Rare and de novo coding variants in chromodomain genes in Chiari I malformation.

Chiari I malformation (CM1), the displacement of the cerebellum through the foramen magnum into the spinal canal, is one of the most common pediatric neurological conditions. Individuals with CM1 can present with neurological symptoms, including severe headaches and sensory or motor deficits, often as a consequence of brainstem compression or syringomyelia (SM). We conducted whole-exome sequencing (WES) on 668 CM1 probands and 232 family members and performed gene-burden and de novo enrichment analyses. A significant enrichment of rare and de novo non-synonymous variants in chromodomain (CHD) genes was observed among individuals with CM1 (combined p = 2.4 × 10-10), including 3 de novo loss-of-function variants in CHD8 (LOF enrichment p = 1.9 × 10-10) and a significant burden of rare transmitted variants in CHD3 (p = 1.8 × 10-6). Overall, individuals with CM1 were found to have significantly increased head circumference (p = 2.6 × 10-9), with many harboring CHD rare variants having macrocephaly. Finally, haploinsufficiency for chd8 in zebrafish led to macrocephaly and posterior hindbrain displacement reminiscent of CM1. These results implicate chromodomain genes and excessive brain growth in CM1 pathogenesis.

Natural history of Chiari I malformation with syrinx and dilatation of the central canal in the pediatric population: the CHEO experience.

PURPOSE: Given that syrinx is often considered an indication of surgery in children with Chiari I malformation (CM1), understanding of the natural history of these patients is very challenging. In this study, we investigate the natural history of children with CM1 that have syrinx and/or prominence of the central canal on presentation. METHODS: All pediatric Chiari I patients who had syrinx and/or prominence of the central canal who underwent MR imaging of the head and spine from 2007 to 2020 were reviewed. Patients were divided into 3 groups (early surgery, delayed surgery, and conservative management). We focused on those patients who did not initially undergo surgery and had at least 1 year of clinical follow-up. We assessed if there were any radiological features that would correlate with need for delayed surgical intervention. RESULTS: Thirty-seven patients met the inclusion criteria. Twenty-one patients were female and 16 were male. The mean age at presentation was 8.7 (5.8 SD). Fourteen (38%) patients had early surgical intervention, with a mean of 2.5 months after initial presentation, 8 (16%) had delayed surgery due to new or progressive neurological symptoms and 46% of patients did not require intervention during follow-up. The length of tonsillar herniation and the position of the obex were associated with the need of surgery in patients who were initially treated conservatively. CONCLUSION: In pediatric patients with CM1 with syringomyelia and prominence of the central canal, conservative treatment is initially appropriate when symptoms are absent or mild. Close follow-up of patients with CM1 and dilatation of the central canal who have an obex position below the foramen magnum and greater tonsillar herniation is suggested, as these patients show a trend towards clinical deterioration over time and may require earlier surgical intervention.

Cerebrospinal Fluid Flow and Brain Motion in Chiari I Malformation: Past, Present, and Future.

Cranio-spinal volume and pressure changes associated with the cardiac-cycle and respiration are altered in Chiari I malformation (CMI) due to obstruction of cerebrospinal fluid (CSF) flow at the foramen magnum. With the introduction of motion-sensitive MRI sequences, it was envisioned that these could provide noninvasive information about volume-pressure dynamics at the cranio-cervical junction in CMI hitherto available only through invasive pressure measurements. Since the early 1990s, multiple studies have assessed CSF flow and brain motion in CMI. However, differences in design and varied approaches in the presentation of results and conclusions makes it difficult to fully comprehend the role of MR imaging of CSF flow and brain motion in CMI. In this review, a cohesive summary of the current status of MRI assessment of CSF flow and brain motion in CMI is presented. Simplified versions of the results and conclusions of previous studies are presented by dividing the studies in distinct topics: 1) comparing CSF flow and brain motion between healthy subjects (HS) and CMI patients (before and after surgery), 2) comparing CSF flow and brain motion to CMI severity and symptoms, and 3) comparing CSF flow and brain motion in CMI with and without syringomyelia. Finally, we will discuss our vision of the future directions of MR imaging in CMI patients. EVIDENCE LEVEL: 2. TECHNICAL EFFICACY: 5.

Surgery for basilar invagination with and without Chiari I malformation.

OBJECTIVE: The surgical treatment for Chiari I malformation and basilar invagination has been discussed with great controversy in recent years. This paper presents a treatment algorithm for these disorders based on radiological features, intraoperative findings, and analyses of long-term outcomes. METHODS: Eight-five operations for 82 patients (mean ± SD age 40 ± 18 years; range 9-75 years) with basilar invagination were evaluated, with a mean follow-up of 57 ± 55 months. Apart from the radiological features and intraoperative findings, findings on neurological examinations before and after surgery were analyzed. Long-term outcomes were evaluated with Kaplan-Meier statistics. All 77 patients with a Chiari I malformation underwent foramen magnum decompression with arachnoid dissection and duraplasty. Patients with ventral compression by the odontoid peg were managed with posterior realignment and C1-2 fusion. Patients without ventral compression did not undergo C1-2 fusion unless radiological or clinical signs of instability were detected. RESULTS: Thirty-three patients without ventral compression or instability underwent foramen magnum decompression without additional fusion, whereas 52 operations on 49 patients involved posterior fusion at C0-2 or C1-2 after realignment of ventral compression and/or treatment of C1-2 instability. Postoperatively, gait ataxia, swallowing functions, and suboccipital pain improved significantly in both treatment groups. In total, 79% and 73% of patients reported that their condition improved after foramen magnum decompression alone and after fusion with or without foramen magnum decompression, respectively. Progression-free survival rates at 10 years were 83% and 81%, respectively. CONCLUSIONS: Among the patients with basilar invagination, a subgroup consisting of 40.2% of the included patients underwent successful long-term treatment with foramen magnum decompression alone and without additional fusion. This subgroup was characterized by the absence of a ventral compression and no atlantoaxial dislocation or other signs of craniocervical instability. The remainder of patients underwent C1-2 fusion with posterior realignment of ventral compression if required. In the presence of basilar invagination, Chiari I malformation should be treated with foramen magnum decompression and duraplasty.

Central nervous system involvement in individuals with RASopathies.

Central nervous system (CNS) anomalies are common in individuals with RASopathies. While certain findings, including relative or absolute macrocephaly, are typical for most RASopathies, other findings are more common in certain conditions, with rare low-grade gliomas in Noonan syndrome (NS); Chiari 1 malformation and tethered cord in Costello syndrome (CS); and variable structural anomalies including heterotopia and hydrocephalus in cardio-facio-cutaneous syndrome (CFC). We performed a literature review and present aggregate data on the common and uncommon CNS manifestations in individuals with RASopathies. A gene-based approach to defining risk for specific abnormalities may be considered. However, limited information on the CNS findings of rare RASopathies, such as autosomal recessive LZTR1-related NS or PPP1CB-related NS with loose anagen hair (NSLH), is currently available. Thus, consideration of the RASopathies as a group of distinct syndromic conditions with shared underlying causes and overlapping clinical presentations remains relevant, and individuals with a RASopathy are at risk for many findings seen in these conditions.

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.

Use of deep learning in the MRI diagnosis of Chiari malformation type I.

PURPOSE: To train deep learning convolutional neural network (CNN) models for classification of clinically significant Chiari malformation type I (CM1) on MRI to assist clinicians in diagnosis and decision making. METHODS: A retrospective MRI dataset of patients diagnosed with CM1 and healthy individuals with normal brain MRIs from the period January 2010 to May 2020 was used to train ResNet50 and VGG19 CNN models to automatically classify images as CM1 or normal. A total of 101 patients diagnosed with CM1 requiring surgery and 111 patients with normal brain MRIs were included (median age 30 with an interquartile range of 23-43; 81 women with CM1). Isotropic volume transformation, image cropping, skull stripping, and data augmentation were employed to optimize model accuracy. K-fold cross validation was used to calculate sensitivity, specificity, and the area under receiver operating characteristic curve (AUC) for model evaluation. RESULTS: The VGG19 model with data augmentation achieved a sensitivity of 97.1% and a specificity of 97.4% with an AUC of 0.99. The ResNet50 model achieved a sensitivity of 94.0% and a specificity of 94.4% with an AUC of 0.98. CONCLUSIONS: VGG19 and ResNet50 CNN models can be trained to automatically detect clinically significant CM1 on MRI with a high sensitivity and specificity. These models have the potential to be developed into clinical support tools in diagnosing CM1.

MRI findings differentiating tonsillar herniation caused by idiopathic intracranial hypertension from Chiari I malformation.

PURPOSE: Some patients with idiopathic intracranial hypertension (IIH) have cerebellar tonsillar herniation ≥ 5 mm mimicking Chiari malformation I (CMI), which can result in misdiagnosis and unjustified treatment. Our purpose was to identify IIH patients with tonsillar herniation ≥ 5 mm (IIHTH) and compare with CMI patients to assess imaging findings that could distinguish the two conditions. METHODS: Ninety-eight patients with IIH, 81 patients with CMI, and 99 controls were retrospectively assessed. Two neuroradiologists blindly reviewed MR images. IIHTH patients were compared with CMI patients and controls regarding the extent of tonsillar herniation (ETH), bilateral transverse sinus stenosis (BTSS), hypophysis-sella ratio (HSR), and bilateral tortuosity of optic nerve (BTON). RESULTS: 13/98 (13.2%) IIH patients had tonsillar herniation ≥ 5 mm (IIHTH) and were significantly younger and had higher BMI compared with CMI patients and controls. ETH was significantly less in the IIHTH than CMI (6.5 ± 2.4 mm vs. 10.9 ± 4.4 mm; p < 0.001). BTSS and HSR < 0.5 were more common in IIHTH than CMI (p < 0.001 and p = 0.003, respectively). No differences were seen between CMI and controls. BTON was significantly more common in IIHTH compared to control (p = 0.01) but not to the CMI (p = 0.36). Sensitivity and specificity to differentiate IIHTH from CMI were 69.2% and 96.1% for BTSS and 69.2% and 75.3% for HSR < 0.5. CONCLUSION: The presence of BTSS and/or HSR < 0.5 in patients with ETH ≥ 5 mm should suggest further evaluation to exclude IIH before considering CMI surgery.

Pediatric Chiari I malformation: novel and traditional measurements associated with syrinx and surgery.

PURPOSE: Multiple imaging parameters have been examined to estimate the presence of syrinx and the need for surgery in Chiari I patients (CM1); however, no consistent or definitive criteria have been proposed. The objective of this study was to review existing and identify novel radiological and clinical characteristics of CM1 patients that associate syrinx development and surgical intervention. METHODS: Patients with Chiari I malformation diagnosed on imaging between 0 and 18 years were retrospectively reviewed from January 1, 2007 to February 12, 2020. Participants were included if they had a baseline MRI of the head and spine prior to surgical intervention if required. Forty age-matched controls with cranial imaging were identified for comparison. Imaging parameters and clinical symptoms were recorded. RESULTS: A total of 122 CM1 patients were included in this study. Of the 122 patients, 28 (23%) had syrinx, and 27 (22%) had surgery. The following imaging parameters associated with syrinx and surgical intervention were identified: midbrain length (P < 0.001; P = 0.032), the obex position (P = 0.002; P < 0.001) and medullary kinking (P = 0.041; P < 0.001). Among the clinical features, the presence of overall pain (P = 0.017; P = 0.042), neck pain (P = 0.005; P = 0.027), and sensory dysfunction (P < 0.001) were found to be strongly associated with syrinx and surgery. CONCLUSION: While further investigation is needed, these specific radiological and clinical parameters should be considered when evaluating CM1 patients and may be used to guide further management.

Various manifestation of Chiari I malformation in children and improvement after surgery.

INTRODUCTION: Chiari I malformation is defined as caudal displacement of the cerebellar tonsils into the foramen magnum. The most commonly associated finding is cervical syringomyelia. The most common presenting symptom is occipital and upper cervical pain. The incidence of syringomyelia is between 30% and 70%. Surgery is recommended for symptomatic patients. The main purpose of the study is to present the data of children with Chiari type I malformation that were treated surgically in low-volume center and to describe some atypical presentations in children. MATERIALS AND METHODS: At University Medical Centre Maribor, Slovenia, we performed a retrospective study of children with Chiari type I malformation that were treated surgically in the period from 2012 until 2021. The indication for surgery was symptomatic Chiari type I malformation. Suboccipital decompression with laminectomy of at least C1 (in one case also C2) with splitting of dura or duraplasty was performed. In a few cases coagulation of both tonsillar tips was necessary to achieve sufficient decompression and restoration of adequate cerebrospinal fluid (CSF) flow. RESULTS: Ten children (under 18 years of age) underwent surgery for Chiari I malformation. Four patients had atypical presentation. In nine patients there was improvement after surgery. Complication rate was zero with no revision surgery. In one case suboccipital headache persisted. In all cases with preoperative syringomyelia it improved after surgery. Scoliosis improved in two out of three cases. There was no mortality after the procedure. DISCUSSION: When patients with Chiari I malformation become symptomatic, it is recommended to perform surgery as soon as possible. Comparing the techniques; dura-splitting technique has advantages of lesser operation duration, lesser intraoperative bleeding and lower complication rates than duraplasty. CONCLUSIONS: The majority of patients with Chiari I malformation improve after surgery. Surgical procedure is safe with very low morbidity and mortality. Surgical technique must be an individualized patient tailored choice.

Management of Sleep Apnea in Children with Chiari I Malformation: A Retrospective Study.

INTRODUCTION: The literature indicates that decompression of Chiari I malformations (CM-1) may resolve symptoms of sleep apnea. This study aims to identify the incidence of obstructive sleep apnea (OSA), central sleep apnea (CSA), and mixed sleep apnea in a cohort of pediatric CM-1 patients treated at our institution. We also assessed apnea-hypopnea index and symptomatology before and after surgery to investigate if Chiari decompression is a viable treatment for sleep apnea in CM-1 patients. Improvement relative to ENT surgical intervention was also considered. METHODS: We identified 75 patients who underwent polysomnography (PSG) from our database of 465 CM-1 patients. Sleep apnea diagnosis was based on the sleep physician's overall interpretation of the PSG. Symptomatology pre- and post-surgery was analyzed. RESULTS: Of the 75 CM-1 patients that underwent PSG, 23 were diagnosed with sleep apnea. Sixteen had OSA, 6 had CSA, and 1 had mixed apnea. Twelve OSA patients received ENT intervention. Eight improved and 2 further improved after Chiari decompression. Of the 4 patients that did not improve, one of those later improved following Chiari decompression. Of the 6 CSA patients, 2 underwent Chiari decompression, but only one improved. The mixed apnea patient underwent several ENT interventions that did not relieve symptoms but improved following Chiari decompression. DISCUSSION/CONCLUSIONS: Based on our results, sleep apnea in CM-1 patients may be obstructive, central, or mixed and is likely multifactorial. A multidisciplinary approach to the management of these patients is important, including neurosurgery, otolaryngology, and sleep medicine. Future prospective studies will lend further insight into this condition and its management.

Minimum 5-year follow-up outcomes for one-stage posterior instrumentation without neurosurgery intervention for correction of scoliosis associated with Chiari I malformation and syringomyelia.

INTRODUCTION: Traditionally, the common belief has been that, all patients with Chiari I malformation (CM-1) and syringomyelia (SM) undergoing a neurosurgical procedure even if they are neurologically asymptomatic. As the pathology of CM-1 and SM has become better understood, the traditional concepts have been challenged. The objective of this study was to investigate the minimum 5-year follow-up clinical outcomes of surgical treatment of patients with scoliosis associated with CM-1 and SM and to evaluate the necessity of neurosurgical intervention before corrective surgery. METHODS: This retrospective study was performed from May 2009 to September 2014. We enrolled 35 patients with scoliosis associated with CM-1 and SM who were undergoing spinal correction surgery without neurosurgical intervention. During the surgery, spinal cord monitor and wake-up test were used. Preoperative, postoperative, and final follow-up major curve coronary Cobb angle, correction rate, apical vertebral rotation (AVR), apical vertebral translation (AVT), thoracic kyphosis angle (T5-T12), lumbar lordosis angle (L1-S1) were analyzed on radiographs. RESULTS: The mean follow-up period was 82.5 months. The preoperative and postoperative mean curve coronary Cobb angle was from 55.7 ± 7.5° to 20.1 ± 5.8°, correction rate was 63.9%, AVR from 2.8 ± 0.6° to 1.3 ± 0.5°, AVT from 5.1 ± 1.4 to 1.7 ± 0.7 cm, thoracic kyphosis angle from 18.7 ± 4.0° to 32.2 ± 2.7°, lumbar lordosis angle from 36.3 ± 4.1° to 43.8 ± 3.2°. No neurological deficits occurred during the operation and follow-up. CONCLUSIONS: Our minimum 5-year follow-up outcomes showed that in a distinct patient population of neurologically asymptomatic individuals with CM-1, SM and progressive scoliosis, posterior instrumented spinal deformity surgery can be safely done without neurosurgical interverventions with the help of preoperative flexibility evaluation and intraoperative neuromonitoring.

A case report: resolution of Chiari I malformation after helmet therapy for deformational brachycephaly.

Positional plagiocephaly is the most common cause of cranial asymmetry. Deformational brachycephaly denotes a head shape characterized by occipital flattening and increased bilateral width, which can also be caused by external deformation of the moldable infant cranium in positional bilateral posterior plagiocephaly. There are reports of craniosynostosis associated with Chiari I malformation (CIM), possibly caused by decreased posterior fossa volume and related to increased intracranial pressure. To the best of our knowledge, this is only the second case report demonstrating acquired CIM in a child with positional brachycephaly. Of note, the fact that the CIM resolved after helmet therapy could support the hypothesis that CIM is associated with decreased volume of the posterior fossa. However, these two conditions may be independent of one another. More research is needed to identify an association between the two conditions.

Chiari I malformation in patients with RASopathies.

PURPOSE: Chiari I malformation (CIM) is a common pediatric neurologic anomaly which could be associated with a variety of genetic disorders. However, it is not always clear whether the observed associations between CIM and RASopathies are real or random. The knowledge of the real association could provide useful guidance to clinicians. Furthermore, it could help to better understand the still unknown genetic etiology of CIM. METHOD AND RESULTS: We reviewed the current knowledge of CIM and RASopathies in the paper. Here, we describe one patient with CIM and Noonan syndrome and three patients with CIM and neurofibromatosis type 1. Three of the four patients underwent standard surgical therapy of Chiari decompression and had a straightforward recovery without further complications from surgery. CONCLUSION: In RASopathy, imaging of the nervous system may be necessary. With the increase in availability of magnetic resonance imaging, we believe that there will be a growing body of evidence to suggest that CIM is more commonly seen in RASopathy. Future studies should attempt to elucidate the pathogenic mechanism responsible for CIM mediated by the RAS/MAPK signaling pathway.

Functional and morphological changes in hypoplasic posterior fossa.

BACKGROUND: The knowledge of the development and the anatomy of the posterior cranial fossa (PCF) is crucial to define the occurrence and the prognosis of diseases where the surface and/or the volume of PCF is reduced, as several forms of craniosynostosis or Chiari type I malformation (CIM). To understand the functional and morphological changes resulting from such a hypoplasia is mandatory for their correct management. The purpose of this article is to review the pertinent literature to provide an update on this topic. METHODS: The related and most recent literature addressing the issue of the changes in hypoplasic PCF has been reviewed with particular interest in the studies focusing on the PCF characteristics in craniosynostosis, CIM, and achondroplasia. RESULTS AND CONCLUSIONS: In craniosynostoses, namely, the syndromic ones, PCF shows different degrees of hypoplasia, according to the different pattern and timing of early suture fusion. Several factors concur to PCF hypoplasia and contribute to the resulting problems (CIM, hydrocephalus), as the fusion of the major and minor sutures of the lambdoid arch, the involvement of the basal synchondroses, and the occlusion of the jugular foramina. The combination of these factors explains the variety of the clinical and radiological phenotypes. In primary CIM, the matter is complicated by the evidence that, in spite of impaired PCF 2D measurements and theories on the mesodermal defect, the PCF volumetry is often comparable to healthy subjects. CIM is revealed by the overcrowding of the foramen magnum that is the result of a cranio-cerebral disproportion (altered PCF brain volume/PCF total volume). Sometimes, this disproportion is evident and can be demonstrated (basilar invagination, real PCF hypoplasia); sometimes, it is not. Some recent genetic observations would suggest that CIM is the result of an excessive growth of the neural tissue rather than a reduced growth of PCF bones. Finally, in achondroplasia, both macrocephaly and reduced 2D and 3D values of PCF occur. Some aspects of this disease remain partially obscure, as the rare incidence of hydrocephalus and syringomyelia and the common occurrence of asymptomatic upper cervical spinal cord damage. On the other hand, the low rate of CIM could be explained on the basis of the reduced area of the foramen magnum, which would prevent the hindbrain herniation.

Pre-operative headaches and obstructive hydrocephalus predict an extended length of stay following suboccipital decompression for pediatric Chiari I malformation.

PURPOSE: For young children and adolescents with Chiari malformation type I (CM-I), the determinants of extended length of hospital stay (LOS) after neurosurgical suboccipital decompression are obscure. Here, we investigate the impact of patient- and hospital-level risk factors on extended LOS following surgical decompression for CM-I in young children to adolescents. METHODS: The Kids' Inpatient Database year 2012 was queried. Pediatric CM-I patients (6-18 years) undergoing surgical decompression were identified. Weighted patient demographics, comorbidities, complications, LOS, disposition, and total cost were recorded. A multivariate logistic regression was used to determine the odds ratio for risk-adjusted LOS. The primary outcome was the degree patient comorbidities or post-operative complications correlated with extended LOS. RESULTS: A total of 1592 pediatric CM-I patients were identified for which 328 (20.6%) patients had extended LOS (normal LOS, 1264; extended LOS, 328). Age, gender, race, median household income quartile, and healthcare coverage distributions were similar between the two cohorts. Patients with extended LOS had significantly greater admission comorbidities including headache symptoms, nausea and vomiting, obstructive hydrocephalus, lack of coordination, deficiency anemias, and fluid and electrolyte disorders. On multivariate logistic regression, several risk factors were associated with extended LOS, including headache symptoms, obstructive hydrocephalus, and fluid and electrolyte disorders. CONCLUSIONS: Our study using the Kids' Inpatient Database demonstrates that presenting symptoms and signs, including headaches and obstructive hydrocephalus, respectively, are significantly associated with extended LOS following decompression for pediatric CM-I.

Chiari I malformation with Klippel-Trenaunay syndrome: case report and review of the literature.

We present a rare case of an 8-year-old male with Klippel-Trenaunay syndrome (KTS) and a Chiari I malformation (CIM). Magnetic resonance imaging (MRI) to investigate facial asymmetry and speech delay at age two revealed CIM with cerebellar tonsils 1.3 cm below the foramen magnum without syringomyelia. The patient underwent a craniectomy and posterior fossa decompression with C1 laminectomy. While gene sequencing determined the patient was negative for the PIK3CA gene mutation, the patient's clinical history strongly suggests KTS. He has hemihypertrophy, leg length discrepancy, hemangiomas and pigmentary mosaicism along the upper and lower extremities, heart murmur, chronic low heart rate, recurrent hip pain, and mild scoliosis. Neurodevelopmental concerns include difficulty reading, attention deficit hyperactivity disorder (ADHD), anxiety, and difficulty running and going downstairs. His most recent MRI shows good decompression at the cervicomedullary junction, global cerebrospinal fluid (CSF) flow, and less peg-like cerebellar tonsils. Also noted were two intravertebral hemangiomas at T5 and T6. While the patient's speech has improved, there is still difficulty with the expressive language. He still has mild delays, runs slowly, and does not alternate feet when climbing stairs. The patient is being followed by multiple specialists including neurology, hematology-oncology, genetics, orthopedic surgery, and developmental pediatrics.

Radiological outcome after surgical treatment of syringomyelia-Chiari I complex in adults: a systematic review and meta-analysis.

Foramen magnum decompression (FMD) is widely accepted as the standard treatment for syringomyelia associated with Chiari type I malformation (CMI). Despite extensive clinical investigations, relevant surgical details are still matter of debate. The authors performed a systematic review and meta-analysis of the literature examining the radiological outcome of syringomyelia in adult patients with CMI after different surgical strategies. PRISMA guidelines were followed. A systematic search of three databases was performed for studies published between 1990 and 2018. Our systematic review included 13 studies with a total of 276 patients with CMI associated with syringomyelia. Overall, the rate of post-operative radiological improvement at last follow-up was 81.1% (95% CI 73.3-88.9%; p < 0.001; I2 = 71.4%). The rate of post-operative syrinx shrinkage did not differ significantly among both groups of decompression with the extra-arachnoidal technique and arachnoid dissection (90%, 95% CI 85.1-94.8%, I2 = 0% vs 79.8%, 95% CI 61.7-98%, I2 = 85.5%). A lower rate of post-operative radiological syrinx shrinkage was observed after decompression with splitting of the outer layer of the dura (55.6% 95% CI 40.5-70.8%, I2 = 0%). CSF-related complications and infections were similar among the different groups. Our meta-analysis found that FMD with the extra-arachnoidal technique and arachnoid dissection provides similar results in terms of post-operative shrinkage of syringomyelia. Patients undergoing decompression with splitting of the dura presented the lower rate of syrinx reduction. These data should be considered when choosing the surgical approach in adult patients with CMI associated with syringomyelia.

Treatment of symptomatic Chiari I malformation by "all-factors-surgery": a report of 194 cases.

PURPOSE: Inadequate decompressions can lead to poor improvement of symptoms in patients with Chiari I malformation (CMI). In this study, the "all-factors-surgery" that including all levels decompressions was performed on symptomatic CMI patients for the snake of eliminating all possible pathogenic factors and reducing the chance of reoperation. METHODS: The "all-factors-surgery" combined operations of posterior fossa decompression, enlarged cranioplasty, duraplasty, cerebellar tonsil partial resection and adhesion release. Total 194 patients from January 2010 to December 2015. The outcome measures included improvement rate of symptoms, patients self-evaluation (improved, unchanged, worsened), Visual Analogue Scale (VAS) score, Japanese Orthopaedic Association (JOA) score, Chicago Chiari Outcome Scale (CCOS) score, the diameter of the syrinx and complications. RESULTS: Postoperative data were collected from the three stages: at discharge, the short-term follow-up (average, 9.39 months), and the long-term follow-up (average, 54.44 months). Patients self-evaluation improvement rate in the three follow-up stages was 92.27%, 90.07% and 85.93%. The VAS scores (mean, 1.49, 1.21, 1.47 vs 3.76) and JOA scores (mean, 15.66, 15.99, 16.10 vs 14.84) were significant difference between the follow-up and pre-operation (P < .05). The CCOS scores of short-term and long-term follow-up were significantly better than that at discharge (mean, 14.75, 14.87 vs 13.68) (P < .05). The diameter of syrinx in each follow-up stage was significantly less than that in pre-operation (mean, 3.39, 1.95, 1.87 vs 5.09) (P < .05). There were no serious complications, and no one asked for reoperation during the follow up. CONCLUSION: Symptomatic CMI patients undergoing "all-factors-surgery" had persistently high rates of symptom relief and rarely needed reoperation.

Histological and intraoperative evaluations of the arachnoid in patients with Chiari I malformation.

BACKGROUND: Arachnoid dissection for decompression of Chiari I malformation is controversial. Whether arachnoid changes have an impact on the clinical course is not established. This paper documents the histological spectrum of arachnoid changes and evaluates correlations with preoperative, intraoperative, and postoperative data. METHOD: Arachnoid samples of 162 consecutive foramen magnum decompressions from 2006 to 2016 were studied. Arachnoid thickness and degrees of fibrosis and cellularity were determined with the examiner blinded for clinical data. Based on 145 first time decompressions, a histological classification for arachnoid features was developed. RESULTS: The arachnoid was thicker in secondary compared with primary decompressions (176.1 ± 158.2 µm vs. 35.9 ± 43.5 µm; p = 0.0026) and in adults compared to children (37.3 ± 45.3 µm vs. 21.8 ± 7.7 µm; p = 0.0007). In primary decompressions, arachnoid thickness, degrees of fibrosis, and cellularity followed a normal distribution with all features shifted significantly to higher grades in secondary decompressions. The histological classification correlated with the preoperative severity of gait ataxia, motor weakness, and sensory deficits, whereas it had no predictive power for postoperative short- or long-term results. By comparison, the intraoperative evaluation of arachnoid changes accounting for relationships between arachnoid and surrounding tissues showed higher correlations with preoperative symptoms and had significant predictive power for postoperative short- and long-term results. CONCLUSIONS: Histological changes of the arachnoid correlate with preoperative symptoms. Relationships between arachnoid and surrounding tissues show even higher correlations with predictive power for short- and long-term outcomes. These findings suggest a pathophysiological role for the arachnoid in Chiari I malformation.