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Spinal Sonography with MRI correlation in Newborns and Infants with Suspected Occult Spinal Dysraphism: A Pictorial Essay 2013

Category General Spine Harigovinda R. Challa, MD
Barbara K Pawley, MD
Edward J Richer, MD
Johanne E. Dillon, MD
Purpose Spinal dysraphism (SD) comprises a spectrum of congenital anomalies caused by incomplete closure of the neural tube in early embryoneogenesis and is the most common congenital central nervous system (CNS) abnormality, with myelomeningoceles occurring in up to 2 per 1000 live births. Radiologic imaging forms a central role in the work up of newborns with suspected occult spinal dysraphism, and early diagnosis is important as occult conus tethering can cause progressive mechanical traction on the spinal cord as the vertebral column grows faster than the spinal cord during childhood. The objective of this presentation is to present an educational exhibit of classical imaging findings of various types of closed spinal dysraphisms on SUS with MR imaging correlation. Materials & Methods Multiple spinal ultrasound and magnatic resonance examinations performed at Kentucky Children’s Hospital in patients with suspected spinal dysraphism were reviewed and examples of classical imaging findings were compiled and placed into a pictorial review Results Spinal dysraphism can be divided into three different types: Type 1 - Open spinal dysraphism characterized by a non-skin covered mass; Type 2 - Closed lesions with a skin covered mass; Type 3 - Occult lesions without a mass. All three dysraphisms can be associated with a tethered cord, which can be identified on imaging by documenting a low position of the conus medullaris below L3.  The Type 1 and Type 2 dysraphisms can be readily identified on prenatal imaging and clinically at birth. The Type 3 occult lesions are seen with increased frequency in two main groups of infants: 1. Those with syndromes which are associated with SD such as anorectal or urogenital malformations including VATER;  2. Those with cutaneous markers suggesting SD. Spinal ultrasound (SUS) has been an accepted screening imaging modality to evaluate infants suspected of having occult SD and can be performed in newborns and infants before the vertebral arches are completely ossified. The availability, portability, and high resolution capabilities of SUS make it an ideal screening modality in the early neonatal period in contrast to MR imaging which more invasive, often requiring sedation. Furthermore, a normal SUS has a high negative predictive value for SD and usually no further imaging is necessary. Conclusion Spinal dysraphism (SD) is the most common congenital central nervous system (CNS) abnormality and requires early detection in order to prevent irreversable neurological injury. Spinal ultrasound and MR imaging provides detailed anatomy of these lesions prior to surgical treatment. References 1. E. A. Dick R. de Bruyn.  Ultrasound of the spinal cord in children: its role. Eur Radiol (2003) 13:552–562 2. Lisa H. Lowe, Andrew J. Johanek, Charlotte W. Moore.  Sonography of the Neonatal Spine: Part 1, Normal Anatomy, Imaging Pitfalls, and Variations That May Simulate Disorders. AJR 2007; 188:733–738 3. Lisa H. Lowe, Andrew J. Johanek, Charlotte W. Moore. Sonography of the Neonatal Spine: Part 2, Spinal Disorders. AJR 2007; 188:739–744 4. Roberto Azzonia, Simonetta Gerevinib and Paolo Cabitzaa. Spinal cord sonography in newborns: anatomy and diseases. Journal of Pediatric Orthopaedics B 2005, 14:185–188