Retrospective review of spinal magnetic resonance
images to determine the margin of safety for epidural
analgesia in pediatric patients

Noah Letofsky; Dana Archibald; Anthony M.-H. Ho; Lais Helena N. e Lima; Rodrigo M. e Lima; Vinicius C. Quintão; Fernando B. Cançado; Ricardo V.
Carlos; Leopoldo M. da Silva; Fernando N. Bellicieri; Saullo Q. Silveira; Arvin
Haghighat; Rachel Phelan; Glenio B. Mizubuti

doi:10.1016/j.bjane.2025.844687

Original Investigation

Retrospective review of spinal magnetic resonance images to determine the margin of safety for epidural analgesia in pediatric patients

Revisão retrospectiva de imagens de ressonância magnética da coluna para determinar a margem de segurança da analgesia epidural em pacientes pediátricos

Noah Letofsky, Dana Archibald, Anthony M.-H. Ho, Lais Helena N. e Lima, Rodrigo M. e Lima, Vinicius C. Quintão, Fernando B. Cançado, Ricardo V. Carlos, Leopoldo M. da Silva, Fernando N. Bellicieri, Saullo Q. Silveira, Arvin Haghighat, Rachel Phelan, Glenio B. Mizubuti

http://dx.doi.org/10.1016/j.bjane.2025.844687 Braz J Anesthesiol, vol.75, n6, 844687, 2025

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Abstract

Background

Deeply sedated children cannot provide feedback if an epidural needle traumatizes the Spinal Cord (SC). Knowing relevant structure depths may, therefore, improve safety. We aimed to determine the epidural margin of safety, i.e., distances from the Ligamentum Flavum (LF) and from the dura mater to the SC in pediatric patients measured (i) Perpendicular to the SC and (ii) Parallel to the spinous process (to approximate needle trajectory).

Methods

Retrospective review of pediatric (0‒12 years-old) T2-weighted sagittal MRI spine scans without spinal pathology. Three investigators independently measured distances from the ventral edge of the LF, and from the ventral edge of the dura mater to the SC at T5/T6, T9/T10, and L1/L2. All measurements were taken perpendicular to the SC and parallel to the angle of the spinous process of the inferior vertebra.

Results

111 MRI scans [52 females, 0.08‒12 (median 7) years-old] were analyzed. The conus medullaris was identiﬁed superior to the L1 vertebra in 47 scans, requiring L1/L2 measurement exclusion. When all ages were combined, the largest median (range) depth [dura-mater−SC = 4.87 (2.30‒10.30) mm, LF−SC = 8.10 (4.57‒12.53) mm, measured perpendicular to the SC; and dura-mater−SC = 8.20 (3.75‒19.57) mm; LF−SC = 13.40 (5.50‒39.77) mm, measured at the angle parallel to the inferior spinous process] was at T5/T6.

Conclusion

Our results suggest that the margin of safety (dura-mater−SC distance and LF−SC distance) for performing epidurals in children may be greatest at the mid-thoracic spinal region. The measured ranges were very wide. Further studies are warranted to validate these ﬁndings in pediatric patients with other relevant “epidural placement” positions.

Keywords

Epidural analgesia; Magnetic resonance imaging; Patient safety; Pediatrics; Retrospective study

Resumo

Introdução

Crianças profundamente sedadas não conseguem fornecer feedback caso uma agulha epidural traumatize a medula espinhal (SC). Conhecer a profundidade das estruturas relevantes pode, portanto, melhorar a segurança. Este estudo teve como objetivo determinar a margem de segurança epidural, ou seja, as distâncias do ligamento amarelo (LF) e da dura-máter até a SC em pacientes pediátricos, medidas (i) perpendicularmente à SC e (ii) paralelamente ao processo espinhoso (para aproximar a trajetória da agulha).

Métodos

Revisão retrospectiva de exames de ressonância magnética (RM) sagital da coluna em ponderação T2 de pacientes pediátricos (0–12 anos) sem patologia espinhal. Três investigadores mediram de forma independente as distâncias da borda ventral do LF e da borda ventral da dura-máter até a SC nos níveis T5/T6, T9/T10 e L1/L2. Todas as medidas foram feitas perpendicularmente à SC e paralelamente ao ângulo do processo espinhoso da vértebra inferior.

Resultados

Foram analisadas 111 RM [52 meninas, 0,08–12 anos (mediana 7)]. O conus medullaris foi identificado acima da vértebra L1 em 47 exames, exigindo a exclusão da medição em L1/L2. Considerando todas as idades, a maior profundidade mediana (intervalo) [dura-máter–SC = 4,87 (2,30–10,30) mm; LF–SC = 8,10 (4,57–12,53) mm, medidas perpendicularmente à SC; e dura-máter–ME = 8,20 (3,75–19,57) mm; LF–SC = 13,40 (5,50–39,77) mm, medidas paralelamente ao processo espinhoso inferior] foi encontrada em T5/T6.

Conclusão

Os resultados sugerem que a margem de segurança (distâncias dura-máter–SC e LF–SC) para a realização de bloqueios epidurais em crianças pode ser maior na região torácica média da coluna. As faixas medidas foram muito amplas. Estudos adicionais são necessários para validar esses achados em pacientes pediátricos em outras posições relevantes para a colocação epidural.

Palavras-chave

Analgesia epidural; Ressonância magnética; Segurança do paciente; Pediatria; Estudo retrospectivo

References

1. Ecoffey C, Lacroix F, Giaufre E, et al. Epidemiology and morbid- ity of regional anesthesia in children: A follow-up one-year prospective survey of the French-Language Society of Paediatric Anaesthesiologists (ADARPEF). Pediatr Anesth. 2010;20:1061−9 .

2. Walker BJ, Long JB, Sathyamoorthy M, et al. Complications in pediatric regional anesthesia: An analysis of more than 100,000 blocks from the Pediatric Regional Anesthesia Network. Anesthesiology. 2018;129:721−32.

3. Llewellyn N, Moriarty A. The national pediatric epidural audit. Pediatr Anesth. 2007;17:520−33.

4. Sawardekar A, Szczody D, Suresh S. Neuraxial Anaesthesia in Paediatrics. Anesth Intens Care. 2013;14:251−4.

5. Wani TM, Mahmood Rafiq AN, Azzam H, et al. Estimation of the depth of the thoracic epidural space in children using magnetic resonance imaging. J Pain Res. 2017;10:757−62.

6. Lee RA, Van Zundert AA, Breedveld P, et al. The anatomy of the thoracic spinal canal investigated with magnetic resonance imaging (MRI). Acta Anaesthesiol Belg. 2007;58:163−7.

7. Park JW, Bae SK, Huh J. Distance from dura mater to spinal cord at the thoracic vertebral level: An introductory study on local subdural geometry for thoracic epidural block. J Int Med Res. 2016;44:950−6.

8. Imbelloni LE, Quirici MB, Ferraz Filho JR, et al. The anatomy of the thoracic spinal canal investigated with magnetic resonance imaging. Anesth Analg. 2010;110:1494−5.

9. Lee RA, Van Zundert AA, Botha CP, et al. The anatomy of the thoracic spinal canal in different postures. Reg Anesth Pain Med. 2010;35:364−9.

10. Wani T, Beltran R, Veneziano G, et al. Dura to spinal cord distance at different vertebral levels in children and its implications on epidural analgesia: A retrospective MRI-based study. Pediatr Anesth. 2018;28:338−41.

11. Bosenberg AT. Skin-epidural distance in children. Anaesthesia. € 1995;50:895−7.

12. Koo TK, Li MY. A Guideline of selecting and reporting intraclass correlation coefficients for reliability research. J Chiropr Med. 2016;15:155−63.

13. Polaner D, Taenzer A, Walker B, et al. Pediatric Regional Anesthesia Network (PRAN): A multi-institutional study of the use and incidence of complications of pediatric regional anesthesia. Anesth Analg. 2012;115:1353−64.

14. Giaufre E, Dalens B, Gombert A. Epidemiology and morbidity of regional anesthesia in children: A one-year prospective survey of the French language society of pediatric anesthesiologists. Anesth Analg. 1996;83:904−12.

15. Kasai T, Yaegashi K, Hirose M, et al. Spinal cord injury in a child caused by an accidental dural puncture with a single-shot thoracic epidural needle. Anesth Analg. 2003;96:65−7.

16. Aldrete JA, Ferrari H. Myelopathy with syringomyelia following thoracic epidural anaesthesia. Anaesth Intensive Care. 2004;32:100−3.

17. Allison CE, Aronson DC, Geukers VGM, et al. Paraplegia after thoracotomy under combined general and epidural anesthesia in a child. Pediatr Anesth. 2008;18:539−42.

18. Meyer MJ, Krane EJ, Goldschneider KR, Klein NJ. Case report: Neurological complications associated with epidural analgesia in children: A report of 4 cases of ambiguous etiologies. Anesth Analg. 2012;115:1365−70. 19. Cometa AM, Lopez BM, Vasilopoulos T, et al. Does the technique for assessing loss of resistance alter the magnitude

of epidural needle tip overshoot? Simul Healthc. 2020;15:154−9.

Submitted date:
02/25/2025

Accepted date:
08/31/2025