Is Neonatal Head Circumference Related to Cerebral Palsy?

A study recently published in Obstetrics and Gynecology International has found a correlation between the size of the cranium (the baby’s head circumference) of infants born at full term and the incidence of cerebral white matter damage (WMD), a condition known to be related to developmental delay and cerebral palsy in childhood. The study indicates the possible need for a change in the observation and management of seemingly asymptomatic newborns who have suffered head trauma during delivery resulting in excessive molding and depression of the baby’s skull. In such cases, fetal cephalopelvic disproportion may be present leading to the compression of the fetal skull and brain during vaginal delivery. In the deliveries of babies with a large head circumference, it is posited that the functional capacity of the maternal pelvis may be inadequate to allow for the unobstructed passage of the fetus during labor. This may be evidenced by prolonged or obstructed labor. The study suggests that cranial ultrasound or magnetic resonance imaging can be used after birth to asses for these intracranial white matter injuries even in seemingly healthy full-term infants with large head circumferences in cases of prolonged or obstructed labor. These imaging techniques can be used to detect and screen for white matter damage after birth, potentially providing the opportunity to administer timely therapeutic interventions. Recent developments point to eventual treatments for WMD which may be only successful if administered within one week after the injury is sustained.

Cerebral white matter consists of the fibrous tracts of the brain that serve an important role in brain development and neuromuscular control. Recent studies have identified a relationship between damage to the white matter of preterm infants and cerebral palsy or other neuromuscular disorders. However, this study confirms the WMD can also occur in term infants. Research at Children’s National Hospital points to a possible treatment for white matter injuries (WMI) in neonates but the treatment must be administered within a short time frame, less than 1 week, after the injury is sustained. Therefore, the timely diagnosis of WMD would need to occur prior to the manifestation of easily recognizable clinical or developmental symptoms of the injury. Clearly recognizable symptoms of a brain injury during birth can often take over a year to manifest.

Diagnosis of white matter injuries can be performed using magnetic resonance imaging after birth. However, screening MRI’s are not routinely performed on asymptomatic newborns and therefore many cases of white matter damage may go unrecognized until later in life and after any chance of administering a potential treatment has passed. Determining pre-natal conditions that might cause or indicate the possibility of WMD in term babies could lead to better screening and diagnosis which in turn could lead to treatments designed to reduce the onset and severity of cerebral palsy and other neurological disorders later in life.

Most of the research into WMD has focused on pre-term babies where the condition was first observed. However, since WMD can and does occur in full term babies, this study sought to determine what predictors might statically correlate with the incidence of WMD in full term infants. By performing cranial ultrasounds on a large number (4,725) of newborns the researchers discovered a statistically significant correlation between large head circumference and the incidence of WMD. They posit that this increased risk of WMD in full-term newborns with large head circumferences may be due to the mechanical complications during vaginal delivery resulting in excessive compression, molding and depression of the fetal skull. The study also identifies additional areas of future research to help narrow down possible intrapartum complications associated with the development of WMD in term newborns. If found, these associations may become helpful in developing new guidelines for the use of MRI after birth to screen for, diagnose and more effectively treat white matter damage. The hope is that an early assessment of WMD in the at-risk tern newborn may lead to a reduction of the incidence and severity of cerebral palsy and other childhood neurological disorders linked to WMD.

In our practice, we often evaluate cases involving term newborns who have sustained significant cranial molding and compression during labor and vaginal delivery leading to a neonatal assessment of cerebral white matter damage. As is indicated in this study, white matter damage of the term newborn might not always be associated with the classic signs, symptoms and laboratory findings consistent with systemic fetal hypoxia. As is referenced in this study, it is understood that the mechanical forces of obstructed or prolonged labor, leading to excessive compression and molding of the fetal cranium, can alone be potentially injurious leading to cerebral white matter damage. This risk is accentuated in those term babies with a large head circumference as is emphasized by this study.

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