The ventriculus terminalis of the spinal cord in the neonate: a normal variant on sonography.

Abstract

The ventriculus terminalis, or fifth ventricle, is an ependymal-lined residual lumen of the caudal most portion of the spinal cord (the conus medullaris). We describe five neonates in whom this normal variant was depicted on sonography. Screening lumbosacral spinal sonograms are performed at our institutions on neonates with lumbosacral cutaneous stigmata. Over a 2-year period (1993-1995), we prospectively found five cases in which spinal sonograms showed the ventriculus terminalis of the conus medullaris in term neonates. Two of the five received follow-up spinal sonograms at the age of 3 months. Sonograms of the lumbosacral spine of these five neonates showed an unusual hypoechoic or split appearance of the central echo complex of the conus medullaris. No other abnormalities were noted, and the finding was unchanged on the follow-up sonograms performed on two of the infants at the age of 3 months. These infants have remained asymptomatic during clinical follow-up periods of up to 2 years. The ventriculus terminalis is a normal anatomic variant of the conus medullaris that can be visualized on spinal sonograms in neonates.