Tracking the Inferior Limit of Human Spinal Cords in Donor Bodies and Live Subjects

Abstract

The human spinal cord is usually reported in medical texts as ending at the L1‐L2 vertebral levels. However, some individuals exhibit terminations at higher or lower vertebral levels. This study investigates variation in the level of caudal termination of the human spinal cord in a geriatric cadaveric sample (n=22; above 63 years of age at death) and in younger, living individuals (n=10). To determine that vertebral columns examined in donor bodies showed normal curvature, a rod was placed from external occipital protuberance (EOP) to sacral hiatus to determine the vertical line of reference (VLR) and its length. Individuals showing deviation from the VLR (i.e., scoliotic patterns) were noted. Laminectomies were performed on donor bodies to expose the vertebral canal, allowing the assignment of vertebral level to the conus medullaris. A similar protocol was followed on MR images of live subjects. All measures were collected by multiple observers to reduce bias and increase accuracy. Most (63%) of the cadavers exhibited termination at or before the superior border of L2. However, variations were present with termination levels ranging from T11‐L3 vertebrae. The live subjects expressed a similar pattern thus demonstrating that termination level of the spinal cord is independent of age. These results underscore the importance of performing spinal taps at the lowest possible vertebral levels.Grant Funding Source: SUNY Downstate College of Medicine