Intrauterine‐diagnosed diastematomyelia

Abstract

Diastematomyelia, which is also called split cord malformation, is a rare form of occult spinal dysraphism1-3. It occurs as a result of abnormal notochord development at days 15–18 of pregnancy3. An echogenic posterior focus in the axial view of the spinal canal is a specific prenatal sign of diastematomyelia4, 5, and has been detected in 0.06% of 10 070 prospective ultrasonographic examinations4. A midline, sagittal osseous or fibrocartilaginous spur produces a complete or incomplete sagittal division of the spinal cord into two hemicords6. Along with isolated forms, complicated forms accompanied by other types of dysraphism, segmental abnormalities in vertebral bodies or visceral malformations may develop4. Prenatal ultrasonographic diagnosis of diastematomyelia can be made in the early second trimester of pregnancy7. Fetal magnetic resonance imaging (MRI), which allows for better assessment of spinal cord content, has been used in unclear cases to confirm sonographic findings and has revealed additional spinal cord abnormalities8-10. We present two cases of diastematomyelia detected by ultrasonography during the prenatal period and discuss the contribution of fetal MRI, which was used in one of these cases. In the first case, fetal ultrasound examination performed at 17 weeks' gestation revealed a midline echogenic cleft at the thoracolumbar junction and a longitudinal division of the cord below the T12–L1 level. Intrauterine MRI at 32 weeks' gestation showed the presence of an osseous sagittal cleft at the thoracolumbar junction and a low conus (Figure 1). There were no additional abnormalities and a diagnosis of isolated diastematomyelia was made. Magnetic resonance image at 32 weeks' gestation showing an osseous sagittal cleft (arrow) at the thoracolumbar level. The second case involved a woman who, at 29 weeks' gestation, was referred to our perinatology clinic with Type II diabetes mellitus. Glycosylated hemoglobin (HgA1c) was 9.82% and ophthalmoscopic findings were consistent with diabetic retinopathy. It was thought that she had non-regulated diabetes at the time of conception. Fetal ultrasound examination revealed a defect at the level of the L2–L3 vertebrae. A midline echogenic bony spur was observed along with a disorganization of the bony processes of the vertebral column and asymmetrical hemicords (Figure 2), suggesting the diagnosis of diastematomyelia. The woman was hospitalized for regulation of her diabetes but, at her request, she was discharged without full regulation. She declined fetal MRI. Postpartum evaluation revealed no other abnormality in the fetus. Ultrasound image at 29 weeks' gestation showing a midline echogenic bony spur (arrow), disorganization of the bony processes of the vertebral column and asymmetrical hemicords. In our cases, diastematomyelia was directly visualized by the presence of two hemicords sonographically. In one case, fetal MRI did not show any additional abnormalities and helped to confirm the diagnosis. Ultrasonography and MRI are complementary methods in evaluating the fetal nervous system and spine. In cases of isolated diastematomyelia, the neonatal prognosis is generally satisfactory and early surgical intervention yields good outcomes. Using a combination of MRI and ultrasonography for prenatal diagnosis in cases of diastematomyelia can be useful for determining the type of diastematomyelia and for ruling out additional spinal abnormalities. Y. Uyar*, Y. B. Baytur*, C. Calli , B. Cetinkaya*, H. Caglar*, * Department of Obstetrics and Gynecology, Faculty of Medicine, Celal Bayar University, Manisa, Turkey, Department of Radiology, Faculty of Medicine, Ege University, İzmir, Turkey