Skip to main content
SpringerLink
Log in

Gestational age-specific reference standards of low-lying conus medullaris level in fetuses: a prospective cohort study

  • Original Article
  • Published:
Child's Nervous System Aims and scope Submit manuscript

Abstract

Purpose

To explore the position change of fetal conus medullaris by ultrasound, and to propose gestational age-specific references for the lower limits of fetal conus medullaris level.

Methods

We prospectively collected the imaging and clinical data of fetuses whose mothers accepted routine prenatal ultrasonic follow-ups in the Department of Medical Ultrasonics, Chinese PLA General Hospital, between November 2020 and April 2021. By assigning to the conus medullaris levels, calculating statistical data, and performing linear regression analysis, we determined the correlation between the conus medullaris level and gestational week, as well as between the 95th percentile of the conus medullaris level, i.e., the lower limit of the conus medullaris level, and gestational week.

Results

We included 1202 different fetuses at 17–40 gestational weeks in the study. Both the conus medullaris level and the 95th percentile of the conus medullaris level were linearly correlated with gestational week. We calculated the adjusted values of the lower limits of fetal conus medullaris levels, that is, the theoretical references of the lower limits, according to the linear regression equation, and composed a comparison table.

Conclusion

The fetal conus medullaris position continues changing cranially with gestational weeks during the whole pregnancy. The conus medullaris of a term fetus should not lie below the L2 vertebra level at birth. We proposed reference criteria of fetal low-lying conus medullaris for each gestational week from 17 to 40 weeks of gestational age, which potentially help prompt diagnosis and improve prognosis of fetal tethered cord syndrome.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Fig. 1
Fig. 2
Fig. 3

Similar content being viewed by others

Availability of data and material

All data and materials supporting the findings of this study will be available from the corresponding author upon a reasonable request.

References

  1. Bischoff A, Pena A, Ketzer J et al (2019) The conus medullaris ratio: a new way to identify tethered cord on MRI. J Pediatr Surg 54:280–284

    Article  PubMed  Google Scholar 

  2. O’Connor KP, Smitherman AD, Milton CK et al (2020) Surgical treatment of tethered cord syndrome in adults: a systematic review and meta-analysis. World Neurosurg 137:e221–e241

    Article  PubMed  Google Scholar 

  3. Bai SC, Tao BZ, Wang LK et al (2018) Aggressive resection of congenital lumbosacral lipomas in adults: indications, techniques, and outcomes in 122 patients. World Neurosurg 112:e331–e341

    Article  PubMed  Google Scholar 

  4. Wilson DA, Prince JR (1989) John Caffey award. MR imaging determination of the location of the normal conus medullaris throughout childhood. AJR Am J Roentgenol 152:1029–1032

    Article  CAS  PubMed  Google Scholar 

  5. Robbin ML, Filly RA, Goldstein RB (1994) The normal location of the fetal conus medullaris. J Ultrasound Med 13:541–546

    Article  CAS  PubMed  Google Scholar 

  6. Widjaja E, Whitby EH, Paley MN, Griffiths PD (2006) Normal fetal lumbar spine on postmortem MR imaging. AJNR Am J Neuroradiol 27:553–559

    CAS  PubMed  PubMed Central  Google Scholar 

  7. Arthurs OJ, Thayyil S, Wade A, Chong WK, Sebire NJ, Taylor AM et al (2013) Normal ascent of the conus medullaris: a post-mortem fetal MRI study. J Matern Fetal Neonatal Med 26:697–702

    Article  CAS  PubMed  Google Scholar 

  8. Perlitz Y, Izhaki I, Ben-Ami M (2019) Sonographic evaluation of the fetal conus medullaris at 20 to 24 weeks’ gestation. Prenat Diagn 30:862–864

    Article  Google Scholar 

  9. Tubbs RS, Oakes WJ (2004) Can the conus medullaris in normal position be tethered? Neurol Res 26:727–731

    Article  PubMed  Google Scholar 

  10. Hill CA, Gibson PJ (1995) Ultrasound determination of the normal location of the conus medullaris in neonates. AJNR Am J Neuroradiol 16:469–472

    CAS  PubMed  PubMed Central  Google Scholar 

  11. Lao LF, Chen ZG, Qiu GX, Shen JX (2013) Whole-spine magnetic resonance imaging study in healthy Chinese adolescents. Orthop Surg 5:164–170

    Article  PubMed  PubMed Central  Google Scholar 

  12. Jung JY, Kim EH, Song IK, Lee JH, Kim HS, Kim JT (2016) 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. Paediatr Anaesth 26:1172–1178

    Article  PubMed  Google Scholar 

  13. Ramirez Zegarra R, Volpe N, Bertelli E, Amorelli GM, Ferraro L, Schera GBL et al (2021) Three-dimensional sonographic evaluation of the position of the fetal conus medullaris at first trimester. Fetal Diagn Ther 48:464–471

    Article  PubMed  Google Scholar 

  14. Wolf S, Schneble F, Tröger J (1992) The conus medullaris: time of ascendence to normal level. Pediatr Radiol 22:590–592

    Article  CAS  PubMed  Google Scholar 

  15. Beek FJ, de Vries LS, Gerards LJ, Mali WP (1996) Sonographic determination of the position of the conus medullaris in premature and term infants. Neuroradiology 38(Suppl 1):S174–S177

    Article  PubMed  Google Scholar 

  16. Hawass ND, el-Badawi MG, Fatani JA, Meshari AA, Abbas FS, Edrees YB, et al (1987) Myelographic study of the spinal cord ascent during fetal development. AJNR Am J Neuroradiol 1987(8):691–695

    Google Scholar 

  17. Zalel Y, Lehavi O, Aizenstein O, Achiron R (2006) Development of the fetal spinal cord: time of ascendance of the normal conus medullaris as detected by sonography. J Ultrasound Med 25:1397–1401; quiz 1402–1403

  18. Vettivel S (1991) Vertebral level of the termination of the spinal cord in human fetuses. J Anat 179:149–161

    CAS  PubMed  PubMed Central  Google Scholar 

Download references

Funding

This work was supported by the National Key Research and Development Program of China (2022YFC2703304) and Capital’s Funds for Health Improvement and Research (CFH2022-2–5022).

Author information

Authors and Affiliations

  1. Department of Neurosurgery, Chinese PLA General Hospital, Beijing, China

    Mengchun Sun, Gan Gao, Benzhang Tao & Aijia Shang

  2. Medical School, Nankai University, Tianjin, China

    Mengchun Sun

  3. Department of Medical Ultrasonics, Chinese PLA General Hospital, Beijing, China

    Mei Chen

  4. Tianjin Medical University, Tianjin, China

    Benzhang Tao

Authors
  1. Mengchun Sun
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Mei Chen
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Gan Gao
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Benzhang Tao
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Aijia Shang
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

Conceptualization: Mengchun Sun, Aijia Shang; methodology: Mengchun Sun, Mei Chen; formal analysis and investigation: Mengchun Sun, Benzhang Tao; writing—original draft preparation: Mengchun Sun; writing—review and editing: Aijia Shang; funding acquisition: Aijia Shang; resources: Mengchun Sun, Mei Chen, Gan Gao; supervision: Benzhang Tao, Gan Gao, Aijia Shang.

Corresponding author

Correspondence to Aijia Shang.

Ethics declarations

Competing interests

The authors declare no competing interests.

Ethics approval and consent to participate

This study was approved by the institutional review board of the Chinese PLA General Hospital (No. S2018-280–01) and followed the tenets of the Declaration of Helsinki. The parents of all the involved fetuses provided written informed consent for the research and publication of the results.

Consent for publication

The parents of all the involved fetuses provided written informed consent for the publication of the results.

Conflict of interest

The authors have no relevant financial or non-financial interests to disclose.

Additional information

Publisher's Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary Information

Below is the link to the electronic supplementary material.

Supplementary file1 (PDF 85 KB)

Rights and permissions

Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Sun, M., Chen, M., Gao, G. et al. Gestational age-specific reference standards of low-lying conus medullaris level in fetuses: a prospective cohort study. Childs Nerv Syst 39, 997–1003 (2023). https://doi.org/10.1007/s00381-022-05802-2

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s00381-022-05802-2

Keywords

Search

Navigation