Int J Clin Pediatr

International Journal of Clinical Pediatrics, ISSN 1927-1255 print, 1927-1263 online, Open Access

Article copyright, the authors; Journal compilation copyright, Int J Clin Pediatr and Elmer Press Inc

Journal website https://www.theijcp.org

Original Article

Volume 11, Number 1, March 2022, pages 2-8

Magnetic Resonance Imaging of the Caudal Epidural Space: Implications for the Clinical Practice Regional Anesthesia in Infants and Children

Figure 1. Magnetic resonance imaging showing termination of the spinal cord at L₁ and the dural sac at S₂ in a 1-year-old patient from the study cohort.

Figure 3. Magnetic resonance imaging showing the end of the spinal cord (1), the termination of the dural sac (2), and the sacrococcygeal ligament (3). These structures were used for the measurements made in the current study.

**Table 1.** Patient Demographic and Physical Data
Variables	All (n = 91)	Male (n = 47)	Female (n = 44)	P-value
Distance is listed in millimeters (mm). The data are presented as the mean (standard deviation). BSA: body surface area.
Age (months)	45.5 (29.3)	47.0 (28.8)	44.0 (30.1)	0.633
Height (cm)	95.2 (25.6)	96.8 (24.4)	93.5 (26.9)	0.543
Weight (kg)	16.7 (8.1)	17.0 (7.0)	16.3 (9.2)	0.684
BSA (m²)	0.66 (0.24)	0.67(0.21)	0.64 (0.26)	0.629
Spinal cord to dural sac (mm)	90.2 (23.7)	92.5 (21.8)	87.7 (25.6)	0.335
Spinal cord to sacral hiatus (mm)	109.0 (28.1)	111.1 (25.4)	106.7 (30.8)	0.45
Spinal cord to skin (mm)	112.3 (28.0)	113.7 (3.7)	110.8 (30.8)	0.624
Dural sac to sacral hiatus (mm)	23.9 (7.2)	23.9 (6.3)	23.8 (8.2)	0.935
Dural sac to skin (mm)	33.3 (9.9)	31.6 (7.9)	35.1 (11.4)	0.092

Table 1. Patient Demographic and Physical Data

Variables

All (n = 91)

Male (n = 47)

Female (n = 44)

P-value

Distance is listed in millimeters (mm). The data are presented as the mean (standard deviation). BSA: body surface area.

Age (months)

45.5 (29.3)

47.0 (28.8)

44.0 (30.1)

0.633

Height (cm)

95.2 (25.6)

96.8 (24.4)

93.5 (26.9)

0.543

Weight (kg)

16.7 (8.1)

17.0 (7.0)

16.3 (9.2)

0.684

BSA (m²)

0.66 (0.24)

0.67(0.21)

0.64 (0.26)

0.629

Spinal cord to dural sac (mm)

90.2 (23.7)

92.5 (21.8)

87.7 (25.6)

0.335

Spinal cord to sacral hiatus (mm)

109.0 (28.1)

111.1 (25.4)

106.7 (30.8)

0.45

Spinal cord to skin (mm)

112.3 (28.0)

113.7 (3.7)

110.8 (30.8)

0.624

Dural sac to sacral hiatus (mm)

23.9 (7.2)

23.9 (6.3)

23.8 (8.2)

0.935

Dural sac to skin (mm)

33.3 (9.9)

31.6 (7.9)

35.1 (11.4)

0.092

**Table 2.** Descriptive Statistics With Regards to Age
Distances (mm)	< 6 months (n = 8)	> 6 to < 12 months (n = 7)	> 12 to < 18 months (n = 9)	> 18 to < 24 months (n = 8)	> 24 to < 36 months (n = 7)	> 36 to < 48 months (n = 6)	> 48 to < 60 months (n = 12)	> 60 to < 72 months (n = 9)	> 72 to < 84 months (n = 18)	> 84 months (n = 7)
Distances are shown in millimeters. Q1: first quartile; Q3: third quartile; IQR: interquartile range.
Spinal cord to dural sac
Median	52.5	54.8	76.4	76.8	78.7	90.4	96.8	112.4	112.6	114.9
IQR (Q1, Q3)	39.7, 55.7	53.9, 69.5	63.8, 85.3	76.1, 82.3	76, 84.9	84.9, 91.1	92.1, 108.7	95.9, 120.1	109, 120.2	110.4, 121.8
Spinal cord to sacral hiatus (sacrococcygeal membrane)
Median	60.5	67.6	92.5	93.5	93.1	110.7	117.2	130.6	137.2	135.4
IQR (Q1, Q3)	53.6, 64.2	65.8, 81.9	71.4, 99.9	89.3, 98.5	90.9, 95.8	107.2, 111.3	113.3, 124.4	121.4, 133.1	129.5, 144.2	135, 146.7
Spinal cord to skin
Median	63.3	74.6	94.3	99.8	98.3	113	121.3	133.9	141	142.8
IQR (Q1, Q3)	56.1, 68.4	70.4, 84.9	74.3, 102.1	94.9, 100.5	93.4, 100.5	108.6, 113.3	115.4, 128.9	124.7, 135.2	131.7, 150.1	138.4, 148.9
Dural sac to sacral hiatus (sacrococcygeal membrane)
Median	13.5	16.6	16.8	21.1	20.8	25	25.5	26.3	31.6	28.2
IQR (Q1,Q3)	12.2, 14.6	14.3, 17.9	15.1, 18.2	19.2, 22.6	20.5, 22.6	21.5, 27.9	22.7, 26.9	23.9, 29.4	27.8, 35.7	27.1, 35
Dural sac to skin
Median	20.7	25.2	25.8	32.2	29.4	32.3	32	35.4	40.2	41.4
IQR (Q1, Q3)	19.8, 23.5	22.1, 34.4	23.4, 29.3	27.6, 36.2	27.1, 33.5	25.1, 36.3	30.7, 35.4	30.1, 40.6	35.5, 47.9	37.6, 45.9

Table 2. Descriptive Statistics With Regards to Age

Distances (mm)

< 6 months (n = 8)

> 6 to < 12 months (n = 7)

> 12 to < 18 months (n = 9)

> 18 to < 24 months (n = 8)

> 24 to < 36 months (n = 7)

> 36 to < 48 months (n = 6)

> 48 to < 60 months (n = 12)

> 60 to < 72 months (n = 9)

> 72 to < 84 months (n = 18)

> 84 months (n = 7)

Distances are shown in millimeters. Q1: first quartile; Q3: third quartile; IQR: interquartile range.

Spinal cord to dural sac

Median

52.5

54.8

76.4

76.8

78.7

90.4

96.8

112.4

112.6

114.9

IQR (Q1, Q3)

39.7, 55.7

53.9, 69.5

63.8, 85.3

76.1, 82.3

76, 84.9

84.9, 91.1

92.1, 108.7

95.9, 120.1

109, 120.2

110.4, 121.8

Spinal cord to sacral hiatus (sacrococcygeal membrane)

Median

60.5

67.6

92.5

93.5

93.1

110.7

117.2

130.6

137.2

135.4

IQR (Q1, Q3)

53.6, 64.2

65.8, 81.9

71.4, 99.9

89.3, 98.5

90.9, 95.8

107.2, 111.3

113.3, 124.4

121.4, 133.1

129.5, 144.2

135, 146.7

Spinal cord to skin

Median

63.3

74.6

94.3

99.8

98.3

113

121.3

133.9

141

142.8

IQR (Q1, Q3)

56.1, 68.4

70.4, 84.9

74.3, 102.1

94.9, 100.5

93.4, 100.5

108.6, 113.3

115.4, 128.9

124.7, 135.2

131.7, 150.1

138.4, 148.9

Dural sac to sacral hiatus (sacrococcygeal membrane)

Median

13.5

16.6

16.8

21.1

20.8

25.5

26.3

31.6

28.2

IQR (Q1,Q3)

12.2, 14.6

14.3, 17.9

15.1, 18.2

19.2, 22.6

20.5, 22.6

21.5, 27.9

22.7, 26.9

23.9, 29.4

27.8, 35.7

27.1, 35

Dural sac to skin

Median

20.7

25.2

25.8

32.2

29.4

32.3

35.4

40.2

41.4

IQR (Q1, Q3)

19.8, 23.5

22.1, 34.4

23.4, 29.3

27.6, 36.2

27.1, 33.5

25.1, 36.3

30.7, 35.4

30.1, 40.6

35.5, 47.9

37.6, 45.9

**Table 3.** Univariate and Multivariate Linear Regression to Assess the Association Between Age and BSA on Measured Distances
	Spinal cord to dural sac	Spinal cord to sacral hiatus	Spinal cord to skin	Dural sac to sacral hiatus	Dural sac to skin
BSA: body surface area; VIF: variance inflation factor; SE: standard error.
Univariate model
Age (years)	0.71 ± 0.04	< 0.001	0.77	0.87 ± 0.04	< 0.001	0.83	0.87 ± 0.04	< 0.001	0.83	0.20 ± 0.01	< 0.001	0.68	0.22 ± 0.03	< 0.001	0.44
BSA (m²)	81.74 ± 6.11	< 0.001	0.67	97.53 ± 7.11	< 0.001	0.68	98.73 ± 6.89	< 0.001	0.7	22.58 ± 2.17	< 0.001	0.55	27.63 ± 3.29	< 0.001	0.44
Multivariate model
Age	0.52 ± 0.07	< 0.001	0.79	0.73 ± 0.08	< 0.001	0.84	0.68 ± 0.08	< 0.001	0.84	0.17 ± 0.03	< 0.001	0.69	0.12 ± 0.05	0.014	0.48
BSA	26.50 ± 9.18	0.005		22.97 ± 9.54	0.018		27.57 ± 9.4	0.004		4.71 ± 3.4	0.17		14.88 ± 9.0	0.015
VIF (age, BSA)	3.51

Table 3. Univariate and Multivariate Linear Regression to Assess the Association Between Age and BSA on Measured Distances

Spinal cord to dural sac

Spinal cord to sacral hiatus

Spinal cord to skin

Dural sac to sacral hiatus

Dural sac to skin

β ± SE

R²

β ± SE

R²

β ± SE

R²

β ± SE

R²

β ± SE

R²

BSA: body surface area; VIF: variance inflation factor; SE: standard error.

Univariate model

Age (years)

0.71 ± 0.04

< 0.001

0.77

0.87 ± 0.04

< 0.001

0.83

0.87 ± 0.04

< 0.001

0.83

0.20 ± 0.01

< 0.001

0.68

0.22 ± 0.03

< 0.001

0.44

BSA (m²)

81.74 ± 6.11

< 0.001

0.67

97.53 ± 7.11

< 0.001

0.68

98.73 ± 6.89

< 0.001

0.7

22.58 ± 2.17

< 0.001

0.55

27.63 ± 3.29

< 0.001

0.44

Multivariate model

Age

0.52 ± 0.07

< 0.001

0.79

0.73 ± 0.08

< 0.001

0.84

0.68 ± 0.08

< 0.001

0.84

0.17 ± 0.03

< 0.001

0.69

0.12 ± 0.05

0.014

0.48

BSA

26.50 ± 9.18

0.005

22.97 ± 9.54

0.018

27.57 ± 9.4

0.004

4.71 ± 3.4

0.17

14.88 ± 9.0

0.015

VIF (age, BSA)

3.51