J Korean Soc Med Ultrasound.  1997 Dec;16(4):389-394.

Sonographic Determination of the Normal Location and Positional Change of the Conus Medullaris in Infants

• Park WG
• Kim SJ
• Kim BG
• Park BR
• Ko KS
• Kim YM
• Moon UH
• Lee JS

Abstract

PURPOSE: To establish the normal location and positional change of the conus medullaris in infants.
MATERIALS AND METHODS
155 neurologically healthy infants, who had no sign suggestive of spinal dysraphism, were sonographically examined their caudal spines to relate the conus medullaris to the vertebral body or intervertebral disc. Postconceptual age (Gestational age plus Posklatal age) was counted by the completed week. Statistical significance between the conus level and PCA, and that between the conus level and birth weight were analyzed with regression analysis. After grouping the babies into two groups-one with PCA of less than 41 weeks and the other with PCA of 41 to 54 weeks-, we compared the mean position and the change of conus position in relation to PCA between the two groups.
RESULTS
The mean position of the conus was midway between the L1-2 disc and upper third of L2 body ranging from T12/L1 disc to L3 body. A small but significant rise was identified in the position of the conus from 30 to 54-week PCA. The mean level of the conus was L1.75 (SD:0.36) in those with PCA of less than 41 weeks and L1.49 (SD:0.29) in those with PCA ranging from 41 to 54 weeks. Though the conus medullaris was elevated continuously until the infant's PCA reached 40 week, it did not show significant elevation in position after that.
CONCLUSION
The mean position of the conus medullaris in infants is midway between the L1-2 disc and upper third of L2 body and it was elevated to the level of L1-2 disc, which is the normal adult level, by the PCA of 41 weeks.

MeSH Terms

Adult
Birth Weight
Conus Snail*
Humans
Infant*
Intervertebral Disc
Passive Cutaneous Anaphylaxis
Spinal Dysraphism
Spine
Ultrasonography*