CEREBRAL LATERAL VENTRICULAR ASYMMETRY - IS THIS A NORMAL ULTRASONOGRAPHIC FINDING IN THE FETAL BRAIN

Objective: To evaluate the clinical significance of in utero detection of fetal cerebral lateral ventricular asymmetry. Methods: We used hig h resolution ultrasonography to study asymmetries of the fetal lateral ventricles in the human brain. A retrospective survey was conducted o n 7200 pregnant women who presented at two large district hospitals in Israel. Only fetuses with a difference of greater than 2.4 mm (two st andard deviations) in the width of the lateral ventricles, with no kno wn brain pathology, were included in the study. Index cases were evalu ated regarding maternal complications, prenatal ultrasound examination s, postnatal imaging studies, and neonatal outcome up to 6 months of a ge. Results: Lateral ventricular asymmetry was found in 21 subjects, a ll with available clinical data. In 15 fetuses (71%), the body or the occipital horn of the left lateral ventricle was larger than the right , whereas in six fetuses (29%), the right was larger than the left. In four cases (20%), serial scans noted resolution of asymmetry; in 15 ( 75%), it was persistent; and in one (5%), asymmetry increased. In one case, termination of pregnancy was performed; however, pathologic exam ination of the fetal brain failed to detect any structural abnormality . Underlying cerebral pathology was later found only in three fetuses (14%); one had subclinical cytomegalovirus ventriculitis, one had insi dious periventricular hemorrhage, and in one fetus with increased asym metry, trisomy 21 was verified. All the remaining 17 cases had normal neurologic development. Conclusions: Some degree of asymmetry of the l ateral ventricles exists in the human fetal brain and is detectable in utero. Lateral ventricular asymmetry alone is probably not clinically significant, and it may be considered as a normal variant, rather tha n a pathologic finding. Copyright (C) 1997 by The American College of Obstetricians and Gynecologists.