Is Brain Injury in the Preterm Infant Preventable?
Neonatal intensive care units across the United States continue to admit newborns who are small for gestational age (SGA) (less than 2,500 grams at birth), or born prematurely (less than 37 completed gestational weeks), whose medical records include an admitting diagnosis of perinatal or birth asphyxia. If fetal asphyxia has occurred, and if the child develops permanent neurological and intellectual handicaps, it is reasonable for the parents to ask a lawyer to determine whether the outcome could have been prevented by different management or earlier delivery. Yet, many lawyers are reluctant to investigate a case involving a premature infant, particularly one born between 28 and 32 weeks, because of the added burden of having to show that the brain injury was not caused by one of the known complications of prematurity.
When trying to determine if cerebral palsy could have been prevented in a preterm infant it is critical to determine whether the brain injury was caused by complications of prematurity or other conditions which the clinician failed to timely diagnose and properly manage. Statistically, a large percentage of preterm infants survive and a large percentage of survivors are normal. Thus, the fact that a baby is born prematurely does not automatically explain why the infant developed an irreversible brain injury. One must perform a careful analysis of all of the potential sources of evidence, including the prenatal chart, the antepartum test results, the fetal heart rate strips, the laboratory tests, the placental pathology examinations, the maternal and fetal complications, the blood gas studies, the newborn neurological findings, and the newborn neuroimaging studies.
Parents should understand the causes and frequency of the major cerebral and pulmonary complications in preterm infants. The pattern of brain damage in preterm neonates who experience intrapartum asphyxia is in the region of the germinal matrix and the surrounding periventricular region. The two major brain lesions that are commonly found in preterm infants suffering irreversible brain injury are Periventricular Leukomalacia ("PVL") and Intraventricular Hemorrhage ("IVH"), and the most common respiratory complication is Respiratory Distress Syndrome ("RDS"), previously referred to as Hyline Membrane Disease ("HMD").
PVL is an ischemic lesion of the white matter that can occur in preterm infants who later develop cerebral palsy. The white matter is damaged when hypoxia or ischemia develops during the preterm period, particularly between 28 and 32 gestational weeks.
IVH is defined as a hemorrhage or bleed that results when the blood vessels in the germinal matrix rupture. IVH is classified as either Grade I, Grade II, Grade III, or Grade IV.
Most newborns recover from a Grade I or Grade II bleed without any permanent injury. It is only when a Grade III or Grade IV bleed occurs, that the infantŐs risk of sustaining a permanent injury increases dramatically. Infants with severe bleeds have signs of apnea, lethargy, seizures, and low hematocrit. The most common cause of IVH is asphyxia. Preterm infants are most vulnerable between 28 and 32 weeks.
The parents of newborns who are diagnosed with intraventricular hemorrhage or periventricular leukomalacia should not assume that these brain injuries were unavoidable. A recent study consisting of 4,593 infants born between 501 and 1500 grams reported that only 11% had severe IVH (grade III or grade IV), and, among those infants who had a cranial ultrasound after two weeks, only 6% had PVL. Many of these infants were born with respiratory distress syndrome; however, the majority survived without permanent lung complications. David K. Stevenson and co-workers, Very low birth weight outcome of the National Institute of Child Health and Human Development Neonatal Research Network, January 1993 through December 1994, American Journal of Obstetrics and Gynecology 1998; 179:1632-39.
RESPIRATORY DISTRESS SYNDROME (RDS)
RDS occurs after the onset of breathing in premature infants with lung immaturity and deficiency of pulmonary surfactants. The risk of RDS increases dramatically when asphyxia occurs. Reduced oxygenation of the heart impairs cardiac output, which in turn leads to reduced perfusion of other organs, such as the kidney and peripheral tissues. This contributes to lactic acidemia and a metabolic acidosis. IVH is associated with HMD, probably due to cerebral hypoxia or ischemia.
There are other causes of respiratory disorders in the newborn. Some may be the result of pulmonary disease, while others are caused by central nervous system disorders and metabolic acidosis. Neonatal respiratory disorders can lead to complications capable of causing irreversible brain injury and/or permanent lung disorders. The respiratory problems can be the result of abnormal lung development, asphyxia, or infection.
Many infants who aspirate amniotic fluid or meconium have mild symptoms that resolve after a few days, and their lungs will function normally. Those with more serious lung disease due to asphyxia, meconium aspiration syndrome, or infection, are at risk for persistent fetal circulation and a chronic lung disease known as bronchopulmonary dysplasia.
It is imperative that qualified individuals are available at the time of a premature birth to correct abnormalities in major organ systems and to reverse ongoing hypoxic conditions that are capable of exacerbating the brain injury during the newborn period. Not only is it necessary to eliminate the original hypoxia, but any abnormality in an organ system that was damaged due to the fetus= compensatory efforts must be corrected. The pediatrician must:
maintain optimal blood flow to the brain,
maintain adequate cardiac output and blood pressure,
maintain adequate oxygenation and respiratory function,
maintain normal blood gases and avoid hypoxemia,
reduce intracranial pressure due to cerebral edema,
correct hypoglycemia and maintain normal glucose levels,
anticipate and treat seizures with anticonvulsants, and
assess brain activity with EEG to monitor the response to therapy.
It is critical to maintain normal blood pressure since both hypotension and hypertension are associated with adverse neurologic outcome. Sodium bicarbonate may be needed to treat severe metabolic acidosis and hypoglycemia must be avoided. Seizures should be recognized and promptly treated to avoid further damage to brain tissue. Brain edema and seizures are further manifestations of this evolving process, and both are capable of exacerbating the initial brain injury. Thus, while one must look at the obstetric management and the timeliness of the delivery, it is also critical to look at the timeliness and appropriateness of the management of new-born complications.
This web site is not intended as legal advice on cerebral palsy, and is not a substitute for obtaining guidance from your own legal counsel about cerebral palsy litigation. It provides general educational information about the standards of care and causation issues that can arise in obstetrical malpractice and cerebral palsy litigation. Readers of the articles contained within this web site should not act upon the cerebral palsy information without first consulting with a lawyer who is experienced in evaluating and litigating cerebral palsy and obstetrical malpractice cases. Mr. Apfel is admitted to practice law in Maryland and the District of Columbia. When Mr. Apfel is asked to participate in cerebral palsy
litigation filed in other states, he will associate with, and act as co-counsel with, an attorney licensed in that state who is familiar with the local laws and procedures.