time.² Further, most child neurologists, child psychiatrists, and pediatric physiatrists do not routinely perform standardized developmental evaluations. While neurodevelopmental pediatricians and developmental-behavioral pediatricians do routinely perform such standardized developmental evaluations, of the 118,292 pediatricians currently certified by the American Board of Pediatrics, only 775 are board-certified in developmental-behavioral pediatrics and only 255 are board-certified in neurodevelopmental disabilities.³ Thus, referral for subspecialty diagnostic evaluation is a futile proposition for the vast majority of children who fail screening.⁴ Given this high prevalence of developmental-behavioral disorders, the scarcity of subspecialists to whom to refer, and the extremely long wait lists at tertiary care developmental centers, developmental evaluation needs to be considered as basic to primary care pediatric practice as are assessing and diagnosing asthma and other common chronic medical conditions encountered daily in pediatric practice.⁴ Thus, it is important to note that the AAP policy statement does include a recommendation that a diagnostic developmental evaluation can be performed by early childhood professionals in conjunction with the child’s primary pediatric health care professional. This chapter describes a neurodevelopmental evaluation process that primary pediatric health care professionals may consider adopting in cases of developmental screening failure in order to make developmental diagnoses within the medical home, rather than waiting for generally inaccessible subspecialty consultation. Through adoption of this process, primary pediatric health care professionals can contribute to both making a developmental diagnosis and attempting to establish a cause of the developmental disorder.

Principles of Development

Neurodevelopment is a complex, dynamic process that begins at birth and typically proceeds in a predictable sequence and at a predictable rate. The study of development has concentrated on the first years of life, as the observations of developmental markers in infants, toddlers, and preschoolers are rich in number and show little variability. Five areas, or “streams” of development (a term coined by Dr Arnold Capute to reflect the fluid or dynamic process of development) that have been consistently studied and are evaluated during developmental evaluations are gross motor, language, visual-motor problem-solving, social skills, and adaptive skills.5 Each of these streams of development has milestones of expected achievements ascribed to specific ages. Milestones do not represent the process of development, but rather, they reflect the product of a developmental process. Defined milestones are the measure by which typical or atypical development is assessed.

Modern developmental evaluations are based largely on the pioneering work of Dr Arnold Gesell, who established the first norms of milestones in the 5 streams of development.⁶ Gesell assiduously recorded the timing and sequence of normal development in infants and children. He found typical development to be an orderly, timed, and sequential process that occurs with such regularity that it is predictable.⁶ The marvel of development, however, is not so much in the regularity of the acquisition of milestones within any given stream, but in the synchrony of development across streams.

In atypical development, the timing, order, or sequence of the acquisition of milestones is disturbed within a given stream or across several streams. The assessment of atypical development employs the principles of delay, deviation (or deviance), and dissociation. Developmental delay describes a phenomenon in which milestones within a given stream are attained in the typical sequence, but at a delayed rate. Delay can occur within a single stream or across several developmental streams. Deviance or deviation represents an uncustomary sequence of milestone attainment within a single stream of development. A child who is able to crawl before he or she is able to sit demonstrates deviation in gross motor skill attainment. Dissociation is a descriptive term that indicates differing rates of development across the 5 streams of development.

The developmental quotient (DQ) is a measure of the rate of development within a stream, and it is the metric by which delay is determined. The DQ represents the percentage of normal development within a given stream that is present at the time of testing. Using the age at which specific milestones are generally present, a functional age equivalent (AE) can be ascribed to a child’s development. For example, a child whose best motor function is sitting unsupported has a functional age equivalent of 6 months (Box 10.1). The DQ is calculated by dividing the child’s age equivalent within a given stream by his or her chronological age (CA). The DQ is arithmetically represented by DQ = AE/CA × 100. Developmental delay has traditionally been defined by a DQ of less than 70.

Box 10.1. Approximate Ages of Gross-Motor Milestones

The application of the DQ to determine delay within a single stream, or dissociation between streams, can imply diagnoses, which should be supported by historical and examination findings. A child with a gross motor DQ of 50, a history of delay in motor milestone acquisition, and abnormal findings on physical and neurological examination is consistent with a diagnosis of cerebral palsy. Delays in language and nonverbal/visual-motor abilities, with DQs of 70 or less in both domains, place a child at risk for a diagnosis of intellectual disability. However, delayed language skills in the presence of age-appropriate nonverbal/visual-motor skills (dissociation) imply a diagnosis of a communication disorder. Unlike delay and dissociation, deviation is not used diagnostically. Rather, it is a finding that suggests atypical development within a single stream, and it should heighten the clinician’s suspicions regarding underlying pathology. For example, identifying letters and reciting the alphabet while not using any words to communicate a request could suggest ASD (see Chapter 11, Making Developmental-Behavioral Diagnoses).

Developmental Milestones

– Gross Motor Milestones

Motor development is the easiest stream to observe because of the numerous achievements that occur within the first year of life. Newborns demonstrate little voluntary motor ability and are restricted by primitive (involuntary) reflexes. At birth, a newborn does not have enough motor control to lift his or her head when lying in a prone position. Over the first 4 months of life, neck and trunk tone are acquired in a cranial-caudal direction. By 1 month of age, an infant in a prone position should have enough neck tone to lift the head from the bed. By 2 months of age, with head and trunk tone, an infant can lift the head and chest off the bed. By 3 months, an infant can prop up on elbows, and by 4 months, on the wrists. After trunk tone is acquired, the ability to dissociate shoulder and hip movement enables derotative rolling at 4 to 5 months of age. By 6 months of age, trunk tone is sufficient to allow the child to be put into a sitting position and to maintain that position. Shortly after sitting, the child integrates trunk tone with the derotational abilities required for pivoting, allowing him or her to come into a sitting position independently at 8 months. Independent sitting gives way to the ability to assume a quadruped position, ultimately leading to reciprocal crawling and pulling to a stand at 8 months, walking with hands held at 11 months, and walking independently at 12 months7 (Box 10.1).

In addition to a developmental history of acquisition of motor skills over time elicited from parents and/or caregivers and direct observation of current motor skills, the motor evaluation requires a standard neurological examination, including the observation of primitive reflexes and postural reactions. Abnormalities of tone, primitive reflexes, and postural reactions can mitigate the sequence and rate of motor development. The infant’s neurological examination should include observation of the position the infant assumes at rest and the repertoire of spontaneous movement of the child in a supine resting position. Abnormal posture of the extremities, or a paucity of movement in one or more extremities, should increase the suspicions of the examiner. Flexor tone predominates in the newborn but diminishes over the first 4 months of life. However, normal infant flexor tone is symmetrical, and despite the flexion, there is a normal passive range of movement across all joints. The persistence of flexor tone past the newborn period, or the absence of flexor tone (generally signaling hypotonia) during the newborn period, can interfere with expected motor development. Asymmetry of tone and exaggerated tone (increased or decreased) are abnormal neurological findings, which are further evaluated with deep tendon reflexes and primitive reflexes.

Primitive reflexes are automated patterns of movement that are present in utero and persist until 3 to 6 months of life. Primitive reflexes are well described patterns that have qualitative and temporal characteristics that add valuable information to the classic neurological examination of infants. Classical primitive reflexes include the Moro, Galant, and Landau reflexes, as well as the asymmetrical tonic neck reflex (ATNR), the tonic labyrinthine reflex (TL), the positive support reflex, and the symmetrical tonic neck reflex (STNR). Each reflex may be observed in the spontaneous movement of the newborn or can be elicited by an examiner. The quality of the reflex, the ability or inability to suppress reflexes with repeated elicitations, and advancing age may precede or accompany motor delay and deviancy.⁸ Primitive reflexes that persist past the first 6 months of age are atypical, and their presence is a useful marker in the detection of motor disorders. For purposes of delineating the clinical usefulness of the primitive reflexes, the ATNR and TL will be described.

The asymmetrical tonic neck reflex (ATNR) is a primitive reflex in which rotation of the head to either side causes extension of the extremities on the chin side and flexion of the extremities on the occipital side. In the typical infant, rotation of the head to one side will elicit an ATNR, but if the head is kept to one side, the flexion and extension patterns caused by the ATNR relax, and the extremities resume a neutral position. Similarly if the head is rotated to one side to elicit the ATNR, successive head rotations produce progressively diminished responses to the head turn. The ATNR is considered obligatory or exaggerated if the child maintains the flexion/extension pattern of the ATNR the entire time the head is turned to one side or if the child does not exhibit diminished response to the ATNR with subsequent repetitions. The tonic labyrinthine (TL) reflex may be elicited with the child in the supine position or in prone suspension. This reflex is produced with flexion and extension of the neck. When the neck is brought into flexion, the infant flexes all extremities, and when the neck is brought into extension, the infant extends all extremities and retracts the shoulders. Like the ATNR, the TL should not be exaggerated or obligatory and should not persist past 6 months of age. Obligatory or exaggerated responses are considered atypical and should be factored into the assessment of the motor examination.

The visual-motor problem-solving stream of development is a domain of nonverbal abilities that are dependent on cognitive function, visual capacity, and fine motor ability. Like gross motor skills, visual-motor and fine motor abilities are acquired in a timed and orderly pattern (Table 10.1). Visual-motor development dominates the first 4 months of life. In the first month of life, an infant will use eye movement and slight head turning for visual fixation and following to the midline. During the second month, visual pursuit uses eye and head movement that extends past the midline and in both vertical and horizontal planes. By the third month, the eyes and head can visually follow in a circle and a visual threat response can be elicited. By the fourth month, the eyes and head turning are coupled with directed upper extremity use.⁹ The ability to visually attend and track provides targets for the upper extremity to engage.

Nonverbal problem-solving skills are the product of visual, fine motor, and intellectual abilities. Once the visual and fine motor milestones of the first year of life are acquired, cognition becomes the testable variable of the nonverbal domain. Parents typically are able to provide a history of gross motor and language skill acquisition, but a history of visual-motor problem-solving skills is more difficult to elicit. Thus, visual-motor problem-solving milestones must be demonstrated by the child in the developmental evaluation. Most standard instruments for evaluating visual-motor problem-solving skills employ test batteries modified from the early work of Arnold Gesell,6 which was considerably shortened by Cattell¹⁰ and further adapted by many authors over the next few decades. To be clinically useful, tests of nonverbal abilities for young children must provide age equivalents in order to quantify development using a developmental quotient.

Atypical visual-motor development can result from visual impairment, significant fine motor impairment, and/or intellectual disability. Impairments sufficient to preclude assessment are identified in the first few months of life in the case of visual impairments and in the latter half of the first year of life in the case of significant fine motor impairment. Occasionally, children demonstrate qualitatively poor fine motor abilities that do not prevent testing but that may slow or diminish the accuracy of movement, but the child should be credited if he/she shows the cognitive intent to perform the test item. In the absence of significant motor or visual impairments, delays in problem-solving skills are the result of cognitive or intellectual disability. Developmental deviance in problem-solving is observed in children with qualitatively poor fine motor skills (children with poor writing skills may be unable to perform age-appropriate graphomotor tasks but do well with other age-appropriate tasks) and in children with attentional deficits sufficient to interfere with task completion, despite the motor and cognitive capacity to perform at age-appropriate levels.

Language development is an intricate process by which an infant establishes a repository of words that becomes a vocabulary available for the understanding of verbally presented information and for communication. Typical language development requires the presence of adequate hearing, the cognitive ability to acquire vocabulary and build a word repository, the ability to attend to verbal information, and the desire to establish rapport with a speaker.11A child who has all the prerequisites of language development will gradually store vocabulary to which he or she is exposed. This stored lexicon also records the visual images, word patterns, and affective associations with which the vocabulary is learned. Over time, the stored lexicon is sufficient for the understanding of very complex communication. This understanding of linguistic cipher is referred to in development as receptive language, and it is measured by a few milestones in the first year of life and more plentiful milestones thereafter (Table 10.2).

Adapted from Accardo PJ, Capute AJ. The Capute Scales: Cognitive Adaptive Test and Clinical Linguistic and Auditory Milestone Scale (CAT/CLAMS). Baltimore, MD: Paul H. Brookes Publishing Co.; 2005.

Expressive language development is dependent on a rich word repository or receptive language skills from which information is drawn, as well as the neurological and oral motor skills to produce speech. Expressive language skills progress over the first 12 months of life, from guttural language from birth to 2 months to prelinguistic skills between 3 and 11 months.9

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