Adult Chiari Malformation Type I Research Articles

The Surgical Strategy Cerebrospinal Fluid Decompression Facilitates Outcomes of Adults with Chiari Malformation Type I: An Observational, Real-World, Single-Center Study of 528 Patients

ObjectivesWe designed this study to introduce the surgical strategy “CSF decompression” in treating Chiari malformation type I (CMI), and compared the “CSF decompression” strategy with other surgical strategies to provide a solid basis for patient counseling. MethodsA total of 528 consecutive CMI patients who underwent surgical interventions from 2012 to 2022 were enrolled. The surgical strategy for these patients was bony and dural decompression (BDD), anatomical reduction of herniated tonsils (AR) or CSF decompression (CSFD). Short-term results were determined after 3 months; long-term outcomes were evaluated at last follow-up and at least 18 months. ResultsThe CSFD strategy was independently associated with better long- or short-term primary outcomes than AR or BDD (P < 0.001). Compared with short-term, the long-term outcomes were better in CSFD patients (P = 0.035), but were worse in BDD patients (P = 0.03). Specific surgical techniques cannot affect the long- and short-term outcomes of CMI patients. CSFD provided better long-term syringomyelia improvement than short-term (181/218, 83% vs 169/218, 77.5%; P < 0.001). ConclusionThe “CSF decompression” surgical strategy, but not a specific surgical technique or operative method, was associated with favorable neurological outcomes in adult CMI patients. The surgical technique and operative method should be selected according to the characteristics of each patient and the intraoperative condition to normalized CSF circulation at CVJ. The intraoperative target maybe smoothly CSF flow, out from the fourth ventricle and in to the bilateral Luschka foramina, could be observed.

Multicenter comparison of Chiari malformation type I presentation in children versus adults.

Treatment for Chiari malformation type I (CM-I) often includes surgical intervention in both pediatric and adult patients. The authors sought to investigate fundamental differences between these populations by analyzing data from pediatric and adult patients who required CM-I decompression. To better understand the presentation and surgical outcomes of both groups of patients, retrospective data from 170 adults and 153 pediatric patients (2000-2019) at six institutions were analyzed. The adult CM-I patient population requiring surgical intervention had a greater proportion of female patients than the pediatric population (p < 0.0001). Radiographic findings at initial clinical presentation showed a significantly greater incidence of syringomyelia (p < 0.0001) and scoliosis (p < 0.0001) in pediatric patients compared with adult patients with CM-I. However, presenting signs and symptoms such as headaches (p < 0.0001), ocular findings (p = 0.0147), and bulbar symptoms (p = 0.0057) were more common in the adult group. After suboccipital decompression procedures, 94.4% of pediatric patients reported symptomatic relief compared with 75% of adults with CM-I (p < 0.0001). Here, the authors present the first retrospective evaluation comparing adult and pediatric patients who underwent CM-I decompression. Their analysis reveals that pediatric and adult patients significantly differ in terms of demographics, radiographic findings, presentation of symptoms, surgical indications, and outcomes. These findings may indicate different clinical conditions or a distinct progression of the natural history of this complex disease process within each population, which will require prospective studies to better elucidate.

A long-term follow-up study of adults with Chiari malformation type I combined with syringomyelia.

There is a considerable amount of controversy regarding the treatment and prognosis of adult patients with Chiari malformation type I (CM-I) at home and abroad; furthermore, no large-sample, long-term, follow-up studies have examined CM-I patients with syringomyelia (SM) comparing posterior fossa decompression with resection of tonsils (PFDRT) vs. posterior fossa decompression with duraplasty (PFDD). This study retrospectively analyzed the factors affecting the treatment and long-term prognosis of adults with CM-I combined with SM. We retrospectively analyzed data from 158 adult CM-I patients combined with SM who underwent PFDRT or PFDD, including 68 patients in group PFDRT and 90 patients in group PFDD. We examined the clinical manifestations, imaging features, and follow-up data of patients. Clinical outcomes were assessed using the Chicago Chiari Outcomes Scale (CCOS), and radiographic outcomes were indicated by the syrinx remission rate. Multivariate logistic regression analysis and multiple linear regression analysis were used to explore the relevant factors affecting the long-term prognosis of patients. This study showed that compared with preoperative patients in the PFDRT group and PFDD group, the sensory impairment, cough-related headache, and movement disorder were significantly improved (p < 0.01); meanwhile, the diameter of the syrinx and the volume of the syrinx decreased significantly (p < 0.001). Additionally, the study found that there were significant differences in the syrinx remission rate (p = 0.032) and the clinical cure rates (p = 0.003) between the two groups. Multivariate logistic regression analysis showed that age (p = 0.021), cerebellar-related symptoms (p = 0.044), preoperative cisterna magna volume (p = 0.043), and peak systolic velocity (p = 0.036) were independent factors for clinical outcomes. Multiple linear regression analysis showed that different surgical procedures were positively correlated with the syrinx remission rate (p = 0.014), while preoperative syrinx diameter (p = 0.018) and age (p = 0.002) were negatively correlated with the syrinx remission rate. In conclusion, this study suggested that, in a long-term follow-up, although both surgical procedures are effective in treating patients with CM-I and SM, PFDRT is better than PFDD; age and cerebellar-related signs independently affect the patient's prognosis. Additionally, an effective prognosis evaluation index can be developed for patients, which is based on imaging characteristics, such as preoperative cisterna magna volume, preoperative syrinx diameter, and preoperative cerebrospinal fluid (CSF) hydrodynamic parameters to guide clinical work.

136 Morphological Clusters of Chiari I Patients With Variable Response After Suboccipital Decompression

INTRODUCTION: Chiari malformation type I (CM-I) can cause debilitating neurologic symptoms, most notably distinctive headaches, and the only existing definitive treatment is suboccipital decompression. While CM-I is typically defined as ≥5 mm downward displacement of cerebellar tonsils, overall CM-I cerebellar morphology is highly heterogeneous, and it is uncertain if this variability represents distinct patient populations or influences clinical response to suboccipital decompression. METHODS: 186 adult CM-I patients with high-resolution T1-MRIs were retrospectively identified. Each patient’s cerebellum was non-linearly and diffeomorphically transformed to template brain, with this transformation’s inverse representing cerebellar deformation. A similarity matrix was generated between patients’ deformations using the Pearson correlation coefficient of their inverse transformations’ log Jacobian determinants within each cerebellar lobule. Spectral clustering was performed on this similarity matrix to identify patient clusters. Headache freedom after suboccipital decompression was compared between clusters by Kaplan-Meier analysis. RESULTS: Three morphological clusters of CM-I patients were identified. Cluster A is characterized by posteroinferior cerebellar fullness and platybasia; B by midline anterior-posterior compression; C solely by tonsillar descent. After suboccipital decompression, headaches were found to recur more frequently and sooner in Cluster B (p &lt; 0.01). CONCLUSIONS: These analyses suggest that CM-I encapsulates morphologically distinct subtypes, here identified as Cluster A and Cluster B, with Cluster C representing an intermediate phenotype. These clusters vary significantly in clinical response to suboccipital decompression, which may have implications for surgical patient selection or operative technique. Future research should involve independent validation of this cluster scheme and optimization of treatment for patients in Cluster B, which is found here to have poorer surgical outcomes.

Long-term outcomes of foramen magnum decompression with duraplasty for Chiari malformation type I in adults: a series of 297 patients.

Foramen magnum decompression with duraplasty (FMDD) is one of the most frequently utilized surgical treatments for Chiari malformation type I (CMI) in adults. However, its long-term outcomes remain controversial. The object of this study was to evaluate the long-term outcomes of FMDD in adults with CMI. In total, 297 adults with CMI who had undergone FMDD at the authors' institution between 2011 and 2020 were included in this retrospective study. Long-term (> 1 year) outcomes were evaluated using the Chicago Chiari Outcome Scale (CCOS), visual analog scale (VAS), and Japanese Orthopaedic Association (JOA) scale. The median patient age was 44 years (range 18-65 years). The mean clinical follow-up period was 67 months (range 14-123 months). Compared with preoperative conditions, the postoperative syringomyelia regression rate was 91.3% (242/265), and the cerebellar tonsil ascended in 18.2% of patients (54/297), was stable in 64.3% (191/297), and continuously descended in 17.5% (52/297). Long-term clinical follow-up data were acquired from 267 patients. According to the CCOS score, the patient's condition improved in 62.5% of cases (167/267), was stable in 31.8% (85/267), and worsened in 5.6% (15/267). According to the VAS score, the patient's condition improved in 59.5% of cases (110/185), remained unchanged in 27.6% (51/185), and worsened in 13.0% (24/185) among the follow-up patients with relevant data. According to the JOA score, the patient's condition improved in 40.1% of cases (107/267), remained unchanged in 50.2% (134/267), and worsened in 9.7% (26/267). Notably, there was no association between clinical outcomes and syringomyelia regression (p = 0.227) or changes in the cerebellar tonsillar position (p = 0.323). FMDD is a simple, safe, and effective surgical procedure for adult CMI that yields significant and sustained improvement in clinical and radiological outcomes. However, clinical improvement does not always correlate with syringomyelia regression and cerebellar tonsillar shift.

Adult Chiari Malformation Type I: Surgical Anatomy, Microsurgical Technique, and Patient Outcomes.

In this study, the authors summarize the current knowledge on epidemiology, demographics, risk factors, and prognostic factors that influence outcomes in patients with adult Chiari malformation type I (CM-I) who underwent posterior fossa decompression surgery with duraplasty. Furthermore, they describe the contribution of their research group to the field of adult CM-I treatment, including association of increased body mass index with severity of CM-I and syringomyelia, relevant surgical anatomy, and surgical technique of 270° microsurgical decompression of foramen magnum. The authors also report on common complications in the literature and describe techniques for prevention of complications.

Posterior fossa decompression and duraplasty with and without tonsillar resection for the treatment of adult Chiari malformation type I and syringomyelia

The current surgical management of adult Chiari malformation type I (CM-I) with associated syringomyelia remains controversial. The objective of this study was to explore posterior fossa decompression and duraplasty (PFDD) with and without tonsillar resection in adult patients with CM-I and syringomyelia. A total of 116 adult patients suffering from both CM-I and syringomyelia who were scheduled to undergo surgical decompression at our institution between 2012 and 2020 were randomly divided into 2 groups: the PFDD group (n = 64) underwent PFDD without tonsillar resection, while the PFDD-T group (n = 52) underwent PFDD with tonsillar resection. The primary outcome was improvement or resolution of the syrinx. The secondary outcome was an improvement in clinical outcome based on Chicago Chiari Outcome Scale (CCOS) scores. All participants were followed-up to 1-year postoperatively. The proportions of patients who had >20% improvement in syrinx size were 60.9% and 78.8% in the PFDD and PFDD-T groups, respectively (P = .038). The improvement in clinical outcome based on CCOS scores was significantly different in the 2 groups (P = .004). The functionality sub-score was significantly different between the 2 groups (P = .027), but there were no significant differences in the pain symptoms, non-pain symptoms, and complications sub-scores. The total CCOS scores were higher in the PFDD-T group than in the PFDD group (P = .037). This study determined the role of tonsillar resection in achieving obvious syrinx improvement following PFDD-T. PFDD with tonsillar resection seems to be a safe and effective surgical option to treat adult CM-I patients with syringomyelia.

Morphometric and volumetric analysis of the posterior cranial fossa in adult Chiari malformation type I with and without group B basilar invagination.

The frequent association of basilar invagination (BI) makes the understanding of the pathogenesis of Chiari malformation type I (CMI) difficult. The influence of group B type of BI (the BI without obvious atlantoaxial instability) on the skeletal morphology has not been thoroughly studied. The objective of this study is to evaluate the skeletal alterations in the posterior cranial fossa (PCF) of adult CMI cases with and without group B BI. Fifty-four adult CMI without BI cases (CMI-only group) and 30 adult CMI with group B BI cases (CMI-BI group) were retrospectively studied. Fifty-six adult patients with unruptured intracranial aneurysms were included as the controls. Several linear and angular variables, and the bony volume of the PCF were analyzed based on thin-slice computed tomography data. Morphological analysis revealed a significant difference in several variables from controls compared to CMI-only, and CMI-BI patients. The clivus and occipital bone, shortened and elevated in CMI-only patients, were further flattened in BI-associated CMI patients. Furthermore, although out of the scope for the diagnostic threshold of BI, the CMI-only cases also had a tendency to form BI. The association of BI modified several variables, without further reducing the bony PCF volume. These findings indicate that the variables associated with group B BI tend to be a continuum of the same pathological abnormalities that originate from the same pathological alterations in CMI patients.

A new hypothesis for the pathophysiology of symptomatic adult Chiari malformation Type I

Chiari malformation Type I (CMI) is characterized by herniation of the cerebellar tonsils through the foramen magnum. The pathophysiology of CMI is not well elucidated; however, the prevailing theory focuses on the underdevelopment of the posterior cranial fossa which results in tonsillar herniation. Symptoms are believed to be due to the herniation causing resistance to the natural flow of cerebrospinal fluid (CSF) and exerting a mass effect on nearby neural tissue. However, asymptomatic cases vastly outnumber symptomatic ones and it is not known why some people become symptomatic. Recently, it has been proposed that CMI symptoms are primarily due to instability of either the atlanto-axial (AA) or the atlanto-occipital (AO) joint and the cerebellar tonsils herniate to prevent mechanical pinching. However, only a small percentage of patients exhibit clinical instability and these theories do not account for asymptomatic herniations. We propose that the pathophysiology of adult CMI involves a combination of craniocervical abnormalities which leads to tonsillar herniation and reduced compliance of the cervical spinal canal. Specifically, abnormal AO and/or AA joint morphology leads to chronic cervical instability, often subclinical, in a large portion of CMI patients. This in turn causes overwork of the suboccipital muscles as they try to compensate for the instability. Over time, the repeated, involuntary activation of these muscles leads to mechanical overload of the myodural bridge complex, altering the mechanical properties of the dura it merges with. As a result, the dura becomes stiffer, reducing the overall compliance of the cervical region. This lower compliance, combined with CSF resistance at the same level, leads to intracranial pressure peaks during the cardiac cycle (pulse pressure) that are amplified during activities such as coughing, sneezing, and physical exertion. This increase in pulse pressure reduces the compliance of the cervical subarachnoid space which increases the CSF wave speed in the spinal canal, and further increases pulse pressure in a feedback loop. Finally, the abnormal pressure environment induces greater neural tissue motion and strain, causing microstructural damage to the cerebellum, brainstem, and cervical spinal cord, and leading to symptoms. This hypothesis explains how the combination of craniocervical bony abnormalities, anatomic CSF restriction, and reduced compliance leads to symptoms in adult CMI.

Is there a morphometric cause of Chiari malformation type I? Analysis of existing literature.

Although many etiologies have been proposed for Chiari malformation type I (CM-I), there currently is no singular known cause of CM-I pathogenesis. Advances in imaging have greatly progressed the study of CM-I. This study reviews the literature to determine if an anatomical cause for CM-I could be proposed from morphometric studies in adult CM-I patients. After conducting a literature search using relevant search terms, two authors screened abstracts for relevance. Full-length articles of primary morphometric studies published in peer-reviewed journals were included. Detailed information regarding methodology and symptomatology, craniocervical instability, syringomyelia, operative effects, and genetics were extracted. Forty-six studies met inclusion criteria, averaging 93.2 CM-I patients and 41.4 healthy controls in size. To obtain measurements, 40 studies utilized MRI and 10 utilized CT imaging, whereas 41 analyzed parameters within the posterior fossa and 20 analyzed parameters of the craniovertebral junction. The most commonly measured parameters included clivus length (n = 30), tonsillar position or descent (n = 28), McRae line length (n = 26), and supraocciput length (n = 26). While certain structural anomalies including reduced clivus length have been implicated in CM-I, there is a lack of consensus on how several other morphometric parameters may or may not contribute to its development. Heterogeneity in presentation with respect to the extent of tonsillar descent suggests alternate methods utilizing morphometric measurements that may help to identify CM-I patients and may benefit future research to better understand underlying pathophysiology and sequelae such as syringomyelia.

Imaging and health metrics in incidental cerebellar tonsillar ectopia: findings from the Adolescent Brain Cognitive Development Study (ABCD).

Incidental cerebellar tonsillar ectopia (ICTE) that meets the radiographic criterion for Chiari malformation type I (CMI) is an increasingly common finding in the clinical setting, but its significance is unclear. The present study examined posterior cranial fossa (PCF) morphometrics and a broad range of health instruments of pediatric ICTE cases and matched controls extracted from the Adolescent Brain Cognitive Development (ABCD) dataset. One-hundred-six subjects with ICTE and 106 matched controls without ICTE were identified from 11,411 anatomical MRI of healthy screened pediatric subjects from the ABCD project. Subjects were matched by sex, age, body mass index, race, and ethnicity. Twenty-two brain morphometrics and 22 health instruments were compared between the two groups to identify unrecognized CMI symptoms and assess the general health impact of ICTE. Twelve and 15 measures were significantly different between the ICTE and control groups for females and males, respectively. Notably, for females, the anterior CSF space was significantly smaller (p = 0.00005) for the ICTE group than controls. For males, the clivus bone length was significantly shorter (p = 0.0002) for the ICTE group compared to controls. No significant differences were found among the 22 health instruments between the two groups. This study demonstrated that pediatric ICTE subjects have similar PCF morphometrics to adult CMI. ICTE alone did not appear to cause any unrecognized CMI symptoms and had no impact on the subjects' current mental, physical, or behavioral health. Still, given their cranial and brain morphology, these cases may be at risk for adult-onset symptomatic CMI.

Adult Age Differences in Self-Reported Pain and Anterior CSF Space in Chiari Malformation.

Chiari malformation type I (CMI) is a neural disorder with sensory, cognitive, and motor defects, as well as headaches. Radiologically, the cerebellar tonsils extend below the foramen magnum. To date, the relationships among adult age, brain morphometry, surgical status, and symptom severity in CMI are unknown. The objective of this study was to better understand the relationships among these variables using causal modeling techniques. Adult CMI patients (80% female) who either had (n = 150) or had not (n = 151) undergone posterior fossa decompression surgery were assessed using morphometric measures derived from magnetic resonance images (MRI). MRI-based morphometry showed that the area of the CSF pocket anterior to the cervico-medullary junction (anterior CSF space) correlated with age at the time of MRI (r = - .21). Also, self-reported pain increased with age (r = .11) and decreased with anterior CSF space (r = - .18). Age differences in self-reported pain were mediated by anterior CSF space in the cervical spine area-and this effect was particularly salient for non-decompressed CMI patients. As CMI patients age, the anterior CSF space decreases, and this is associated with increased pain-especially for non-decompressed CMI patients. It is recommended that further consideration of age-related decreases in anterior CSF space in CMI patients be given in future research.

The 270° Circumferential Microsurgical Decompression of the Foramen Magnum in Adult Chiari Malformation Type I: Single Surgeon Series of 130 Patients with Syringomyelia, Neurologic, and Headache Outcomes

Chiari malformation type I (CM-I) is a craniocervical junction disorder associated with descent of the cerebellar tonsils >5 mm. The prevalence of CM-I is common, including 0.5%-3.5% in the general population, 0.56%-0.77% on magnetic resonance imaging, and 0.62% in anatomic dissection studies. We sought to measure our surgical outcomes related to resolution/improvement of headaches, neurologic outcomes, and syringomyelia compared with reported adult CM-I studies from 2000-2019. From December 2003 to June 2018, the first author (K.I.A.) performed 270° circumferential decompression on adult (>18 years) patients with CM-I. At admission and follow-up, all parameters were numerically evaluated; headaches were self-reported on the visual analog scale, neurologic condition was evaluated using Karnofsky Performance Status and European Myelopathy Score, and syrinx width (if present) was measured on magnetic resonance imaging by grades I-IV. All parameters were analyzed, compared, and statistically tested. We compared results with our previously reported and updated systematic review of operative adult CM-I studies (studies from 2000 to 2019). In our series, 118/121 (98%) experienced headache improvements and 100% experienced neurologic improvements. Complete syrinx resolution was experienced by 35/43 (81%); 8 (19%) showed significant improvement. In data from reported studies (2000-2019), only 79% experienced headache resolution, 77% improvement of neurologic status, and 74% resolution/improvement of syrinx (mean). Our modified 270° circumferential microsurgical foramen magnum decompression for adult CM-I appears to be beneficial in improvement of outcomes, namely in resolution of the syrinx, neurologic symptoms, and headaches. We also confirm the association of body mass index with CM-I. Further studies are needed to confirm our results.

Chiari Malformations Type I without Basilar Invagination in Adults: Morphometric and Volumetric Analysis

Chiari malformation type I (CMI) cases are frequently associated with basilar invagination (BI), which complicates the understanding of the pathology of CMI. We specifically evaluated the morphometric and volumetric alterations in the bony structures of CMI patients without BI. Fifty adult CMI patients without BI treated at our institution from January 2015 to December 2019 were retrospectively studied. The morphometric and volumetric characteristics of the posterior cranial fossa (PCF) were analyzed using thin-slice computed tomography images. Compared with the controls, the clivus length (P < 0.001), supraoccipital length (P < 0.001), Klaus height index (P < 0.001), axial length (P < 0.001), clivo-axial angle (P < 0.001), tentorial angle (P < 0.05), and bony PCF volume (P < 0.001) of the CMI-only group were significantly smaller, and the distance between the Chamberlain line and the dens axis (P < 0.001), clivus angle (P < 0.001), and basal angle (P < 0.001) of the CMI-only group were significantly larger, while the distance between the McRae line and the dens axis, McRae line, anteroposterior diameter of the PCF, occipital angle, occipital canal angle, and tentorial Twining line angle showed no significant difference between the 2 groups. Hypoplasia of the clivus and occipital bone were confirmed in CMI patients without BI, thus providing further evidence for the notion that CMI is secondary to the underdevelopment of the PCF.

External validation of current prediction systems of improvement after decompression surgery in Chiari malformation type I patients: can we do better?

The Chiari Severity Index (CSI) and points-based algorithm of Thakar et al. are two prognostic tools that have been developed to predict the likelihood of improvement after suboccipital decompression in adult patients with Chiari malformation type I (CM-I). This study aimed to externally validate and critically evaluate these algorithms in the interest of guiding the development of improved prediction systems. A consecutive cohort of CM-I patients undergoing suboccipital decompression between September 2006 and September 2018 were included. The CSI and Thakar point score were computed for all patients, and associations with improvement were analyzed. The ability of both prediction systems to predict improvement as measured by different Chicago Chiari Outcome Scale (CCOS) cutoffs was assessed using receiver operating curve analysis. Post hoc correlations between the algorithms and different CCOS subcomponents were also assessed. The surgical cohort was composed of 149 adult CM-I patients, of whom 39 (26%) had a syrinx. Most patients experienced improvement after surgery (80% CCOS ≥ 13; 96% CCOS ≥ 11). The proportion of patients improving decreased with increasing CSI, but the results were not statistically significant (p = 0.246). No statistically significant difference in the mean Thakar point score was identified between improved and nonimproved patients using both CCOS cutoffs (p = 0.246 for a cutoff of 13 and p = 0.480 for a cutoff of 11). The CSI had a poor ability in identifying improved patients at a CCOS cutoff of 13 (area under the curve [AUC] 0.582) and 11 (AUC 0.646). The Thakar point score similarly had poor discrimination at a cutoff of 13 (AUC 0.467) and 11 (AUC 0.646). Neither algorithm had significant correlation with any of the CCOS subcomponents except for CSI and nonpain symptom improvement (coefficient = -0.273, p = 0.001). Previously published algorithms failed to provide prediction value with regard to clinically meaningful improvement following suboccipital decompression in adult CM-I patients. Future models and practical scoring systems are still required to improve the decision-making process.

Risk Factors Portending Extended Length of Stay After Suboccipital Decompression for Adult Chiari I Malformation

For adult patients undergoing surgical decompression for Chiari malformation type I (CM-I), the patient-level factors that influence extended length of stay (LOS) are relatively unknown. The aim of this study was to investigate the impact of patient-baseline comorbidities, demographics, and postoperative complications on extended LOS after intervention after adult CM-I decompression surgery. A retrospective cohort study using the National Inpatient Sample years 2010-2014 was performed. Adults (≥18 years) with a primary diagnosis of CM-I 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. A total of 29,961 patients were identified, 6802 of whom (22.7%) had extended LOS. The extended LOS cohort had a significantly greater overall complication rate (normal LOS, 10.6% vs. extended LOS, 29.1%; P < 0.001) and total cost (normal LOS, $14,959 ± $6037 vs. extended LOS, $25,324 ± $21,629; P < 0.001) compared with the normal LOS cohort. On multivariate logistic regression, black race, income quartiles, private insurance, obstructive hydrocephalus, lack of coordination, fluid and electrolyte disorders, and paralysis were all independently associated with extended LOS. Additional duraplasty (P= 0.132) was not significantly associated with extended LOS after adjusting for other variables. The odds ratio for extended LOS was 2.07 (95% confidence interval, 1.59-2.71) for patients with 1 complication and 9.47 (95% confidence interval, 5.86-15.30) for patients with >1 complication. Our study shows that extended LOS after adult CM-I decompression surgery may be influenced by multiple patient-level factors.

Tonsillectomy with modified reconstruction of the cisterna magna with and without craniectomy for the treatment of adult Chiari malformation type I with syringomyelia

In light of the controversies regarding the surgical treatment of adult Chiari malformation type I (CM-I) with syringomyelia, a retrospective study was conducted to evaluate the safety and efficacy of tonsillectomy followed by modified reconstruction of the cisterna magna with or without craniectomy. Between 2008 and 2017, 78 adult CM-I patients (36 males and 42 females, mean age 40.6years old) with syringomyelia were treated with posterior fossa decompression (PFD) with tonsillectomy and modified reconstruction of the cisterna magna. Patients were divided into two study groups: group A (n = 40) underwent cranioplasty with replacement of the bone flap; group B (n = 38) underwent suboccipital craniectomy. Neurological outcomes were evaluated by traditional physician assessment (improved, unchanged, and worsened) and the Chicago Chiari Outcome Scale (CCOS). Syringomyelia outcomes were assessed radiologically. The procedure was successfully performed in all patients, and restoration of normal cerebrospinal fluid (CSF) flow was confirmed by intraoperative ultrasonography. The median postoperative follow-up was 20.3months (range 18-60months). Clinical improvement was evident in 66 (84.6%) patients, with no significant differences between the two groups (85.0% vs. 84.2%, P = 0.897). According to the CCOS, 36 patients (90.0%) in group A were labeled as "good" outcome, compared with that of 34 (86.8%) in group B (P = 0.734). Improvement of syringomyelia was also comparable between the groups, which was observed in 35 (87.5%) vs. 33 (86.8%) patients (P = 0.887). The postoperative overall (7.5% vs. 23.7%, P = 0.048) and CSF-related (2.5% vs. 18.4%, P = 0.027) complication rates were significantly lower in group A than group B. Tonsillectomy with modified reconstruction of the cisterna magna without craniectomy seems to be a safe and effective surgical option to treat adult CM-I patients with syringomyelia, though future well-powered prospective randomized studies are warranted to validate these findings.

"Stealth cranioplasty:" A novel endeavor for symptomatic adult Chiari I patients with syringomyelia: Technical note, appraisal, and philosophical considerations.

Aim and Objective:In this article, we describe a novel technique of reconstruction of posterior fossa by cranioplasty with use of preshaped titanium mesh following posterior fossa decompression (PFD) for Chiari malformation type I (CMI) with syringomyelia (SM) in symptomatic adults.Materials and Methods:Eleven patients underwent limited PFD and expansive cranioplasty with preshaped titanium mesh, what we term as “Stealth Cranioplasty” (SCP), following arachnoid preserving duraplasty (APD) and hexagonal tenting of the duraplasty with the cranioplasty (HTDC) for the management of symptomatic adult CMI with SM. All these patients had syringes extending from 3 to >10 vertebral levels.Results:Seven male and four female symptomatic CMI adult patients, between age ranges of 22 and 44 years (mean 29.45 years), presented with different neurological symptoms related to CMI and SM for 6–84 months (mean 37.09 months). All the patients underwent PFD, APD followed by SCP and HTDC and were followed up for 7–54 months (mean 35.90 months). Of 11 patients, 8 patients improved according to the Chicago Chiari Outcome Scale (CCOS) with score of 13–15 while 3 patients remained unchanged with CCOS of 12, and there was no worsening. There was no complication related to Chiari surgery in any of the patients. All the patients had good reestablishment of cisterna magna. Two patients had marked reduction of syrinx while eight patients had moderate-to-mild reduction and one patient had no change of syrinx. None of the patients needed redo surgery.Conclusion:SCP is an effective, fruitful, and cost-effective technique for the management of symptomatic adult CMI with SM. This technique has the advantages of preventing complications and recurrences in addition to the improvement of symptoms by addressing the basic pathology.

Odontoid process inclination in normal adults and in an adult population with Chiari malformation Type I.

Posterior odontoid process inclination has been demonstrated as a factor associated with Chiari malformation Type I (CM-I) in the pediatric population; however, no studies to date have examined this measurement in the adult CM-I population. The purpose of this study was to evaluate craniocervical junction (CCJ) measurements in adult CM-I versus a control group. The odontoid retroflexion, odontoid retroversion, odontoid height, posterior basion to C-2 line measured to the dural margin (pB-C2 line), posterior basion to C-2 line measured to the dorsal odontoid cortical margin (pB-C2* line), and clivus-canal angle measurements were retrospectively analyzed in adult patients with CM-I using MRI. These measurements were compared with normative values established from CT scans of the cervical spine in adults without CM-I. A statistically significant difference was found between 55 adults with CM-I and 150 sex-matched controls (125 used for analysis) in the mean clivus-canal angle and the mean pB-C2 line. These data suggest that there are sex-specific differences with respect to measurements at the CCJ between men and women, with women showing a more posteriorly inclined odontoid process. There were also differences between the CM-I and control groups: a more acute clivus-canal angle was associated with CM-I in the adult population. These CCJ findings could have an influence on presurgical planning.

Posterior cranial fossa morphometry in symptomatic adult Chiari I malformation patients: Comparative clinical and anatomical study

Background and objectives The cerebellar tonsillar herniation occurring in Chiari malformation Type I (CMI) mainly results from overcrowding of a normally developing hindbrain within a primary small posterior cranial fossa (PCF) due to an anomaly in the embryological development of the occipital bone. In the present study, the lengths of PCF parameters were studied in adult CMI patients. Patients and methods The authors retrospectively examined 15 adult patients with CMI. Multiple measurements were made on magnetic resonance images (MRIs). The results were compared with the findings in 25 controls and 30 dry skulls. Results Length of the neural structures did not significantly differ between the CMI and the control groups. The average length of the basiocciput was significantly shorter in the CMI group as compared with the control group. The mean length of the supraocciput was significantly shorter and the average diameter of the foramen magnum was significantly longer in the CMI group when compared to the control group and dry skulls. Conclusions The morphometric data suggest that, in CMI, a hypoplastic occipital bone, possibly due to the paraxial mesodermal defect of the parachordal plate, causes overcrowding in PCF, which contains the normally developed neural structures.