Chiari Malformation Research Articles

A child with unilateral abducens nerve palsy and neurovascular compression in Chiari malformation type 1 resolved with posterior fossa decompression: illustrative case.

Unilateral cranial nerve (CN) VI, or abducens nerve, palsy is rare in children and has not been reported in association with Chiari malformation type 1 (CM1) in the absence of other classic CM1 symptoms. A 3-year-old male presented with acute incomitant esotropia consistent with a unilateral, left CN VI palsy and no additional neurological symptoms. Imaging demonstrated CM1 without hydrocephalus or papilledema, as well as an anterior inferior cerebellar artery (AICA) vessel loop in the immediate vicinity of the left abducens nerve. Given the high risk of a skull base approach for direct microvascular decompression of the abducens nerve and the absence of other classic Chiari symptoms, the patient was initially observed. However, as his palsy progressed, he underwent posterior fossa decompression with duraplasty (PFDD), with the aim of restoring global cerebrospinal fluid dynamics and decreasing possible AICA compression of the left abducens nerve. Postoperatively, his symptoms completely resolved. In this first reported case of CM1 presenting as a unilateral abducens palsy in a young child, possibly caused by neurovascular compression, the patient's symptoms resolved after indirect surgical decompression via PFDD.

Are Chiari malformation and basilar invagination associated with jugular foramen stenosis?

To compare the diameter of the jugular foramen (JF) between normal individuals and those with the diagnosis of craniovertebral junction abnormalities, such as Chiari malformation type I (CMI) and/or basilar invagination (BI). This cross-sectional analytical study measured the diameter of right and left JF in magnetic resonance imaging of patients that were split into four groups: 68 with combined CMI and BI (CMI+BI), 42 with isolated BI, 45 with isolated CMI, and 102 control cases. The t test determined sex differences, while univariate ANOVA with Tukey's post-hoc test assessed JF differences between groups. Considering all combinations of laterality and sex, CMI+BI had JF narrower than their respective controls. The JF was bilaterally narrower in BI than the control, only in females. Regardless of laterality, CMI had wider JF than the CMI+BI in males, and it did not differ from the control. In the females of CMI, the right JF did not differ from the control, and it was wider than the CMI+BI; while the left JF was narrower than the control, and it did not differ from the CMI+BI. JF narrowing is associated with CMI and BI when they are found combined in the same patient. When CMI or BI are detected separately, they do not imply evident changes in JF morphometry. It is expected that these findings could bring empiric substrate to support theories that claims a possible role of intracranial pressure disturbances as a triggering factor for CMI.

Chiari type 1.5 malformation as a cause of secondary trigeminal neuralgia: case report and literature discussion

BackgroundChiari syndrome is a very rare cause of secondary trigeminal neuralgia (TN). There are a few cases of TN associated with Chiari syndrome in the literature, and all of these cases were reported as Chiari type 1. In this report, we present a case of secondary trigeminal neuralgia caused by Chiari type 1.5 for the first time unlike the literature.Case presentationA 38-year-old male patient, who had frequent and severe attacks of pain under the orbit, at the chin and rim of the mouth, was evaluated with craniocervical Magnetic Resonance Imaging (MRI) and revealed Chiari type 1.5 malformation and syringomyelia.ConclusionsThe mechanism of TN associated with Chiari malformation is unclear. However, the main concepts emphasized in cases presented in the literature are compression and stretching. The rapid relief of pain after decompression surgery in these cases also supports this situation. It can be predicted that compression and tension forces will become more pronounced in Chiari type 1.5 malformation, in which the brainstem elongation and ventral pressure are more prominent. Decompression of the foramen magnum provides rapid and effective pain control in the treatment of TN accompanying Chiari 1.5 syndrome that does not respond to medical treatment.

A Staged Approach for Surgical Management of Basilar Invagination

BACKGROUND AND OBJECTIVES: Patients with basilar invagination (BI) can be treated with several surgical options, ranging from simple posterior decompression to circumferential decompression and fusion. Here, we aimed at examining the indications and outcomes associated with these surgical strategies to devise a staged algorithm for managing BI. METHODS: We conducted a retrospective cohort study in 2 neurosurgical centers and included patients with a BI, as defined by a position of the dens tip at least 5 mm above the Chamberlain line. Other craniovertebral junction anomalies, such as atlas assimilation, platybasia, and Chiari malformations, were documented. C1-C2 stability was assessed with a dynamic computed tomography scan. RESULTS: We included 30 patients with BI with a mean follow-up of 56 months (min = 12, max = 166). Posterior decompression and fusion (n = 8) was only performed in cases of obvious atlanto-axial instability (eg, increased atlanto-dental interval or hypermobility on flexion/extension), while anterior decompression (transoral or transnasal) was reserved to patients with lower cranial nerves deficits (eg, swallowing dysfunction) and irreducible anterior compression (n = 9). Patients with posterior signs (eg, Valsalva headaches) or myelopathy but without C1-C2 instability nor anterior signs were managed with an isolated foramen magnum decompression, with or without duraplasty (n = 13). Complications were more frequent for combined procedures, including neurological deterioriation (n = 4) and tracheostomy (n = 2), but reinterventions were more likely in patients undergoing posterior decompression alone (n = 3). CONCLUSION: Patient selection is key to determine the appropriate surgical strategy for BI: In our experience, combined approaches are only needed for patients with irreducible and symptomatic anterior compression, while fusion should be restricted to patient with obvious signs of atlanto-axial instability. Other BI patients can be managed by foramen magnum decompression alone to minimize surgical morbidity.

Headache to a Patient with the Coexistence of Chiari I Malformations and Primary Empty Sella Syndrome: A Case Report la Syndrome: A Case Report

Background: Chiari I malformations (CM-I) and Primary Empty Sella syndrome (PESS) are rare disorders of structural defects within a skull. Headache is the most common presenting symptom in both conditions. However, CM-I and ESS comorbidity in patients with severe headaches is yet to be reported. Case description: The patient was a 38-year-old woman with a one-year history of headaches at various localisations (occipital and bilateral frontal) preceded by mood agitation. Physical examination was significant for obesity. Magnetic resonance imaging (MRI) revealed a 6.4 mm cerebellar tonsil descent through the foramen magnum and hypointense (CSF-filled) flattened sella. The lipid panel showed elevated cholesterols (total) and low-density lipoprotein (LDL) levels.  She was medically managed, with no report of symptoms relapses at one-month and two-month follow-ups. Conclusion: This is the first report on comorbid CM-I and PESS in adults presenting with cephalalgia. PESS and CM-I co-occurrence may present with mixed headache localisation; careful history-taking and imaging are mandatory for diagnosis confirmation. Future extensive studies are warranted to analyse the pathophysiological interplay between these two rare disorders.

Familial Chiari malformation: a systematic review and illustrative cases.

Chiari malformations (CMs) are a group of congenital or acquired disorders characterized by hindbrain overcrowding into an underdeveloped posterior cranial fossa. CM is considered largely sporadic-however, there exists growing evidence of transmissible genetic underpinnings. The purpose of this systematic review of all familial studies of CM was to investigate the existence of an inherited component and provide recommendations to manage and monitor at-risk family members. This paper includes the following: 1) a unique case report of dizygotic twins who presented at the Toronto Western Hospital Spinal Cord Clinic with symptomatic CM type 1 (CM-1) and syringomyelia; and 2) a systematic review of familial CM. The EMBASE and MEDLINE databases were searched on June 27, 2023, in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Only articles in the English language concerning the diagnosis of CM in > 1 human family member presented as a case study, case series, or literature review were included. Among the 29 articles included in the final analysis, a total of 34 families with CM were analyzed. An average of 3 cases of CM were found per family among all generations. Eighty-one cases (88%) reported CM-1, whereas the other 11 (12%) cases reported either CM-0, CM-1.5, or tonsillar ectopia. A syrinx was present in 37 (54%) cases, with 14 (38%) of these patients also reporting a skeletal abnormality, the most common comorbidity. Most family members diagnosed with CM were siblings (18; 35%), followed by monozygotic twins/triplets (12; 23%). Patients most often presented with headaches, sensory disturbances, or generalized symptoms. Overall, there exists mounting evidence for a hereditary component of CM. It is unlikely to be explained by a classic mendelian inheritance pattern, but is rather a polygenic architecture influenced by variable penetrance, cosegregation, and entirely nongenetic factors. For first-degree relatives of those affected by CM, the authors' findings may influence clinicians to conduct closer clinical and radiographic monitoring, promote patient education, and consider earlier genetic testing.

872 Natural History of Conservatively Managed Patients With Chiari Malformation Type I and Syringomyelia

INTRODUCTION: Chiari malformation type 1 (CM1) describes caudal ectopia of the cerebellar tonsils. Though often asymptomatic earlier in life and found incidentally on imaging, CM1 can disturb cerebrospinal fluid (CSF) flow and generate an array of symptoms. Surgical treatment for CM1 centers around procedures to increase the posterior fossa volume and improve CSF circulation. Many surgeons elect to operate on CM1 patients in the setting of a syrinx, making it difficult to understand the natural history of these patients. METHODS: Retrospective study of 37 CM1 patients with syrinx who were managed conservatively at our institution. All patients had initial and follow-up clinic visits with a neurologist or neurosurgeon. Of the 37 patients, 27 had initial and follow-up MRI images at least six months apart. Student t-tests were used to compare radiological parameters. RESULTS: A total of three patients saw complete resolution of their syrinxes. Regarding clinical symptomatology, 19 out of 32 patients who were initially symptomatic saw clinical improvement by follow up, while 13 remained stable, and five declined. Of the five patients that declined, three had worsening neurological conditions not attributed to the syrinx or CM1 while the remaining two patients were the only patients that declined surgery despite recommendation. A total of 16 patients saw decreases in both syrinx size and tonsillar descent. There were no statistically significant differences between tonsillar descent, syrinx size, and number of vertebral bodies spanned by syrinx between the initial and latest follow up. The presence of tonsillar pegging was predictive of decrease in syrinx size. Tonsillar descent and syrinx size were not predictive of clinical outcomes. CONCLUSIONS: Although the surgical treatment of the CM1 patient successfully resolves the syrinx, the natural history of the syrinx can be benign.

Machine learning for enhanced prognostication: predicting 30-day outcomes following posterior fossa decompression surgery for Chiari malformation type I in a pediatric cohort.

Chiari malformation type I (CM-I) is a congenital disorder occurring in 0.1% of the population. In symptomatic cases, surgery with posterior fossa decompression (PFD) is the treatment of choice. Surgery is, however, associated with peri- and postoperative complications that may require readmission or renewed surgical intervention. Given the associated financial costs and the impact on patients' well-being, there is a need for predictive tools that can assess the likelihood of such adverse events. The aim of this study was therefore to leverage machine learning algorithms to develop a predictive model for 30-day readmissions and reoperations after PFD in pediatric patients with CM-I. This was a retrospective study based on data from the National Surgical Quality Improvement Program-Pediatric database. Eligible patients were those undergoing PFD (Current Procedural Terminology code 61343) for CM-I between 2012 and 2021. Patients undergoing surgery for tumors or vascular lesions were excluded. Unplanned 30-day readmission and unplanned 30-day reoperation were the main study outcomes. Additional outcome data considered included the length of hospital stay, 30-day complications, discharge disposition, and 30-day mortality. Training and testing samples were randomly generated (80:20) to study the 30-day readmission and reoperation using logistic regression, decision tree, random forest (RF), K-nearest neighbors, and Gaussian naive Bayes algorithms. A total of 7106 pediatric patients undergoing PFD were included. The median age was 9.2 years (IQR 4.7, 14.2 years). Most of the patients were female (56%). The 30-day readmission and reoperation rates were 7.5% and 3.4%, respectively. Headaches (32%) and wound-related complications (30%) were the most common reasons for 30-day readmission, while wound revisions and evacuation of fluid or blood (62%), followed by CSF diversion-related procedures (28%), were the most common reasons for 30-day reoperation. RF classifiers had the highest predictive accuracy for both 30-day readmissions (area under the curve [AUC] 0.960) and reoperations (AUC 0.990) compared with the other models. On feature importance analysis, sex, developmental delay, ethnicity, respiratory disease, premature birth, hydrocephalus, and congenital/genetic anomaly were some of the variables contributing the most to both RF models. Using a large-scale nationwide dataset, machine learning models for the prediction of both 30-day readmissions and reoperations were developed and achieved high accuracy. This highlights the utility of machine learning in risk stratification and surgical decision-making for pediatric CM-I.

The role of occipital condyle and atlas anomalies on occipital cervical fusion outcomes in Chiari malformation type I with syringomyelia: a study from the Park-Reeves Syringomyelia Research Consortium.

Congenital anomalies of the atlanto-occipital articulation may be present in patients with Chiari malformation type I (CM-I). However, it is unclear how these anomalies affect the biomechanical stability of the craniovertebral junction (CVJ) and whether they are associated with an increased incidence of occipitocervical fusion (OCF) following posterior fossa decompression (PFD). The objective of this study was to determine the prevalence of condylar hypoplasia and atlas anomalies in children with CM-I and syringomyelia. The authors also investigated the predictive contribution of these anomalies to the occurrence of OCF following PFD (PFD+OCF). The authors analyzed the prevalence of condylar hypoplasia and atlas arch anomalies for patients in the Park-Reeves Syringomyelia Research Consortium database who underwent PFD+OCF. Condylar hypoplasia was defined by an atlanto-occipital joint axis angle (AOJAA) ≥ 130°. Atlas assimilation and arch anomalies were identified on presurgical radiographic imaging. This PFD+OCF cohort was compared with a control cohort of patients who underwent PFD alone. The control group was matched to the PFD+OCF cohort according to age, sex, and duration of symptoms at a 2:1 ratio. Clinical features and radiographic atlanto-occipital joint parameters were compared between 19 patients in the PFD+OCF cohort and 38 patients in the PFD-only cohort. Demographic data were not significantly different between cohorts (p > 0.05). The mean AOJAA was significantly higher in the PFD+OCF group than in the PFD group (144° ± 12° vs 127° ± 6°, p < 0.0001). In the PFD+OCF group, atlas assimilation and atlas arch anomalies were identified in 10 (53%) and 5 (26%) patients, respectively. These anomalies were absent (n = 0) in the PFD group (p < 0.001). Multivariate regression analysis identified the following 3 CVJ radiographic variables that were predictive of OCF occurrence after PFD: AOJAA ≥ 130° (p = 0.01), clivoaxial angle < 125° (p = 0.02), and occipital condyle-C2 sagittal vertical alignment (C-C2SVA) ≥ 5 mm (p = 0.01). A predictive model based on these 3 factors accurately predicted OCF following PFD (C-statistic 0.95). The authors' results indicate that the occipital condyle-atlas joint complex might affect the biomechanical integrity of the CVJ in children with CM-I and syringomyelia. They describe the role of the AOJAA metric as an independent predictive factor for occurrence of OCF following PFD. Preoperative identification of these skeletal abnormalities may be used to guide surgical planning and treatment of patients with complex CM-I and coexistent osseous pathology.

274 Predicting Reoperation in Surgically Managed Pediatric Chiari I Malformation

INTRODUCTION: Chiari I malformation (CMI) involves the herniation of cerebellar tonsils into the spinal canal, without brainstem involvement. When patients are symptomatic, surgical decompression is recommended, but reoperation rates can be as high as 30%. METHODS: Patients were queried from the 2007-2016 MarketScan Databases with the CPT code (61343) for CM decompression. To be included, a patient had to have been diagnosed with CMI, received decompressive surgery, and be eighteen or younger at the time of first operation. Patients were excluded if they had a diagnosis of any other class of Chiari malformation at any point. Next, the Elixhauser Comorbidity Index was constructed for each patient. These variables were then used as covariates in a multivariate regression model to predict reoperation following surgical decompression. Odds ratios, their corresponding confidence intervals, and metrics of significance were determined. RESULTS: 2,823 patients were included, with an average age of 10.4 (SD = 5.4). 169 (6.0%) patients underwent reoperations. As patient age at first operation increased, their reoperation rate decreased steadily (OR = 0.95, 95% CI = 0.93-0.98, p = 0.002). This association was primarily driven by a sharp decline in reoperation rate after the first three years of life. Patients in their first year had a mean reoperation rate of 17.6%; by age three, the reoperation rate declined to 5.2%, remaining fairly stable from age four (5.1%) to eighteen (4.9%). Use of duraplasty (OR = 0.75, 95% CI = 0.52-1.06, p = 0.112) did not alter the likelihood of reoperation. CONCLUSIONS: In a national pediatric cohort of patients with surgically managed Chiari I malformations, there was a significantly increased likelihood of reoperation in younger children. Our findings suggest that, when medically feasible, initial CMI surgery should be delayed until the age of three to minimize the chance of reoperation.

358 Quantifying Cognitive and Affective Dysfunction in Chiari Malformation Type I Patients With the Cerebellar Cognitive Affective Syndrome Scale and the Cerebellar Neuropsychiatric Rating Scale

INTRODUCTION: Cognitive and affective dysfunction in Chiari Malformation Type I (CM1) patients are well-documented, but often rely on extensive neuropsychological tests. METHODS: Symptomatic CM1 patients considering surgical decompression were assessed by a board-certified neuropsychologist using the 105-point CNRS (N = 87) and the 10-task CCAS (N = 23), as well as a full neuropsychological battery (N = 24: Wechsler Full Scale IQ, Digit Span, Coding; WRAML Finger Windows; DKEFS Trail Making; verbal list learning; Grooved Pegboard). Descriptive and correlative measures were computed. RESULTS: The study included 66 adults and 21 children. A neuropsychological battery revealed impairment in 29% of patients on 1 test, 12.8% on 2 tests, and 20.8% on 3 or more tests. The CCAS indicated 26% with "possible CCAS" (1 task), 27% with "probable CCAS" (2 tasks), and 18% with "definite CCAS" (3 or more tasks). The median CNRS composite score was 31.0 (IQR: 18.5, 49.0), with positive and negative symptom sub-scores of 18.0 (10.0, 26.5) and 14.0 (7.5, 23.5), respectively. Moderate correlation with the neuropsychological battery was found between impairment detected by CCAS (Spearman rank coefficient ρ = 0.67, p = 0.002) and CNRS (ρ = 0.56, p = 0.003). CONCLUSIONS: A high prevalence of cognitive and affective impairments in pre-operative CM1 patients was observed by all three testing batteries. In this first report of CNRS and CCAS usage in CM1 patients, increased CNRS and CCAS impairment correlated with impairment on standard neuropsychological testing. These tools show promise for future studies CM1, providing a more concise alternative to traditional testing for cognitive and affective dysfunction.

A CASE REPORT OF MYELOMENIGOCELE WITH ARNOLD CHIARI MALFORMATIN II-HIGHLIGHTING THE IMPORTANCE OF ANEMIA MUKTH BHARATH PROGRAMME

Introduction:Neural tube defects are common complex congenital malformations resulting from failure of neural tube closure during embryogenesis, which usually completes by 28 days post conception. Myelomeningocele is almost always associated with Arnold Chiari Malformation II (CM II)and vice versa. Aims &amp;Objectives : As most of the neural tube defects can be prevented by pre-conceptional folate supplements, we would like to high light the importance of proper implementation and utilization of Anemia Mukhth Bharath Programme. Background: Neural tube defects (NTDs) are caused by a combination of multiple genes and multiple environmental factors like folic acid deficiency, insulin dependent diabetes, obesity and certain medications which interfere with folate metabolism.One of the beneficiaries under the Anemia Mukth Bharath programme are women in the reproductive age group in the pre-conception period and up to the first trimester of the pregnancy. They are advised to have400 mcg of Folic Acid tablets, daily, to reduce the incidence of neural tube defects in the fetus. Case report :We present a case of Chiari malformation associated with megaloblastic anemia with an attempt to highlight the importance of proper utilization of national program for prevention of iron and folate deficiency in women of reproductive age group. Clinical relevance : Neural tube defects are largely preventable anomalies by simple and effective management of folate deficiency preconceptionally. Conclusion :Proper utilization of the Anemia Mukth Bharath program which is available to the beneficiaries at their doorstep can not only prevent maternal anemia but also prevent fetal loss due to NTD.

The Role of Phase-Contrast MRI in Diagnosing Cerebrospinal Fluid Flow Abnormalities.

Background Cerebrospinal fluid (CSF) dynamics play a crucial role in maintaining the homeostasis of the central nervous system (CNS). Any disruption in CSF flow can lead to various congenital and acquired conditions, impacting neurological function and overall health. This study aims to analyze the significance of phase-contrast MRI in evaluating abnormalities in CSF flow and its diagnostic utility in various CSF-related disorders. Phase contrast MRIhas emerged as a valuable tool for evaluating CSF dynamics non-invasively by examining CSF flow characteristics such as pulsatile flow patterns, hyperdynamic or hypodynamic flow, and disruptions in CSF circulation. Alterations in CSF pulsatility and stroke volume can indicate changes in intracranial compliance, vascular resistance, or CSF production and absorption rates. The findings of this study will advance our understanding of CSF physiology and its relevance in neurological pathologies, potentially leading to improved patient outcomes and management approaches. Materials and methods The study involved 36 patients and was conducted as an observational, prospective study over 18 months (October 2020 to March 2022) at the Department of Radiology, Saveetha Medical College and Hospital, Chennai. We utilized a 1.5 T Philips Multiva MRI scanner by Philips Healthcare in Amsterdam, Netherlands.The study included patients with suspected CSF flow abnormalities and abnormal MRI findings (normal pressure hydrocephalus (NPH), age-related brain atrophy, aqueduct stenosis (AS), Chiari malformation type 1, syringomyelia, or arachnoid cyst), alongside control exhibiting normal neurological symptoms and MRI results. Exclusions involved individuals with febrile seizures, neurological diseases, cerebrovascular accidents, anti-convulsive medication use, cardiac arrhythmia, or MRI contraindications. Post-processing involved analyzing stroke volume (SV), peak systolic velocity (PSV), end diastolic velocity (EDV), and mean flux. Statistical analysis was conducted using the StatisticalPackage for the Social Sciences (IBMSPSSStatisticsforWindows,IBMCorp., Version 24.0, Armonk,NY), employing the χ2-test for categorical variables and nonparametric tests like Mann-Whitney U and Kruskal-Wallis H-tests for quantitative variables. A p-value < 0.05 was considered significant. Results The 36 patients, aged 1 to 80 years, were referred by the neurology department and categorized into four subgroups based on clinical history and conventional MRI findings: NPH, AS, age-related brain atrophy, and a normal control group. MRI CSF flowmetry evaluation focused on PSV, PDV, and SV. We found peak diastolic velocity (PDV), PSV, and average blood velocity (ABV) to be significantly higher in NPH compared to the control group (PSV, EDV, and SV: 9.96 +/- 1.73, 4.72 +/- 0.62, and 63 +/- 12.88 for NPH versus 4.8 +/- 0.39, 3.21 +/- 0.55, and 20.72 +/- 5.7 for control, respectively; p = 0.000). Conversely, patients with age-related brain atrophy and AS exhibited lower values (1.6 +/- 0.44, 1.13 +/- 0.09, and 6.33 +/- 2.08 for AS, and 2.07 +/- 0.09, 1.62 +/- 0.33, and 6.8 +/- 2.16 for age-related brain atrophy versus control; p = 0.002). Conclusion MRI CSF flowmetry emerges as a rapid, accurate, and non-invasive diagnostic tool for various neurological disorders associated with abnormal CSF flow. Additionally, this technique may aid in selecting appropriate treatment strategies.

Tethered Cord Syndrome in Association with Chiari Type II Malformation: A Case Report

Tethered Cord Syndrome in Association with Chiari Type II Malformation: A Case Report

Safe Delivery of Electroconvulsive Therapy in Postpartum Depression Patient With Type 1 Chiari Malformation: A Case Study.

Safe Delivery of Electroconvulsive Therapy in Postpartum Depression Patient With Type 1 Chiari Malformation: A Case Study.

MRI Insights in Chiari Malformation Type 1 and Variations With Hydrosyringomyelia.

Chiari malformation (CM) type 1 is a complex neurological disorder characterized by the displacement of the cerebellar tonsils into the upper spinal canal. Hydrosyringomyelia (HSM), which frequently coexists with this condition, presents diagnostic and treatment problems due to its broad spectrum of symptoms. There are various forms of CMs, with CM type 1 (CM1) being the most common type. Magnetic resonance imaging (MRI) is the best imaging technique to properly identifyand diagnose CM1 and HSM. Important imaging findings include downward displacement of the cerebellar tonsils across the foramen magnum, the appearance of the syrinx in the spinal cord, and the alteration of the flow dynamics of the cerebrospinal fluid. This study was conducted at Datta Meghe Medical College, Nagpur, and Government Medical College & Super Speciality Hospital, Nagpur, India. It focuses on the diagnostic use of MRI in CM1 and its variations associated with HSM. Individuals who are asymptomatic may not need any treatment; however, those who are symptomatic or have HSM may require surgical decompression and restoration of the flow. We discuss the findings of MRI of six cases of CM1 and its variants with HSMand search for possible underlying causes. We conclude that magnetic resonance imaging is an imaging modality for the identification and evaluation of CM1 in cases of HSM.

Successful treatment of unilateral facial nerve palsy in a pediatric patient with syringobulbia and Chiari malformation type I: illustrative case.

Unlike syringomyelia, syringobulbia is not commonly observed in pediatric patients with Chiari malformation type I (CMI). Previous series have reported the incidence of syringobulbia as between 3% and 4% in these patients. Presentation is typically chronic, with the slow onset of neurological symptoms and cranial nerve (CN) palsies resulting from lower brainstem involvement. The authors report the first case of a pediatric patient with simultaneous CMI, syringobulbia, and unilateral CN VII palsy. A 7-year-old male presented with right facial weakness in addition to headaches, ataxia, urinary incontinence, and falls. Magnetic resonance imaging revealed CMI with a syrinx of the cervicothoracic spine and syringobulbia. Posterior fossa decompression with duraplasty was performed without complications, and the patient was discharged home on postoperation day 5. At the 3-week follow-up, the patient's neurological deficits had largely subsided. At the 3-month follow-up, his CN VII palsy and syringobulbia had completely resolved. Pediatric CMI patients with syringomyelia are at risk for developing syringobulbia and brainstem deficits, including unilateral facial palsy. However, craniocervical decompression can prove successful in treating such deficits.

Topographic Anatomy and Pneumatization of the Posterior Clinoid Process in Chiari Type I Malformation

ObjectiveThis study aimed to examine pneumatization and topographic location of the posterior clinoid process (PCP) in Chiari type I malformation (CIM) for skull base approaches. MethodsComputed tomography images of 52 (23 males / 29 females) CIM subjects aged 23.87±16.09 years, and 71 (26 males / 45 females) healthy subjects aged 42.48±21.48 years constituted the study universe. ResultsThe distances of PCP to the foramen magnum (p=0.037), superior orbital fissure (p<0.001), foramen rotundum (p<0.001), and foramen ovale (p<0.001) were smaller, but the distance of PCP to the crista galli (p=0.038) was greater in CIM patients, compared to normal subjects. In CIM, the fusion between PCP and the anterior clinoid process was observed in nine sides (8.70%), while in controls, in 12 sides (8.50%). PCP pneumatization was observed in 40 sides (38.50%) in CIM patients, while in 28 sides (19.70%) in normal subjects. This data displayed that PCP pneumatization was affected by CIM (p<0.001). ConclusionThe distances of PCP to the crista galli and foramen magnum indicate the anterior fossa length and the posterior fossa depth, respectively; thus, CIM patients have longer anterior fossa and shallow posterior fossa. In addition, the distances of PCP to superior orbital fissure, foramen rotundum and foramen ovale indicate the middle fossa width; thence, CIM patients have less middle fossa width than normal individuals. CIM patients have approximately 50% higher PCP pneumatization rate, and this may increase the risk of complications such as cerebrospinal fluid fistula during the application of posterior clinoidectomy.

Association between structural rib autograft and the rate of arthrodesis in children undergoing occiput-C2 instrumentation and fusion.

The purpose of this study was to identify factors associated with fusion success among pediatric patients undergoing occiput-C2 rigid instrumentation and fusion. The Pediatric Spine Study Group registry was queried to identify patients ≤ 21 years of age who underwent occiput-C2 posterior spinal rigid instrumentation and fusion and had a 2-year minimum clinical and radiographic (postoperative lateral cervical radiograph or CT scan) follow-up. Fusion failure was defined clinically if a patient underwent hardware revision surgery > 30 days after the index procedure or radiographically by the presence of hardware failure or screw haloing on the most recent follow-up imaging study. Univariate comparisons and multivariable logistic regression analyses were subsequently performed. Seventy-six patients met inclusion criteria. The median age at surgery was 9 years (range 1.5-17.2 years), and 51% of the cohort was male. Overall, 75% of patients had syndromic (n = 41) or congenital (n = 15) etiologies, with the most frequent diagnoses of Down syndrome (28%), Chiari malformation (13%), and Klippel-Feil syndrome (12%). Data were available to determine if there was a fusion failure in 97% (74/76) of patients. Overall, 38% (28/74) of patients had fusion failure (95% CI 27%-50%). Univariate analysis demonstrated that use of a rigid cervical collar postoperatively (p = 0.04) and structural rib autograft (p = 0.02) were associated with successful fusion. Multivariable logistic regression analysis determined that patients who had rib autograft used in surgery had a 73% decrease in the odds of fusion failure (OR 0.27, 95% CI 0.09-0.82; p = 0.02). Age, etiology including Down syndrome, instrumentation type, unilateral instrumentation, use of recombinant human bone morphogenetic protein, and other variables did not influence the risk for fusion failure. In this multicenter, multidisciplinary, international registry of children undergoing occiput-C2 instrumentation and fusion, fusion failure was seen in 38% of patients, a higher rate than previously reported in the literature. The authors' data suggest that postoperative immobilization in a rigid cervical collar may be beneficial, and the use of structural rib autograft should be considered, as rib autograft was associated with a 75% higher chance of successful fusion.

Chiari Type I Revision Decompressive Surgery Indications and Operative Technique: Experience in a Large Adult Cohort

IntroductionChiari Malformation is characterized by inferior displacement of the cerebellar tonsils through the foramen magnum, frequently resulting in strain related headaches, and motor/sensory dysfunction. Chiari decompression technique varies significantly, possibly contributing to frequent revisions. We reviewed revision Chiari decompressions at our institution to determine the primary indications for revision and outcomes after revision. MethodWe retrospectively reviewed patients who underwent revision of Chiari decompression at our institution from 2005-2020. Demographics, indications for revision surgery, operative techniques, imaging findings, and pre-/post-operative symptoms were collected. Chi-squared test was performed to determine statistical significance using a p<0.05. Independent predictors of operative outcomes were identified. ResultA total of 46 patients (91% female, mean age 38.8 years) were included for analysis. The median time to revision surgery was 69.1 months (range 0-364 months) with headache (n=37, 80%) being the most commonly recurring symptom. Large craniectomy (n=28, 61%) was the most frequent indication for revision surgery. Thirty-two (70%) patients underwent cranioplasty, 20 (43%) required duraplasty, 15 (33%) required arachnoid dissection, and 15 (33%) required tonsillar reduction during revision surgery. Post-revision follow-up (at 8.9 ± 5.2 months average, range 1-18 months), revealed an average reduction in all Chiari-related symptoms relative to symptoms before the revision. ConclusionThe most common indication for revision Chiari decompression was a large craniectomy resulting in cerebellar ptosis. We found that tonsillar reduction paired with modest craniectomy achieved near-complete resolution of symptoms with minimal complications. For patients with recurrent or persistent sequelae of Chiari malformation after decompression, revision may reduce symptom severity.