Chiari complex in children--neuroradiological diagnosis, neurosurgical treatment and proposal of a new classification (312 cases)

Volumetric segmentation in the context of posterior fossa-related pathologies: a systematic review

BACKGROUND

Segmentation tools continue to advance, evolving from manual contouring to deep learning. Researchers have utilized segmentation to study a myriad of posterior fossa-related conditions, such as Chiari malformation, trigeminal neuralgia, post-operative pediatric cerebellar mutism syndrome, and Crouzon syndrome. Herein, we present a summary of the current literature on segmentation of the posterior fossa. The review highlights the various segmentation techniques, and their respective strengths and weaknesses, employed along with objectives and outcomes of the various studies reported in the literature.

METHODS

A literature search was conducted in PubMed, Embase, Cochrane, and Web of Science up to November 2023 for articles on segmentation techniques of posterior fossa. The two senior authors searched through databases based on the keywords of the article separately and then enrolled joint articles that met the inclusion and exclusion criteria.

RESULTS

The initial search identified 2205 articles. After applying inclusion and exclusion criteria, 77 articles were selected for full-text review after screening of titles/abstracts. 52 articles were ultimately included in the review. Segmentation techniques included manual, semi-automated, and fully automated (atlas-based, convolutional neural networks). The most common pathology investigated was Chiari malformation.

CONCLUSIONS

Various forms of segmentation techniques have been used to assess posterior fossa volumes/pathologies and each has its advantages and disadvantages. We discuss these nuances and summarize the current state of literature in the context of posterior fossa-associated pathologies.

Chiari type III malformation associated with Klippel-Feil syndrome, a case report with a narrative review of the literature

BACKGROUND

Chiari malformation type III (CM III), a rare hindbrain anomaly, often presents with various concurrent anomalies. This paper reports a unique case of CM III associated with Klippel-Feil syndrome (KFS), a condition previously unreported in Saudi Arabia and documented in only one other case globally in Turkey. This study aims to share insights into the unusual association between CM III and KFS, considering their close embryological development and involvement in the craniocervical junction.

METHODOLOGY

The study presents a case of a 2.5-year-old female diagnosed with CM III and KFS. Diagnostic tools such as ultrasound, CT scans, MRI, and physical examinations were used to confirm the patient's condition. Surgical interventions, including decompression and encephalocele repair, were performed.

RESULTS

Successful surgical interventions, including encephalocele repair and duraplasty, were carried out. Follow-up visits indicated a stable condition, marked improvement in lower limb strength, and the patient's ability to walk with assistance. CT follow-up affirmed a satisfactory surgical outcome.

CONCLUSION

This case study illustrates the potential for an optimistic prognosis in CM III, even when accompanied by complex conditions such as KFS, through early diagnosis and intervention. It underscores the significance of antenatal screening for effective care planning and calls for further research and publications due to the rarity of this association. These findings contribute to our understanding of CM III and its related conditions, emphasizing the need for open-minded consideration of potential embryological associations.

A Novel Craniocervical Junction Compression Severity Index-Based Grading System for Multidirectional Quantification of the Biomechanics at Foramen Magnum of Chiari Malformation Type I

Objective  This study aimed to establish a novel grading system, based on the craniovertebral junction compression severity index (CVJCSI) for multidirectional quantification at the foramen magnum plane for Chiari malformation type I (CMI). Methods  The CVJCSI grading system was established to stratify patients based on the ventral (modified clivoaxial angle < 138°), dorsal (tonsil herniation), and central (brainstem herniation) CVJ (craniovertebral junction) compression, the CVJCSI grading system was established to stratify patients. The optimal surgical method for each grade was recommended by intragroup comparisons regarding the efficacy of the three operations. Finally, according to the CVJCSI grading system, a prospective validation trial was performed and surgically treated for internal validation. Results  Based on the retrospective study ( n  = 310), the CVJCSI included six grades: I: syrinx alone without compression; II: dorsal compression; III: dorsal and central compression; IV: ventral compression; V: dorsal and ventral compression; and VI: ventral, dorsal, and central compression. Among all available variables, only the CVJCSI and surgical methods significantly affected the CCOS. The CCOS scores, overall and for each CVJCSI grade, increased in the prospective cohort ( n  = 42) compared with that in the retrospective analysis. Conclusions  The CVJCSI can be used to stratify CMI patients. The higher the CVJCSI grade, the more severe the CVJ compression and the worse posterior fossa deformity. Meanwhile, the CVJCSI was negatively correlated with the CCOS. The lower the CVJCSI grade, the better the response to surgery, and the less-invasive surgical procedures were warranted. Finally, the prospective cohort study validated the proposed CVJCSI-based surgical protocols.

Pedunculated Chiari 3 malformation with proatlas defect

Chiari III malformation is considered to be a rare congenital abnormality in human with very high mortality rates. Seventy percent of Chiari III is found to be associated with C1 arch defect as reported by Cakirer (Clin Imaging 27:1-4, 2003). The herniation of posterior fossa elements or dysplastic neural tissue is a must to stamp it as Chiari 3 malformation. The malformation is a result of the abnormal development of craniovertebral junction (CVJ). The CVJ developed from the occipital somites and the first spinal sclerotome. The major role in the development of the CVJ is played by the fourth occipital somite, which is otherwise known as "proatlas." The Chiari III anomalies are due to a result of proatlas defect, which results from failures of segmentation, failures of fusion of different components of each bone, or hypoplasia and ankylosis. We are presenting a case of a 1-year 4-month-old female child who presented with pedunculated swelling at the suboccipital region. The swelling was cystic and with pulsation. On evaluation, we found Chiari III anomaly with C1 posterior arch deficiency (proatlas defect). He was surgically managed. The outcome of the patient was good. Despite literature concluding Chiari 3 malformation with an unfavorable outcome, however, meticulous management and good pre- and postoperative care, physical therapy, and follow-up are necessary for good outcome.

Research process, recap, and prediction of Chiari malformation based on bicentennial history of nomenclature and terms misuse

There is an absent systematic analysis or review that has been conducted to clarify the topic of nomenclature history and terms misuse about Chiari malformations (CMs). We reviewed all reports on terms coined for CMs for rational use and provided their etymology and future development. All literature on the nomenclature of CMs was retrieved and extracted into core terms. Subsequently, keyword analysis, preceding and predicting (2023-2025) compound annual growth rate (CAGR) of each core term, was calculated using a mathematical formula and autoregressive integrated moving average model in Python. Totally 64,527 CM term usage was identified. Of these, 57 original terms were collected and then extracted into 24 core-terms. Seventeen terms have their own featured author keywords, while seven terms are homologous. The preceding CAGR of 24 terms showed significant growth in use for 18 terms, while 13, three, three, and five terms may show sustained growth, remain stable, decline, and rare in usage, respectively, in the future. Previously, owing to intricate nomenclature, Chiari terms were frequently misused, and numerous seemingly novel but worthless even improper terms have emerged. For a very basic neuropathological phenomenon tonsillar herniation by multiple etiology, a mechanism-based nosology seems to be more conducive to future communication than an umbrella eponym. However, a good nomenclature also should encapsulate all characteristics of this condition, but this is lacking in current CM research, as the pathophysiological mechanisms are not elucidated for the majority of CMs.

Abnormal prenatal brain development in Chiari II malformation

Introduction

The Chiari II is a relatively common birth defect that is associated with open spinal abnormalities and is characterized by caudal migration of the posterior fossa contents through the foramen magnum. The pathophysiology of Chiari II is not entirely known, and the neurobiological substrate beyond posterior fossa findings remains unexplored. We aimed to identify brain regions altered in Chiari II fetuses between 17 and 26 GW.

Methods

We used in vivo structural T2-weighted MRIs of 31 fetuses (6 controls and 25 cases with Chiari II).

Results

The results of our study indicated altered development of diencephalon and proliferative zones (ventricular and subventricular zones) in fetuses with a Chiari II malformation compared to controls. Specifically, fetuses with Chiari II showed significantly smaller volumes of the diencephalon and significantly larger volumes of lateral ventricles and proliferative zones.

Discussion

We conclude that regional brain development should be taken into consideration when evaluating prenatal brain development in fetuses with Chiari II.

Impact of Brain Malformations on Neurodevelopmental Outcome in Children with a History of Prenatal Surgery for Open Spina Bifida

INTRODUCTION

This retrospective study investigates brain malformations and their impact on neurodevelopmental outcome in children after prenatal surgery for spina bifida (SB).

METHODS

Sixty-one patients were included. On neonatal MRI, SB-associated brain malformations were assessed. Ventricular size, ventriculo-peritoneal shunt (VPS), and endoscopic third ventriculostomy (ETV) were also documented. Neurodevelopment was assessed with the Bayley-III and correlated with brain malformations, ventricular size, and VPS/ETV placement.

RESULTS

Chiari II malformation was detected in all patients. Corpus callosum (CC) abnormality was noted in 40%, heterotopies in 35%, and cerebellar parenchymal defects in 11%. 96% had ventriculomegaly; in 46%, VPS/ETV was performed. Cognitive and language testing yielded results in the low-average range (Bayley-III: Cognitive Composite Score 93.6, Language Composite Score 89.7), motor testing was below average (Motor Composite Score 77.4). CC abnormalities, heterotopies, and cerebellar defects were not associated with poorer Bayley-III scores, whereas patients with severe ventriculomegaly performed poorer in all subtests, significantly so for the language composite score. Patients requiring intervention for hydrocephalus had significantly lower scores in motor testing.

DISCUSSION/CONCLUSION

Additional brain malformations in open SB do not seem to have an impact on cognitive function at 2 years of age. Severe ventriculomegaly is a risk factor for poorer cognitive outcome; hydrocephalus surgery adds an additional risk for delayed motor function.

Outcomes of Chiari Malformation III: A Review of Literature

Purpose

Chiari malformation type III (CM III) is the rarest type compared to other types of CMs. CM III usually reported as sporadic case reports which reflect the rarity of this anomaly. We report two cases of operated CM III at our institute with a reasonable outcome and reviewed the literature to illustrate the variability of prognosis and related hydrocephalus.

Materials and Methods

We operated two cases of CM III in our hospital followed by ventriculoperitoneal shunt (VPS) placement with an accepted neurological outcome at 10 and 6 months follow-up. We reviewed the literature for other cases of CM III with focusing on prognosis to illustrate the real image of reported prognosis and related hydrocephalus.

Results

After follow-up for 10 and 6 months, respectively, both cases had mild developmental delays. In this review, we report 51 cases of CM III over the last 30 years since 1989, there was slight male predilection, hydrocephalus was evident in 27 cases which was almost managed with VPSs and was evident in seven deaths.

Conclusion

CM III is a rare anomaly which usually carries a bad prognosis, but death is not ultimate, and there may be a minority who carry good prognosis. This bad prognosis pushes some parents to refuse surgery otherwise repair should be done. With good pre- and postoperative care, physical therapy, and follow-up, the outcome is reasonable.

A Practical Approach to Diagnosis of Spinal Dysraphism

Spinal dysraphisms (SDs) are congenital malformations of the spinal cord, determined by derangement in the complex cascade of embryologic events involved in spinal development. They represent a heterogeneous group ranging from mild clinical manifestations-going unnoticed or being discovered at clinical examination-to a causal factor of life quality impairment, especially when associated with musculoskeletal, gastrointestinal, genitourinary, or respiratory system malformations. Knowledge of the normal embryologic development of the spinal cord-which encompasses three main steps (gastrulation, primary neurulation, and secondary neurulation)-is crucial for understanding the pathogenesis, neuroradiologic scenarios, and clinical-radiologic classification of congenital malformations of the spinal cord. SDs can be divided with clinical examination or neuroradiologic study into two major groups: open SDs and closed SDs. Congenital malformations of the spinal cord include a wide range of abnormalities that vary considerably in imaging and clinical characteristics and complexity and therefore may represent a diagnostic challenge, even for the experienced radiologist. Online supplemental material is available for this article. ^©RSNA, 2021.

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.

Management: opinions from different centers-the Istituto Giannina Gaslini experience

PURPOSE

Describe presentation and management of Chiari type 1 malformation. We report our surgical case series proposing a decision making scheme for helping surgeons decide which surgical procedure to perform and when.

METHODS

We retrospectively examined a series of surgically treated patients with Chiari type 1 malformation. Treatment of associated anomalies, surgical complications, and need for reintervention for insufficient decompression at first surgery are discussed.

RESULTS

A total of 172 patients have been surgically treated for Chiari type 1 malformation at the Neurosurgery Unit of IRCCS Giannina Gaslini Children Hospital of Genoa, Italy, in a period between 2006 and 2017. The first treatment addressing Chiari type 1 malformation was bone and ligamentous decompression alone in 104 patients (65%), associated with dural delamination in 3 patients (1.9%) and associated with duraplasty with autologous graft in 53 patients (33.1%). Postoperative complications occurred in 5 patients (2.9%). Reintervention for insufficient decompression at follow-up was needed in 6 patients (3.5%).

CONCLUSIONS

Surgical decompression of the posterior cranial fossa (PCF) is indicated in symptomatic patients while asymptomatic patients must be followed in a wait and see fashion. Different types of surgical decompression of different invasiveness have been proposed from only bone and ligamentous decompression to coagulation of cerebellar tonsils. Intraoperative ultrasonography is a useful tool to define when a decompression is sufficient. We did not find correlation between the need for reintervention for insufficient decompression and different invasiveness of the techniques. We believe that this finding suggests that our proposed scheme leads to the best tailored treatment for the single patient.

Basilar invagination associated with chiari malformation type I: A literature review

Basilar invagination (BI) and Chiari malformation type I (CM-I) are very important anomalies that introduce instability and compression in the occipitocervical transition region and have complex clinical characteristics. These anomalies vary according to the affected structures. The present study revises current knowledge regarding the anatomy, anatomo-physiology, clinical manifestations, and radiological findings of these entities and the associated surgical treatment approaches. A bibliographic survey was performed through a search in the Medline, PubMed, SciELO, Science and LILACS databases. When associated, these craniovertebral malformations result in neurological deficits due to neural parenchyma compression; however, the presence of microtraumas due to repetitive lesions caused by the bulb and cervical marrow instability has been highlighted as a determinant dysfunction. Surgical treatment is controversial and has many technical variations. Surgery is also challenging due to the complex anatomical characteristics and biomechanics of this region. Nevertheless, advances have been achieved in our understanding of related mechanisms, and compression and atlantoaxial instability are considered key elements when selecting the surgical approach.

3D structural complexity analysis of cerebellum in Chiari malformation type I

Chiari malformation type I (CM-I), described by a descent of the cerebellar tonsils, is assumed to be a neurological developmental disorder. The aim of the present study was to investigate morphological variance in cerebellar sub-structures, including gray matter (GM), white matter (WM), and cerebrospinal fluid (CSF), using magnetic resonance (MR) images with three-dimensional (3D) fractal dimension (FD) analysis in patients with CM-I. MRI data of 16 patients and 15 control subjects were obtained, and structural complexity analyses were performed using a box-counting FD algorithm. Results showed that patients with CM-I had significantly reduced FD values for WM and CSF in comparison with controls, and statistically significant differences in cerebellar GM and CSF volumes between patients and controls were found. Moreover, a significant difference was not found between the WM volumes. This may suggest that there are changes in structural complexity in WM even when its volume is unaffected. We conclude that the findings of this preliminary study indicate the possibility of using FD analysis to understand the pathophysiology of CM-I in patients.

Chiari III malformation: a comprehensive review of this enigmatic anomaly

INTRODUCTION

Chiari III is one of the rarest of the Chiari malformations and is characterized by a high cervical or low occipital encephalocele and osseous defect with or without spinal cord involvement and may include many of the anatomical characteristics seen in the Chiari II malformation. Herein, we provide a comprehensive review of this rare anomaly as well as a translation of Chiari's original description.

METHODS

We review all reported cases of Chiari III malformation found in the extant literature.

CONCLUSIONS

Out of 57 reported cases of Chiari III malformation, encephaloceles were in a high cervical/low occipital position in 23, 8 were in a high cervical position, 17 were in low occipital position, and the position in 9 cases was not reported. The pathogenesis of Chiari III malformation remains unclear. The majority of patients have concomitant hydrocephalus. Brain parts occurring in the sac from the most to least common include the following: cerebellum, occipital lobe, and parietal lobe. The severity of symptoms is correlated with the amount of brain structures within the encephalocele. Neurologic functional outcomes have been varied and depend on the neurological status of the patient before surgery.

The Chiari 3 Malformation and a Systemic Review of the Literature

INTRODUCTION

Chiari type 3 is a rare hindbrain malformation that has been reported in the literature primarily as case reports and case series. Radiological, pathophysiological and surgical definitions of the malformation are inconsistent in the literature and subsequently can be confusing, and outcomes have also been uniformly poor. The definition of this rare malformation will be clarified through a case presentation.

METHODS

A retrospective review of prior publications in the PubMed and MEDLINE databases was performed looking for reports of 'Chiari 3 +/- malformation' and 'occipital encephalocele'. Relevant papers were reviewed and compiled into table format with associated descriptions of a Chiari type 3 malformation. A case illustration is presented with radiological and intraoperative imaging to reinforce and clarify the definition.

RESULTS

Upon review of the prior publications in the detail of the descriptions and imaging associated with each article, there is a wide range of variability in the description of what is considered a Chiari 3 malformation. Occipital, occipitocervical and high cervical defects have all been described as Chiari 3 malformation. Our case illustration presents a patient with an occipitocervical encephalocele with neural elements, which is the classic and accepted definition of the Chiari 3 malformation.

CONCLUSION

Chiari type 3 is a rare congenital malformation, and prior publications describing this developmental disorder have not demonstrated a consensus in its definition. In addition, outcomes have traditionally been reported as poor. This case illustration of a Chiari type 3 enforces the definition of an occipitocervical encephalocele with hindbrain herniation, and with proper management not all Chiari 3 malformation patients have bad outcomes.

Fractal dimension analysis of cerebellum in Chiari Malformation type I

Chiari Malformation type I (CM-I) is a serious neurological disorder that is characterized by hindbrain herniation. Our aim was to evaluate the usefulness of fractal analysis in CM-I patients. To examine the morphological complexity features of this disorder, fractal dimension (FD) of cerebellar regions were estimated from magnetic resonance images (MRI) of 17 patients with CM-I and 16 healthy control subjects in this study. The areas of white matter (WM), gray matter (GM) and cerebrospinal fluid (CSF) were calculated and the corresponding FD values were computed using a 2D box-counting method in both groups. The results indicated that CM-I patients had significantly higher (p<0.05) FD values of GM, WM and CSF tissues compared to control group. According to the results of correlation analysis between FD values and the corresponding area values, FD and area values of GM tissues in the patients group were found to be correlated. The results of the present study suggest that FD values of cerebellar regions may be a discriminative feature and a useful marker for investigation of abnormalities in the cerebellum of CM-I patients. Further studies to explore the changes in cerebellar regions with the help of 3D FD analysis and volumetric calculations should be performed as a future work.

Arnold-Chiari Malformation Type III With Meningoencephalocele: A Case Report

Arnold-Chiari malformation type III (CM III) is an extremely rare anomaly with poor prognosis. An encephalocele with brain anomalies as seen in CM II, and herniation of posterior fossa contents like the cerebellum are found in CM III. The female infant was a twin, born at 33 weeks, weighing 1.7 kg with a huge hydrocele on the craniocervical junction. After operations were performed, she was referred to the department of rehabilitation medicine for poor motor development, swallowing dysfunction, and poor eye fixation at 22 months. The child was managed with neurodevelopmental treatment, oromotor facilitation, and light perception training. After 14 months, improvement of gross motor function was observed, including more stable head control, rolling, and improvement of visual perception. CM III has been known as a condition with poor prognosis. However, with the improvement in operative techniques and intensive rehabilitations, the prognosis is more promising than ever before. Therefore, more attention must be paid to the rehabilitation issues concerning patients with CM III.

Influence of congenital central nervous system malformations on postoperative complications following placement of cerebrospinal fluid shunts in pediatric and adolescent patients

BACKGROUND

This retrospective study was designed to evaluate whether patients with hydrocephalus associated with central nervous system (CNS) anomalies, compared with patients with hydrocephalus and absent CNS anomalies, present with significantly higher rate of postoperative complications, including more serious clinical presentation, increased life threat, and higher postoperative or late mortality rate.

METHODS

We performed a retrospective study using medical records of 100 patients of pediatric and adolescent age (0-18 years) between 2004 and 2010 treated with operative cerebrospinal fluid (CSF) shunt placement.

RESULTS

In both groups of patients, there were 43 postoperative complications, including 12 mechanical obstructions of the CSF drainage systems, 13 disconnections, 11 dislocations of proximal catheter, 6 inflammatory complications (meningitis), and 1 latex allergy. Patients with hydrocephalus associated with CNS anomalies were presented with statistically higher rate of postoperative complications (U = 303.5, z = -3.27, p = 0.001), higher number of operations, at least one complication more per patient, more complicated clinical course, higher life threat, and higher late mortality rate.

CONCLUSIONS

After installing the CSF drain system, children and adolescents with hydrocephalus associated with anomalies of the CNS require regular and careful follow-up.

Chiari type I malformation in children

The diagnosis of Chiari type I malformation (CIM) is more and more frequent in clinical practice due to the wide diffusion of magnetic resonance imaging. In many cases, such a diagnosis is made incidentally in asymptomatic patients, as including children investigated for different reasons such as mental development delay or sequelae of brain injury. The large number of affected patients, the presence of asymptomatic subjects, the uncertainties surrounding the pathogenesis of the malformation, and the different options for its surgical treatment make the management of CIM particularly controversial.This paper reports on the state of the art and the recent achievements about CIM aiming at providing further information especially on the pathogenesis, the natural history, and the management of the malformation, which are the most controversial aspects. A historial review introduces and explains the current classification. Furthermore, the main clinical, radiological, and neurophysiological findings of CIM are described to complete the picture of this heterogeneous and complex disease.

Diagnosis of Chiari III malformation by second trimester fetal MRI with postnatal MRI and CT correlation

We report a case of Chiari III malformation diagnosed by fetal MRI. Ultrasound (US) performed at a gestational age of 18 weeks demonstrated a posterior skull base cyst. Repeat US at 19 weeks demonstrated neural tissue in the cyst, consistent with an encephalocele. MR imaging at 23 weeks confirmed the presence of an occipital encephalocele, demonstrated additional bony defect in the upper cervical spine, and identified abnormal morphology and position of the brainstem consistent with the diagnosis of Chiari III. Postnatal MRI and CT confirmed the fetal MRI findings and demonstrate the utility of fetal MRI in the early evaluation of songraphically detected posterior fossa abnormalities.

CHERI: time to identify the syndrome?

Chiari I malformations are congenital abnormalities that are etiologically heterogeneous. Some studies recognize a probable association between Chiari 1 malformation, delayed language or motor development, and mental retardation with or without epilepsy. The present patient appeared to have an isolated cleft palate and Chiari 1 malformation with co-existing functional and behavioral disorders (i.e., speech delay, mental retardation, and deviant electroencephalography [EEG]). In consideration of the cleft palate population, the implication of the present case study is that more attention should be paid to the developmental milestones in children with cleft palate. Because several cases of Chiari I anomaly co-occurring with mental retardation and deviant EEG or epilepsy have been recognized, it appears justified to identify a syndrome, which is here called CHERI (Chiari 1 malformation with or without cleft palate, deviant EEG or epilepsy, and retarded intelligence with delayed language development). It will be important in the future to describe those cases identified to delineate the clinical picture and to estimate the frequency of the occurrence of various characteristics.

Causes of lumbosacral plexopathy

The lumbosacral plexus represents the nerve supply to the lower back, pelvis and legs. This review will focus on diseases and disorders affecting the pathway as demonstrated by magnetic resonance imaging (MRI) and computed tomography (CT). We stress the need to review the lumbosacral plexus in patients with non-specific symptoms such as back, hip, pelvic pain, and in those who present with sciatica unaccompanied by demonstrable intervertebral disc prolapse. We illustrate that the imaging appearances may be non-specific and re-inforce the importance of the clinical history and the use of tissue sampling to achieve an accurate diagnosis.

Chiari malformation type III treated with primary closure

Chiari malformations represent various clinical and anatomic processes that entail varying degrees of involvement of the rhombencephalon (hindbrain). The type III Chiari malformation is distinctly rare. Chiari described only one case of his type III deformity, which is indicative of its rarity. We report a case of Chiari malformation type III, a female child who presented to us at the age of 1 month with a swelling at the back of the neck since birth. MRI revealed a Chiari type III malformation with a high cervical meningoencephalocele along with herniation of cerebellar tissue through the bony defect in the posterior elements of the C2 vertebra. At surgery, the meningoencephalocele was excised along with the gliotic cerebellar tissue, and a posterior fossa decompression along with augmentation duraplasty was done. The postoperative period was uneventful. The case and relevant literature is reviewed.

Evaluating the Effect of Decompression Surgery on Cerebrospinal Fluid Flow and Intracranial Compliance in Patients with Chiari Malformation with Magnetic Resonance Imaging Flow Studies

OBJECTIVE:

To quantify the effect of decompression surgery on craniocervical junction hydrodynamics and on global intracranial compliance (ICC) in patients with Chiari I malformation by use of magnetic resonance measurements of cerebrospinal fluid and blood flow. Studying the effect of decompression surgery may improve our understanding of the pathophysiological characteristics of Chiari I malformation and aid in identifying patients who will benefit from the procedure.

METHODS:

Twelve patients were studied with a 1.5-T magnetic resonance imaging scanner before and after decompression surgery. Cine phase contrast magnetic resonance images were used to quantify maximum cord displacement, maximum systolic cerebrospinal fluid velocity and volumetric flow rate, and overall ICC. ICC was derived by use of a previously reported method that measures small changes in intracranial volume and pressure that occur naturally with each cardiac cycle.

RESULTS:

After surgery, changes were documented both in the local hydrodynamic parameters and in ICC. However, only the change in ICC, an average increase of more than 60%, was statistically significant. Increased ICC, which was associated with improved outcome, was measured in 10 of the 12 patients, no significant change was documented in 1 patient, and decreased ICC was measured in 1 patient whose symptoms persisted after surgery.

CONCLUSION:

An increase in the overall compliance of the intracranial compartment is the most significant and consistent change measured after decompression surgery. Changes in cord displacement, cerebrospinal fluid velocities, and flow in the craniospinal junction were less consistent and less affected by the operation. Thus, ICC may play an important role in the outcome of decompression surgery related to improving symptoms and restoring normal neurological hydrodynamics in patients with Chiari I malformations.

Imaging in spine and spinal cord malformations

Spinal and spinal cord malformations are collectively named spinal dysraphisms. They arise from defects occurring in the early embryological stages of gastrulation (weeks 2-3), primary neurulation (weeks 3-4), and secondary neurulation (weeks 5-6). Spinal dysraphisms are categorized into open spinal dysraphisms (OSDs), in which there is exposure of abnormal nervous tissues through a skin defect, and closed spinal dysraphisms (CSD), in which there is a continuous skin coverage to the underlying malformation. Open spinal dysraphisms basically include myelomeningocele and other rare abnormalities such as myelocele and hemimyelo(meningo)cele. Closed spinal dysraphisms are further categorized based on the association with low-back subcutaneous masses. Closed spinal dysraphisms with mass are represented by lipomyelocele, lipomyelomeningocele, meningocele, and myelocystocele. Closed spinal dysraphisms without mass comprise simple dysraphic states (tight filum terminale, filar and intradural lipomas, persistent terminal ventricle, and dermal sinuses) and complex dysraphic states. The latter category further comprises defects of midline notochordal integration (basically represented by diastematomyelia) and defects of segmental notochordal formation (represented by caudal agenesis and spinal segmental dysgenesis). Magnetic resonance imaging (MRI) is the preferred modality for imaging these complex abnormalities. The use of the aforementioned classification scheme is greatly helpful to make the diagnosis.

Spinal dysraphism: MR imaging rationale

Spinal cord development occurs through the three consecutive periods of gastrulation (weeks 2-3), primary neurulation (weeks 3-4), and secondary neurulation (weeks 5-6). Spinal cord malformations derive from defects in these early embryonic stages, and are collectively called spinal dysraphisms. Spinal dysraphisms may be categorized clinically into open and closed, based on whether the abnormal nervous tissue is exposed to the environment or covered by skin. Open spinal dysraphisms include myelomeningocele and other rare abnormalities such as myelocele, hemimyelomeningocele, and hemimyelocele, and are always associated with a Chiari II malformation. Closed spinal dysraphisms are further divided into two subsets based on whether a subcutaneous mass is present in the low back. Closed spinal dysraphisms with mass comprise lipomyelocele, lipomyelomeningocele, meningocele, and myelocystocele. Closed spinal dysraphisms without mass comprise simple dysraphic states (tight filum terminale, filar and intradural lipomas, persistent terminal ventricle, and dermal sinuses) and complex dysraphic states. The latter category involves abnormal notochordal development, either in the form of failed midline integration (ranging from complete dorsal enteric fistula to neurenteric cysts and diastematomyelia) or of segmental agenesis (caudal agenesis and spinal segmental dysgenesis). Magnetic resonance imaging is the imaging modality of choice for evaluation of this complex group of disorders.

Chiari III malformation: varieties of MRI appearances in two patients

Chiari III malformation is an extremely rare anomaly, which is characterized by the herniation of posterior fossa contents, i.e., cerebellum, brain stem and fourth ventricle, and in some cases upper cervical spinal cord through a low occipital and/or upper cervical osseous defect. We report different presentations of Chiari III malformation in two unusual cases to show the diversity of imaging findings of this rare malformation.

Tonsillectomy without craniectomy for the management of infantile Chiari I malformation

OBJECT

The authors report their experience with 15 pediatric patients who underwent resection or shrinkage of the cerebellar tonsils without craniectomy or laminectomy, for the management of Chiari I malformation.

METHODS

The procedure was performed in six boys and nine girls with a mean age of 10 years. Thirteen patients presented with the congenital form of this disorder and two patients with Chiari I malformation caused by lumboperitoneal shunting. Clinical complaints included headaches (seven patients), scoliosis (four patients), numbness of the extremities (four patients), and upper-limb weakness (two patients). Two patients presented with failure to thrive and one with vocal cord palsy. Eight patients (six girls and two boys) had syringomyelia. The patients' symptoms had developed within a mean time period of 21 months (range 1-70 months). In all patients the cerebellar tonsils were exposed through a dura mater-arachnoid incision at the occipitoatlantal space. In seven patients the tonsils were resected and in the remaining eight patients the tonsils were shrunk by coagulating their surfaces. All patients improved postoperatively. Gliosis with cortical atrophy was observed in the resected neural tissue. Syringomyelia was reduced in seven of eight patients. The mean length of the follow-up period was 7 months.

CONCLUSIONS

Removal of herniated cerebellar tonsils can be sufficient for alleviating symptoms in patients with Chiari I malformations.

Magnetic resonance imaging of spinal dysraphism

Spinal cord development occurs through three consecutive periods. Gastrulation (weeks 2-3) is characterized by conversion of the embryonic disk from a bilaminar to a trilaminar arrangement and establishment of a notochord. Primary neurulation (weeks 3-4) produces the uppermost nine tenths of the spinal cord. Secondary neurulation and retrogressive differentiation (weeks 5-6) result in formation of the conus tip and filum terminale. Defects in these early embryonic stages produce spinal dysraphisms, which are characterized by anomalous differentiation and fusion of dorsal midline structures. Spinal dysraphisms may be categorized clinically into two subsets. In open spinal dysraphisms, the placode (non-neurulated neural tissue) is exposed to the environment. These disorders include myelomeningocele, myeloschisis, hemimyelomeningocele, and hemimyelocele, and are always associated with a Chiari II malformation. Closed spinal dysraphisms are covered by intact skin, although cutaneous stigmata usually indicate their presence. Two subsets may be identified based on whether a subcutaneous mass is present in the low back. Closed spinal dysraphisms with mass comprise lipomyeloschisis, lipomyelomeningocele, meningocele, and myelocystocele. Closed spinal dysraphisms without mass comprise complex dysraphic states (ranging from complete dorsal enteric fistula to neurenteric cysts, split cord malformations, dermal sinuses, caudal regression, and spinal segmental dysgenesis), bony spina bifida, tight filum terminale, filar and intradural lipomas, and persistent terminal ventricle. Magnetic resonance imaging is the imaging method of choice for investigation of this complex group of disorders.

Association of Chiari I malformation, mental retardation, speech delay, and epilepsy: a specific disorder?

OBJECTIVE

The Chiari I malformation is defined as tonsillar herniation of at least 3 to 5 mm below the foramen magnum. Although Chiari I malformation is considered to derive from a mesodermal disorder resulting in underdevelopment of the posterior fossa relative to its content, evidence for a possible heterogeneous etiology also has been reported. The aim of the present study is to elucidate the relationship between Chiari I malformation and mental retardation, speech delay, and epilepsy to consider a possible specific pathogenetic background.

METHODS

Thirty-five patients with Chiari I malformations were identified by use of magnetic resonance imaging during a period between 1993 and 1999. The study consisted of nine patients (four boys and five girls) who were affected by mental retardation, speech delay, and epilepsy. All patients underwent electroencephalography and brain and cervical spine magnetic resonance imaging.

RESULTS

All patients were mentally retarded with a mean intelligence quotient of 50. Seven patients had a positive history for speech delay, and five were epileptic. Electroencephalograms demonstrated abnormalities in seven patients. The mean tonsillar displacement was 10.1 mm. A thin corpus callosum and a wide cavum septum pellucidum were present in three patients. Neither hydromyelia nor scoliosis was observed. No correlation between the degree of the ectopia and clinical manifestation was noted.

CONCLUSION

The association of Chiari I malformation with epilepsy, speech delay, and mental retardation may not be a mere incidental finding but may be a marker for a different pathogenetic background.