Spinal hemorrhages are associated with early neonatal motor function loss in human spina bifida aperta

Electrophysiological Study in the Right Upper and Lower Limbs in Infants with Lumbosacral Meningomyelocele and in Normal Infants: A Case-control Study

Objective

The study aimed to assess the electrophysiological parameters (Hofmann reflex [H-reflex] and motor nerve conduction velocity [MNCV]) on children's upper and lower limbs with lumbosacral meningomyelocele (MMC) and age-matched control to see the effect of the MMC on the cervical segment of the spinal cord.

Materials and Methods

The present study was performed on infants with lumbosacral MMC. Twenty-five infants were examined with a mean age of 50 days of either sex. Out of them, 13 infants were in control and the remaining 12 were diagnosed with MMC. The H-reflex parameter and MNCV were recorded in these children's right upper and lower limbs.

Results

H-reflex was elicited in all the control group babies. In MMC, the H-reflex was elicited in the upper limbs. However, H-reflex was not elicited in the lower limbs of a few MMC babies. The upper limb's H-reflex parameters and conduction velocity were significantly higher than those corresponding lower limbs in control babies. In MMC, where the H-reflex was elicited, such differences in the lower and upper limbs were not observed. However, the values of MNCV in the upper limb (right median nerve) were significantly less, and the values of Hmax in the lower limb (soleus muscle) were significantly more in MMC babies than in the control group.

Conclusions

The values of electrophysiological parameters were higher in the upper limbs as compared to the corresponding lower limbs in control. These values were not altered in the upper limbs than those corresponding lower limbs of MMC, suggesting that motor function development was impaired/delayed in the spinal segment cranial to MMC lesion, and motor impairment in MMC children is mostly a result of upper motor neuron dysfunction.

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

OBJECTIVE

To assess the trophism of the lower limbs of fetuses with open spina bifida using fractional thigh volume (TVOL) of three-dimensional (3D) ultrasound.

METHODS

A prospective cross-sectional study was carried out with normal fetuses and with open spina bifida (myelomeningocele and rachischisis) at 26 weeks' gestation. The TVOL (delimitation of five cross-sectional areas of the middle portion of the limb) was evaluated, as well as the subjective assessment of hypotrophy and lower limb movement.

RESULTS

Thirty-one fetuses with open spina bifida, 21 with myelomeningocele and 10 with rachischisis, and 51 normal fetuses were included. There were no significant differences in the TVOL between normal and spina bifida fetuses (p = 0.623), as well as between normal fetuses, with myelomeningocele and with rachischisis (p = 0.148). There was no significant difference in the TVOL of fetuses with spina bifida with or without lower limb hypotrophy (p = 0.148). Fetuses with spina bifida and with lower limb movement had higher TVOL values than fetuses without lower limb movement (p = 0.002).

CONCLUSION

There were no significant differences in the TVOL measurement of normal and spina bifida fetuses (rachischisis and myelomeningocele). Fetuses with spina bifida without spontaneous movement of the lower limbs had lower TVOL values.

The Lower Limb Movements of the Fetus in Uterus: A Narrative Review

The fetus movements play an important role in fetal well-being. With the continuous advancement of real-time scanning machines, it is feasible to observe the fetus movement in detail. The characteristics of fetal lower limb movements in prenatal examination have not been systematically investigated. This review proposes the patterns of fetal lower limb movements, the maternal influence on fetal lower limb movements, and the application of fetal lower limb movements for the diagnosis of prenatal diseases. A systematic search of literature on the lower limb movements of the fetus in uterus was performed in the databases, namely, Web of Science and Scopus. Thirty-four publications were selected. This review demonstrates that isolated fetal lower limb movements are rare and always accompanied with the movements of other body segments. Detection of the presence of fetal leg movements seems to be of no diagnostic value for fetuses with prenatal diseases. The isolated lower limb movement was statistically significant different between fetuses of low- and high-risk pregnant women. The coordinated movements of the fetal lower limbs and other parts should be considered when analyzing fetal movements in the future study.

Neurologic Outcome Comparison between Fetal Open-, Endoscopic- and Neonatal-Intervention Techniques in Spina Bifida Aperta

INTRODUCTION

In spina bifida aperta (SBA), fetal closure of the myelomeningocele (MMC) can have a neuroprotective effect and improve outcomes. In Europe, surgical MMC closure is offered by fetal-open (OSBAR), fetal-endoscopic (FSBAR), and neonatal (NSBAR) surgical techniques. Pediatric neurologists facing the challenging task of counseling the parents may therefore seek objective outcome comparisons. Until now, such data are hardly available. In SBA, we aimed to compare neurologic outcomes between OSBAR, FSBAR, and NSBAR intervention techniques.

METHODS

We determined intervention-related complications, neuromuscular integrity, and neurologic outcome parameters after OSBAR (n = 17) and FSBAR (n = 13) interventions by age- and lesion-matched comparisons with NSBAR-controls. Neurological outcome parameters concerned: shunt dependency, segmental alterations in muscle ultrasound density (reflecting neuromuscular integrity), segmental motor-, sensory- and reflex conditions, and the likelihood of intervention-related gain in ambulation.

RESULTS

Compared with NSBAR-controls, fetal intervention is associated with improved neuromuscular tissue integrity, segmental neurological outcomes, reduced shunt dependency, and a higher chance of acquiring ambulation in ≈20% of the operated children. Children with MMC-lesions with a cranial border at L3 revealed the most likely intervention-related motor function gain. The outcome comparison between OSBAR versus FSBAR interventions revealed no significant differences.

CONCLUSION

In SBA, OSBAR- and FSBAR-techniques achieved similar neuroprotective results. A randomized controlled trial is helpful in revealing and compare ongoing effects by surgical learning curves.

Measurement of the Area and Circumference of the Leg: Preliminary Results of a New Method for Estimating Leg Muscle Trophism in Fetuses With Open Lumbosacral Spina Bifida

OBJECTIVE

To standardize a new technique to evaluate the fetal leg muscle trophism by measuring the area and circumference, and comparing this technique between normal and fetuses with open lumbosacral spina bifida (SB).

METHODS

Observational cross-sectional study was carried out on pregnant women with 26 weeks who were divided into two groups: Group I-fetuses with diagnosis of open lumbosacral SB; Group II-normal fetuses (control). In fetuses with SB, subjective evaluation of the lower limbs was performed (muscle echogenicity and leg movements). To estimate the leg muscle trophism, the measurement of the area and circumference of the leg were standardized, and the reproducibility of this method was performed.

RESULTS

Thirty-one fetuses with open lumbosacral SB and 51 normal fetuses were evaluated. The measurements of the area and circumference of the leg proved to be highly reproducible (intraclass correlation coefficient-ICC > 0.95). The leg area and circumference measurements were statistically lower in the SB group than in the control group (p < .001). When subjective ultrasound assessment demonstrated hypotrophy of the lower limbs, the measurements of the area and circumference of the leg were statistically lower when compared to normal fetuses (p < .001). Fetuses with open SB with abnormal lower limb movements had lower measurements of the area and circumference of the leg than fetuses with normal movements (p < .001).

CONCLUSION

A new technique for estimating fetal leg muscle trophism was standardized, which proved to be highly reproducible and was able to show the difference between normal and fetuses with SB.

Variability in lower extremity motor function in spina bifida only partially associated with spinal motor level

PURPOSE

Previous studies have found motor function to correlate with spinal motor level and, accordingly, individuals with spina bifida are frequently categorized clinically in this manner. The aim of the current study was to describe how lower extremity functions including strength, selective motor control, and mirror movements vary by motor level in children and young adults with spina bifida.

METHODS

A single center, retrospective, cross-sectional, descriptive study using data collected in the National Spina Bifida Patient Registry and by a gait laboratory was performed.

RESULTS

Seventy-seven individuals with spina bifida were included with the majority having myelomeningocele (59 lumbar, 18 sacral motor level). Lower extremity strength and selective motor control varied to a certain extent with motor level. However, 90% of individuals showed strength or weakness in at least one muscle group that was unexpected based on their motor level. Mirror movements did not clearly vary with motor level.

CONCLUSION

Lower extremity strength, selective motor control, and mirror movements in individuals with spina bifida were not entirely predicted by motor level. This highlights the possible need for an improved spina bifida classification system that describes not only spinal motor level but more clearly defines a particular individual's functional motor abilities.

Longitudinal evaluation of motor function in patients who underwent prenatal or postnatal neural tube defect repair

OBJECTIVE

To compare the evolution of motor function from mid-gestation to 12 months of age between prenatally and postnatally repaired cases of open neural tube defect (ONTD).

METHODS

This was a retrospective cohort study of all fetuses that underwent prenatal (fetoscopic or open hysterotomy) or postnatal ONTD repair at a single institution between November 2011 and December 2018. The anatomical level of the lesion was defined as the upper bony spinal defect at initial magnetic resonance imaging assessment. Prenatal motor function of the lower extremities was evaluated by ultrasound according to the metameric level of the neurological lesion, based on the methodology of Carreras et al. Fetal motor function was assessed at referral, at 6 weeks after surgery in prenatally repaired cases or 6 weeks after referral in postnatally repaired cases (6-week follow-up) and at the last scan before delivery. In addition, motor function was assessed by a detailed neurological examination at birth and 12 months of age. First sacral (S1) neurological level of the lesion was considered as intact motor function. For statistical comparisons, we attributed numerical scores to each neurological level and motor function was expressed as median (range) neurological level. Motor function (as numerical score) and the proportion of cases with intact motor function and with motor function two or more levels better than expected based on the anatomical level of the lesion were compared between the prenatal- and postnatal-repair groups. Fetal motor function was compared to the anatomical level of the lesion at referral and a better motor function was defined when it was two or more levels better than the anatomical level of the lesion. To assess the evolution of motor function, we compared motor function at referral with that at each follow-up assessment using paired t-tests.

RESULTS

We included 127 patients with ONTD, of whom 93 underwent prenatal (51 fetoscopic and 42 open hysterotomy) and 34 postnatal repair. At the time of referral, cases in the prenatal- and postnatal-repair groups presented with a similar anatomical level of lesion (L3 (T9-S1) vs L3 (T7-S1); P = 0.52), similar motor function (S1 (L1-S1) vs S1 (L1-S1); P = 0.52) and a similar proportion of cases with intact motor function (81% vs 79%; P = 0.88) and with motor function two or more levels better than expected based on the anatomical level of the lesion (62% vs 74%; P = 0.24). When compared with prenatally repaired cases, postnatally repaired cases showed worse motor function at birth (S1 (L1-S1) vs L4 (L1-S1); P < 0.01) and at 12 months of age (S1 (L1-S1) vs L4 (L1-S1); P < 0.01). In the prenatal-repair group, motor function remained stable from the time of referral to 12 months of age (P = 0.26). Furthermore, the proportion of patients with intact motor function at referral (81% (75/93)) was similar to that at the 6-week follow-up (74% (64/87)), at the last scan before birth (74% (42/57)), at birth (68% (63/93)) and at 12 months of age (67% (39/58)) in the prenatal-repair group. In the postnatal-repair group, worse motor function, starting from the third trimester to 12 months of age, was observed. The proportion of patients with intact motor function at referral (79% (27/34)) was similar to that at 6-week follow-up (80% (12/15); P = 0.92), but was lower at the last assessment before birth (25% (2/8); P < 0.01), at birth (24% (8/34); P < 0.01) and at 12 months of age (28% (7/25); P < 0.01). Similar findings were noted when assessing the evolution of the proportion of cases with motor function two or more levels better than expected based on the anatomical level of the lesion in each group.

CONCLUSIONS

Infants with ONTD that underwent postnatal repair had worse motor function at birth and at 12 months of age than at mid-gestation and when compared with infants that underwent prenatal ONTD repair. Prenatal motor function assessment by ultrasound is an adequate tool to identify those infants who should have a good clinical motor function after delivery. Information obtained by fetal motor function assessment can have an important role for patient counseling and case selection for surgery. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

Impact of the cystic neural tube defects on fetal motor function in prenatal myelomeningocele repairs: A retrospective cohort study

OBJECTIVE

To determine the impact of the lesion type (cystic [myelomeningocele] or flat [myeloschisis]) on the fetal motor function (MF) in cases candidates for prenatal open neural tube defect (ONTD) repair.

METHODS

Retrospective cohort study of patients with ONTD who underwent prenatal repair at a single institution between 2011 and 2019. The lesion type and the measurements of the length and width of the lesions to calculate the surface of the ellipsoid lesion were performed using MR scans. Prenatal MF of the lower extremities was evaluated by ultrasound following a metameric distribution at the time of referral. Intact MF was defined as the observation of plantar flexion of the ankle. Logistic regression was performed to determine the predictive value of the type of lesion for having an intact MF at the time of referral.

RESULTS

103 patients were included at 22.9 (19-25.4) weeks; 65% had cystic and 35% had flat lesions. At the time of referral, there was a higher proportion of cases with an intact MF in the presence of flat lesions (34/36; 94.4%) as compared to cystic lesion (48/67; 71.6%, p < 0.01). When adjusting for gestational age and anatomical level of the lesion, flat ONTD were 3.1 times more likely to be associated by intact motor function (CI%95 [2.1-4.6], p < 0.01) at the time of referral.

CONCLUSION

Cystic ONTD are more likely to be associated with impaired MF at mid-gestation in candidates for prenatal ONTD repair.

Impact of the volume of the myelomeningocele sac on imaging, prenatal neurosurgery and motor outcomes: a retrospective cohort study

To investigate the association of the myelomeningocele (MMC) volume with prenatal and postnatal motor function (MF) in cases who underwent a prenatal repair. Retrospective cohort study (11/2011 to 03/2019) of 63 patients who underwent a prenatal MMC repair (37 fetoscopic, 26 open-hysterotomy). At referral, measurements of the volume of MMC was performed based on ultrasound scans. A large MMC was defined as greater than the optimal volume threshold (ROC analysis) for the prediction of intact MF at referral (2.7 cc). Prenatal or postnatal intact motor function (S1) was defined as the observation of plantar flexion of the ankle based on ultrasound scan or postnatal examination. 23/63 participants presented a large MMC. Large MMC lesions was associated with an increased risk of having clubfeet by 9.5 times (CI%95[2.1–41.8], p < 0.01), and reduces the chances of having an intact MF at referral by 0.19 times (CI%95[0.1–0.6], p < 0.01). At birth, a large MMC reduces the chance of having an intact MF by 0.09 times (CI%95[0.01–0.49], p < 0.01), and increases the risk of having clubfeet by 3.7 times (CI%95[0.8–18.3], p = 0.11). A lower proportion of intact MF and a higher proportion of clubfeet pre- or postnatally were observed in cases with a large MMC sac who underwent a prenatal repair.

Trial registration: Clinicaltrials.gov NCT02230072 and NCT03794011 registered on September 3rd, 2014 and January 4th, 2019.

Severe and progressive neuronal loss in myelomeningocele begins before 16 weeks of pregnancy

BACKGROUND

Despite undisputable benefits, midtrimester prenatal surgery is not a cure for myelomeningocele (MMC): residual intracranial and motor deficits leading to lifelong handicap question the timing of prenatal surgery. Indeed, the timing and intensity of intrauterine spinal cord injury remains ill defined.

OBJECTIVE

We aimed to describe the natural history of neuronal loss in MMC in utero based on postmortem pathology.

STUDY DESIGN

Pathology findings were analyzed in 186 cases of myelomeningocele with lesion level between S1 and T1. Using a case-control, cross-sectional design, we investigated the timewise progression and topographic extension of neuronal loss between 13 and 39 weeks. Motor neurons were counted on histology at several spinal levels in 54 isolated MMC meeting quality criteria for cell counting. These were expressed as observed-to-expected ratios, after matching for gestational age and spinal level with 41 controls.

RESULTS

Chiari II malformation increased from 30.7% to 91.6% after 16 weeks. The exposed spinal cord displayed early, severe, and progressive neuronal loss: the observed-to-expected count dropped from 17% to ≤2% after 16 weeks. Neuronal loss extended beyond the lesion to the upper levels: in cases <16 weeks, the observed-to-expected motor neuron count was 60% in the adjacent spinal cord, decreasing at a rate of 16% per week. Progressive loss was also found in the upper thoracic cord, but in much smaller proportions. The observed-over-expected ratio of motor neurons was not correlated with the level of myelomeningocele.

CONCLUSIONS

Significant neuronal loss is present ≤16 weeks in the exposed cord and progressively extends cranially. Earlier prenatal repair (<16 weeks) could prevent Chiari II malformation in 69.3% of cases, rescue the 17% remaining motor neurons in the exposed cord, and prevent the extension to the upper spinal cord.

Fetal surgical intervention for myelomeningocele: lessons learned, outcomes, and future implications

Fetal myelomeningocele (fMMC) closure (spina bifida aperta) has become a care option for patients that meet inclusion criteria, but it is clear that fetal intervention, while improving outcomes, is not a cure. This review will: (1) focus on the rationale for fMMC surgery based on preclinical studies and observations that laid the foundation for human pilot studies and a randomized controlled trial; (2) summarize important clinical outcomes; (3) discuss the feasibility, efficacy, and safety of recent developments in fetal surgical techniques and approaches; and (4) highlight future research directions. Given the increased risk of maternal and fetal morbidity associated with prenatal intervention, accompanied by the increasing number of centres performing interventions worldwide, teams involved in the care of these patients need to proceed with caution to maintain technical expertise, competency, and patient safety. Ongoing assessment of durability of the benefits of fMMC surgery, as well as additional refinement of patient selection criteria and counselling, is needed to further improve outcomes and reduce the risks to the mother and fetus. WHAT THIS PAPER ADDS: High-quality prospective studies are needed to broaden the indication for fetal surgery in the general myelomeningocele population. Innovative minimally invasive approaches have had promising results, yet lack comprehensive and robust experimental or clinical evaluation. Important information to help families make informed decisions regarding fetal surgery for myelomeningocele is provided.

Early neonatal loss of inhibitory synaptic input to the spinal motor neurons confers spina bifida-like leg dysfunction in a chicken model

Spina bifida aperta (SBA), one of the most common congenital malformations, causes lifelong neurological complications, particularly in terms of motor dysfunction. Fetuses with SBA exhibit voluntary leg movements in utero and during early neonatal life, but these disappear within the first few weeks after birth. However, the pathophysiological sequence underlying such motor dysfunction remains unclear. Additionally, because important insights have yet to be obtained from human cases, an appropriate animal model is essential. Here, we investigated the neuropathological mechanisms of progression of SBA-like motor dysfunctions in a neural tube surgery-induced chicken model of SBA at different pathogenesis points ranging from embryonic to posthatch ages. We found that chicks with SBA-like features lose voluntary leg movements and subsequently exhibit lower-limb paralysis within the first 2 weeks after hatching, coinciding with the synaptic change-induced disruption of spinal motor networks at the site of the SBA lesion in the lumbosacral region. Such synaptic changes reduced the ratio of inhibitory-to-excitatory inputs to motor neurons and were associated with a drastic loss of γ-aminobutyric acid (GABA)ergic inputs and upregulation of the cholinergic activities of motor neurons. Furthermore, most of the neurons in ventral horns, which appeared to be suffering from excitotoxicity during the early postnatal days, underwent apoptosis. However, the triggers of cellular abnormalization and neurodegenerative signaling were evident in the middle- to late-gestational stages, probably attributable to the amniotic fluid-induced in ovo milieu. In conclusion, we found that early neonatal loss of neurons in the ventral horn of exposed spinal cord affords novel insights into the pathophysiology of SBA-like leg dysfunction.

Muscle ultrasound quantifies segmental neuromuscular outcome in pediatric myelomeningocele

In pediatric spina bifida aperta (SBA), non-invasive assessment of neuromuscular integrity by muscle ultrasound density (MUD) could provide important information about the clinical condition. We therefore aimed to determine the association between pediatric SBA MUD and segmental neurologic function. We included 23 children (age range: 1-18 y) with SBA with L4-5 lesions, and we associated SBA MUD with control values and segmental neuromuscular function. Results revealed that MUD outcomes in the lower extremities: (i) are independent of age, (ii) exceed control values, (iii) differ intra-individually (i.e., between the left and right sides in the same individual) in association with segmental neuromuscular function. We concluded that SBA leg MUD can quantify the segmental neuromuscular condition throughout childhood.

In spina bifida aperta, muscle ultrasound can quantify the "second hit of damage"

PURPOSE

In spina bifida aperta (SBA), the "second-hit hypothesis" addresses consequences by delayed neurological damage superimposed upon the congenital myelomeningocele (MMC). This secondary damage is postulated to underlie the disappearance of leg movements shortly after birth. Innovative fetal surgery might prevent this, but results are methodologically hard to prove in small and heterogeneous treatment groups. We reasoned that delayed postnatal alterations in muscle ultrasound density (MUD = muscle echogenicity) could quantitatively reflect consequences by "the second hit" of damage. In the present study, we investigated whether delayed postnatal leg-MUD alterations are associated with postnatal muscle function loss.

METHODS

We cross-sectionally assessed leg-MUD in 16 postnatally operated SBA children (MMC-L5; at 0, 6, and 12 months; in n = 11/16; 11/16, and 15/16 children, respectively) and compared outcomes with 13 healthy control children. Additionally, we assessed SBA MUD caudal and cranial to the MMC and calculated MMC-L5 impact by: dMUD((MMC-L5)) = [MUD(calf muscle/S1-2)] - [MUD(quadriceps muscle/L2-4)] and associated outcomes with leg muscle function caudal to the MMC.

RESULTS

At 0 month, clinically discernible dMUD was more often increased in SBA than in control newborns (p < .05), but a relationship between absolute quantitative differences and leg muscle dysfunction was still lacking. At 6-12 months, additionally increased dMUD outcomes coincided with SBA leg muscle dysfunction (p < .05).

CONCLUSIONS

In post-neonatal SBA, secondarily increased dMUD (i.e., MMC impact) coincides with leg muscle dysfunction. This may implicate that muscle ultrasound could provide a quantitative tool to assess the neuromuscular impact by the second hit of damage.

Changes in muscle activation patterns in response to enhanced sensory input during treadmill stepping in infants born with myelomeningocele

Infants with myelomeningocele (MMC) increase step frequency in response to modifications to the treadmill surface. The aim was to investigate how these modifications impacted the electromyographic (EMG) patterns. We analyzed EMG from 19 infants aged 2-10 months, with MMC at the lumbosacral level. We supported infants upright on the treadmill for 12 trials, each 30 seconds long. Modifications included visual flow, unloading, weights, Velcro and lcriction. Surface electrodes recorded EMG from tibialis anterior, lateral gastrocnemius, rectus femoris and biceps femoris. We determined muscle bursts for each stride cycle and from these calculated various parameters. Results indicated that each of the five sensory conditions generated different motor patterns. Visual flow and friction which we previously reported increased step frequency impacted lateral gastrocnemius most. Weights, which significantly decreased step frequency increased burst duration and co-activity of the proximal muscles. We also observed an age effect, with all conditions increasing muscle activity in younger infants whereas in older infants visual flow and unloading stimulated most activity. In conclusion, we have demonstrated that infants with myelomeningocele at levels which impact the myotomes of major locomotor muscles find ways to respond and adapt their motor output to changes in sensory input.

Visual assessment of segmental muscle ultrasound images in spina bifida aperta

In spina bifida aperta (SBA), spinal MRI provides a surrogate marker to estimate muscle damage caudal to the myelomeningocele (MMC). This muscle damage by the MMC can be quantified by intra-individual comparison of muscle ultrasound density (MUD) caudal versus cranial to the MMC (dMUD = [MUD(caudal-to-the-MMC)] - [MUD(cranial-to-the-MMC)]). Quantitative dMUD assessment requires time, equipment and expertise, whereas it could also be visually determined by differences in muscle echodensity caudal vs. cranial to the MMC (visual-dMUD). If visual and quantitative dMUD correspond, visual dMUD assessment could provide a clinical screening parameter. In 100 SBA muscle ultrasound recordings of patients with various MMC levels, we aimed to compare quantitative dMUD (dMUD = [MUD(calf-muscle/S1)] - [MUD(quadriceps-muscle/L2-L4)]) with visual dMUD assessments by 20 different observers. Results indicate that quantitative dMUD can be visually detected (sensitivity 86%; specificity 57%), implicating that visual dMUD screening could provide a quick, clinical screening tool for muscle impairment by the MMC.

Fetal endoscopic myelomeningocele closure preserves segmental neurological function

AIM

  Our aim was to compare the effect of prenatal endoscopic with postnatal myelomeningocele closure (fetally operated spina bifida aperta [fSBA]) versus neonatally operated spina bifida aperta [nSBA]) on segmental neurological leg condition.

METHOD

  Between 2003 and 2009, the fetal surgical team (Department of Obstetrics, University of Bonn, Germany) performed 19 fetal endoscopic procedures. Three procedures resulted in fetal death, three procedures were interrupted by iatrogenic hemorrhages and 13 procedures were successful. We matched each successfully treated fSBA infant with another nSBA infant of the same age and level of lesion, resulting in 13 matched pairs (mean age 14 mo; SD 16 mo; f/m=1.6; female-16, male-10). Matched fSBA and nSBA pairs were compared in terms of segmental neurological function and leg muscle ultrasound density (MUD). We also determined intraindividual difference in MUD (dMUD) between myotomes caudal and cranial to the myelomeningocele (reflecting neuromuscular damage by the myelomeningocele) and compared dMUD between fSBA and nSBA infants. Finally, we correlated dMUD with segmental neurological function.

RESULTS

  We found that, on average, the fSBA group were born at a lower gestational age than the nSBA group (median 32 wks [range 25-34 wks] vs 39 wks [34-41 wks]; p=0.001) and experienced more complications (chorioamnionitis, premature rupture of the amniotic membranes, oligohydramnios, and infant respiratory distress syndrome necessitating intermittent positive-pressure ventilation). Neurological function was better preserved after fSBA than after nSBA (median motor and sensory gain of two segments; better preserved knee-jerk [p=0.006] and anal [p=0.032] reflexes). The dMUD was smaller in fSBA than in nSBA infants (mean difference 24, 95% confidence interval [CI] 15-33; p<0.05), which was associated with better preserved segmental muscle function.

INTERPRETATION

  Fetal endoscopic surgery is associated with spinal segmental neuroprotection, but it results in more complications. Before considering clinical implementation of fetal endoscopic myelomeningocele closure as standard care, the frequency of complications should be appropriately reduced and results assessed in larger groups over a longer period of time.

Fetal surgery for myelomeningocele: progress and perspectives

Myelomeningocele (MMC), one of the most common congenital malformations, can result in severe lifelong disabilities, including paraplegia, hydrocephalus, Chiari II malformation, bowel and bladder dysfunction, skeletal deformations, and neurocognitive impairment. Experimental studies provide compelling evidence that the neurological deficits associated with MMC are not simply caused by incomplete neurulation but rather by the prolonged exposure of the vulnerable neural elements to the intrauterine environment. MMC is the first non-lethal anomaly considered for fetal surgical intervention, necessitating a careful analysis of risks and benefits. Retrospective and prospective randomized studies suggest that fetal surgery of MMC before 26 weeks of gestation may preserve neuromotor function, reverse hindbrain herniation, and reduce the need for ventriculoperitoneal shunting. However, these studies also demonstrate that fetal surgery is associated with significant maternal and fetal risks. Consequently, additional research is necessary to further elucidate the pathophysiology of MMC, to define the ideal timing and technique of fetal closure, and to evaluate the long-term implications of prenatal intervention.

Neuroependymal denudation is in progress in full-term human foetal spina bifida aperta

In human spina bifida aperta (SBA), cerebral pathogenesis [hydrocephalus, Sylvius aqueduct (SA) stenosis and heterotopias] is poorly understood. In animal models, loss of ventricular lining (ependymal denudation) causes SA stenosis and hydrocephalus. We aimed to investigate whether ependymal denudation also takes place in human foetal SBA. Considering that ependymal denudation would be related to alterations in junction proteins, sections through SA of five SBA and six control foetuses (gestational ages ranged between 37 and 40 weeks) were immunostained for markers of ependyma (caveolin 1, βIV-tubulin, S100), junction proteins (N-cadherin, connexin-43, neural cell adhesion molecule (NCAM), blood vessels (Glut-1) and astrocytes [glial fibrillary acidic protein (GFAP)]. In control foetuses, ependymal denudation was absent. In SBA foetuses different stages of ependymal denudation were observed: (i) intact ependyma/neuroepithelium; (ii) imminent ependymal denudation (with abnormal subcellular location of junction proteins); (iii) ependymal denudation (with protrusion of neuropile into SA, formation of rosettes and macrophage invasion); (iv) astroglial reaction. It is suggested that abnormalities in the formation of gap and adherent junctions result in defective ependymal coupling, desynchronized ciliary beating and ependymal denudation, leading to hydrocephalus. The presence of various stages of ependymal denudation within the same full-term SBA foetuses suggests continuation of the process after birth.

Amniotic fluid levels of glial fibrillary acidic protein in fetal rats with retinoic acid induced myelomeningocele: a potential marker for spinal cord injury

OBJECTIVE

The objective of this study was to determine whether amniotic fluid levels of glial acidic fibrillary protein (GFAP) would reflect myelomeningocele-related neurodegeneration in the rat model of retinoic acid-induced myelomeningocele, which is a model that is very similar to human myelomeningocele and develops the entire spectrum of disease severity including features of the Chiari II malformation.

STUDY DESIGN

Time-dated (embryonic day 10) pregnant Sprague-Dawley rats were gavage fed 60 mg/kg/bodyweight retinoic acid that had been dissolved in olive oil or olive oil alone. Myelomeningocele, retinoic acid-exposed no myelomeningocele, and control fetuses were harvested at specific time points throughout gestation. A standard set of pinching tests was performed to interrogate the sensorimotor reflex arc of hindpaws and tails. Amniotic fluid-GFAP levels were analyzed by standard enzyme-linked immunosorbent assay techniques.

RESULTS

Amniotic fluid-GFAP levels were similar between groups at embryonic days 14, 16, and 18, respectively. Compared with control fetuses, amniotic fluid GFAP levels were significantly increased in myelomeningocele fetuses at embryonic days 20 and 22 (P < .001). Defect size (P < .001), presence of clubfoot deformity (P = .0004), and absence of sensorimotor function (P < .01) at embryonic day 22 correlated with amniotic fluid-GFAP levels.

CONCLUSION

Amniotic fluid-GFAP levels appear to correlate with spinal cord injury as gestation proceeds in fetal rats with myelomeningocele.

Muscle ultrasound density in human fetuses with spina bifida aperta

BACKGROUND

In fetal spina bifida aperta (SBA), leg movements caudal to the meningomyelocele (MMC) are transiently present, but they disappear shortly after birth. Insight in the underlying mechanism could help to improve treatment strategies. In fetal SBA, the pathogenesis of neuromuscular damage prior to movement loss is still unknown. We reasoned that prenatal assessment of muscle ultrasound density (fetal-MUD) could help to reveal whether progressive neuromuscular damage is present in fetal SBA, or not.

AIM

To reveal whether prenatal neuromuscular damage is progressively present in SBA.

PATIENTS/METHODS

In SBA fetuses (n=6; 22-37 weeks gestational age), we assessed fetal-MUD in myotomes caudal to the MMC and compared measurements between myotomes cranial to the MMC and controls (n=11; 17-36 weeks gestational age). Furthermore, we intra-individually compared MUD and muscle histology between the pre- and postnatal period.

RESULTS

Despite persistently present fetal leg movements caudal to the MMC, fetal-MUD was higher caudal to the MMC than in controls (p<0.05). Fetal-MUD caudal to the MMC did not increase with gestational age, whereas fetal-MUD in controls and cranial to the MMC increased with gestational age (p<0.05). In 5 of 6 patients assessed, comparison between pre- and postnatal MUD and/or muscle histology indicated consistent findings.

CONCLUSIONS

In fetal SBA, persistent leg movements concur with stable, non-progressively increased fetal-MUD. These data may implicate that early postnatal loss of leg movements is associated with the impact of additional neuromuscular damage after the prenatal period.

Pathogenesis of cerebral malformations in human fetuses with meningomyelocele

Background

Fetal spina bifida aperta (SBA) is characterized by a spinal meningomyelocele (MMC) and associated with cerebral pathology, such as hydrocephalus and Chiari II malformation. In various animal models, it has been suggested that a loss of ventricular lining (neuroepithelial/ependymal denudation) may trigger cerebral pathology. In fetuses with MMC, little is known about neuroepithelial/ependymal denudation and the initiating pathological events.

The objective of this study was to investigate whether neuroepithelial/ependymal denudation occurs in human fetuses and neonates with MMC, and if so, whether it is associated with the onset of hydrocephalus.

Methods

Seven fetuses and 1 neonate (16–40 week gestational age, GA) with MMC and 6 fetuses with normal cerebral development (22–41 week GA) were included in the study. Identification of fetal MMC and clinical surveillance of fetal head circumference and ventricular width was performed by ultrasound (US). After birth, MMC was confirmed by histology. We characterized hydrocephalus by increased head circumference in association with ventriculomegaly. The median time interval between fetal cerebral ultrasound and fixing tissue for histology was four days.

Results

At 16 weeks GA, we observed neuroepithelial/ependymal denudation in the aqueduct and telencephalon together with sub-cortical heterotopias in absence of hydrocephalus and/or Chiari II malformation. At 21–34 weeks GA, we observed concurrence of aqueductal neuroepithelial/ependymal denudation and progenitor cell loss with the Chiari II malformation, whereas hydrocephalus was absent. At 37–40 weeks GA, neuroepithelial/ependymal denudation coincided with Chiari II malformation and hydrocephalus. Sub-arachnoidal fibrosis at the convexity was absent in all fetuses but present in the neonate.

Conclusion

In fetal SBA, neuroepithelial/ependymal denudation in the telencephalon and the aqueduct can occur before Chiari II malformation and/or hydrocephalus. Since denuded areas cannot re-establish cell function, neuro-developmental consequences could induce permanent cerebral pathology.