Table 1 Comparison of all reliable outcome measures used to determine a spina bifida phenotype.

From: Validation of the Fetal Lamb Model of Spina Bifida

Groups

Normal

Non-myelotomy

P value Non-myel. vs. Normal

Myelotomy

P value

Myel. vs. Normal

P value

Myel. vs. Non-myel.

Survival at birth of open defects

71.4% (25/35)

54.5% (6/11)

0.501

70.0% (7/10)

0.758

0.781

BRAIN PHENOTYPE

Neurological examination

N = 14

N = 6

N = 7

Abnormal spontaneous head movement (tremor/spasm)

7% (1/14)

83.3% (5/6)

0.004

85.7% (6/7)

0.002

0.514

MRI

N = 11

N = 6

N = 7

Presence of HH

0.0% (0/11)

0.0% (0/6)

1.000

85.7% (6/7)

0.001

0.011

HH distance (mm)

−4.9 ± 1.5

−3.7 ± 2.2

0.787

3.2 ± 6.0

<0.001

0.006

Clivus-supraocciput angle (°)

66.5 ± 7.6

63.8 ± 6.6

0.793

64.9 ± 9.7

0.914

0.968

Transverse cerebellum diameter (mm)

27.7 ± 1.6

25.6 ± 1.2

0.022

24.2 ± 1.4

<0.001

0.204

Transverse posterior fossa diameter (mm)

27.7 (1.9)

25.8 (2.2)

0.033

25.1 (3.3)

<0.001

1.000

Right Parietal ventricle diameter (mm)

1.6 ± 0.5

3.0 ± 1.5

0.255

4.5 ± 1.7

0.004

0.162

Left Parietal ventricle diameter (mm)

1.7 ± 0.4

3.2 ± 1.5

0.143

4.3 ± 1.5

0.005

0.314

Presence of brain hemorrhage

0% (0/11)

0% (0/6)

1.000

0% (0/7)

1.000

1.000

Presence of brain ischemia

0% (0/11)

0% (0/6)

1.000

14% (1/7)

0.815

0.936

Histology

N = 6

N = 3

N = 5

Density of prefrontal cortex (neurons/mm2)

1560 ± 381

1240 ± 367

0.339

1268 ± 103

0.298

0.991

Density of parietal cortex (neurons/mm2)

1692 ± 412

1443 ± 300

0.668

1256 ± 407

0.229

0.792

Density of hippocampus (neurons/mm2)

1427 ± 280

1112 ± 255

0.184

1030 ± 189

0.049

0.889

Density of caudate nucleus (neurons/mm2)

945 ± 175

790 ± 366

0.585

774 ± 155

0.425

0.995

Density of thalamus (neurons/mm2)

853 ± 145

890 ± 116

0.922

595 ± 113

0.037

0.036

Density of corpus callosum (neurons/mm2)

844 ± 148

594 ± 201

0.102

451 ± 137

0.004

0.443

SPINAL CORD PHENOTYPE

Gross examination

N = 14

N = 6

N = 7

Size of defect (mm)

   - Length

0.0 (0.0)

22.0 (22.3)

0.012

77.0 (20.0)

<0.001

0.453

   - Width

0.0 (0.0)

11.0 (12.5)

0.008

30.0 (40.0)

<0.001

0.680

Lumbar CSF leakage

0/14 (0%)

3/6 (50%)

0.029

7/7 (100%)

<0.001

0.141

MRI

N = 11

N = 6

N = 7

Kyphosis angle (°)

169 ± 8

142 ± 22

0.005

147 ± 11

0.011

0.794

Histology

N = 6

N = 5

N = 6

SC adhesions

0.0% (0/11)

80.0% (4/5)

0.005

83.3% (5/6)

0.002

0.521

Coverage thickness (µm)

   Left

13010

(1176)

1248

(2224)

0.020

726

(1412)

<0.001

1.000

   Middle

12846

(1173)

1257

(1696)

0.020

706

(1308)

<0.001

1.000

   Right

12975

(1212)

1275

(1467)

0.022

448

(1629)

<0.001

1.000

Neuronal cells (b3t) area

(106 pixels)

21.7

(4.9)

3.2

(6.1)

0.011

3.4

(3.5)

0.015

1.000

Negative control

1.7 (2) × 103

     

Astroglial cells (GFAP) area

(106 pixels)

25.5 ± 5.1

5.0 ± 4.2

<0.001

8.3 ± 3.3

<0.001

0.431

Negative control

4.2 ± 4 × 103

     

Myelin (MBP) area

(106 pixels)

9.5 (3.8)

0.1 (2.4)

0.006

0.2 (0.7)

0.026

1.000

Negative control

1.7 (2) × 103

     

HINDLIMB PHENOTYPE

Neurological examination

N = 14

N = 6

N = 7

Abnormal gait (paraparesis or paraplegia)

0% (0/12)

100% (6/6)

<0.001

100% (7/7)

<0.001

1.000

Lumbar-sacral sensory deficit

0% (0/14)

100% (6/6)

<0.001

100% (7/7)

<0.001

1.000

HL neuromotor deficit

N = 13

N = 5

N = 7

- Joint movement score (/12)

12.0 ± 0

7.2 ± 5.35

0.004

3.2 ± 2.19

<0.001

0.039

- Locomotor grade (/15)

14.2 ± 0.34

3.0 ± 2.26

<0.001

1.4 ± 0.72

<0.001

0.044

Hindlimb MEP

N = 6 × 2

N = 2 × 2

N = 5 × 2

Threshold (Volts)

25 (15)

80 (51)

NA

45 (41)

NA

 

AUC

11.4 ± 6.48

3.0 ± 3.53

0.027

3.5 ± 3.54

0.005

0.987

P2P (uVolts)

0.22 ± 0.15

0.08 ± 0.09

0.113

0.08 ± 0.07

0.036

0.981

Hindlimb SEP

N = 6 × 2

N = 3 × 2

N = 2 × 2

Forelimbs

100% (6/6)

100% (3/3)

1.000

100% (2/2)

1.000

1.000

Hindlimbs

100% (6/6)

0% (0/3)

0.003

0% (0/2)

0.005

1.000

Histology

N = 6 × 2

N = 4 × 2

N = 4 × 2

Proximal bilateral HL muscle atrophy

0% (0/6)

25% (1/4)

0.830

50% (2/4)

0.259

1.000

BLADDER AND RECTUM PHENOTYPE

Clinical examination

N = 14

N = 7

N = 7

Urinary incontinence

7.1% (1/14)

83.3% (5/6)

0.004

85.7% (6/7)

0.002

0.514

Histological examination

N = 2

N = 1

N = 1

Thickness of bladder muscle (µm)

841 ± 293

1209

NA

1298

NA

NA

Thickness of rectum muscle (µm)

   - Circular layer

500 ± 180

558

NA

860

NA

NA

   - Longitudinal layer

377 ± 197

368

NA

696

NA

NA

  1. Binomial and ordinal variables were expressed as percentage and score. Continuous variables normally distributed were expressed as mean ± standard deviation (SD) and those not normally distributed were expressed as median and interquartile range (IQR). Some lambs were too weak to get more results than from the neurological examination and MRI. Abbreviations: Myel., myelotomy; Non-myel. Non-myelotomy; HH, hindbrain herniation; SC, spinal cord; HL, hindlimb; FL, forelimb; MEP, motor evoked potentials; AUC, area-under-the-curve; P2P, peak-to-peak; SEP, somatosensory evoked potentials; b3t, beta-III tubulin antibody; GFAP, glial fibrillary acidic protein antibody antibody; MBP, myelin binding protein antibody; NA, non-applicable; NS, non-specified. Significant results are highlighted in bold.
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