Clinical Manifestations of Diseases in the Newborn Period

Abnormal Movements

Neonatal seizures usually suggest a central nervous system (CNS) disorder, such as hypoxic-ischemic encephalopathy (HIE), intracranial hemorrhage, stroke, cerebral anomaly, subdural effusion, or meningitis (see Chapter 611.7 ). In the neonate, seizures can also be secondary to hypocalcemia, hypoglycemia, benign familial seizures, or rarely, pyridoxine dependence, hyponatremia, hypernatremia, inborn errors of metabolism, or drug withdrawal.

Seizures in premature infants are often subtle and associated with abnormal eye movement (fluttering, tonic horizontal deviation, sustained eye opening with ocular fixation) or facial movement (chewing, tongue thrusting); the motor component is often that of tonic extension of the limbs, neck, and trunk. Autonomic phenomena include hypertension and tachycardia. Term infants may have focal or multifocal, clonic or myoclonic movements, but they may also have subtler manifestations of seizure activity. Apnea may be the 1st manifestation of seizure activity, particularly in a premature infant. Seizures may adversely affect the subsequent neurodevelopmental outcome and may even predispose an infant to seizures outside the neonatal period. Electroencephalographic evidence of seizures can occur without clinical manifestations, particularly in preterm infants. If seizures are suspected, continuous amplitude integrated EEG (aEEG), or more accurately, long-term video EEG monitoring, will improve detection of both subtle and electrographic but clinically silent seizures. Many medications used to treat seizures have important side effects and limited efficacy, but current evidence suggests that the benefits of treating seizures outweigh the risks.

Seizures should be distinguished from the jitteriness , defined as recurrent tremors, that may be present in normal newborns, in infants of diabetic mothers, in those who experienced birth asphyxia or drug withdrawal, and in polycythemic neonates. An examiner may stop the tremors by holding the infant's extremity; jitteriness often depends on sensory stimuli and occurs when the infant is active, and it is not associated with abnormal eye movements. Tremors are often more rapid with a smaller amplitude than those of tonic-clonic seizures.

After severe birth asphyxia, infants may exhibit motor automatisms characterized by recurrent oral-buccal-lingual movements, rotary limb activities (rowing, pedaling, swimming), tonic posturing, or myoclonus. These motor activities are not usually accompanied by time-synchronized EEG discharges, may not signify cortical epileptic activity, respond poorly to anticonvulsant therapy, and are associated with a poor prognosis. Such automatisms may represent cortical depression that produces a brainstem release phenomenon or subcortical seizures.

Failure to move an extremity ( pseudoparalysis ) suggests fracture, dislocation, or nerve injury, often following a traumatic delivery. It is also seen in septic arthritis, osteomyelitis, and other infections that cause pain on movement of the affected part.

Altered Mental Status

Lethargy may be a manifestation of infection, asphyxia, hypoglycemia, hypercapnia, sedation from maternal analgesia or anesthesia, a cerebral defect, or, indeed, almost any severe disease, including an inborn error of metabolism. Shortly after birth, lethargy is most likely caused by maternal medications (opioids, magnesium, general anesthesia) or severe HIE. Lethargy appearing after the 2nd day should suggest infection or an inborn error of metabolism manifesting with hyperammonemia, acidosis, or hypoglycemia. Lethargy with emesis suggests increased intracranial pressure or an inborn error of metabolism.

Irritability may be a sign of discomfort accompanying intraabdominal conditions, meningeal irritation, drug withdrawal, infections, congenital glaucoma, trauma (birth, abuse), or any condition producing pain. It must be distinguished from normal crying behavior associated with hunger or benign environmental stimuli. Hyperactivity , especially in a premature infant, may be a sign of hypoxia, pneumothorax, emphysema, hypoglycemia, hypocalcemia, CNS damage, drug withdrawal, neonatal thyrotoxicosis, bronchospasm, esophageal reflux, or discomfort from a cold environment.

Failure to feed is an important sign of the sick newborn infants and should prompt a careful search for infection, a CNS (brain or spine) or peripheral nervous system disorder, inborn error of metabolism, intestinal obstruction, and other abnormal conditions.

Apnea

Periods of apnea, particularly in premature infants, can be attributed to many different underlying causes (see Chapter 122.2 ). When apnea recurs, or when the intervals are >20 sec or associated with cyanosis or bradycardia, an immediate diagnostic evaluation for the underlying cause is imperative.

Congenital Anomalies

Congenital anomalies are a major cause of stillbirths and in the United States and other developed countries are one of the main causes of neonatal mortality. In addition, congenital anomalies are a major cause of acute illness and long-term morbidity. Anomalies are discussed in general in Chapters 98 and 128 and specifically in the chapters on the various systems of the body. Early recognition of anomalies during fetal life is important to plan for delivery room management and subsequent neonatal care. Some malformations, including congenital heart disease, tracheoesophageal fistula, diaphragmatic hernia, choanal atresia, and intestinal obstruction, require immediate medical/surgical therapy for postnatal survival ( Table 119.1 ). Parents are likely to feel anxious and guilty on learning of the existence of a congenital anomaly and require thoughtful, sensitive counseling.

Cyanosis

Central cyanosis generates a broad differential diagnosis encompassing respiratory, cardiac, CNS, infectious, hematologic, and metabolic etiologies ( Table 119.2 ). Typically, 5 g/dL of deoxyhemoglobin must be present in the blood for central cyanosis to be clinically apparent. If respiratory insufficiency is caused by pulmonary conditions, respirations tend to be rapid with increased work of breathing. If caused by CNS depression, respirations tend to be irregular and weak and are often slow. Cyanosis unaccompanied by obvious signs of respiratory difficulty suggests cyanotic congenital heart disease or methemoglobinemia. Cyanosis resulting from congenital heart disease may, however, be difficult to distinguish clinically from cyanosis caused by respiratory disease. Episodes of cyanosis may also be the initial sign of hypoglycemia, bacteremia, meningitis, shock, or pulmonary hypertension. Peripheral acrocyanosis is common in neonates and thought to represent peripheral venous congestion associated with immature control of peripheral vascular tone. It does not usually warrant concern unless poor perfusion is suspected.

Gastrointestinal Disturbances

Vomiting during the 1st day of life can suggest obstruction in the upper digestive tract, metabolic disease, or increased intracranial pressure and must be distinguished from benign reflux . Abdominal distention with emesis , usually a sign of intestinal obstruction or an intraabdominal mass, may also be seen in infants with enteritis, necrotizing enterocolitis (NEC), isolated intestinal perforation, ileus accompanying sepsis, respiratory distress, ascites, or hypokalemia. Imaging studies are indicated when obstruction is suspected; proximal intestinal obstruction often occurs with a normal physical examination, whereas distal obstruction will likely be accompanied by distention. Vomiting may also be a nonspecific symptom of an illness such as septicemia with associated abdominal distention and ileus. It is a common manifestation of overfeeding, inexperienced feeding technique, or normal reflux. Rarely, vomiting is caused by pyloric stenosis, milk allergy, duodenal ulcer, stress ulcer, an inborn error of metabolism (hyperammonemia, metabolic acidosis), or adrenal insufficiency. Vomitus containing dark blood is usually a sign of a serious illness; but the benign possibility of swallowed maternal blood associated with the delivery process should also be considered. Tests for maternal vs fetal hemoglobin can help discriminate between these possibilities. Bilious emesis strongly suggests obstruction below the ampulla of Vater and warrants urgent contrast-enhanced radiography.

Diarrhea may be a symptom of overfeeding (especially high–caloric density formula), acute gastroenteritis, congenital diarrhea syndromes, or malabsorption, or it may be a nonspecific symptom of infection. Diarrhea should be differentiated from the normal loose, seedy, yellow stool seen typically in breastfed infants. Diarrhea may occur in conditions accompanied by compromised circulation of part of the intestinal or genital tract, such as mesenteric thrombosis, NEC, strangulated hernia, intussusception, and torsion of the ovary or testis.