Fractional Limb Volume in Spina Bifida Fetuses as an Assessment Tool for Postnatal Ambulation

Abstract

Background: Prenatal fractional limb volume (FLV) can be used to assess muscle atrophy in fetuses with myelomeningocele. Objective: We hypothesize that FLV in fetal myelomeningocele (fMMC) repair is different from postnatal repair (PNR). Assessing intrauterine muscle development can predict ambulation. Methods: A prospective observational study was performed from July 2012 to April 2016. Demographics, clinical outcomes, and FLV of the fetal thigh were assessed by ultrasound. Ambulation videos were collected from patients over 30 months of age. FLV was compared between the fMMC and PNR groups and between ambulators and non-ambulators. Two-sample t test, ANOVA, Spearman's rho correlation, and Bland-Altman plots were used for analysis. A p value < 0.05 was used for statistical significance. Results: Fifty-nine patients were included, 24 had fMMC and 35 had PNR. Videos were obtained in 47 cases (73%). There was no difference in baseline demographics between the groups. There was no significant change in the fMMC group between the FLV at initial presentation and the repeat at 34 weeks gestation (54.5 ± 28.2 and 62.2% ± 16.4; p = 0.6). In contrast, the FLV in the PNR decreased between the initial evaluation and the repeat at 34 weeks (54.1 ± 27.7 to 35.8 ± 34.1%; p = 0.04). FLV at 34 weeks gestation was higher in the fMMC group as compared to the PNR group (62.2 ± 16.4 vs. 35.8 ± 34.1%; p = 0.02). There was no difference in FLV between ambulators and non-ambulators either at initial evaluation (p = 0.8) or at 34 weeks gestation (p = 0.6). Conclusion: Lower FLV in the PNR group compared to fMMC may suggest in utero muscle atrophy. No correlation was seen between FLV and subsequent ambulation; however, future larger studies may be needed.

Measurement of the Area and Circumference of the Leg

“…25,26 And studies that followed longitudinally fetuses with spinal dysraphism observed a worsening of the parameters evaluated in the lower limbs from the third trimester. 2,3,27 In view of this, we can assume that the pattern of muscle trophism observed in fetuses at 26 weeks of age with spinal dysraphism would probably be similar to that of fetuses between 20 and 24 weeks, thus being able to reinforce our findings. Anyway, further studies, involving earlier gestational ages (20-24 weeks) would be interesting to validate our ultrasound technique.…”

“…In 2019, Donepudi et al 2 used the fractional thigh volume (TVOL) for this purpose. They compared TVOL in fetuses with open SB submitted to fetal surgery for SB repair and fetuses with open SB operated after birth; and studied whether TVOL could be used as a predictor of the motor prognosis after birth (at 30 months of life).…”

Assessment of lower limb trophism in fetuses with open spina bifida using fractional thigh volume of three‐dimensional ultrasound

“…21,22 To estimate thigh muscle trophism in fetuses with spina bifida, we used the TVOL technique, a validated and reproducible method for predicting nutritional status and detecting fetal growth disorders. 23 Donepudi et al 1 In this study, we separated the group of fetuses with open spina bifida into rachischisis and myelomeningocele, however, we did not observe significant differences in TVOL in both subgroups. Oliver et al 24 rachischisis and investigated whether the presence and size of the meningeal sac correlated with greater impairment of lower limb motor function.…”

“…Donepudi et al 1 evaluated the TVOL of fetuses with open spina bifida who underwent intrauterine fetal surgery and operated in the postnatal period, in addition to evaluating whether the TVOL could be used as predictor of motor prognosis in the postnatal period. They carried out a prospective study with 24 fetuses submitted to intrauterine surgery and 35 in the postnatal period.…”

“…It has a multifactorial etiology and incidence around 1/1000 births. 1 Spina bifida represents the most common anomaly of the central nervous system compatible with life, with an approximate mortality rate of 10%. 2,3 However, survivors have high rates of morbidities, such as motor deficiencies of the lower limbs and bladder and bowel dysfunction.…”