Spinal cord sonography in newborns: anatomy and diseases

Sonography of the spinal cord is a relatively recent acquisition that makes it possible to evaluate the content of the vertebral canal and study its pathologies. The aim of this study was to verify the reliability of ultrasound images by comparing them with magnetic resonance ones in healthy controls as well as in patients referred to us between 1991 and 2004. In this period, we studied 436 newborns: 88 without any suspicion of disease as normal controls, and 348 with suspected congenital diseases or in order to screen the children of diabetic mothers, a group that has shown an increased incidence of dysraphism. After explaining normal sonograms, we describe the pathological pictures observed in the 12 pathological cases in our series: conus hypomobility in five cases; lack of visualization of the conus medullaris in one case; and an enlarged ependymal canal in six cases. Four cases presented all three pathological conditions, and seven the association of two pathologies. All of these patients also underwent magnetic resonance imaging (MRI), which confirmed the ultrasound findings in four cases: three cases of enlarged ependymal canal and one of tethered cord hypomobility of the roots with an associated lipoma; the MRI findings were normal in the other seven cases. Sonography was highly specific but not very sensitive, because it is partially conditioned by patient collaboration. Nevertheless, subsequent MRI confirmed 37% of the suspected pathological cases. The ultrasound resolution of both normal and pathological spinal cord structures was particularly clear. The images were similar, easily comparable and often identical to the MRI results, although MRI was certainly more sensitive. The advantages of sonography are its non-invasiveness, low cost, the virtually ubiquitous availability of ultrasound equipment, the simplicity and rapidity of the examination, and its specificity. We believe that the indications for its use are lumbo-sacral skin alterations, neurological disorders caused by congenital malformations, traumas due to childbirth or a lumbar puncture, occult dysraphism, all of the compressive spinal cord neo-formations involving nerves, the dura mater and vertebral bone and joint structures, and the screening of the newborns of diabetic mothers.