Spinal Imaging Findings of Open Spinal Dysraphisms on Fetal and Postnatal MRI

MRI analysis of neurodevelopmental anatomy in myelomeningocele: prenatal vs postnatal repair

OBJECTIVE

Compared with postnatal repair, prenatal myelomeningocele (MMC) repair is associated with improved motor function and decreased need for cerebrospinal fluid (CSF) diversion. It is unknown how prenatal surgery alters neuroanatomical structures identifiable on magnetic resonance imaging (MRI). The purpose of this study was to use MRI to compare neurodevelopmental anatomy in patients undergoing fetal MMC repair compared with those undergoing postnatal repair.

METHODS

This was a retrospective review of neonates who underwent prenatal or postnatal MMC repair at our institution between 2016 and 2021. Imaging data, including prenatal ultrasound and pre- and postnatal MRI examinations, if available, were retrieved. We analyzed anatomical findings characteristically seen on MRI of the neuroaxis in patients with MMC and compared imaging findings between patients with prenatal vs postnatal MMC repair.

RESULTS

The study population included 61 patients who underwent surgical repair for MMC during the 6-year study period, of whom 25 underwent prenatal repair and 36 postnatal repair. CSF diversion was required in 24% of the prenatally repaired cohort vs 67% of the postnatally repaired cohort (P = 0.001). On postnatal MRI, a syrinx was present in 13% of the prenatally repaired cohort vs 42% in the postnatally repaired cohort (P = 0.02). Postnatal corpus callosal (CC) morphology was abnormal in 54% of the prenatally repaired cohort vs 53% of the postnatally repaired cohort (P = 0.92), while falx morphology was normal in 92% of the prenatally repaired cohort vs 34% of the postnatally repaired cohort (P < 0.001). On postnatal MRI, patients in the prenatally repaired cohort had a shorter tentorium-to-foramen-magnum distance compared with those in the postnatally repaired cohort (mean, 18.43 mm vs 22.42 mm; P = 0.01), a larger foramen magnum diameter (mean, 22.87 mm vs 18.94 mm; P < 0.001) and a smaller degree of hindbrain herniation (mean, 1.53 mm vs 8.72 mm; P < 0.001). The cerebral aqueduct was patent in 79% of the prenatally repaired cohort vs 100% of the postnatally repaired cohort on postnatal MRI (P = 0.008). Between the two cohorts, at postnatal MRI there was no significant difference in the presence of gray-matter heterotopia, presence of the septum pellucidum or size of the massa intermedia.

CONCLUSIONS

We report variations in developmental neuroanatomy in patients with MMC, including rates of CC dysgenesis, gray-matter heterotopia and additional cranial and spinal MRI findings. Compared to postnatal surgery, prenatal surgery is associated with changes to infratentorial anatomy, with minimal effect on supratentorial brain development. This information will be useful in counseling parents affected by fetal MMC and in understanding how prenatal repair of MMC affects brain development. © 2024 International Society of Ultrasound in Obstetrics and Gynecology.

Imaging Fetal Spine Malformations in the Context of In Utero Surgery

This review covers the embryology, definition, and diagnosis of open spinal dysraphism with a focus on fetal ultrasound and MR imaging findings. Differentiating open versus closed spinal dysraphic defects on fetal imaging will also be discussed. Current fetal surgery practices and imaging findings in the context of fetal surgery are also reviewed.

International Consensus Statement on the Radiological Evaluation of Dysraphic Malformations of the Spine and Spinal Cord

Dysraphic malformations of the spine and spinal cord (DMSSC) represent a spectrum of common congenital anomalies typically (though not exclusively) affecting the lower spinal segments. These may be responsible for varying degrees of neurologic, orthopedic, and urologic morbidity. With advances in neuroimaging, it is now possible to better diagnose and evaluate these disorders both prenatally and postnatally. Neuroimaging, performed at the right time and with technique optimization, is integral in guiding clinical management. However, the terminology used to describe these lesions has become increasingly confusing, and there is a lack of consensus regarding the essential radiologic features and their clinical weighting. This variability in radiologic practice risks unstructured decision making and increases the likelihood of suboptimal, less informed clinical management. In this manuscript, the first of a series of consensus statements, we outline a standardized international consensus statement for the radiologic evaluation of children with suspected DMSSC derived from a critical review of the literature, and the collective clinical experience of a multinational group of experts. We provide recommendations for plain radiography, sonography, CT, and MR imaging in the evaluation of DMSSC with an emphasis on technique of imaging and imaging protocols.

Family experiences of antenatal counselling of spina bifida: a systematic review

OBJECTIVE

To describe families' experiences of antenatal counselling of spina bifida.

DESIGN

Systematic review.

METHODS

MEDLINE, CINAHL, PsycINFO and Embase databases were searched using a combination of Medical Subject Headings and text/abstract terms. Case reports, survey results and qualitative interview data were included. The quality of research was evaluated using the Critical Appraisal Skills Programme checklist.

RESULTS

8 papers were included. Families described shock and grief at diagnosis, with some immediately offered termination of pregnancy (TOP) even though they knew little about the condition. Positive and negative aspects of care were found. Teams that were gentle, kind and empathetic, who did not use jargon, and highlighted positive and negative aspects of the baby's life were seen favourably. Callous language, and overly negative or incorrect counselling was not, particularly if there was pressure to agree to TOP. Families based their decisions on how they would cope, the effect on siblings and the baby's likely quality of life. Prenatal surgery was viewed positively. The views of families who chose TOP, were happy with their care, partners, families, and the LGBTQ+ community were under-represented in the literature.

CONCLUSIONS

Unlike other conditions where limited data on outcome exist or the spectrum is genuinely broad, the outcomes of children with spina bifida is well described. Poor aspects of antenatal counselling were described frequently by families, and further work is needed to capture the full spectrum of views on antenatal counselling, how it can be improved, and what training and resources healthcare professionals need to perform it better.

Comparison between MRI and the Combination of 2D and 3D US in the Prenatal Diagnosis of Closed Spina Bifida

INTRODUCTION

Closed spina bifida (CSB) is a rare condition with a challenging prenatal diagnosis. Herein, we assess the conventional two-dimensional (2D) ultrasound (US) combined with three-dimensional (3D) ultrasound (US) and magnetic resonance imaging (MRI) in the prenatal diagnosis of CSB.

METHODS

In this retrospective study, we included 20 cases of fetal CSB confirmed by postnatal MRI, post-mortem pathological examination, or postpartum surgery. Prenatal 2D US complemented with the 3D US was performed in all fetuses to evaluate the characteristics of the conus, vertebral arch, and scoliosis. Moreover, MRI was performed to establish the split vertebrae, with or without a bulging mass. Thereafter, we compared the performance of the US and MRI.

RESULTS

Diagnosis accuracy of US was comparable with MRI (70% vs. 75%, κ = 0.62); US detected more cases with interpediculate distance ≥95% (55% vs. 35%, κ = 0.22) than MRI. On the other hand, MRI had a superior capacity for identifying vertebral arch fissures (20% vs. 35%, κ = 0.39). MRI and ultrasound had good agreement in the conus medullaris (65% vs. 70%, κ = 0.42) and scoliosis (45% vs. 35%, κ = 0.59). Both US and MRI detected 1 (5.0%) case with "lemon sign" and "banana sign." The missed diagnosis rates of US and MRI were 15% (3/20) and 5% (1/20), respectively. The misdiagnosis rates of US and MRI were 15.0% (3/20) and 20.0% (4/20), respectively.

CONCLUSION

Both MRI and 2D US combined with the 3D US had excellent performance in prenatal diagnosis of CSB.

Advances in Fetal Surgical Repair of Open Spina Bifida

Spina bifida remains a common congenital anomaly of the central nervous system despite national fortification of foods with folic acid, with a prevalence of 2-4 per 10,000 live births. Prenatal screening for the early detection of this condition provides patients with the opportunity to consider various management options during pregnancy. Prenatal repair of open spina bifida, traditionally performed by the open maternal-fetal surgical approach through hysterotomy, has been shown to improve outcomes for the child, including decreased need for cerebrospinal fluid diversion surgery and improved lower neuromotor function. However, the open maternal-fetal surgical approach is associated with relatively increased risk for the patient and the overall pregnancy, as well as future pregnancies. Recent advances in minimally invasive prenatal repair of open spina bifida through fetoscopy have shown similar benefits for the child but relatively improved outcomes for the pregnant patient and future childbearing.

Fetal MRI prior to intrauterine surgery of open neural tube defects: What does the radiologist need to know

The management of myelomeningocele study trial showed significant prognostic improvement in fetal repair before 26 weeks of gestation. Hence, surgery in utero represents the best treatment option for open-neural tube defects (NTDs). Fetal surgery of open-NTDs has specific inclusion and exclusion criteria, which can be adequately studied with fetal MRI. The main concern: the spine (spinal defects other than Myelomeningocele and Myeloschisis, the level of the lesion higher than T1 or lower than S1 and the degree of kyphosis ≥ 30°), the skull/brain (no cerebellum herniation and Chiari II malformation and the presence of any intracranial abnormality unrelated to open NTDs), the uterus (cervix length less than 2 cm, multiple gestations and placental and uterine abnormalities) and any other fetal abnormality not attributed to spinal defect. In this review, we describe the fundamental role of fetal MRI in supporting therapeutic decisions in pre-surgery intrauterine planning through the accurate and comprehensive description of findings, providing a proposal of a structured report. In addition, we describe how post-surgical MRI is important in investigating the effectiveness of surgery and detecting repairing complications.

The Role of Fetal Brain Magnetic Resonance Imaging in Current Fetal Medicine

In open spina bifida we studied the use of MRI for the assessment of the posterior fossa and prevalence of supratentorial anomalies before and after in utero repair. New postprocessing techniques were applied to evaluate fetal brain development in this population compared to controls. In fetuses with congenital diaphragmatic hernia, we evaluated the brain development in comparison to controls. Diffusion weighted imaging was applied to study difference between fetuses with proven first trimester cytomegalovirus infection and controls. Finally, we investigated the value of third trimester fetal brain MRI after treatment for complicated monochorionic diamniotic pregnancies.

Fetoscopic Myelomeningocele Repair with Complete Release of the Tethered Spinal Cord Using a Three-Port Technique: Twelve-Month Follow-Up-A Case Report

Open spina bifida is one of the most common congenital defects of the central nervous system. Open fetal surgery, which is one of the available therapeutic options, remains the gold standard for prenatal repairs. Fetoscopic closure may lower the number of maternal complications associated with open fetal surgery. Regardless of the approach, the outcome may be compromised by the development of tethered spinal cord (TSC) syndrome. At 24.2 weeks of gestation, a primipara was admitted due to fetal myelomeningocele and was deemed eligible for fetoscopic repair. Fetal surgery was performed at 25.0 weeks of gestation. It was the first complete untethering of the spinal cord and anatomic reconstruction (dura mater, spinal erectors, skin) achieved during a fetoscopic repair of spina bifida. Cesarean section due to placental abruption was performed at 31.1 weeks of gestation. VP shunting, with no need for revision, was performed at 5 weeks postdelivery due to progressing ventriculomegaly. No clinical or radiological signs of secondary tethering were observed. Neurological examination at 11 months postdelivery revealed cranial nerves without any signs of damage, axial hypotonia, decreased muscle tone in the lower extremities, and absent pathological reflexes. Motor development was slightly retarded. Complete untethering of the neural structures should always be performed, regardless of the surgical approach, as it is the only course of action that lowers the risk for developing secondary TSC.

Ascent of the conus medullaris in human foetuses: a systematic review and meta-analysis

The aim of the present systematic review and meta-analysis was to identify when the ascent of the conus medullaris occurs in human foetuses considering differences in evaluation methods and sample characteristics. Five databases were searched for relevant articles using different combinations of keywords. Article selection and data extraction were performed independently by two reviewers. Disagreements were resolved by a third reviewer. The variables were distributed into four groups according to the gestational age of the specimens: I (13-18 weeks); II (19-25 weeks); III (26-32 weeks); IV (33 weeks to the probable date of birth). Eighteen articles were included. The majority used imaging exams as the evaluation method. Cadaveric dissections were reported in the remaining articles. Only morphological studies were included in the meta-analysis. Significant ascent occurs between groups I and III as well as groups II and IV. Despite the considerable heterogeneity among the studies included in the present review, the findings enabled the determination that the conus medullaris reaches its normal birth level by the 26th week. Further analyses should be performed based on nationality and ethnicity to diminish the heterogeneity of the data.

Value of pre- and postnatal magnetic resonance imaging in the evaluation of congenital central nervous system anomalies

Fetal MRI and neonatal MRI of the central nervous system (CNS) are complementary tools that can help to accurately counsel and direct the management of children with anomalies of the central nervous system. Postnatal MRI can add to fetal MRI by allowing for monitoring of changes in the severity of disease, better delineation of a suspected prenatal anomaly, evaluation for secondary pathologies related to the primary diagnosis, and surgical management direction. In this review we discuss the roles of fetal and neonatal MRI in the diagnosis and treatment of congenital anomalies of the CNS through a series of case examples and how both are important in patient management.

Fetal magnetic resonance imaging of lumbar spine development in vivo: a retrospective study

OBJECTIVE

The aim of this study is to describe MR imaging appearances of the fetal lumbar spine in vivo at different gestational ages (GAs).

METHODS

This retrospective study was approved by the Third Affiliated Hospital of Zhengzhou University. We collected MR images and clinical data of 93 fetuses in our hospital. All the MR images were obtained by 3-T MR. All had the mid-sagittal plane of steady state free precession sequence (Trufi) of the lumbar spine, which could show the lumbar vertebra and conus medullaris (CM). Regression analysis was made between GA and heights of lumbar vertebral body ossification center (LVBOC), lengths of LVBOC, and heights of intervertebral gap (IVG).

RESULTS

There were good linear correlations between the heights of LVBOC and GA (P < 0.001), lengths of LVBOC and GA (P < 0.001), and heights of IVG and GA (P < 0.001).

CONCLUSION

We showed the different development of each LVBOC and IVG which caused the difference of the shape of LVBOC and IVG.

Antenatal counselling for prospective parents whose fetus has a neurological anomaly: part 2, risks of adverse outcome in common anomalies

After diagnosis of a fetal neurological anomaly, prospective parents want to know the best and worst-case scenarios and an estimation of the risk to their infant of having an atypical developmental outcome. The literature on developmental outcomes for fetal neurological anomalies is poor: studies are characterized by retrospective design, small sample size, often no standardized assessment of development, and differing definitions of anomalies. This review provides an aide-memoir on the risks of adverse neurodevelopmental outcome for ventriculomegaly, cortical anomalies, microcephaly, macrocephaly, agenesis of the corpus callosum, posterior fossa anomalies, and myelomeningocele, to assist healthcare professionals in counselling. The data in this review should be used alongside recommendations on counselling and service design described in part 1 to provide antenatal counselling.

Arnold-Chiari Malformation: Core Concepts

Arnold-Chiari malformation (ACM), a defect that involves downward displacement of the hindbrain and herniation of the cerebellar vermis, tonsils, pons, medulla, and fourth ventricle through the foramen magnum, is the most complex of the 4 types of Chiari malformations. Unique to the other types of Chiari malformations, approximately 95 percent of infants with ACM also present with an associated myelomeningocele (MMC), the most severe form of spina bifida. Among affected infants, those with symptomatic comorbidities incur a significantly higher morbidity and mortality risk. Prompt identification and diagnosis of ACM, as well as evidence-based postnatal and postsurgical nursing and medical care, is critical. Early surgical intervention can repair an existing MMC and restore proper cerebrospinal fluid circulation, which can dramatically improve patient outcomes and quality of life, and reduce disease and health care burden.

Myelomeningocele-Chiari II malformation-Neurological predictability based on fetal and postnatal magnetic resonance imaging

Objective

This systematic comparison between pre‐ and postnatal imaging findings and postnatal motor outcome assesses the reliability of MRI accuracy in the prognostication of the future long‐term (mean, 11.4 years) ambulatory status in a historic group of postnatally repaired myelomeningocele (MMC) cases.

Methods

A retrospective, single‐center study of 34 postnatally repaired MMC patients was performed. We used fetal and postnatal magnetic resonance imaging (MRI) to compare the fetal and postnatal radiological lesion level to each other and to the postnatal ambulatory level as a standard of reference and analyzed Chiari II malformation characteristics.

Results

In 13/15 (87%) and 29/31 (94%) cases, the functional level was equal to or better than the prenatal and postnatal radiological lesion level. A radiological lesion level agreement within two segments could be achieved in 13/15 (87%) patients. A worse than expected functional level occurred in cases with Myelocele (2/3 patients), coexistent crowding of the posterior fossa (2/3 patients) and/or abnormal white matter architecture, represented by callosal dysgenesis (1/3 patients). In all patients (2/2) with a radiological disagreement of more than two segments, segmentation disorders and scoliosis were observed.

Conclusion

Fetal and postnatal MRI are predictive of the long‐term ambulatory status in postnatally repaired MMC patients.

What's already known about this topic?

Fetal and postnatal magnetic resonance imaging (MRI) show a good correlation in identifying the level of the myelomeningocele (MMC) lesion.

Prenatal ultrasound (US) and fetal MRI show a comparable agreement, within two segments, in predicting the short‐term ambulatory status.

What does this study add?

Fetal and postnatal MRI have a good predictive value for the long‐term ambulatory status in patients with postnatal MMC closure.

MMC patients with worse than expected ambulatory status showed signs of vermian displacement and corpus callosum dysgenesis.

In MMC patients with spinal segmentation disorders and scoliosis, there was a major disagreement between fetal and postnatal MRI, specifically with regard to the MMC lesion level.

Diagnostic accuracy of prenatal ultrasound in identifying the level of the lesion in fetuses with open spina bifida: A systematic review and meta-analysis

INTRODUCTION

The role of prenatal ultrasound in correctly identifying the level of the lesion in fetuses with open spina bifida has yet to be determined. The primary aim of this systematic review was to report the diagnostic accuracy of ultrasound in determining the level of the lesion in fetuses with open spina bifida. The secondary aim was to elucidate whether prenatal magnetic resonance imaging (MRI) improves the diagnostic performance of prenatal imaging in correctly identifying the level of the lesion.

MATERIAL AND METHODS

Inclusion criteria were studies reporting the agreement between ultrasound, MRI and postnatal or postmortem assessment of fetuses with spina bifida. Agreement was defined as: complete (when the upper level of the lesion detected prenatally was the same recorded at postnatal or postmortem evaluation), within one (when the upper level of the lesion recorded prenatally was within one vertebral body higher or lower than that reported postnatally) and within two vertebral bodies (when the upper level of the lesion recorded prenatally was within two vertebral bodies higher or lower than that reported postnatally or postmortem evaluation). Meta-analyses of proportions were used to combine data.

RESULTS

Fourteen studies (655 fetuses) were included. Ultrasound was able to identify the correct level of the lesion in 40.9% (95% confidence interval [CI] 26.9-55.6) of cases. The upper level of the lesion recorded on ultrasound was within one vertebral body in 76.2% (95% CI 65.0-85.9) of cases and within two segments in 92.4% (95% CI 84.3-97.7). Fetal MRI detected the exact level of the lesion in 42.5% (95% CI 35.9-45.2) of cases; the level of the lesion recorded on MRI was higher in 26.4% (95% CI 20.0-33.3) of cases and lower in 32.4% (95% CI 25.5-39.7) than that confirmed postnatally. The upper level of the lesion recorded on MRI was within one vertebral body in 76.2% (95% CI 65.9-85.2) of cases and within two segments in 94.2% (95% CI 90.2-97.2).

CONCLUSIONS

Both ultrasound and MRI have a moderate diagnostic accuracy in identify the upper level of the lesion in fetuses with open spina bifida.

Imaging of open spinal dysraphisms in the era of prenatal surgery

Over the last decade fetal surgery to repair open spinal dysraphisms has become an acceptable and in some cases desirable alternative to the traditional method of postnatal closure. Fetal MRI is an essential part of the workup in these patients, not only to select the appropriate candidates for fetal surgery but also to guide prenatal counseling and perinatal management. In this article we review current surgical techniques for prenatal repair, relevant imaging findings in the era of fetal surgery, and expected imaging findings of the brain and spine in the fetal and postnatal periods.

The Perplexity Surrounding Chiari Malformations - Are We Any Wiser Now?

Chiari malformations are a diverse group of abnormalities of the brain, craniovertebral junction, and the spine. Chiari 0, I, and 1.5 malformations, likely a spectrum of the same malformation with increasing severity, are due to the inadequacy of the para-axial mesoderm, which leads to insufficient development of occipital somites. Chiari II malformation is possibly due to nonclosure of the caudal end of the neuropore, with similar pathogenesis in the rostral end, which causes a Chiari III malformation. There have been significant developments in the understanding of this complex entity owing to insights into the pathogenesis and advancements in imaging modalities and neurosurgical techniques. This article aims to review the different types and pathophysiology of the Chiari malformations, along with a description of the various associated abnormalities. We also highlight the role of ante- and postnatal imaging, with a focus on the newer techniques in the presurgical evaluation, with a brief mention of the surgical procedures and the associated postsurgical complications.

Unveiling the tale of the tail: an illustration of spinal dysraphisms

Spinal dysraphism is an umbrella term describing herniation of meninges or neural elements through defective neural arch. They can be broadly categorized into open and closed types. MRI is the investigation of choice to study neural abnormalities and to assess the severity of hydrocephalus and Chiari malformation. Knowledge of the embryology of these disorders is valuable in correctly identifying the type of dysraphism. The aim of surgery is untethering and dural reconstruction. Accurate depiction of the abnormal anatomy in cases of spinal dysraphism is of utmost importance for surgical management of these patients. MRI makes this possible due to its excellent soft tissue contrast resolution and multiplanar capability, allowing the radiologist to evaluate the intricate details in small pediatric spinal structures. Imaging enlightens the surgeons about the status of spinal cord and other associated abnormalities and helps detect re-tethering in operated cases. Besides, antenatal surgery to repair myelomeningoceles has made detection of open dysraphisms on fetal MRI and antenatal ultrasound critical. The purpose of this review is to describe the development of spine, illustrate the myriad imaging features of open and closed spinal dysraphisms, and enlist the reporting points the operating surgeon seeks from the radiologist.

Prenatal and postnatal MRI findings in open spinal dysraphism following intrauterine repair via open versus fetoscopic surgical techniques

PURPOSE

The purpose of the study is to examine MRI findings of the brain and spine on prenatal and postnatal MRI following intrauterine repair of open spinal dysraphism (OSD) by open hysterotomy and fetoscopic approaches.

MATERIALS AND METHODS

This study is a single-center HIPAA-compliant and IRB-approved retrospective analysis of fetal MRIs with open spinal dysraphism from January 2011 through December 2018 that underwent subsequent prenatal repair of OSD.

RESULTS

Sixty-two patients met inclusion criteria: 47 underwent open repair, and 15 underwent fetoscopic repair, with an average gestational age of 22.6 ± 1.4 weeks at initial MRI. On postnatal MRI, spinal cord syrinx was seen in 34% (16/47) of patients undergoing open versus 33.3% (5/15) undergoing fetoscopic repair (P = 0.96). Postnatally, there was no significant difference in hindbrain herniation between the open versus fetoscopic repair groups (P = 0.28). Lateral ventricular size was significantly larger in the open (20.9 ± 6.7 mm) versus the fetoscopic repair (16.1 ± 4.9 mm) group (P = 0.01).

CONCLUSION

Though lateral ventricular size in the open repair group was larger than the fetoscopic repair group, this can likely be explained by initial selection criteria used for fetoscopic repair. Other postoperative imaging parameters on postnatal MRI were not significantly different between the two groups.