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Split Cord Malformation Diagnosed on Fetal MRI with Large Fibro-osseous Spur: Benefit of Fetal MRI in Prenatal Assessment and Management 2014

Category General Spine Anant Krishnan
Stefan Margiewicz
Luis F. Goncalves, Pediatric Radiologist
Purpose 1. Present a clinically important finding on Fetal MRI not seen/suspected on Prenatal Ultrasound 2. Correlate prenatal US, MRI and Post natal MRI of the spine in this child to depict the complicated findings 3. Briefly discuss the benefits of fetal MRI in prenatal assessment as a complementary tool to routine US and as part of Multidisciplinary Conference. Materials & Methods 29 year old G1 P0 was found to have a finding suspicious for a neural tube defect on screening and repeat prenatal Ultrasound (US) . A definite skin defect was not seen and preliminary diagnosis was an isolated meningocele on US report at 27 weeks and 4 days (by dates). To further characterize and for patient counselling, a fetal MRI was recommended and performed on a 1.5 T MR scanner at 29 weeks gestation. Scanning of fetal spine and head was performed. Results A singleton pregnancy with cephalic presentation was visualized. There was widening of the spinal canal and interpediculate distance from approximately L2 to approximately S1. In these locations, there was splitting of the spinal cord into 2 hemicords without a definite syrinx. The cords were split by a large markedly hypointense on T2 lesion (fibro-osseous spur) that extended from paraspinal region into the spinal canal. Possible tethering of the cord to the surface of the spur was seen. A skin defect was not seen. The meningocele suspected on US was difficult to visualize given the close apposition of the back to uterus. Cranial examination was within normal limits without a posterior fossa abnormality. Limited imaging of fetal abdomen and pelvis demonstrated a distended urinary bladder. The examinations were reviewed in the Maternal-Fetal Multidisciplinary conference. A neurosurgical consult was also performed. The pregnancy progressed, complicated by gestational diabetes. Following premature rupture of membranes and non-reassuring fetal heart tones, the baby was delivered by Cesarean section at 37w 2d. On examination skin irregularity without a defect was seen. On day 2, imaging of the spine and brain was performed confirming a Type 1 split cord malformation separated by a large fibro-osteocartilaginous spur dividing the spinal canal and cord. A meningocele was seen without skin defect. No definite dermal sinus was seen. Brain MRI was unremarkable. On day 4, the child underwent surgical untethering of the split cord and resection of a large spur with repair of dura. The meningocele was also resected. Conclusion Accurate assessment prenatally of the fetus is critical both for patient counselling and elective surgical planning. In this case, the detection of a split cord malformation by MRI allowed appropriate management and prevented surprises at birth. US even in academic centers can be limited in assessing for split cord malformations and fetal MRI is advisable when neural tube defects are seen. References Sonigo-Cohen P et al. Prenatal diagnosis of diastematomyelia. Childs Nerv Syst. 2003 19(7-8):555-60