CENTRAL NERVOUS SYSTEM

CNS dysfunction secondary to systemic illness occurs quite commonly in infants and children. Seizures, head trauma, CNS infections, and hypoxic or metabolic encephalopathy are the common causes of acute neurologic dysfunction in the PICU. Assessment of neurologic function depends on an understanding and awareness of the age-dependent progression of motor and cognitive skills. Table 76-11 lists the developmental milestones.

Functional Postnatal Neurologic Development

Motor function in the newborn is dependent on gestational rather than postnatal age.^[188] That is, an infant born at 28 weeks' gestation who is 3 months old exhibits motor responses similar to those of a full-term newborn. Motor function and tone as well as reflex behavior serve as the basis for assessing gestational age in a newborn. Though potentially modifiable by cortical influence, most neonatal motor behavior is subcortically controlled, ^[189] thus permitting normal motor behavior in newborn infants with severe cortical damage.

Intellectual development is difficult to assess in a newborn; initially, it is predicated on the loss of some newborn reflexes and the acquisition of new motor skills. Adaptive or interactive behavior is first seen with accommodation to repeated stimuli and eye contact. The infant's intellectual development depends on the presence of significant external stimulation and social interaction, preferably from

2855