Trimyelia with divergent cord pathways and three foramina magni

Split medulla in association with multiple closed neural tube defects

PURPOSE

We describe the case of a patient with a split medulla associated with multiple closed neural tube defects.

CASE REPORT

This 13-year-old female initially presented to our service at just over a year of age for neck abnormalities and a congenital midline occipital dermal sinus. MRI and CT scans showed the presence of multiple cervical vertebral segmentation abnormalities, a bony spur at the level of the craniocervical junction, split medulla, split cervical spinal cord, and a midline occipital dermal sinus. Since the patient's neurological course had remained stable during follow-up for over 11 years, the only surgical procedure undertaken was excision of the dermal sinus to prevent infection.

CONCLUSIONS

The constellation of abnormalities indicates that the notochord was split early during gestation, both rostral and caudal to the cervicomedullary junction. Surgical intervention to treat the other malformations needs to be considered only if the patient develops a progressive neurological deficit.

Nomograms of the axial transverse diameter of the fetal foramen magnum between 14 and 40 weeks' gestation

OBJECTIVE

The purpose of this study was to create reference range nomograms of the axial transverse diameter of the fetal foramen magnum (TDFM) between 14 and 40 weeks' gestation.

METHODS

This cross-sectional study included pregnant patients between 14 and 41 weeks' gestation. Inclusion criteria consisted of well-established dates (confirmed by early sonography) and nonanomalous singleton fetuses with intact amniotic membranes. Sonographic measurements included biparietal diameter, head circumference, abdominal circumference, femur length, humerus length, transcerebellar diameter, and sonographically estimated fetal weight. Values of the TDFM were each calculated as the mean of 3 separate measurements. The 5th, 50th, and 95th percentiles were estimated at each week of gestational age (GA) by least squares regression for the mean and SD of the TDFM as functions of GA. R(2) and associated P values for the relationships between the TDFM and other biometric measurements were calculated.

RESULTS

The study included 602 consecutive patients meeting the inclusion criteria. The mean maternal age +/- SD was 27.5 +/- 6.4 years; median gravidity, 3 (range, 1-12); and median parity, 1 (range, 0-7). The mean TDFM was 13.5 +/- 3.7 mm. The reference curve formulas for the mean and SD of the TDFM (mm) were TDFM = -12.58 + GA/0.5616 - GA(2)/24.9 + GA(3)/2430.7, and SD(TDFM) = 1.05 - GA/19.4 + GA(2)/588.8. The TDFM correlated significantly and strongly with biparietal diameter, head circumference, abdominal circumference, humerus length, femur length, transcerebellar diameter, and estimated fetal weight (all R(2) >or= 0.90; all P < .0001).

CONCLUSIONS

We present reference range nomograms of the TDFM between 14 and 40 weeks' gestation.