The influence of age on positions of the conus medullaris, Tuffier's line, dural sac, and sacrococcygeal membrane in infants, children, adolescents, and young adults.

Abstract

The purpose of this study was to analyze the distances between the conus medullaris and the Tuffier's line, and between the dural sac and the sacrococcygeal membrane (SCM) in the same pediatric population. Spinal magnetic resonance images and simple X-ray images of 350 patients aged from 1 month to 20 years were reviewed. Positions of the conus medullaris, Tuffier's line, the dural sac, and the SCM were identified. Each position was recorded in relation to the corresponding vertebral body segments. The distances between the conus medullaris and Tuffier's line, and between the dural sac and the SCM, were measured and then assessed according to age using an analysis of variance and a linear regression analysis. The median levels of the conus medullaris and Tuffier's line were in the lower third of L1 [the first lumbar vertebral body] and the middle third of L5, respectively. The levels of the conus medullaris and Tuffier's line were lower in younger populations. The distance between the conus medullaris and Tuffier's line ranged from 1.5 to 4.75 vertebral body height. However, a narrow range of 1.5-2.5 vertebral height was observed only in children younger than 2 years. The level of the dural sac did not differ greatly by age, but the upper limit of the SCM was lower in older populations. The distance between the dural sac and the upper limit of the SCM increased with age. In children, there is a distance of 1.5-4.75 vertebral body height between the conus medullaris and the Tuffier's line. However, these distances were narrower among younger populations. The distance between the dural sac and the upper limit of the SCM increased with age.