Neonatal spine ultrasound...normal and abnormal findings

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This lecture illustrates the ultrasound technique ,spinal anatomy and congenital anomalies of neonatal spines diagnosable by ultrasound

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Neonatal spine ultrasound...normal and abnormal findings

  1. 1. Dr/Ahmed Bahnassy Consultant Radiologist Riyadh Military Hospital
  2. 2. Why US spines ? Spinal ultrasound (SUS) is becoming increasingly accepted as a first line screening test in neonates suspected of spinal dysraphism .
  3. 3. Challenging MRI The advantages of SUS are not only a diagnostic sensitivity equal to MRI but that, unlike MRI, SUS can be performed portably, without the need for sedation or general anaesthesia. In addition, MRI is highly dependent on factors affecting resolution, including patient movement, physiological motion from cerebral spinal fluid (CSF) pulsation and vascular flow, factors that do not affect SUS . New generation high frequency ultrasound machines with extended field of view capability now permit imaging of high diagnostic quality in young babies.
  4. 4. When to perform ? SUS is possible in the neonate owing to a lack of ossification of the predominantly cartilaginous posterior arch of the spine . The quality of ultrasound assessment decreases after the first 3–4 months of life as posterior spinous elements ossify, and in most children SUS is not possible beyond 6 months of age. However, the persisting acoustic window in children with posterior spinal defects of SD enables ultrasound to be performed at any age
  5. 5. When to request US spines ? Current RCR guidelines are that all neonates with a hairy patch or sacral dimple should undergo SUS . However, while more than 90% of patients with occult SD have a cutaneous abnormality over the lower spine , a cutaneous marker may have a low yield in predicting the presence of a clinically significant abnormality. In a recent review of 200 SUS examinations performed over an 11-year period, SD was found in less than 1% of cases when a cutaneous marker was the only clinically detected abnormality .
  6. 6. Gastrulation stage
  7. 7. Neurulation stage
  8. 8. Retrogressive differentiation and relative cord ascent Formation of the ventriculus terminalis, the caudal portion of the conus medullaris, and the filum terminale through the processes of canalization and retrogressive differentiation.
  9. 9. Sonographic examination of the neonatal spine is performed with the infant in a warm room lying in a prone, lateral decubitus, or semi-erect position. Feeding the infant before examination helps him or her to relax. Placing a towel under the infant’s pelvis will flex the spine enough to separate the midline posterior arches . .
  10. 10. A high frequency (7- to 15-MHz) lineararray transducer should be used .. higher frequency transducers are beneficial for optimization of superficial structures such as skin lesions and sinus tracts. Extended field-of-view (EFOV) imaging is an additional feature that can demonstrate the whole neonatal spine from T12 to the coccyx
  11. 11. • Mark T 12 in transverse plane (presence of ribs witnessing) • Then count downwards to end of cord.
  12. 12. Alternatively by Locating the last lumbar vertebra, L5, by evaluating the lumbosacral junction. Then count cephalad to the conus medullaris. Locating the last ossified vertebral body, the first coccygeal segment. Then count the five sacral segments cephalad into the lumbar vertebra.
  13. 13. The spinal cord lies in the spinal canal within anechoic CSF of the subarachnoid space. Surrounding the canal is the dura mater, which is shown by anechogenic line dorsal and ventral to the canal. The cord is lined with the arachnoid sheet, which exhibits an echogenic line parallel to the cord’s surface. Caudally, the lumbar enlargement tapers, forming the conus medullaris, which extends and becomes the filum terminale.
  14. 14. Filum teminale The filum terminale images as an echogenic cordlike structure that is surrounded by echogenic nerve roots of the cauda equina. For that reason, separation of the two is difficult. However, the filum terminale is commonly more echogenic than the surrounding cauda equina. The filum terminale normally measure less than or equal to 2 mm.
  15. 15. Cord On a sagittal image, the spinal cord appears as a hypoechoic cylindrical structure with two echogenic complexes centrally. These represent the central echo complex. The normal cord lies one third to one half of the way between the dorsal and ventral walls of the spinal canal On a transverse image, the cervical spinal cord appears as an oval shape, whereas the thoracic and lumbar portions are more circular.
  16. 16. Conus level The level of the conus usually ends between T12 and L1 or L2 .If it ends at the L2-L3 disk space or lower, it is abnormal, and one should explore for any tethering masses. However, it must be noted that a normal cord may lie around L3, mainly in preterm infants. The normal position of the cord should be central in the spinal canal. The spinal cord is held in place by echogenic dentate ligaments passing laterally from each side of the cord. The normal spinal cord produces a rhythmic movement
  17. 17. • Standard views
  18. 18. Cystic ventriculus terminalis (normal variant)
  19. 19. Cystic distension of distal spinal canal (normal variant ) Size smaller than 5 mm and stability over time distinguish this normal variant from small syrinx.
  20. 20. Filar cyst (normal variant) criteria for filar cyst: location just below conus medullaris, fusiform shape, well defined, thin walled, and hypoechoic.
  21. 21. Pseudo-masses • Clumped nerve roots.. • Use 2 planes..to see the whole length of nerve root.
  22. 22. Dysmorphic coccyx • Cartilagenous angulated lesion. • Not dermal sinus track.
  23. 23. Three processes can lead to congenital anomalies: First, premature separation of the skin ectoderm from the neural tube can lead to entrapment of mesodermal elements, such as fat. Second, failed neurulation leads to dysraphisms, such as myelomeningocele(overt or closed )
  24. 24. Last ,anomalies of the filum terminale, such as fibrolipomas and caudal regression syndrome caused by disembryogenesis of the caudal cell mass
  25. 25. Classification Congenital spinal dysraphisms can be classified on the basis of the presence or absence of a soft-tissue mass and skin covering . Those without a mass include tethered cord, diastematomyelia, anterior sacral meningocele, and spinal lipoma. Those with a skin covered soft-tissue mass include lipomyelomeningocele and myelocystocele. And those with a back mass but without skin covering include myelomeningocele and myelocele
  26. 26. Lipoma
  27. 27. Dorsal dermal sinus track
  28. 28. Tethered cord Search for cause Sonographically, tethered cord is diagnosed in neonates by the presence of a low-lying conus (below the L2–L3 disk space) and lack of normal nerve root motion during realtime sonography
  29. 29. Intradural lipoma • Hyperechoic dural mass.. • Tethered cord.
  30. 30. Thick filum terminale
  31. 31. Fatty filum
  32. 32. Lipoma of filum terminale L3 Tethered cord
  33. 33. Diastematomyelia • Echogenic spur between two hemicords in transverse image.
  34. 34. Caudal regression syndrome • Blunted conus medullaris. • Fatty filum • Absence of sacral vertebrae and coccyx .
  35. 35. Myelomeningocele • Cystic mass (CSF) • +tethered cord • +neural elements. • +soft tissue mass
  36. 36. Unilocular meningocele
  37. 37. Lipomyelomenimgeocyle
  38. 38. Neuroblastoma
  39. 39. Sacrococcygeal teratoma
  40. 40. Other renal anomalies
  41. 41. Conclusion • Spinal ultrasound (SUS) is becoming accepted as a first line screening test in neonates with high sensitivity and specificity. • Recognizing normal anatomy ,variants and congenital anomalies early in life help in futur planning of management .

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