Disorders of segmentation of the neural tube: Chiari malformations

Use of Artificial Intelligence in Recognition of Fetal Open Neural Tube Defect on Prenatal Ultrasound

To compare the axial cranial ultrasound images of normal and open neural tube defect (NTD) fetuses using a deep learning (DL) model and to assess its predictive accuracy in identifying open NTD.It was a prospective case-control study. Axial trans-thalamic fetal ultrasound images of participants with open fetal NTD and normal controls between 14 and 28 weeks of gestation were taken after consent. The images were divided into training, testing, and validation datasets randomly in the ratio of 70:15:15. The images were further processed and classified using DL convolutional neural network (CNN) transfer learning (TL) models. The TL models were trained for 50 epochs. The data was analyzed in terms of Cohen kappa score, accuracy score, area under receiver operating curve (AUROC) score, F1 score validity, sensitivity, and specificity of the test.A total of 59 cases and 116 controls were fully followed. Efficient net B0, Visual Geometry Group (VGG), and Inception V3 TL models were used. Both Efficient net B0 and VGG16 models gave similar high training and validation accuracy (100 and 95.83%, respectively). Using inception V3, the training and validation accuracy was 98.28 and 95.83%, respectively. The sensitivity and specificity of Efficient NetB0 was 100 and 89%, respectively, and was the best.The analysis of the changes in axial images of the fetal cranium using the DL model, Efficient Net B0 proved to be an effective model to be used in clinical application for the identification of open NTD. · Open spina bifida is often missed due to the nonrecognition of the lemon sign on ultrasound.. · Image classification using DL identified open spina bifida with excellent accuracy.. · The research is clinically relevant in low- and middle-income countries..

Prenatal assessment of brain malformations on neuroimaging: an expert panel review

Brain malformations represent a heterogeneous group of abnormalities of neural morphogenesis, often associated with aberrations of neuronal connectivity and brain volume. Prenatal detection of brain malformations requires a clear understanding of embryology and developmental morphology through the various stages of gestation. This expert panel review is written with the central aim of providing an easy-to-understand road map to improve prenatal detection and characterization of structural malformations based on the current understanding of normal and aberrant brain development. For every developmental stage, the utility of each available neuroimaging modality, including prenatal multiplanar neuro sonography, anatomical MRI and advanced MRI techniques, as well as further insights from post-mortem imaging, has been highlighted.

The Genetics of Chiari 1 Malformation

Chiari malformation type 1 (CM1) is a structural defect that involves the herniation of the cerebellar tonsils through the foramen magnum, causing mild to severe neurological symptoms. Little is known about the molecular and developmental mechanisms leading to its pathogenesis, prompting current efforts to elucidate genetic drivers. Inherited genetic disorders are reported in 2-3% of CM1 patients; however, CM1, including familial forms, is predominantly non-syndromic. Recent work has focused on identifying CM1-asscoiated variants through the study of both familial cases and de novo mutations using exome sequencing. This article aims to review the current understanding of the genetics of CM1. We discuss three broad classes of CM1 based on anatomy and link them with genetic lesions, including posterior fossa-linked, macrocephaly-linked, and connective tissue disorder-linked CM1. Although the genetics of CM1 are only beginning to be understood, we anticipate that additional studies with diverse patient populations, tissue types, and profiling technologies will reveal new insights in the coming years.

Revisiting the Pathophysiology of Intracranial Hemorrhage in Fetuses with Chiari II Malformation: Novel Imaging Biomarkers of Disease Severity?

BACKGROUND AND PURPOSE

Intracranial hemorrhage (ICH) has emerged as a notable concern in Chiari II malformation (CM II), yet its origins and clinical implications remain elusive. This study aims to validate the in utero prevalence of ICH in CM II and investigate contributing factors, and visualize the findings in a network format.

MATERIALS AND METHODS

A single-center retrospective review of fetal MRI scans obtained in fetuses with CM II (presenting January 2007 to December 2022) was performed for ICH utilizing EPI-T2* blood-sensitive sequence. Fetuses with aqueduct stenosis (AS) were included as a control group. The incidence of ICH and corresponding gestational ages were compared between CM II and AS cases, and morphometric measurements (inner/outer CSF spaces, posterior fossa, venous structure) were compared among the 4 1:1 age-matched groups: CM II+ICH, CM II-ICH, AS+ICH, and AS-ICH. Additionally, a co-occurrence network was constructed to visualize associations between phenotypic features in ICH cases.

RESULTS

A total of 101 fetuses with CM II and 90 controls with AS at a median gestational age of 24.4 weeks and 22.8 weeks (P = .138) were included. Prevalence of ICH in fetuses with CM II was higher compared with the AS cases (28.7% versus 18.9%, P = .023), accompanied by congested veins (deep vein congestion mainly in young fetuses, and cortical veins may also be affected in older fetuses). ICH was notably correlated with specific anatomic features, essentially characterized by reduced outer CSF spaces and clivus-supraocciput angle. The co-occurrence network analysis reveals complex connections including bony defects, small posterior fossa dimensions, vermis ectopia, reduced CSF spaces, as well as venous congestion and venous sinus stenosis as pivotal components within the network.

CONCLUSIONS

The high prevalence of ICH-detected by fetal MRI-among fetuses with CM emphasizes the pathophysiologic importance of venous congestion, ICH, and vasogenic edema. As indicators of disease severity, these features may serve as helpful additional imaging biomarkers for the identification of potential candidates for fetal surgery.

Multiparametric prenatal imaging characterization of fetal brain edema in Chiari II malformation might help to select candidates for fetal surgery

OBJECTIVE

To identify brain edema in fetuses with Chiari II malformation using a multiparametric approach including structural T2-weighted, diffusion tensor imaging (DTI) metrics, and MRI-based radiomics.

METHODS

A single-center retrospective review of MRI scans obtained in fetuses with Chiari II was performed. Brain edema cases were radiologically identified using the following MR criteria: brain parenchymal T2 prolongation, blurring of lamination, and effacement of external CSF spaces. Fractional anisotropy (FA) values were calculated from regions of interest (ROI), including hemispheric parenchyma, internal capsule, and corticospinal tract, and compared group-wise. After 1:1 age matching and manual single-slice 2D segmentation of the fetal brain parenchyma using ITK-Snap, radiomics features were extracted using pyradiomics. Areas under the curve (AUCs) of the features regarding discriminating subgroups were calculated.

RESULTS

Ninety-one fetuses with Chiari II underwent a total of 101 MRI scans at a median gestational age of 24.4 weeks and were included. Fifty scans were visually classified as Chiari II with brain edema group and showed significantly reduced external CSF spaces compared to the nonedema group (9.8 vs. 18.3 mm, p < 0.001). FA values of all used ROIs were elevated in the edema group (p < 0.001 for all ROIs). The 10 most important radiomics features showed an AUC of 0.81 (95%CI: 0.71, 0.91) for discriminating between Chiari II fetuses with and without edema.

CONCLUSIONS

Brain edema in fetuses with Chiari II is common and radiologically detectable on T2-weighted fetal MRI sequences, and DTI-based FA values and radiomics features provide further evidence of microstructure differences between subgroups with and without edema.

CLINICAL RELEVANCE STATEMENT

A more severe phenotype of fetuses with Chiari II malformation is characterized by prenatal brain edema and more postnatal clinical morbidity and disability. Fetal brain edema is a promising prenatal MR imaging biomarker candidate for optimizing the risk-benefit evaluation of selection for fetal surgery.

KEY POINTS

Brain edema of fetuses prenatally diagnosed with Chiari II malformation is a common, so far unknown, association. DTI metrics and radiomics confirm microstructural differences between the brains of Chiari II fetuses with and without edema. Fetal brain edema may explain worse motor outcomes in this Chiari II subgroup, who may substantially benefit from fetal surgery.

Chiari malformation type III with satisfactory developmental progress postrepair

The authors were presented with a term female neonate with a large occipital mass, who was already being treated for neonatal pneumonia at another hospital. On assessment, apart from the mass, the patient presented with an unremarkable systemic and neurological physical examination. She underwent repair of the occipital mass, which was complicated by nosocomial ventriculitis. However, the patient was discharged well after completing antibiotic treatment. On regular outpatient follow-ups, the patient presented with a good cry, suck, and activity. There have been no reports of seizures, decrease in sensorium, aspiration episodes, stridor or any other complaints, apart from poor head and sitting control. The workup also showed profound bilateral hearing loss. Despite these complications, the patient currently exhibits good visual and social development. This is attributed to timely intervention as well as the minimal amount of herniated cerebellar tissue that the patient presented with, highlighting the individualised management and outcomes for cases of Chiari malformation type III.

Decoding Chiari Malformation and Syringomyelia: From Epidemiology and Genetics to Advanced Diagnosis and Management Strategies

Chiari Malformation and Syringomyelia are neurosurgical entities that have been the subject of extensive research and clinical interest. Globally prevalent, these disorders vary demographically and have witnessed evolving temporal trends. Chiari Malformation impacts the normal cerebrospinal fluid flow, consequently affecting overall health. Key observations from canine studies offer pivotal insights into the pathogenesis of Syringomyelia and its extrapolation to human manifestations. Genetics plays a pivotal role; contemporary knowledge identifies specific genes, illuminating avenues for future exploration. Clinically, these disorders present distinct phenotypes. Diagnostically, while traditional methods have stood the test of time, innovative neurophysiological techniques are revolutionizing early detection and management. Neuroradiology, a cornerstone in diagnosis, follows defined criteria. Advanced imaging techniques are amplifying diagnostic precision. In therapeutic realms, surgery remains primary. For Chiari 1 Malformation, surgical outcomes vary based on the presence of Syringomyelia. Isolated Syringomyelia demands a unique surgical approach, the effectiveness of which is continually being optimized. Post-operative long-term prognosis and quality of life measures are crucial in assessing intervention success. In conclusion, this review amalgamates existing knowledge, paving the way for future research and enhanced clinical strategies in the management of Chiari Malformation and Syringomyelia.

Midline suprapineal pseudocyst in brain of fetuses with open spina bifida

OBJECTIVES

Recently, it was noted that fetuses with open spina bifida (OSB) may have a midline cystic structure evident on ultrasound. Our aims were to determine the prevalence of this cystic structure, shed light on its pathophysiology and investigate the association between its presence and other characteristic brain findings in fetuses with OSB.

METHODS

This was a single-center retrospective study of all fetuses with OSB and available cineloop images in the axial plane referred to the Ontario Fetal Centre, Toronto, Canada, between June 2017 and May 2022. Ultrasound and magnetic resonance imaging (MRI) data obtained between 18 + 0 and 25 + 6 weeks were reviewed in search of a midline cystic structure. Pregnancy and lesion characteristics were collected. Transcerebellar diameter (TCD), clivus-supraocciput angle (CSA) and additional brain abnormalities (abnormal cavum septi pellucidi (CSP), abnormal corpus callosum (CC) and periventricular nodular heterotopia (PNH)) were assessed. In cases of in-utero repair, imaging findings were reviewed postoperatively. In cases of termination, neuropathological findings were reviewed, if available.

RESULTS

Of 76 fetuses with OSB, 56 (73.7%) had a suprapineal cystic structure on ultrasound. The percentage of agreement between ultrasound and MRI detection was 91.5% (Cohen's kappa coefficient, 0.78 (95% CI, 0.57-0.98)). Brain autopsy in terminated cases revealed a dilatation of the posterior third ventricle, with redundant tela choroidea and arachnoid forming the membranous roof of the third ventricle, anterior and superior to the pineal gland. A cyst wall could not be identified, indicating that the structure was a pseudocyst. The presence of the pseudocyst was associated with a smaller CSA (pseudocyst absent, 62.11 ± 9.60° vs pseudocyst present, 52.71 ± 8.22°; P = 0.04). When the pseudocyst was present, its area was correlated inversely with TCD (r, -0.28 (95% CI, -0.51 to -0.02); P = 0.04). Fetal surgery did not have any impact on the growth rate of the pseudocyst (fetal surgery, 5.07 ± 3.29 mm2 /week vs expectant management, 4.35 ± 3.17 mm2 /week; P = 0.58). The presence of the pseudocyst was not associated with abnormal CSP, CC or presence of PNH. None of the cases with available postnatal follow-up required surgical procedure related to the pseudocyst.

CONCLUSIONS

Approximately 75% of all OSB cases have a suprapineal pseudocyst. Its presence is associated with the degree of hindbrain herniation but not with abnormalities of the CSP and CC or presence of PNH. Thus, it should not be regarded as additional brain pathology and should not preclude fetuses from undergoing fetal surgery for OSB. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Unusual Etiology of Chronic Cough and Syncope as Chiari Malformation Type 1

Chronic cough is a common chief complaint in ambulatory clinics. Unlike most cases that are caused by upper airway cough syndrome, gastroesophageal reflux disease, asthma, and non-asthmatic eosinophilic bronchitis, chronic cough can also be the presenting feature of a Chiari malformation. Our case is that of a 39-year-old female who had a chronic cough associated with shortness of breath, and when severe, associated with loss of consciousness. Her cough was refractory to conventional management. Further workup including pulmonary functions tests (PFT), laryngoscopy, high-resolution CT of the chest, an upper GI series, and esophageal pH manometry study were all normal. An MRI of her brain was obtained due to her syncopal episodes and revealed findings concerning a type 1 Chiari malformation. She subsequently underwent a Chiari decompression with patchy duraplasty and tonsilloplasty with cervical vertebrae 1 and 2 (C1-C2) laminectomy with a resolution of her symptoms. Chiari malformations are sometimes inherited but are often sporadic in nature, and, thus, appropriate diagnosis is key. Our patient is unique in that she presented at an older age, suggesting that atypical etiologies of a chronic cough refractory to conventional treatments must be considered.

Headache characteristics and postoperative course in Chiari I malformation

Background

Chiari I malformation typically presents with cough headache. However, migraine-like or tension-type-like headaches may also occur. There are limited publications on Chiari I malformation-associated headache semiologies and the effect of foramen magnum decompression on different headache types.

Methods

A retrospective analysis complemented by structured phone interviews was performed on 65 patients with Chiari I malformation, treated at our hospital between 2010 and 2021. Headache semiology (according to ICHD-3), frequency, intensity, and radiological characteristics were evaluated pre- and postoperatively.

Results

We included 65 patients. 38 patients were female and 27 male. Mean age was 43.9 ± 15.7 years. Headache was predominant in 41 patients (63.0%). Twenty-one patients had cough headache and 20 had atypical headache (12 migrainous, eight tension-type headache-like). Thirty-five patients with headache underwent surgery. Frequency, intensity, and analgesic use was significantly reduced in cough headache (p < 0.001). Atypical headaches improved less (p = 0.004 to 0.176). Exploratory analysis suggested that larger preoperative tonsillar descent correlated with larger postoperative headache intensity relief (p = 0.025).

Conclusion

Decompression was effective in Chiari I malformation-related cough headache. Atypical headache responded less well, and the causal relation with Chiari I malformation remains uncertain. For atypical headache, decompression should only be considered after failed appropriate preventive therapy and within an interdisciplinary approach involving a neurologist.

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.

Long-term outcomes of surgical management in subtypes of Chiari malformation

Objective: Chiari malformations (CMs) are a heterogeneous group of disorders defined by anatomic anomalies of the cerebellum, brainstem, and craniovertebral junction (CVJ). The aims of this study are to establish the demographic and clinical features, incidence, surgical procedures, and outcomes in large series of old and new subtypes of CMs.Material and Methods: All patients were evaluated and operated on for CM-0, 1, and 1.5 between 1985 and 2016. The patients were grouped into various subtypes. Demographic data, additional diseases, clinical features, surgical procedures, complications and outcomes were recorded.Results: 191 patients who underwent various surgical procedures were evaluated. Their mean age was 37.21 ± 9.89. We detected 15 cases of CM-0 (7.8%), 121 cases of CM-1 (63.4%), 55 cases of CM-1.5 (28.8%). In total there were 191 cases, and 220 surgical procedures were performed. 29 (13.2%) of all surgical procedure was reoperations and secondary operations. SM Cyst is found to be decreased in 72 (76.5%) patients, unchanged in 14 (14.8%) and increased in 8(8.5%) of 94 patients radiologically. Clinical outcomes are better for 131 (65.8%), same for 31 (16.2%) and worse for 9 (15%).Conclusion: This study with 172 patients is a large series that includes CM-0, 1, and 1.5 subtypes. CM-1.5 also differs for symptom presentation and durations from CM-1. There are more neurological abnormalities in patients with SM. CVD alone are an effective, useful and safe surgical procedure for CM-0, CM-1 and CM-1.5. Surgical procedure, SM existence, and symptom duration have powerful effects on outcomes.

Cranial findings detected by second-trimester ultrasound in fetuses with myelomeningocele: a systematic review

Background

Abnormal intracranial findings are often detected at mid‐trimester ultrasound (US) in fetuses with myelomeningocele (MMC). It is unclear whether these findings constitute a spectrum of the disease or are an independent finding, which should contraindicate fetal surgery.

Objective

To ascertain the spectrum and frequency of US‐detected cranial findings in fetuses with MMC.

Search strategy

MEDLINE, Embase, Web of Science and CENTRAL were searched from January 2000 to June 2020.

Selection criteria

Study reporting incidence of cranial US findings in consecutive cases of second‐trimester fetuses with MMC.

Data collection and analysis

Publication quality was assessed by Newcastle–Ottawa Scale (NOS) and modified NOS. Meta‐analysis could not be performed as a result of high clinical diversity and study heterogeneity.

Main results

Fourteen cranial US findings were reported in 15 studies. Findings in classic Chiari II malformation (CIIM) spectrum included posterior fossa funnelling (96%), small transcerebellar diameter (82–96%), ‘banana’ sign (50–100%), beaked tectum (65%) and ‘lemon’ sign (53–100%). Additional cranial findings were small biparietal diameter (BPD) and head circumference (HC) (<5th centile; 53 and 71%, respectively), ventriculomegaly (45–89%), abnormal pointed shape of the occipital horn (77–78%), thinning of the posterior cerebrum, perinodular heterotopia (11%), abnormal gyration (3%), corpus callosum disorders (60%) and midline interhemispheric cyst (42%).

Conclusions

We identified 14 cranial findings by second‐trimester US in fetuses with MMC. The relatively high incidence of these findings and their unclear prognostic significance might not contraindicate fetal surgery in the case of normal fetal genetic testing. Some cranial findings may independently affect postnatal outcome, however. Long‐term detailed follow‐up is required to investigate this.

Tweetable abstract

A high rate of cranial abnormalities found on second‐trimester ultrasound in fetuses with myelomeningocele.

A high rate of cranial abnormalities found on second‐trimester ultrasound in fetuses with myelomeningocele.

Acute Vertigo After CrossFit Workout in a Young Woman With Chiari I Malformation

CrossFit workout is associated with injuries mostly located over the spine and upper limb. Chiari I malformation (CIM) is characterized by migration of the cerebellar tonsils below the foramen magnum and this clinical condition has never been described after high-intense training such as CrossFit. A 19-year-old woman presented to the ED with acute vertigo, nausea, vomiting, and horizontal spontaneous nystagmus; symptoms began after an intense workout session. During neuro-otological examination, spontaneous positional left-beating horizontal nystagmus, normal response to bi-thermal caloric stimulations, and unremarkable cervical vestibular evoked myogenic potentials in both ears were observed; pure tone audiometry showed normal hearing. Central vertigo was suspected; therefore, an MRI was done, which identified a CIM. The patient's symptoms spontaneously improved at short term. The six-month follow-up MRI confirmed no changes. The subject completely stopped any training and remained asymptomatic over a 12-month follow-up. Our case report is the first describing CIM presented with acute vertigo after a high-intensity training.

Protrusion of brain stem into oropharynx in newborn: Unusual severe case of Chiari 1 malformation and Clival hypoplasia

Chiari 1 Malformation in children is defined as 6 mm or more caudal extension of cerebellar tonsils below the foramen magnum. It is one of the deformities in the spectrum of craniovertebral junction anomalies. We report an unusual case of newborn girl with hypoplasia of bassiocciput of the clivus and extension of brainstem into the oropharynx, in addition to extension of cerebellar tonsils below the foramen magnum. Right anterior arch and right posterior arch of C1 vertebra are absent. Dens of C2 vertebra is asymmetric. Laryngoscope showed a membrane covering the brainstem in the oropharynx. Endotracheal and orogastric tubes were placed. A ventriculo-peritoneal shunt was placed for hydrocephalus. The patient was discharged home at 4.5 months of age with home Hospice care. To the best of our knowledge, this has not been described in the literature. The case illustrates a rare defect in the clivus and unusual protrusion of brainstem into oropharynx.

Management of Rare Causes of Pediatric Chronic Respiratory Failure

The need for long-term noninvasive positive pressure ventilation (NiPPV) in children with chronic respiratory failure is rapidly growing. This article reviews pediatric-specific considerations of NiPPV therapy. Indications for NiPPV therapy can be categorized by the cause of the respiratory failure: (1) upper airway obstruction, (2) musculoskeletal and/or neuromuscular disease, (3) lower respiratory tract diseases, and (4) control of breathing abnormalities. The role of NiPPV therapy in select rare conditions (spinal muscular atrophy, congenital central hypoventilation syndrome, cerebral palsy, scoliosis, and Chiari malformations) is also reviewed.

Arnold-Chiari malformation type 1 as an unusual cause of acute respiratory failure: A case report

The authors urge clinicians to consider the possibility of Arnold-Chiari Malformation type 1 with other central causes especially in cases where acute respiratory failure is unexplainable.

Multiple-site neural tube defects: embryogenesis with complete review of existing literature

OBJECTIVE

Multiple-site neural tube defects (MNTDs) are very uncommon, with the predominant number of cases being reported in developing countries. The classic theory of neural tube closure fails to explain the occurrence of these defects. Multisite closure theory, first proposed in 1995, explains most of the occurrences with a few modifications specific to a few defects. In this paper, the authors endeavor to explain all the defects, along with their genetic and embryological bases, and to review the available literature and discuss their own experience in the management of these complex cases.

METHODS

The authors retrospectively reviewed the data of all the patients treated surgically for MNTDs over that past 14 years. All possible demographic data, clinical details, and radiological imaging data were reviewed. In addition, surgical parameters, complications, and status at follow-up of more than 12 months were evaluated. All previously reported cases of MNTD were analyzed, and comparisons with the present series were made.

RESULTS

A total of 3 major series (including the present one) on MNTDs have been from India. A total of 57 such cases (including those of the present series) have been reported in the available literature. While previous series reported a higher incidence of spinal defects, the present series had a higher rate of cephalic defects (55%). Among the reported cases, insertion of a ventriculoperitoneal shunt was necessary in 12 (26%), and only 4 patients were operated on in 2 stages. Neurological status at presentation dictated outcome.

CONCLUSIONS

MNTDs are extremely rare, and their embryogenesis is different from that of single neural tube defects. Simultaneous repair of 2 or even 3 defects is possible in a single-stage surgery. The requirement of a shunt is uncommon, and complications following surgery are rare. Folic acid supplementation may reduce the incidence of defects.

Chiari Malformation Type I in a Patient with a Novel NKX2-1 Mutation

Chiari Malformation Type 1 is a congenital, condition characterized by abnormally shaped cerebellar tonsils that are displaced below the level of the foramen magnum. NKX2-1 gene encodes a transcription factor expressed during early development of thyroid, lung, and forebrain, and germline NKX2-1 mutations can lead to dysfunction in any of these three organs, resulting in brain-lung-thyroid syndrome. There have been few reports of structural brain anomalies in patients with an NKX2-1-related disorder. We report the first case of a girl with a genetically identified mutation in NKX2-1 that presents with a Chiari Malformation Type 1, eventually expanding the phenotypic spectrum of NKX2-1-related disorders while also highlighting a novel heterozygous pathogenic variant at exon 3 that disrupts the reading framework, originating an NKX2-1 protein with a different C-terminal.

Choosing an anesthetic technique in pregnant women with Arnold – Chiari malformation

We want to present the clinical case of a female patient with the asymptomatic Chiari I type malformation, without surgical correction and with concomitant epilepsy who underwent planned C-section under epidural anesthesia. A 29-year old pregnant women on the 39 week of pregnancy entered the maternity hospital for the delivery. It was decided to conduct a planned caesarean section. The epidural anesthesia with 0.75 % solution of the ropivacaine was chosen as the method of anesthesia. The patient did not receive antiepileptic treatment due to her implacable refusal. She underwent surgery and anesthesia well. On the third day after surgery, the patient suffered of a convulsive as sault, which was stopped by intravenous administration of diazepam. This article briefly describes the genetic background, classification, clinical manifestations and treatment tactics for patients with Chiari malformation and the features of C-section anesthesia in pregnant women with this pathology.

The 2016 Bernard Sachs Lecture: Timing in Morphogenesis and Genetic Gradients During Normal Development and in Malformations of the Nervous System

Nervous system development is quadradimensional. Both normal ontogenesis and developmental malformations are explained in the context of the fourth dimension, timing. Timing of the onset of either the genetic expression of a mutation or an epigenetic event that may be teratogenic is primordial in determining morphogenesis and the forms of malformations with their functional consequences. Multiple genotypes may cause similar phenotypes or a single genotype with different degrees of retained normal genetic expression may result in variable phenotypes. In this treatise, examples are presented of these principles, including both delayed and precocious maturation of processes such as synaptogenesis that may be out of synchrony with other simultaneous processes of neuronal maturation. In postzygotic somatic mosaicism, timing of onset determines not only the character but also the extent of a lesion; focal cortical dysplasia IIb and hemimegalencephaly are the same disease, both sharing activation of the mTOR pathway as the primary mechanism; the difference is timing of onset within the 33 mitotic cycles of the periventricular neuroepithelium. Genetic expression often follows gradients along the 3 axes of the neural tube. Defective gradients often can be identified by their morphological result without knowing the precise mutation. Upregulation in the vertical axis produces hyperplasia or duplication of either dorsal or ventral structures, whereas downregulation yields hypoplasia or fusion in the midline of bilateral structures. Disorders of segmentation or neuromere formation in the neural tube are increasingly recognized as another pathogenesis of cerebral dysgenesis. Our recent investigations show the participation of the U-fibre layer beneath FCD in epileptic networks because of neuronal dispersion with elaborate synaptic plexi and a barrier to deep heterotopia.

Clinical Notes on Chiari Malformation

Chiari malformations (CMs) are variant structural setup of cerebellum and brain stem at the craniovertebral junction. Normally the cerebellum and parts of the brain stem lie above the foramen magnum. When the part of the cerebellum and/or brainstem protrudes into the upper spinal canal through foramen magnum, it is defined as CM. Chiari malformations may develop when part of the skull is smaller than normal or misshapen, due to which the cerebellum herniates into spinal canal through foramen magnum. This compresses the cerebellum and brainstem affecting functions controlled by these parts and blocks the flow of cerebrospinal fluid that surrounds and cushions the brain and spinal cord. Chiari malformation may cause sensory loss, ataxia, weakness, nystagmus, spastic limbs to name a few. Thus, various morbid and mortal neurologic disorders result from CM. Therefore, sound and thorough knowledge of CM and its variant anatomy are essential for diagnosis and management of neurologic disorders. Therefore, review study has been carried out for updating and consolidating the knowledge of all the variations of CMs. Literature search was carried out using databases, SciELO, ScopeMed, MEDLINE, PubMed, and Wiley Online Library. Papers containing original data were selected and secondary references retrieved from bibliographies. Various terms related to CMs were used for net surfing. The knowledge will be of immense importance to neurologists and neurosurgeons to diagnose and treat the CMs and decrease the mortality associated with CM and to radiologists for correctly interpreting the magnetic resonance imaging.

Chiari malformation and tuberculous meningitis: aetiology and management

This is the first reported case of a Chiari 1 malformation in association with tuberculous (TB) meningitis. We present a case of a 23-year-old woman with a 2-week history nocturnal fever, vertigo, headache and projectile vomiting. She had nystagmus, scanning speech, bilateral papilloedema and ataxia. Cranial imaging showed a 10 mm tonsillar herniation. Posterior fossa decompression was done. Because the patient's gamut of symptoms was highly suspicious for a central nervous system infection, a lumbar tap was done which revealed TB meningitis. Four years later, after anti-TB medications and rehabilitation, all her symptoms except gait instability resolved.

Chiari 1 deformity in children: etiopathogenesis and radiologic diagnosis

The metamerically associated normal hindbrain and normal posterior fossa are programmed to grow together in such a way that the tonsils are located above the foramen magnum and surrounded by the cerebrospinal fluid (CSF) of the cisterna magna. This allows the pulsating CSF to move freely up and down across the craniovertebral junction (CVJ). A developmental mismatch between the rates of growth of the neural tissue and of the bony posterior fossa may result in the cerebellar tonsils being dislocated across the foramen magnum. The cause of this may be, rarely, an overgrowth of the cerebellum. More commonly, it is due to an insufficient development of the posterior fossa, possibly associated with a malformation of the craniocervical joint. When it is not due to a remediable cause, such a herniation is called a Chiari 1 deformity. This definition is anatomic (descent of the tonsils below the plane of the foramen magnum) and not clinical: many patients with the deformity are and will remain asymptomatic. Most authors consider that a descent of 5 mm or more is clinically significant but other factors, such as the diameter of the foramen magnum and the degree of tapering of the upper cervical "funnel," are likely to be as important. Morphologic markers of severity on magnetic resonance imaging are, beside the degree of descent, the peg-like deformity of the tonsils, the obstruction of the surrounding CSF spaces (at the craniocervical junction and in the whole posterior fossa), a compression of the cord, an abnormal signal of the cord, and a syringomyelia, typically cervicothoracic. The syringomyelia is assumed to be explained by the "Venturi effect" that is associated with the increased velocity of the CSF across the restricted CSF spaces. Radiologically, the etiopathogenic assessment should address the size and morphology of the posterior fossa, and the functional status of the craniocervical flexion joint. The posterior fossa is best evaluated on sagittal cuts by the posterior fossa pentagon proportionality associated with the line of Chamberlain, and on coronal cuts, by showing a possible shallowness of the posterior fossa. The functional status of the craniocervical joint is altered in case of a proatlantal hypoplasia, as this condition results in a cranial shift of the joint that brings the tip of the dens and of the flexion axis in front of the medulla, that is, in a situation of osteoneural conflict. Less commonly, similar conflicts may also occur when an abnormal craniocervical segmentation results in an instability of the joint.

Cerebellar networks and neuropathology of cerebellar developmental disorders

The cerebellar system is a series of axonal projections and synaptic circuits as networks, similar to those of the limbic system and those subserving the propagation and spread of seizures. Three principal cerebellar networks are identified and cerebellar disease often affects components of the networks other than just the cerebellar cortex. Contemporary developmental neuropathology of the cerebellum is best considered in the context of alterations of developmental processes: embryonic segmentation and genetic gradients along the three axes of the neural tube, individual neuronal and glial cell differentiation, migration, synaptogenesis, and myelination. Precisely timed developmental processes may be delayed or precocious rhombencephalosynapsis and pontocerebellar hypoplasia exemplify opposite gradients in the horizontal axis. Chiari II malformation may be reconsidered as a disorder of segmentation rather than simply due to mechanical forces upon normally developing hindbrain structures. Cellular nodules in the roof of the fourth ventricle are heterotopia of histologically differentiated but architecturally disoriented and disorganized neurons and glial cells; they often are less mature immunocytochemically than similar cells in adjacent normal folia. Cell rests are nodules of undifferentiated neuroepithelial cells. Both are frequent in human fetuses and neonates. Axonal projections from heterotopia to adjacent cerebellar folia or nuclei are few or absent, hence these nodules are clinically silent despite neuronal differentiation.

Imaging of the Posterior Skull Base

The posterior skull base can be involved by a variety of pathologic processes. They can be broadly classified as: traumatic, neoplastic, vascular, and inflammatory. Pathology in the posterior skull base usually involves the lower cranial nerves, either as a source of pathology or a secondary source of symptoms. This review will categorize pathology arising in the posterior skull base and describe how it affects the skull base itself and surrounding structures.

Tonsillar contusion associated with benign tonsillar ectopia following minor head trauma

PURPOSE

The relationship between tonsil position and symptomatic cerebellar contusion is unclear. To date, there are no reports of symptomatic traumatic brain injury associated with benign tonsillar ectopia. Reported cases are limited to prominent cerebellar tonsillar displacement by ≥5 mm (i.e., Chiari malformations).

METHODS

The authors describe a case of symptomatic concussion in a toddler with unusual computerized tomography (CT) presentation and incidental finding of benign tonsillar ectopia, hemorrhagic contusion of the tonsils, blood-brain barrier (BBB) disruption and delayed atrophy shown using magnetic resonance imaging (MRI) studies. The radiological presentation and the clinical challenges are discussed through a review of the literature.

CONCLUSION

This case suggests that damage to cerebellar structures is not limited only to overt tonsillar herniation. Benign tonsillar ectopia may predispose to cerebellar contusion even after minor concussion and thus has a clinical significance. The current paradigm viewing only noticeable tonsillar herniation as a risk factor for hindbrain injury should be revisited.

Acute porphyria in a patient with Arnold Chiari malformation

Patient: Female, 33

Final Diagnosis: Acute porphyria

Symptoms: Abdominal pain • alternating bowel habits

Medication: Metronidazole • bactrim • oxybutynin

Clinical Procedure: EMG • porhyria workup

Specialty: Neurology

MR-based morphometry of the posterior fossa in fetuses with neural tube defects of the spine

Objectives

In cases of “spina bifida,” a detailed prenatal imaging assessment of the exact morphology of neural tube defects (NTD) is often limited. Due to the diverse clinical prognosis and prenatal treatment options, imaging parameters that support the prenatal differentiation between open and closed neural tube defects (ONTDs and CNTDs) are required. This fetal MR study aims to evaluate the clivus-supraocciput angle (CSA) and the maximum transverse diameter of the posterior fossa (TDPF) as morphometric parameters to aid in the reliable diagnosis of either ONTDs or CNTDs.

Methods

The TDPF and the CSA of 238 fetuses (20–37 GW, mean: 28.36 GW) with a normal central nervous system, 44 with ONTDS, and 13 with CNTDs (18–37 GW, mean: 24.3 GW) were retrospectively measured using T2-weighted 1.5 Tesla MR -sequences.

Results

Normal fetuses showed a significant increase in the TDPF (r = .956; p<.001) and CSA (r = .714; p<.001) with gestational age. In ONTDs the CSA was significantly smaller (p<.001) than in normal controls and CNTDs, whereas in CNTDs the CSA was not significantly smaller than in controls (p = .160). In both ONTDs and in CNTDs the TDPF was significantly different from controls (p<.001).

Conclusions

The skull base morphology in fetuses with ONTDs differs significantly from cases with CNTDs and normal controls. This is the first study to show that the CSA changes during gestation and that it is a reliable imaging biomarker to distinguish between ONTDs and CNTDs, independent of the morphology of the spinal defect.

Audio-vestibular signs and symptoms in Chiari malformation type i. Case series and literature review

INTRODUCTION

Chiari malformation is an alteration of the base of the skull with herniation through the foramen magnum of the brain stem and cerebellum. Although the most common presentation is occipital headache, the association of audio-vestibular symptoms is not rare. The aim of our study was to describe audio-vestibular signs and symptoms in Chiari malformation type i (CM-I).

MATERIALS AND METHODS

We performed a retrospective observational study of patients referred to our unit during the last 5 years. We also carried out a literature review of audio-vestibular signs and symptoms in this disease.

RESULTS

There were 9 patients (2 males and 7 females), with an average age of 42.8 years. Five patients presented a Ménière-like syndrome; 2 cases, a recurrent vertigo with peripheral features; one patient showed a sudden hearing loss; and one case suffered a sensorineural hearing loss with early childhood onset. The most common audio-vestibular symptom indicated in the literature in patients with CM-I is unsteadiness (49%), followed by dizziness (18%), nystagmus (15%) and hearing loss (15%). Nystagmus is frequently horizontal (74%) or down-beating (18%). Other audio-vestibular signs and symptoms are tinnitus (11%), aural fullness (10%) and hyperacusis (1%). Occipital headache that increases with Valsalva manoeuvres and hand paresthesias are very suggestive symptoms.

CONCLUSIONS

The appearance of audio-vestibular manifestations in CM-I makes it common to refer these patients to neurotologists. Unsteadiness, vertiginous syndromes and sensorineural hearing loss are frequent. Nystagmus, especially horizontal and down-beating, is not rare. It is important for neurotologists to familiarise themselves with CM-I symptoms to be able to consider it in differential diagnosis.

Dural sinus filling defect: intrasigmoid encephalocele

Filling defects of dural venous sinuses are considered to be a challenging problem especially in case of symptomatic patients. Many lesions have to be ruled out such as sinus thrombosis, arachnoid granulations and tumours. Encephalocele into dural sinus is also a rare cause of these filling defects of dural sinuses. Here, we report an extremely rare case with spontaneous occult invagination of temporal brain tissue into the left sigmoid sinus and accompanying cerebellar ectopia.

Comprehensive Assessment of 1-Year Outcomes and Determination of Minimum Clinically Important Difference in Pain, Disability, and Quality of Life After Suboccipital Decompression for Chiari Malformation I in Adults

BACKGROUND:

To date, there has been no study to comprehensively assess the effectiveness of suboccipital craniectomy (SOC) for Chiari malformation I (CMI) using validated patient-reported outcome measures.

OBJECTIVE:

To determine the effectiveness and minimum clinically important difference thresholds of SOC for the treatment of adult patients with CMI using patient-reported outcome metrics.

METHODS:

Fifty patients undergoing first-time SOC and C1 laminectomy for CMI at a single institution were followed up for 1 year. Baseline and 1-year postoperative pain, disability, quality of life, patient satisfaction, and return to work were assessed. Minimum clinically important difference thresholds were calculated with 2 anchors: the Health Transition Index and North American Spine Society satisfaction questionnaire.

RESULTS:

The severity of headaches improved in 37 patients (74%). Improvement in syrinx size was seen in 12 patients (63%) and myelopathy in 12 patients (60%). All patient-reported outcomes showed significant improvement 1 year postoperatively (P &lt; .05). Of the 38 patients (76%) employed preoperatively, 29 (76%) returned to work postoperatively at a median time of 6 weeks (interquartile range, 4-12 weeks). Minimum clinically important difference thresholds after SOC for CMI were 4.4 points for numeric rating scale for headache, 0.7 points for numeric rating scale for neck pain, 13.8 percentage points for Headache Disability Index, 14.2 percentage points for Neck Disability Index, 7.0 points for Short Form-12 Physical Component Summary, 6.1 points for Short Form-12 Mental Component Summary, 4.5 points for Zung depression, 1.7 points for modified Japanese Orthopaedic Association, and 0.34 quality-adjusted life-years for Euro-Qol-5D.

CONCLUSION:

Surgical management of CMI in adults via SOC provides significant and sustained improvement in pain, disability, general health, and quality of life as assessed by patient-reported outcomes. This patient-centered assessment suggests that suboccipital decompression for CMI in adults is an effective treatment strategy.

Non-visualisation of cavum septi pellucidi: implication in prenatal diagnosis?

OBJECTIVE

This manuscript reviews congenital anomalies and imaging findings associated with non-visualisation of the cavum septi pellucidi (CSP) found on prenatal sonogram.

BACKGROUND

Observation of a normal cavum septi pellucidi (CSP) is an important landmark in the second and third trimester prenatal ultrasound evaluation of the fetal brain, and its visualisation provides reassurance of normal central forebrain development. Non-visualisation of the CSP is a prenatal sonographic finding, which in most cases is associated with neuroanatomical anomalies that include agenesis of the corpus callosum, schizencephaly, septo-optic dysplasia, holoprosencephaly, chronic hydrocephalus and acquired fetal brain injury. Isolated septal deficiency, a rare but controversial entity, is considered a variant of normal. Common pitfalls in the sonographic evaluation of CSP include columns of the fornix that mimic CSP, and prominent cavum vergae that can simulate non-visualisation of the CSP. When non-visualisation of the CSP is suspected, magnetic resonance imaging (MRI) of the fetal brain can confirm and evaluate associated anomalies.

CONCLUSION

Visualisation of the CSP is an integral component of the prenatal ultrasound and its non-visualisation is associated with other malformations, diagnosis of which is aided by MRI.

TEACHING POINTS

• Cavum septi pellucidi (CSP) is an important landmark in the prenatal ultrasound evaluation of the fetal brain, and is a marker for normal central forebrain development. • Non-visualisation of the CSP is most commonly associated with other neuroanatomical abnormalities. • Examination of the fetal brain by MRI can confirm the sonographic findings and evaluate for associated anomalies.

Accurately Measuring Outcomes After Surgery for Adult Chiari I Malformation

BACKGROUND:

There has been a transition to using patient-reported outcome instruments (PROi) to assess surgical effectiveness. However, none of these instruments have been validated for outcomes of adult Chiari I malformation (CMI).

OBJECTIVE:

The aim of this study was to determine the relative validity and responsiveness of various PROi in measuring outcomes after surgery for CMI.

METHODS:

Fifty patients undergoing suboccipital craniotomy for adult CMI were prospectively followed for 1 year. Baseline and 1-year patient-reported outcomes (visual analog scale for head pain and visual analog scale for neck pain, Neck Disability Index [NDI], Headache Disability Index, SF-12, Zung Self-Rating Depression Scale, and EuroQol-5D [EQ-5D]) were assessed. A level of improvement in general health after surgery was defined as meaningful improvement. Receiver-operating characteristic curves were generated to assess the validity of PROi to discriminate between meaningful improvement and not. The difference between standardized response means (SRMs) in patients reporting meaningful improvement vs not as calculated to determine the relative responsiveness of each outcome instrument.

RESULTS:

For pain and disability, the NDI was the most accurate discriminator of meaningful effectiveness (area under the curve: 0.90) and also most responsive to postoperative improvement (standardized response means difference: 1.87). For general health and quality of life, the SF-12 PCS, EQ-5D, and Zung Self-Rating Depression Scale were all accurate discriminators; however, SF-12 Physical Component Scale (SF-12 PCS) and EQ-5D were most accurate. SF-12 PCS was also most responsive.

CONCLUSION:

For pain and disability, NDI is the most valid and responsive measure of improvement after surgery for CMI. For health-related quality of life, SF-12 PCS and EQ-5D are the most valid and responsive measures. NDI with SF-12 or EQ-5D is the most valid in patients with CMI and should be considered in cost-effectiveness studies.

Sudden unexpected death due to Chiari type I malformation in a road accident case

This case concerns a sudden death of a patient with Chiari I malformation. A 17-year-old female was seen unconscious then fell off a motorbike during the vehicle acceleration. The girl was confirmed dead on the way to hospital, being previously asymptomatic and with a clean medical record. Autopsy findings showed an extremely extra-long cerebellar tonsillar herniation in the left side and unexplained multiple small cavities in cerebral hemispheres. Microscopic findings revealed loss and abnormal migration of the Purkinje cells, as well as capillary congestion in the herniated tonsil. The cause and mechanisms of this sudden death are considered as the cardiopulmonary dysfunction and arrest resulted from compression of the medulla and cervical cord, which was induced by both the positional insult and minor head trauma. In addition, this study stresses the importance of cervical cord examination in the case of unexpected sudden death following road accidents.

Chiari malformation and central sleep apnoea: successful therapy with adaptive pressure support servo-ventilation following surgical treatment

Sleep apnoea is a common disorder with significant morbidity. It is categorised into obstructive and central sleep apnoea. There are a variety of conditions associated with central sleep apnoea ranging from cardiac failure to structural brain anomalies. We herein report a case of 57-year-old woman with Chiari malformation associated with significant sleep-disordered breathing. There was a family history of Chiari malformation. Although neurosurgical intervention had a significant impact on apnoea hypopnoea index (AHI) with a reduction from 81/h preoperatively to 22.1/h after the surgical treatment, it failed to cure the sleep disorder breathing completely and adaptive non-invasive servo-ventilation had a dramatic effect on symptoms and normalised the AHI. Although, central sleep apnoea is associated with a number of common disorders, this case illustrates that there may be an unusual cause. Moreover, adaptive pressure support servo-ventilation may provide a promising treatment option following surgical correction of Chiari malformation.

Primary cerebellar tuberculoma in Arnold-Chiari malformation mimicking posterior cranial fossa tumor: the first report

Chiari malformations are a congenital heterogeneous group of disorders characterized by anatomic anomalies of the cerebellum, brain stem, and craniocervical junction associated with downward displacement of the cerebellum, alone or with lower medulla, into the cervical spine canal. The patient was a 23-year-old woman, a known case of Arnold-Chiari malformation with peripheral neuropathy and muscular atrophy, who presented with headache, drowsiness, decreased vision, and severe gait dysfunction lasting for several years. Brain magnetic resonance imaging confirmed a hypointense signal mass in the left hemisphere of the cerebellum causing mass effects on the fourth ventricle, which shifted it, accompanied with dilation of third and lateral ventricles.