Pediatric Spine, Sonographic Approach

Spinal dysraphism is the second most common congenital abnormality and ultrasound provides an excellent means for imaging the spine up to three to six months of age. Fusion of the bony portion of posterior elements is complete by one year of age, but since this fusion progresses from caudal to cranial, the thecal sac can be obscured by fused dorsal elements in the lumbar region as early as three months. Indications for pediatrics spines ultrasound include, those with cutaneous markers that place them at risk for dysraphism and if the cutaneous dimple is more than 2.5 cm from the anus and larger than 5 mm, it is considered at risk and those with syndromes that are associated with an increased incidence of dysraphism, including vertebral defects, cardiac anomalies, anal atresia, tracheoesophageal fistula, renal anomalies, and limb dysplasia associations
The spinal cord is predominantly hypoechoic, with a “central echo complex” that is echogenic. The spinal cord is normally widest in the cervical and the lumbar spine, where large exiting nerve roots are present.
Tethered Cord is a pathologic fixation of the spinal cord in an abnormal caudal location so that the cord suffers mechanical stretching, distortion and ischemia with growth and development.it is considered when, conus medullaris below L3 in a neonate and below L2/3 in older patients. Tethering may result in decreased pulsatility of the cord.
Tight filum terminale syndrome is considered when it is thickened to more than
2 mm (by fibrous or lipomatous tissue) and may occur in the absence of tethering of the cord, in which case the filum is thickened but the conus is at the normal level
Spinal dysraphism is a broad term given to groups of anomalies, where there are malformation in dorsum of embryo. Its types include spina bifida aperta: Dysraphism associated with a “dorsal mass that is not covered with skin” and spina bifida cystica: dorsal mass covered with skin and occult dysraphism (spina bifida occulta): dysraphism is present but there is no associated mass.
meningocele is a herniation of meninges alone, without spinal cord or nerve root, into defect in spinal canal
Diastematomyelia is a longitudinal split of the spinal cord and at the point of division, there may be an osseous, fibrous or cartilaginous dividing septum.
hydromyelia is a fluid accumulation/ dilatation within the central canal, therefore, lined by ependyma, and syringomyelia: cavitary lesion within cord parenchyma, of any cause (there are many); located adjacent to the central canal, therefore not lined by ependymal and syringohydromyelia: a term used for either of the above, since the two may overlap and cannot be discriminated on imaging, also known as hydrosyringomyelia!
keywords: ultrasound, dysraphism, Diastematomyelia, syringohydromyelia