Minor cranial ultrasound abnormalities, such as mild ventricular enlargement, choroid plexus cysts, and subependymal cysts, have been identified in 3% to 5% of the newborn population. Although clinicians generally consider these abnormalities to be insignificant for the outcome of the newborn, few convincing data have been published to support this optimism. The objectives of this study were to identify potential risk factors associated with the identification of cranial ultrasound abnormalities at birth and to determine if the abnormalities were related to neurobehavioral sequelae in the newborn.
Three hundred eight women were enrolled in this prospective, longitudinal maternal-infant health and development study either at the time they entered the public health care system for prenatal care or at delivery if they had no prenatal care. Each woman participated in an in-depth psychosocial interview at the end of each trimester of pregnancy. Retrospective chart review by experienced medical personnel was used to compile data for the Hobel perinatal risk score for each study participant after delivery. Offspring underwent cranial ultrasound evaluation, the Amiel-Tison Neurologic Assessment, and the Brazelton Neonatal Behavioral Assessment Scale within 96 hours of birth by experienced examiners blinded to any maternal-infant history.
Of the 308 women originally enrolled in the study, 301 delivered living infants. Of these, 266 infants (88%) underwent a cranial ultrasound evaluation and are the subject of this article. For the purposes of the current study, infants were divided into those with normal (n = 239) and those with abnormal (n = 27) ultrasound results. Abnormal ultrasound results included the following lesions: subependymal cyst (n = 13); mild ventricular enlargement (n = 6); choroid plexus cysts (n = 3); a combination of cysts and increased ventricular size (n = 2); a 7-mm midline cyst in the superior posterior portion of the third ventricle (n = 1); subependymal hemorrhage and ventricular enlargement (n = 1); and increased ventricular size, subependymal hemorrhage and cysts, and two small, right thalamic calcifications (n = 1). There were no significant differences between those with an abnormal ultrasound and those with a normal ultrasound for birth weight, length, gestational age, rate of prematurity, frequency of nulliparity, or frequency of small for gestational age infants. However, infants with an abnormal ultrasound had a significantly smaller mean head circumference than those with a normal ultrasound (34.5 ± 1.9 cm vs 33.7 ± 1.9 cm). The infants with an abnormal ultrasound had a higher median prenatal (50 vs 45), neonatal (14 vs 8), and total (94 vs 77) Hobel risk score but not a higher labor-delivery score. There were no significant differences when these groups were compared on additional risk factors not included in the Hobel scoring system such as race and socioeconomic status. In addition, mothers who used a greater number of drugs during the first trimester of pregnancy were more likely to have an infant with an abnormal ultrasound at birth such that the probability of having an abnormal ultrasound rose to 22% by the time the pregnant women were using four drugs. Neurologic examinations revealed no differences between the infants with normal and abnormal ultrasounds. There were also no group differences for five of the seven Brazelton cluster scores, the excitable or depressed clusters, or eight of the nine qualifier scores. However, infants with abnormal ultrasounds performed significantly better on the habituation (7.3 ± 0.8 vs 6.6 ± 1.5) and autonomic regulation (6.5 ± 0.8 vs 6.0 ± 1.0) clusters but more poorly on the cost of attention qualifier score (4.9 ± 1.2 vs 5.5 ± 1.2) on the Brazelton Neonatal Behavioral Assessment Scale.
Infants with an abnormal cranial ultrasound at birth had higher perinatal risk scores. Additionally, we conclude that the abnormalities identified on cranial ultrasound within the first 96 hours of life were most likely benign with no clinical significance in the immediate neonatal period. However, because of the finding of several subtle differences in behavior, follow-up beyond the neonatal period would be advisable to determine if any late-onset abnormalities occur.