Systematic Classification of Spina Bifida

Gestational age at birth varies by surgical technique in prenatal open spina bifida repair: a systematic review and meta-analysis

OBJECTIVE

Prenatal repair of open spina bifida has become well-established. Several surgical approaches have emerged, each focused on optimizing outcomes while minimizing risks. This study aims to compare the gestational age at delivery following the various surgical techniques.

DATA SOURCES

This systematic review and meta-analysis synthesizes data from 37 studies between 2010 and 2023.

STUDY ELIGIBILITY CRITERIA

Eligible studies included pregnant patients diagnosed with open spina bifida who underwent the following intrauterine repair techniques: open repair, mini-hysterotomy, laparotomy-assisted fetoscopic repair, and percutaneous fetoscopic repair.

STUDY APPRAISAL AND SYNTHESIS METHODS

The primary outcome investigated was gestational age at delivery, while secondary outcomes were preterm premature rupture of membranes, vaginal birth, and perinatal mortality. The programming language software R (version 4.0.5) was used to execute the analysis.

RESULTS

In this meta-analysis, 2333 prenatal repair of open spina bifida procedures arising from 14 countries were analyzed. Of these, open repair accounted for 65.7%, mini-hysterotomy accounted for 14.4%, laparotomy-assisted fetoscopic repair accounted for 5.36%, and percutaneous fetoscopic repair accounted for 14.6%. The subgroup analyses revealed a nonsignificant mean gestational age at birth: 34+1 weeks for open repair, 34+2 weeks for mini-hysterotomy, 35+3 weeks for laparotomy-assisted repair, and 32+3 weeks for percutaneous fetoscopic repair (P=.26). While the gestational age at birth was not different, there were significant differences (P<.01) in pooled proportions of preterm premature rupture of membranes and preterm birth by surgical approach (overall rates: 75% and 30% respectively). Vaginal birth rates had significant subgroup differences (P<.01), with the laparotomy-assisted fetoscopic group more likely to have vaginal deliveries (0.02, 0.04, 0.49, 0.18 for open, mini, laparotomy, and percutaneous, respectively).

CONCLUSION

The advanced secondary Bayesian analysis of data from this meta-analysis suggests that the mean gestational age at birth may differ among the 4 surgical techniques for prenatal repair of open spina bifida, with a potential advantage for the decrease in preterm births associated with a laparotomy-assisted approach. However, these findings should be interpreted cautiously, and further direct comparison studies are needed to confirm these observations.

Togaram1 is expressed in the neural tube and its absence causes neural tube closure defects

Neural tube closure defect pathomechanisms in human embryonic development are poorly understood. Here we identified spina bifida patients expressing novel variants of the TOGARAM gene family. TOGARAM1 has been associated with the ciliopathy Joubert syndrome, but its connection to spina bifida and role in neural development is unknown. We show that Togaram1 is expressed in the neural tube and Togaram1 knockout mice have abnormal cilia, reduced sonic hedgehog (Shh) signaling, abnormal neural tube patterning, and display neural tube closure defects. Neural stem cells from Togaram1 knockout embryos showed reduced cilia and defects in Shh signaling. Overexpression in IMCD3 and HEK293 cells of TOGARAM1 carrying the variant found in the spina bifida patient resulted in cilia defect along with reduced pericentriolar material one (PCM1), a critical constituent of centriolar satellites involved in transporting proteins toward the centrosome and primary cilia. Our results demonstrate the role of TOGARAM1 in regulating Shh signaling during early neural development that is critical for neural tube closure and elucidates potential mechanisms whereby the ciliopathy-associated gene TOGARAM1 gives rise to spina bifida aperta in humans.

Complex neural tube and skeletal malformations, resembling Chiari malformations, in two calves

Two 1-day-old full-term female calves from different farms located in the Brazilian state of Rio Grande do Sul were unable to stand due to paresis of the pelvic limbs. Both calves had spina bifida on the spinal lumbar segment and were submitted to euthanasia due to poor prognosis. Postmortem examination revealed cerebellar herniation, caudal displacement of the brainstem, rostral deviation of the cranial nerves, caudal extension of occipital lobes, absence of dorsal lamina of lumbar vertebrae with exposed spinal cord, myelodysplasia, kyphosis, segmental spinal agenesis, renal fusion, muscular atrophy, and arthrogryposis. Histology highlighted myelodysplasia (syringomyelia and diplomyelia) and muscular atrophy. The reverse transcription-polymerase chain reactions for ruminant pestivirus were negative. Based on these lesions, the diagnosis of complex neural tube and skeletal malformations was made. A review of previous publications on calves diagnosed with these malformations, originally called Chiari or Arnold-Chiari malformations, revealed a wide range of nervous system and skeletal lesions. These variations amplified the uncertainty regarding whether all cases represent the same disorder and reinforced the importance of reconfiguring the terminology.

Initial experience with the anaesthetic management of fetoscopic spina bifida repair at a German University Hospital: A case series of 15 patients

Spina bifida aperta (SBA) is a serious neural tube defect that can lead to a range of disabilities and health complications in affected individuals. In recent years, fetoscopic surgical repair has emerged as a promising new approach to treat spina bifida prenatally, offering the potential for improved outcomes compared with traditional open surgery. As one of the few centres in Europe to offer this innovative technique, the Departments of Obstetrics and Gynaecology, Neurosurgery, and Anaesthesiology and Intensive Care Medicine at the University Medical Centre of Marburg (UKGM Marburg) have faced unique challenges in developing and establishing standards of care for the pregnant patients undergoing this complex procedure. In this publication, we aim to present details of our initial experience with the first 15 patients and propose a clinical concept for the rather complex perioperative management of these patients.

Differences between Myeloschisis and Myelomeningocele in Patients Undergoing Prenatal Repair of Open Spina Bifida

INTRODUCTION

Open spina bifida (OSB) manifests as myelomeningocele (MMC) or myeloschisis (MS). Both lesions theoretically leak cerebrospinal fluid (CSF) and produce different degrees of Chiari II malformation (CHMII). However, it is not entirely clear whether these forms of OSB have different clinical manifestations. This study aimed to evaluate the clinical and/or radiological differences between MS and MMC in patients who underwent prenatal OSB repair.

METHODS

A total of 71 prenatal repairs were performed with the open technique at the Public Hospital of Rancagua, Chile, between 2012 and 2022. We performed follow-up magnetic resonance imaging (MRI) of fetuses that qualified for prenatal OSB repair surgery. We examined the correlations between various anthropomorphic measurements and clinical and imaging variables, such as the type of lesion and dimensions such as ventricle atrium diameter, degree of severity of CHMII, need for CSF shunt at 12 months, and walking at 30 months.

RESULTS

This study included 71 fetuses with OSB for which 38 MRI examinations were analyzed; 61% (43/71) of lesions were MMC and 39% (28/71) were MS. Grade 3 (severe) Chiari II malformations were found in 80% (12/15) of MS and 43% (10/23) of MMC (p < 0.05). Fetuses with an atrial diameter less than 13.48 mm had a lower probability of requiring a CSF shunt at 12 months (p < 0.05). MMC was associated with a significantly higher frequency of clubfoot at birth (p < 0.05), whereas MS was significantly associated with more severe CHMII (p < 0.05). Although the correlations were not significant, we observed clear trends that more children with MS required shunts at 12 months and could walk at 30 months compared to children with MMC.

CONCLUSIONS

MS and MMC are distinct subtypes of OSB. Further studies of larger cohorts that include biomolecular and histological analysis are required to better understand the differences between these lesions. The findings of this study may enable healthcare providers to better advise parents and prepare healthcare teams earlier for the management of patients undergoing prenatal repair of OSB.

Histopathological presence of dermal elements in resected margins of neural structures obtained from initial repair surgery for myelomeningocele

Background

Development of dermoid or epidermoid cysts in myelomeningocele (MMC) sites is generally thought to occur in a delayed fashion due to implantation of dermal elements during initial repair surgery. Another theory is that dermal and dermoid elements may already be present within dysplastic neural structures at birth.

Methods

We experienced histopathological presence of dermal elements in resected tissues at initial repair surgery in four out of 18 cases with MMC who required resection of parts or margins of the neural structures to perform cord untethering. Since one of these cases has already been reported, we describe the clinicopathological findings for the remaining three cases.

Results

In Case1, cryptic dermoid elements were discovered in the terminal filum-like structure (FT-LS) caudal to the open neural placode (NP). The FT-LS had histopathological characteristics similar to the retained medullary cord. In Case 2, dermoid elements were discovered in the caudal margin of the dysplastic conus medullaris. In Case 3, a thin squamous epithelial layer overlapped the rostral margin of the NP where the NP was located near the skin. Case 1 developed an epidermoid cyst at 1 year and 2 months of age, which was totally resected.

Conclusion

Prenatally existing cryptic dermoid elements in the caudal portion of neural structures and remnants of dermal elements overlapping the rostral margin of the NP are associated with delayed occurrence of dermoid/ epidermoid cysts. Postoperative histopathological investigation of the resected specimens is recommended. Once dermal elements are revealed, repeated imaging examination and additional surgery should be considered.

Sacral Spina Bifida Occulta: A Frequency Analysis of Secular Change

Substantial relaxation of natural selection beginning around 1900 changed the mutation/selec­tion balance of modern genetic material, producing an increase in variable anatomical structures. While multiple structures have been affected, the temporal increase in variations of the sacrum, specifically, ‘Sa­cral Spina Bifida Occulta,’ have been reliably demonstrated on a localised scale. Calculation of largescale frequency has been hindered by the localised nature of these publications, the morphological variability of this variation, and potential pathological associations, which have produced divergent classifications, and conflicting reported rates of occurrence. A systematic review of the reported literature was conducted to provide an objective analysis of Sacral Spina Bifida Occulta frequency from 2500 BCE to the present. This review was designed to compensate for observed inconsistencies in reporting and to ascertain, for the first time, the temporal trajectory of this secular trend. A systematic review of Sacral Spina Bifida Occulta lit­erature was conducted through the strict use of clinical meta-analysis criteria. Publications were retrieved from four databases: PubMed, Embase, the Adelaide University Library database, and Google Scholar. Data were separated into three historical groups, (1 = <1900, 2 = 1900 to 1980 and 3 = >1980), and frequency outcomes compared, to determine temporal rates of occurrence. A total of 39/409 publications were included in the final analysis, representing data for 16,167 sacra, spanning a period of 4,500 years. Statistically significant results were obtained, with total open S1 frequen­cy increasing from 2.34%, (79 to 1900CE), to 4.80%, (1900 to 1980CE) and to 5.43% (>1980CE). These increases were significant at p<0.0001, with Chi-squared analysis. A clear secular increase in the global frequency of Sacral Spina Bifida Occulta has been demonstrated from 1900 to the present. This research provides a novel and adaptable framework for the future assessment of variation distribution, with impor­tant implications for the fields of biological anthropology and bioarchaeology.

Construction and predictive value of risk models of maternal serum alpha-fetoprotein variants and fetal open neural tube defects

The correlation of maternal serum alpha-fetoprotein (AFP) variants (AFP-L2, AFP-L3), free beta-human chorionic gonadotropin (free β-hCG), and open neural tube defects (ONTDs) during the second trimester, and the screening efficiency of different risk models remain indistinct. We conducted a retrospective case-control study, and studied 57 pregnant women with ONTD fetuses and 569 pregnant women with normal fetuses. The receiver operating characteristic curve method indicated the best cutoff value and area under the curve (AUC). The predictive value of ONTD risk models by free β-hCG, AFP, AFP-L2, and AFP-L3 was investigated via integrated discrimination improvement (IDI), net reclassification improvement (NRI), and decision curve analysis (DCA). Compared to the control group, AFP, AFP-L2, and AFP-L3 levels were significantly higher, while free β-hCG level was significantly lower in the study group. The triple-index model of free β-hCG + AFP-L2 + AFP-L3 and the dual-index model of AFP-L2 + AFP-L3 showed the best predictive values, respectively (AUC = 0.905; AUC = 0.885). The order of the single-index model AUCs was AFP-L3 > AFP-L2 > AFP > free β-hCG. The negative predictive value, false positive rate, and negative likelihood ratio of AFP-L2, AFP-L3 alone, or combined with free β- hCG were better than those of AFP alone; however, the positive likelihood ratio was the opposite. The replacement of AFP by AFP-L2 or AFP-L3 combined with free β-hCG increased the IDI and NRI for predicting ONTD. The top five DCAs were AFP-L2 + free β-hCG, free β-hCG, AFP-L3, AFP + free β-hCG, and AFP. Indicators of maternal serum free β-hCG, AFP-L2, and AFP-L3 in the second trimester exhibited high sensitivity and specificity screening for ONTD fetuses. Risk models constructed using AFP-L2 + AFP-L3 and AFP-L2 + AFP-L3 + free β-hCG demonstrated better screening efficiency.

Cerebral Abnormalities in Spina Bifida: A Neuropathological Study

INTRODUCTION

Spina bifida (SB) is the most common neural tube defect in humans. Here, we analyzed systematically the neuropathological findings of the brain in SB cases.

METHODS

79 cases with SB aperta (SBA) and 6 cases with SB occulta (SBO) autopsied at the Charité Neuropathology from 1974 to 2000 were re-evaluated retrospectively. For this, case files and spinal cord as well as brain sections were studied.

RESULTS

While no brain malformations were detected in SBO cases, 95% of SBA cases had brain malformations. Main brain anomalies identified were hydrocephalus (71%), Chiari II malformation (36%), heterotopia (34%), other cerebellar anomalies (36%), gyrification defects (33%), and ependymal denudation (29%). Hydrocephalus was observed as early as gestational week 17 and was highly associated to Chiari II and ependymal denudation. In 55% SBA was accompanied by further anomalies not primarily affecting the CNS.

CONCLUSION

We confirm using neuropathologic methods brain malformations in most SBA but none in SBO cases. In addition to our previous radiologic study, we now demonstrate the high prevalence of cerebellar malformations and cerebral heterotopias in SBA. The early detection of hydrocephalus and Chiari II malformation in fetuses raises the question whether these arise parallel rather than in strict temporal sequence.