Ascent of the conus medullaris in human foetuses: a systematic review and meta-analysis

Abstract

The aim of the present systematic review and meta-analysis was to identify when the ascent of the conus medullaris occurs in human foetuses considering differences in evaluation methods and sample characteristics. Five databases were searched for relevant articles using different combinations of keywords. Article selection and data extraction were performed independently by two reviewers. Disagreements were resolved by a third reviewer. The variables were distributed into four groups according to the gestational age of the specimens: I (13–18 weeks); II (19–25 weeks); III (26–32 weeks); IV (33 weeks to the probable date of birth). Eighteen articles were included. The majority used imaging exams as the evaluation method. Cadaveric dissections were reported in the remaining articles. Only morphological studies were included in the meta-analysis. Significant ascent occurs between groups I and III as well as groups II and IV. Despite the considerable heterogeneity among the studies included in the present review, the findings enabled the determination that the conus medullaris reaches its normal birth level by the 26th week. Further analyses should be performed based on nationality and ethnicity to diminish the heterogeneity of the data.

Tethered Cord Syndrome: Role of Imaging Findings in Surgical Decision-Making

“…In most healthy infants, children, and adults, the conus terminates at the L1-L2 intervertebral disc level [ 3 ]. The conus medularis is below the L1-L2 level in all fetuses less than 18 weeks gestational age and progressively ascends in the vertebral canal throughout gestation [ 4 ]. Regardless of gestational age, the conus medullaris terminates below the adult level in 13% of neonates less than 30 days old and in 4.7% of neonates around 61-100 days [ 5 , 6 ].…”

Functional Vascular Anatomy and Arteriovenous Shunts of the Spine

“…In addition, the conus medullaris ascends from a lower position in the spinal canal to its final location at birth during development (approximately at the level of the L2 vertebra). 5 This is because the length of the spinal cord shortens relative to the spinal canal owing to the difference in the growth rate. This tendency is weaker on the rostral side than that on the caudal side.…”