New insights in cerebral findings associated with fetal myelomeningocele: a retrospective cohort study in a single tertiary centre

Molecular insights into myelomeningocele via proteomic analysis of amniotic fluid

Despite numerous studies on fetal therapy for myelomeningoceles (MMC), the pathophysiology of this malformation remains poorly understood. This study aimed to analyze the biochemical profile and proteome of amniotic fluid (AF) supernatants from MMC fetuses to explore the prenatal pathophysiology. Biochemical analysis of 61 AF samples from MMC fetuses was compared with 45 healthy fetuses' samples. Proteome analysis was conducted in 18 MMC and 18 healthy singleton fetuses, and in 5 dichorionic pregnancies with MMC fetuses and their healthy co-twins. ELISA tests were used to validate proteome results. Biochemical analysis revealed anal incontinence in 37 % of MMC cases, absent in controls (p < 0.0001). Proteomics identified 2453 quantified proteins with 39 significantly up-regulated and 10 down-regulated in the MMC group. Up-regulated proteins included ectodomains of CHL1, APLP1, SEZ6, SEZ6L, known targets of the protease BACE1. We explored the overlap of neonatal cerebrospinal fluid (CSF) and AF proteome and highlighted 411 proteins in common, mostly upregulated in MMC AF compared to controls. Our study thoroughly characterizes the AF proteome and reveals numerous proteins to be changed as a consequence of MMC. Many of these proteins are typical constituents of CSF. No difference in AF inflammation markers were observed between MMC and healthy fetuses. SIGNIFICANCE: This study provides good evidence that neuroepithelial destruction in MMC is independent of inflammation or presumed meconium toxicity.

Periventricular nodular heterotopia in patients with a prenatal diagnosis of myelomeningocele/myeloschisis: associations with seizures and neurodevelopmental outcomes during early childhood

PURPOSE

Historically, the presence of gray matter heterotopia was a concern for adverse postnatal neurocognitive status in patients undergoing fetal closure of open spinal dysraphism. The purpose of this study was to evaluate neurodevelopmental outcomes and the onset of seizures during early childhood in patients with a prenatal diagnosis of myelomeningocele/myeloschisis (MMC) and periventricular nodular heterotopia (PVNH).

METHODS

All patients evaluated at the Center for Fetal Diagnosis and Treatment with a diagnosis of MMC between June 2016 to March 2023 were identified. PVNH was determined from prenatal and/or postnatal MRI. The Bayley Scales of Infant and Toddler Development (edition III or IV) were used for neurodevelopmental assessments. Patients were screened for seizures/epilepsy.

RESULTS

Of 497 patients evaluated with a prenatal diagnosis of MMC, 99 were found to have PVNH on prenatal MRI, of which 35 had confirmed PVNH on postnatal imaging. From the 497 patients, 398 initially did not exhibit heterotopia on prenatal MRI, but 47 of these then had confirmed postnatal PVNH. The presence of PVNH was not a significant risk factor for postnatal seizures in early childhood. The average neurodevelopmental scores were not significantly different among heterotopia groups for cognitive, language, and motor domains.

CONCLUSION

The presence of PVNH in patients with a prenatal diagnosis of MMC does not indicate an increased risk for neurodevelopmental delay at 1 year of age. We did not demonstrate an association with seizures/epilepsy. These findings can aid clinicians in prenatal consultation regarding fetal repair of open spinal dysraphism. Long-term follow-up is required to discern the true association between PVNH seen on prenatal imaging and postnatal seizures/epilepsy and neurodevelopmental outcomes.

Prenatal imaging of the normal and abnormal spinal cord: recommendations from the Fetal Task Force of the European Society of Paediatric Radiology (ESPR) and the European Society of Neuroradiology (ESNR) Pediatric Neuroradiology Committee

Spinal dysraphisms are amenable to diagnosis in utero. The prognosis and the neonatal management of these conditions differ significantly depending on their types, mainly on the distinction between open and closed defects. A detailed evaluation not only of the fetal spine, but also of the brain, skull, and lower limbs is essential in allowing for the right diagnosis. In this article, recommendations from the Fetal Task Force of the European Society of Paediatric Radiology (ESPR) and the European Society of Neuroradiology (ESNR) Pediatric Neuroradiology Committee will be presented. The aim of this paper is to review the imaging features of the normal and abnormal fetal spinal cord, to clarify the prenatal classification of congenital spinal cord anomalies and to provide guidance in their reporting.

Assessment of longitudinal brain development using super-resolution magnetic resonance imaging following fetal surgery for open spina bifida

OBJECTIVES

Prenatal surgery is offered for selected fetuses with open spina bifida (OSB) to improve long-term outcome. We studied the effect of fetal OSB surgery on brain development using advanced magnetic resonance imaging (MRI) techniques to quantify the volume, surface area and shape of cerebral structures and to analyze surface curvature by means of parameters that correspond to gyrification.

METHODS

We compared MRI data from 29 fetuses with OSB before fetal surgery (mean gestational age (GA), 23 + 3 weeks) and at 1 and 6 weeks after surgery, with that of 36 GA-matched control fetuses (GA range, 21 + 2 to 36 + 2 weeks). Automated super-resolution reconstruction provided three-dimensional isotropic volumetric brain images. Unmyelinated white matter, cerebellum and ventricles were segmented automatically and refined manually, after which volume, surface area and shape parameter (volume/surface area) were quantified. Mathematical markers (shape index (SI) and curvedness) were used to measure gyrification. Parameters were assessed according to lesion type (myelomeningocele vs myeloschisis (MS)), postoperative persistence of hindbrain herniation (HH) and the presence of supratentorial anomalies, namely partial agenesis of the corpus callosum (pACC) and heterotopia (HT).

RESULTS

Growth in ventricular volume per week and change in shape parameter per week were higher at 6 weeks after surgery in fetuses with OSB compared with controls (median, 2500.94 (interquartile range (IQR), 1689.70-3580.80) mm3 /week vs 708.21 (IQR, 474.50-925.00) mm3 /week; P < 0.001 and 0.075 (IQR, 0.047-0.112) mm/week vs 0.022 (IQR, 0.009-0.042) mm/week; P = 0.046, respectively). Ventricular volume growth increased 6 weeks after surgery in cases with pACC (P < 0.001) and those with persistent HH (P = 0.002). During that time period, the change in unmyelinated white-matter shape parameter per week was decreased in OSB fetuses compared with controls (0.056 (IQR, 0.044-0.092) mm/week vs 0.159 (IQR, 0.100-0.247) mm/week; P = 0.002), particularly in cases with persistent HH (P = 0.011), MS (P = 0.015), HT (P = 0.022), HT with corpus callosum anomaly (P = 0.017) and persistent HH with corpus callosum anomaly (P = 0.007). At 6 weeks postoperatively, despite OSB fetuses having a lower rate of change in curvedness compared with controls (0.061 (IQR, 0.040-0.093) mm-1 /week vs 0.094 (IQR, 0.070-0.146) mm-1 /week; P < 0.001), reversing the trend seen at 1 week after surgery (0.144 (IQR, 0.099-0.236) mm-1 /week vs 0.072 (IQR, 0.059-0.081) mm-1 /week; P < 0.001), gyrification, as determined using SI, appeared to be increased in OSB fetuses overall compared with controls. This observation was more prominent in fetuses with pACC and those with severe ventriculomegaly (P-value range, < 0.001 to 0.006).

CONCLUSIONS

Following fetal OSB repair, volume, shape and curvedness of ventricles and unmyelinated white matter differed significantly compared with those of normal fetuses. Morphological brain changes after fetal surgery were not limited to effects on the circulation of cerebrospinal fluid. These observations may have implications for postnatal neurocognitive outcome. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Evaluation of the height of the corpus callosum body region in fetal meningomyelocele malformation

PURPOSE

To investigate height of the corpus callosum (CC) in order to describe the corpus callosum anomalies in fetuses with meningomyelocele (MMC) and compare these findings with the corpus callosum of healthy fetuses.

METHODS

In this study, fetal MRI examinations were performed on 44 fetal MMC malformation cases. As the control group, 34 fetal MRI examinations, which were anatomically normal, were evaluated retrospectively. In the study group, lateral ventricle diameter, the level and diameter of the MMC defect, and CC height were measured. In the control group, CC height and lateral ventricular diameter were measured.

RESULTS

The mean CC body height was 1.36 mm in the study group, and 2.48 mm in the control group. The height of the CC body region of the study population was inclined to be thinner compared with the control population (p<0.001).

CONCLUSIONS

The fact that the height of the CC body region was found to be thinner in fetal MRI in cases of MMC compared with normal fetuses suggests that various callosal anomalies are uncertain, investigation of additional callosal anomalies may be beneficial in the decision for the continuation of pregnancy, and termination or intrauterine surgery in cases with MMC. Further large case group studies are needed.

Long-Term Imaging Follow-up from the Management of Myelomeningocele Study

BACKGROUND AND PURPOSE

Short-term results demonstrate that prenatal repair of a myelomeningocele is associated with a reduction in hydrocephalus and an increased likelihood of the reversal of Chiari II malformations compared with postnatal repair. The purpose of this study was to identify the long-term imaging findings at school age among subjects who underwent pre- versus postnatal repair of a myelomeningocele.

MATERIALS AND METHODS

A subset of subjects enrolled in the Management of Myelomeningocele Study who underwent either prenatal (n = 66) or postnatal (n = 63) repair of a lumbosacral myelomeningocele and had follow-up brain MR imaging at school age were included. The prevalence of posterior fossa features of Chiari II malformation and supratentorial abnormalities and the change in these findings from fetal to school-age MR imaging were compared between the 2 groups.

RESULTS

Prenatal repair of a myelomeningocele was associated with higher rates of normal location of fourth ventricle and lower rates of hindbrain herniation, cerebellar herniation, tectal beaking, brainstem distortion, and kinking at school age compared with postnatal repair (all P < .01). Supratentorial abnormalities, including corpus callosal abnormalities, gyral abnormalities, heterotopia, and hemorrhage, were not significantly different between the 2 groups (all P > .05). The rates of resolution of brainstem kinking, tectal beaking, cerebellar and hindbrain herniation, and normalization of fourth ventricle size from fetal to school age MR imaging were higher among the prenatal compared with postnatal surgery group (all, P < .02).

CONCLUSIONS

Prenatal repair of a myelomeningocele is associated with persistent improvement in posterior fossa imaging findings of Chiari II malformation at school age compared with postnatal repair.

What brain abnormalities can magnetic resonance imaging detect in foetal and early neonatal spina bifida: a systematic review

PURPOSE

Open spina bifida (OSB) encompasses a wide spectrum of intracranial abnormalities. With foetal surgery as a new treatment option, robust intracranial imaging is important for comprehensive preoperative evaluation and prognostication. We aimed to determine the incidence of infratentorial and supratentorial findings detected by magnetic resonance imaging (MRI) alone and MRI compared to ultrasound.

METHODS

Two systematic reviews comparing MRI to ultrasound and MRI alone were conducted on MEDLINE, EMBASE, and Cochrane databases identifying studies of foetal OSB from 2000 to 2020. Intracranial imaging findings were analysed at ≤ 26 or > 26 weeks gestation and neonates (≤ 28 days). Data was independently extracted by two reviewers and meta-analysis was performed where possible.

RESULTS

Thirty-six studies reported brain abnormalities detected by MRI alone in patients who previously had an ultrasound. Callosal dysgenesis was identified in 4/29 cases (2 foetuses ≤ 26 weeks, 1 foetus under any gestation, and 1 neonate ≤ 28 days) (15.1%, CI:5.7-34.3%). Heterotopia was identified in 7/40 foetuses ≤ 26 weeks (19.8%, CI:7.7-42.2%), 9/36 foetuses > 26 weeks (25.3%, CI:13.7-41.9%), and 64/250 neonates ≤ 28 days (26.9%, CI:15.3-42.8%). Additional abnormalities included aberrant cortical folding and other Chiari II malformation findings such as lower cervicomedullary kink level, tectal beaking, and hypoplastic tentorium. Eight studies compared MRI directly to ultrasound, but due to reporting inconsistencies, it was not possible to meta-analyse.

CONCLUSION

MRI is able to detect anomalies hitherto underestimated in foetal OSB which may be important for case selection. In view of increasing prenatal OSB surgery, further studies are required to assess developmental consequences of these findings.

Incidence and patterns of abnormal corpus callosum in fetuses with isolated spina bifida aperta

OBJECTIVE

To determine the incidence and characterise corpus callosum (CC) abnormalities in fetuses with spina bifida aperta (SBA) between 18 and 26 weeks of gestation.

METHODS

This was a retrospective study on fetuses with isolated SBA and who were assessed for fetal surgery. Digitally stored ultrasound images of the brain were reviewed for the presence/absence of the CC, and the length and diameter of its constituent parts (rostrum, genu, body and splenium). We used regression analysis to determine the relationship between CC abnormalities and gestational age, head circumference, ventricle size, lesion level and lesion type.

RESULTS

Nearly three-quarters of fetuses with isolated SBA had an abnormal CC (71.7%, 76/106). Partial agenesis was most common in the splenium (18.9%, 20/106) and the rostrum (13.2%, 14/106). The most common abnormal pattern was of a short CC with normal diameter throughout. Of note, 20.8% (22/106) had a hypoplastic genu and 28.3% (30/106) had a thick body part. Larger lateral ventricle size was associated with partial agenesis of the CC (odds ratio [OR]: 0.14, p < 0.001) and inversely associated with a shorter CC (OR: 2.60, p < 0.01).

CONCLUSION

An abnormal CC is common in fetuses with isolated SBA who are referred for fetal surgery.

[Prenatal ultrasound prognostic of myelomeningocele at the era of fetal surgery]

Myelomeningocele (MMC) is a severe congenital condition responsible for motor and sensory impairments of the lower limbs, incontinence and cognitive impairment. Its screening, sometimes as early as the first trimester, is one of the major goals of modern prenatal care, supported by the emergence of prenatal surgery that results in a significant improvement in motor function, ambulation and ventriculoperitoneal shunt rate in patients undergoing in-utero surgery. From screening to pre- and post-operative prognostic evaluation, prenatal ultrasound is now an essential tool in the antenatal management of this condition. Using the multi planar and three-dimensional modes, it can be used to assess the vertebral level of MMC, which remains the key antenatal prognostic marker for motor function and ambulation, incontinence and the need for a ventriculo-peritoneal shunt. A careful and systematic ultrasound examination also makes it possible to assess the severity and progression of ventriculomegaly, to search for associated cerebral, spinal cord or vertebral anomalies, or to rule out exclusion criteria for in-utero surgery such as severe kyphosis or serious cortical anomalies. New tools from post-natal evaluation, such as the "metameric" ultrasound assessment of lower limb mobility, appear to be promising either for the initial examination or after in-utero surgery. Ultrasonography, associated with fetal MRI, cytogenetic and next generation sequencing, now allows a highly customized prognostic evaluation of these fetuses affected by MMC and provides the parents with the best possible information on the expected benefits and limitations of fetal surgery.