Spinal sonography in newborns and infants--Part I: method, normal anatomy and indications.

Spinal sonography can be performed in newborns and young infants as long as the vertebral arches are not completely ossified. With high resolution linear transducers (>10 MHz), excellent detailed images of the spine may be obtained from the base of the skull to the caudal end of the thecal sac. Sagittal and axial sections are performed routinely. Beside the spinal cord, the dorsal and ventral nerve roots and the cauda equina can be shown. The medullary conus normally ends above the level of L2/L3. Lower positions are suspective of tethered cord. M-mode sonographic examinations reveal oscillations of the cord due to respiration and the pulse cycle. Colour Doppler sonography displays the epidural venous plexus as well as the central branches of the anterior spinal artery. Normal variants are transient widening of the central canal, terminal ventricle and asymmetric nerve roots. Indications for spinal sonography are midline cutaneous markers in the lumbosacral region, subcutaneous masses, foot abnormalities, anorectal and genitourinary malformations and neurological abnormalities of the lower extremities. All these clinical symptoms are suspicious of spina bifida occulta and tethered cord which should be ruled out by spinal sonography.