Chronology of neurological manifestations of prenatally diagnosed open neural tube defects

Objective: To evaluate the incidence and chronology of sonographic markers of neurological compromise in prenatally diagnosed neural tube defects. Methods: We reviewed our ultrasound database from 1988 to 1999 to identify all cases of prenatally diagnosed neural tube defects. All patients received an initial detailed targeted ultrasound evaluation with subsequent evaluations every 4-6 weeks. Cases involving multiple congenital anomalies, aneuploidy, or inadequate follow-up were excluded. Specific ultrasound markers assessed included the presence of ventriculomegaly (> 10 mm) and clubfoot. Results: Forty-seven cases of neural tube defects were identified over the study interval. After exclusions, 42 cases were available for evaluation. The overall incidence of ventriculomegaly and clubfoot in the study cohort was 86% and 38%, respectively. In the 33 patients with initial ultrasound examination performed at < 24 weeks' gestation, 76% (25/33) had evidence of ventriculomegaly and 30% (10/33) and clubfoot. Only 9% (1/11) of the patients managed expectantly developed evidence of ventriculomegaly and 3/11 (27%) developed clubfoot from the time of the initial ultrasound examination to delivery. Conclusions: Ultrasound markers of neurological compromise are early and frequent findings associated with fetal neural tube defects. Development of ventriculomegaly is an uncommon occurrence later in gestation, while the risk for developing clubfoot appears to increase as gestation progresses.