Clinical outcomes that fetal surgery for myelomeningocele needs to achieve

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.

Fetal surgery for neural tube defects

Open spina bifida remains a major source of disability despite an overall decrease in incidence. It is frequently diagnosed prenatally and can thus - potentially - be treated by fetal surgery. Animal studies and preliminary human studies strongly suggest that at least a portion of the neurological abnormalities seen in these patients are secondary, and occur in mid-gestation. It is estimated that approximately 400 fetal operations have now been performed for myelomeningocele world wide. Despite this large experience, the technique remains of unproven benefit. Preliminary results suggest that fetal surgery results in reversal of hindbrain herniation (the Chiari II malformation), a decrease in shunt-dependent hydrocephalus, and possibly improvement in leg function, but these findings might be explained by selection bias and changing management indications. A randomized prospective trial (the MOMS trial) is currently being conducted by three centers in the United States, and is estimated to be completed in 2009.

In utero topographic analysis of astrocytes and neuronal cells in the spinal cord of mutant mice with myelomeningocele

OBJECT

Myelomeningocele (MMC) is the most severe form of spina bifida causing severe neurological deficits. Injury to the placode has been attributed to in utero aggression. In this study, glial and neuronal cell changes in both number and topography in mice with MMC were investigated during gestation.

METHODS

The curly tail/loop-tail mice model of MMC was used, and fetuses were harvested using caesarean surgery at Days 14.5, 16.5, and 18.5 (full gestation at 19 days). Immunohistochemical analyses of the MMC placodes and the normal spinal cords from the control group were performed using anti-glial fibrillary acidic protein (astrocytes) and mouse anti-neuronal nuclear (neurons) antibodies. Light microscopy was used along with computer-assisted morphometric evaluation. Progressive increases in astrocytes in the spinal cord of all mouse fetuses were found between Days 14.5 and 18.5 of gestation. This increase was significantly higher in the placodes of mice with MMC than in those of normal mice, particularly in the posterior region. Neuronal labeling at Day 14.5 of gestation was similar between mice with MMC and control mice. At Day 16.5 of gestation there was a deterioration of neural tissue in MMC fetuses, mainly in the posterior region, progressing until the end of gestation with a marked loss of neurons in the entire MMC placode.

CONCLUSIONS

This study delineated the quantitative changes in astrocytes and neurons associated with MMC development during the late stages of gestation. The detailed topographic analysis of the MMC defines the timing of the intrauterine insult and how the placode lesions progress. This study supports the current concept of placode protection through in utero surgery for fetuses with MMC.

Spina bifida--a follow-up study of neonates born from 1991 to 2001

AIMS

To follow the development of children born with myelomeningocoele.

METHODS

We followed 54 infants born with myelomeningocele between 1991 and 2001 in the Obstetrical Department of the Medical University of Gdansk, Poland.

RESULTS

The mortality rate for live births was 40.8%. 13.0% of the children were stillborn and 5.5% were lost for observation. Late diagnosis, a high localization of the lesion, the presence of other malformations, and low birth weight increased the risk of death. Diagnosis was most commonly made in the 31-35(th) week of pregnancy. For 18.5% of the subjects, the diagnosis was postnatal. There was no correlation between the time and mode of delivery and mental development. Only some of the children were able to walk, to use braces, or use a wheelchair. Most of the children had poor bladder and bowel control. We found a correlation between these dysfunctions and the level of myelomeningocele.

CONCLUSIONS

Myelomeningocoele is associated with high rates of mortality and severe psychomotoric retardation. The localization of the lesion has an impact on survival rate and sphincter control. Mental development depends on neonatal condition after delivery. Mode of delivery does not influence the child's further development.

Diagnosis and prevention of neural tube defects

PURPOSE OF REVIEW

Neural tube defects, including anencephaly, meningomyelocele and encephalocele, are among the most common birth defects that result in severe mortality and morbidity. Neural tube defects occur with an incidence of 1-5 per 1000 births, showing marked geographic, ethnic and temporal variations. Although clear evidence exists on preventability of a large proportion of neural tube defects by periconceptional folic acid intake, only a low percentage of women are following the recommendations.

RECENT FINDINGS

In the past few decades diagnostic modalities have undergone a change from blood screening tests, such as alpha-fetoprotein, to imaging methods. Ultrasound has become the standard tool for early diagnosis, whereas fetal magnetic resonance imaging has gained importance in evaluating distinct coexisting anomalies of the central nervous system. Since the United States authorized the addition of folic acid to grain products in 1996, many other countries are considering folic acid fortification of their grain products, or have started fortification. Hitherto there is no consensus either to the duration of supplementation or to the best dose.

SUMMARY

Ultrasound and magnetic resonance imaging offer the possibility of early and accurate diagnosis of neural tube defects, and have therefore improved medical counseling and parents' decision making. Food fortification is the most practical way of ensuring sufficient folate supplementation and is warranted during the periconceptional period.