Pediatric Spinal Sonography

In the neonate, vertebral ossification is not complete. Hence in the first half of infancy before the spinous processes ossify and fuse, it is possible to image the spinal canal from a dorsal view. Later in life a paramedian approach can be used when the spinous processes are more ossified and lead to posterior acoustic shadowing hence precluding imaging in the midline sagittal plane. A high frequency 7–12 MHz linear array transducer is used. Images are obtained in sagittal/longitudinal and axial/transverse planes. Typically a sagittal and axial cine clip at the level of the conus in rest is obtained to document spinal pulsations due to Cerebrospinal Fluid (CSF) pulsation. Pulsation is restricted in tethered cord. However pulsation is best seen a couple weeks after birth. Typically scanning is done in the prone position in a wellfed infant. Having the caregiver hold the baby in prone position just after feeding increases the chances of an easy motion free exam [1]. The lumbar vertebrae can be labeled by various methods. One method is to assume that the last rib bearing vertebra is T12, another to assign the last square shaped ossified vertebra as S5 and yet another uses the lumbosacral junction as L5-S1 with the vertebra at the end of the lumbar lordosis being L5. When counting the sacral and coccygeal bodies note that the coccygeal vertebras have a central ossification center compared to the square shaped ossification of the sacral vertebrae. All these methods are an approximation. Usually two or more of these criteria are used to determine the lumbar levels.