Descriptive study of the differences in the level of the conus medullaris in four different age groups

Abstract

In performing neuraxial procedures, knowledge of the location of the conus medullaris in patients of all ages is important. The aim of this study was to determine the location of conus medullaris in a sample of newborn/infant cadavers and sagittal MRIs of children, adolescents, and young adults. The subjects of both the samples were subdivided into four developmental stages. No statistical difference was seen between the three older age groups (P > 0.05). A significant difference was evident when the newborn/infant stage was compared with the other, older stages (P < 0.001 for all comparisons). In the newborn/infant group the spinal cord terminated most frequently at the level of L2/L3 (16%). In the childhood stage, the spinal cord terminated at the levels of T12/L1 and the lower third of L1 (21%). In the adolescent population, it was most often found at the level of the middle third of L1 and L1/L2 (19%). Finally, in the young adult group, the spinal cord terminated at the level of L1/L2 (25%). This study confirmed the different level of spinal cord termination between newborns/infants less than one-year-old and subjects older than one year. In this sample the conus medullaris was not found caudal to the L3 vertebral body, which is more cranial than the prescribed level of needle insertion recommended for lumbar neuraxial procedures. It is recommended that the exact level of spinal cord termination should be determined prior to attempting lumbar neuraxial procedures in newborns or infants.

Keywords: anatomy; conus medullaris; lumbar epidural; lumbar puncture; neonate; spinal anesthesia.