Observation over centuries confirms that infants and children learn developmental skills in a predictable order within a predictable age range. These skills occur in the following neurodevelopmental streams: neuromotor (including gross motor, fine motor, and oral motor), neurocognitive (including language, social, nonverbal/visual-motor problem solving, and adaptive), and neurobehavior (including attention and activity/impulsivity). Gross motor skills include rolling over, crawling, and walking, and progressing to running, jumping, and skipping; fine motor skills include picking up an item, first with a full fist and then progressing to doing the same with a mature pincer grasp; oral motor skills include speech articulation and feeding. Nonverbal/visual-motor problem-solving skills include determining how to obtain an item that is out of reach or determining which of two containers is smaller. Expressive language skills include cooing, babbling, and progressing to saying words, phrases, and sentences. Receptive language skills include following a one-step command given with a gesture and progressing to following nongestured commands. Social skills include reciprocally smiling and progressing to interactive play with others.
One of the primary responsibilities of a primary care pediatric medical provider is the monitoring of each patient’s skill attainment in each developmental stream to make certain that each patient acquires age-expected skills, which is considered meeting developmental milestones. Pediatric medical providers need to partner with their patients’ parents and caregivers in this monitoring responsibility, since parents and caregivers observe their children daily, which allows them to report skill attainment, lack of skill attainment, or skill loss in a timely manner.
Global Developmental Delay
Developmental delay occurs when a child gains a skill at an age beyond the expected age range for that skill’s acquisition. Given that the most common etiologies for developmental delay tend to affect the brain diffusely (eg, chromosomal/genetic abnormalities), global developmental delay is more prevalent than focal or dissociated delay. Global developmental delay is defined by a significant delay in two or more developmental domains. While a mild or borderline delay is usually defined by developmental quotient, or DQ (developmental age/chronologic age × 100), below 85%, a significant delay is usually defined as a DQ of less than 70%. Thus, an 18-month-old child whose nonverbal/visual-motor problem-solving skills are at a 12-month level (DQ = 12 months/18 months × 100 = 67%) and whose language skills are at a 10-month level (DQ = 10 months/18 months × 100 = 56%) would be considered to have global developmental delay.
Infants and toddlers with global developmental delay who have delays involving both nonverbal/visual-motor problem solving and receptive language development are at significant risk for intellectual disability. The more severe the intellectual disability is, the younger the age a child is when it can be reliably identified. However, mild intellectual disability may be more difficult to confirm at early ages, particularly in children who have not received appropriate developmental stimulation. A hearing and seeing child with exposure to developmentally stimulating ...