Posterior Fossa Decompression Surgery Research Articles

Use of Artificial Intelligence in the Prediction of Chiari Malformation Type 1 Recurrence After Posterior Fossa Decompressive Surgery.

Purpose The purpose of this study was to train a deep learning-based method for the prediction of postoperative recurrence of symptoms in Chiari malformation type 1 (CM1) patients undergoing surgery. Studies suggest that certain radiological and clinical features do exist in patients with treatment failure, though these are inconsistent and poorly defined. Methodology This study was a retrospective cohort study of patients who underwent primary surgical intervention for CM1 from January 2010 to May 2020. Only patients who completed pre- and postoperative 12-item short form(SF-12) surveys were included and these were used to classify the recurrence or persistence of symptoms. Forty patients had an improvement in overall symptoms while 17 had recurrence or persistence. After magnetic resonance imaging (MRI) data augmentation, a ResNet50, pre-trained on the ImageNet dataset, was used for feature extraction, and then clustering-constrained attention multiple instance learning (CLAM), a weakly supervised multi-instance learning framework, was trained for prediction of recurrence. Five-fold cross-validation was used for the development of MRI only, clinical features only, and a combined machine learning model. Results This study included 57 patients who underwent CM1 decompression. The recurrence rate was 30%. The combined model incorporating MRI, pre-operative SF-12 physical component scale (PCS), and extent of cerebellar ectopia performed best with an area under the curve (AUC) of 0.71 and an F1 score of 0.74. Conclusion This is the first study to our knowledge to explore the prediction of postoperative recurrence of symptoms in CM1 patients using machine learning methods and represents the first steptowarddeveloping a clinically useful prognostication machine learning model. Further studies utilizing a similar deep learning approach with a larger sample size are needed to improve the performance.

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.

Long-term outcome of operated Chiari I patients between 2005 and 2020 in Eastern Finland

PurposeThe purpose of our study was to examine the long-term outcomes of operated Chiari malformation type 1 (CM1) patients and evaluate whether different duraplasty techniques affected outcome after surgery in Kuopio University Hospital catchment area.MethodsIn this retrospective study, a total of 93 patients were diagnosed with CM1 and underwent posterior fossa decompression surgery with or without duraplasty between 2005 and 2020. All patients’ medical records were examined for baseline characteristics, surgical details, and long-term follow-up data after operation.ResultsThe mean age of CM1 patients was 25.9 years (SD 19.2 years), with female preponderance 69/93 (73.4%). The mean clinical follow-up time was 26.5 months (SD 33.5 months). The most common presenting symptoms were headache, symptoms of extremities, and paresthesia. Posterior fossa decompression with duraplasty was performed in 87 (93.5%) patients and bony decompression in 6 (6.5%) patients. After surgery, preoperative symptoms alleviated in 84.9% (79/93) and the postoperative syringomyelia regression rate was 89.2% (33/37) of all patients. The postoperative complication rate was 34.4% (32/93), with aseptic meningitis being the most common, 25.8% (24/93). Revision surgery was required in 14% (13/93) of patients. No significant correlation between postoperative outcome and extent of dural decompression, or type of duraplasty performed was found.ConclusionThis is the largest reported series of surgically treated CM1 patients in Finland. Posterior fossa decompression is an effective procedure for CM1 symptomology. Duraplasty technique had no significant difference in complication rate or long-term outcomes.

Type one chiari malformation as a cause of central sleep apnea and hypoventilation in children

ObjectivesChiari type 1 malformation (CM1) may occasionally lead to central sleep apnea (CSA). We studied, in a large clinical cohort of pediatric CM1 patients, the effect of CM1 on breathing during sleep. MethodsThis is a retrospective single pediatric pulmonology center study with a systematic evaluation of pediatric CM1 patients under age 18 with polysomnography (PSG) during 2008–2020. Children with syndromes were excluded. All patients had undergone head and spine magnetic resonance imaging. ResultsWe included 104 children with CM1 with a median age of 7 (interquartile range (IQR) 5–13) years. The median extent of tonsillar descent (TD) was 13 (IQR 10–18) mm. Syringomyelia was present in 19 children (18%). Of all children, 53 (51%) had normal PSG, 35 (34%) showed periodic breathing or central apnea and hypopnea index ≥5 h−1, and 16 (15%) displayed features of compensated central hypoventilation and end-tidal or transcutaneous carbon dioxide 99th percentile level above 50 mmHg. TD had the best predictive value for central breathing disorders. In a linear model, both age (61%) and TD (39%) predicted median breathing frequency (R = 0.33, p < 0.001). ConclusionsAlthough severe CSA is a rare complication of brainstem compression in pediatric patients with CM1, short arousal-triggered episodes of periodic breathing and mild compensated central hypoventilation are common. TD shows the best but still poor prediction of the presence of a central breathing disorder. This highlights the use of PSG in patient evaluation. Posterior fossa decompression surgery effectively treats central breathing disorders.

The Effect of Posterior Fossa Decompression Surgery on Brainstem and Cervical Spinal Cord Dimensions in Adults with Chiari Malformation Type 1

Posterior fossa decompression (PFD) surgery creates more space at the skull base, reduces the resistance to the cerebrospinal fluid motion, and alters craniocervical biomechanics. In this paper, we retrospectively examined the changes in neural tissue dimensions following PFD surgery on Chiari malformation type 1 adults. Measurements were performed on T2-weighted brain magnetic resonance images acquired before and 4months after surgery. Measurements were conducted for neural tissue volume and spinal cord/brainstem width at 4 different locations; 2 width measurements were made on the brainstem and 2 on the spinal cord in the midsagittal plane. Cerebellar tonsillar position (CTP) was also measured before and after surgery. Twenty-five adult patients, with a mean age of 38.9±8.8years, were included in the study. The cervical cord volume increased by an average of 2.3 ± 3.3% (P= 0.002). The width at the pontomedullary junction increased by 2.2 ± 3.5% (P < 0.01), while the width 10mm caudal to this junction increased by 4.2 ± 3.9% (P < 0.0001). The spinal cord width at the base of second cervical vertebra and third cervical vertebra did not significantly change after surgery. The CTP decreased by 60 ± 37% (P < 0.0001) after surgery, but no correlation was found between CTP change and dimension change. The brainstem width and cervical cord volume showed a modest increase after PFD surgery, although standard deviations were large. A reduction in compression after PFD surgery may allow for an increase in neural tissue dimension. However, clinical relevance is unclear and should be assessed in future studies with high-resolution imaging.

442 Reversible Cognitive Dysfunction and Neuropsychiatric Symptoms in Patients With Chiari Malformation Type I

INTRODUCTION: Chiari malformation type I (CMI) is a congenital/acquired structural condition where the cerebellar tonsils herniate through the foramen magnum, resulting in cerebellar and lower medulla/upper cervical spinal cord compression. Symptoms typically include occipital headaches, however, additional symptoms have been reported by symptomatic patients. We have observed a proportion reporting cognitive dysfunction and neuropsychiatric symptoms, which appear to improve following posterior fossa decompression (PFD). METHODS: Patients completed comprehensive neuropsychological evaluations, including a 90-minute standardized assessment of cognitive function across multiple domains and a self-reported assessment of neuropsychiatric symptoms, pre- and approximately 6-months post-surgery. RESULTS: This prospective study included patients with CMI who opted to undergo PFD surgery and reported cognitive or neuropsychiatric impairment between 2015 to 2021. All patients completed a comprehensive pre-operative neuropsychological assessment. A parallel assessment was completed at 6-month post-operative follow-up. 112 patients (Mage = 35.1 years; SD = 10.4) were included in pre-operative analyses, and of these, 31 patients (Mage = 32.5 years; SD = 10.5) were included in paired pre-post-operative analyses. Pre-operatively, CMI patients performed significantly worse than a standard norm on measures of executive function, attention, visuospatial memory, verbal memory, and neuropsychiatric symptoms. CONCLUSIONS: This is the first study to 1) demonstrate significant impairments in cognitive function and neuropsychiatric symptoms in CMI patients pre-operatively, and 2) show significant improvements in these domains at post-operative follow-up. This work calls attention to a significant proportion of CMI patients who suffer debilitating and life altering symptoms and provides compelling evidence for a role of the cerebellum in such conditions. In addition to CMI, cerebellar pathology should be considered as potential neuroanatomical site for patients with cognitive and neuropsychiatric impairment from other etiologies.

Diagnosis and treatment of 18 cases of Chiari malformation with hoarseness

Objective: To investigate the diagnosis and treatment of Chiari malformation patients with hoarseness and other otorhinolaryngological symptoms. Methods: The clinical data of 18 patients of Chiari malformation with hoarseness were retrospectively collected, which was composed of 5 men and 13 women, aged 3-71 with median age of 52. All the patients were admitted to the Affiliated Hospital of Qingdao University from January 1989 to January 2020. All patients underwent brain MRI and laryngoscopy. The patient's symptoms and first diagnosis department, diagnosis time, total course of disease, hoarseness course, diagnosis and treatment, and postoperative recovery time were summarized. Follow-up time was 3-16 years, with median follow-up time of 6.5 years. Descriptive methods were used for analysis. Results: The first visit departments of 18 patients included neurology (9 cases), otorhinolaryngology head and neck surgery (5 cases), pediatrics (2 cases), orthopedics (1 case) and respiratory department (1 case). Except for the 7 cases in neurology department, the other 11 patients were not diagnosed in time. The disease duration of 18 patients with Chiari malformation ranged from 2 months to 5 years, and hoarseness was present from 20 days to 5 years. After diagnosis, 9 patients underwent posterior fossa decompression surgery, and 1 of them underwent syrinx drainage at the same time. The symptoms of 8 cases improved significantly after operation, with the improvement time from 1 to 30 days. In addition, 9 patients chose conservative treatment, among whom 8 had no improvement in symptoms and 6 progressed. Conclusions: Posterior fossa decompression is an effective treatment for Chiari malformation, and the prognosis is good. Timely diagnosis and treatment can improve the prognosis of patients.

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.

Clinical and Computerized Volumetric Analysis of Posterior Fossa Decompression for Space-Occupying Cerebellar Infarction.

Background and PurposeSurgical decompression of the posterior fossa is often performed in cases with a space-occupying cerebellar infarction to prevent coma and death. In this study, we analyzed our institutional experience with this condition. We specifically attempted to address timing issues and investigated the role of cerebellar necrosectomy using imaging data and conducting volumetric analyses.MethodsWe retrospectively studied pertinent clinical and imaging data, including computerized volumetric analyses (preoperative/postoperative infarction volume, necrosectomy volume, and posterior fossa volume), from all 49 patients who underwent posterior fossa decompression surgery for cerebellar infarction in our department from January 2012 to January 2021.ResultsThirty-five (71%) patients had a Glasgow Coma Scale (GCS) of 14–15 at admission vs. only 14 (29%) before vs. 41 (84%) following surgery. Seven (14%) patients had preventive surgery (initial GCS 14–15, preoperative GCS change ≤ 1). Only 18 (37%) patients had an mRS score of 0–3 at discharge. Estimated overall survival was 70.5% at 1 year. Interestingly, 18/20 (90%) surviving cases had a modified Rankin Scale (mRS) outcome of 0–3 (mRS 0–2: 12/20 [60%]) 1 year after surgery. Surgical timing, including preventive surgery and mass effect of the infarct, in the posterior fossa assessed semi-quantitatively (Kirollos grade) and with volumetric parameters that were not predictive of the patients' (functional) outcomes.ConclusionPosterior fossa decompression for cerebellar infarction is a life-saving procedure, but rapid recovery of the GCS after surgery does not necessarily translate into good functional outcome. Many patients died during follow-up, but long-term mRS outcomes of 4–5 are rare. Surgery should probably aim primarily at pressure relief, and our clinical as well as volumetric data suggest that the impact of removing an infarcted tissue may be limited. It is presumably relatively safe to initially withhold surgery in cases with a GCS of 14–15.

Cerebellar and Brainstem Displacement Measured with DENSE MRI in Chiari Malformation Following Posterior Fossa Decompression Surgery

Background Posterior fossa decompression (PFD) surgery is a treatment for Chiari malformation type I (CMI). The goals of surgery are to reduce cerebellar tonsillar crowding and restore posterior cerebral spinal fluid flow, but regional tissue biomechanics may also change. MRI-based displacement encoding with stimulated echoes (DENSE) can be used to assess neural tissue displacement. Purpose To assess neural tissue displacement by using DENSE MRI in participants with CMI before and after PFD surgery and examine associations between tissue displacement and symptoms. Materials and Methods In a prospective, HIPAA-compliant study of patients with CMI, midsagittal DENSE MRI was performed before and after PFD surgery between January 2017 and June 2020. Peak tissue displacement over the cardiac cycle was quantified in the cerebellum and brainstem, averaged over each structure, and compared before and after surgery. Paired t tests and nonparametric Wilcoxon signed-rank tests were used to identify surgical changes in displacement, and Spearman correlations were determined between tissue displacement and presurgery symptoms. Results Twenty-three participants were included (mean age ± standard deviation, 37 years ± 10; 19 women). Spatially averaged (mean) peak tissue displacement demonstrated reductions of 46% (79/171 µm) within the cerebellum and 22% (46/210 µm) within the brainstem after surgery (P < .001). Maximum peak displacement, calculated within a circular 30-mm2 area, decreased by 64% (274/427 µm) in the cerebellum and 33% (100/300 µm) in the brainstem (P < .001). No significant associations were identified between tissue displacement and CMI symptoms (r < .74 and P > .012 for all; Bonferroni-corrected P = .0002). Conclusion Neural tissue displacement was reduced after posterior fossa decompression surgery, indicating that surgical intervention changes brain tissue biomechanics. For participants with Chiari malformation type I, no relationship was identified between presurgery tissue displacement and presurgical symptoms. © RSNA, 2021 Online supplemental material is available for this article.

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.

Obex position is associated with syringomyelia and use of posterior fossa decompression among patients with Chiari I malformation.

Chiari I malformation (CM-I) has traditionally been defined by measuring the position of the cerebellar tonsils relative to the foramen magnum. The relationships of tonsillar position to clinical presentation, syringomyelia, scoliosis, and the use of posterior fossa decompression (PFD) surgery have been studied extensively and yielded inconsistent results. Obex position has been proposed as a useful adjunctive descriptor for CM-I and may be associated with clinical disease severity. A retrospective chart review was performed of 442 CM-I patients with MRI who presented for clinical evaluation between 2003 and 2018. Clinical and radiological variables were measured for all patients, including presence/location of headaches, Chiari Severity Index (CSI) grade, tonsil position, obex position, clival canal angle, pB-C2 distance, occipitalization of the atlas, basilar invagination, syringomyelia, syrinx diameter, scoliosis, and use of PFD. Radiological measurements were then used to predict clinical characteristics using regression and survival analyses, with performing PFD, the presence of a syrinx, and scoliosis as outcome variables. Among the radiological measurements, tonsil position, obex position, and syringomyelia were each independently associated with use of PFD. Together, obex position, tonsil position, and syringomyelia (area under the curve [AUC] 89%) or obex position and tonsil position (AUC 85.4%) were more strongly associated with use of PFD than tonsil position alone (AUC 76%) (Pdiff = 3.4 × 10-6 and 6 × 10-4, respectively) but were only slightly more associated than obex position alone (AUC 82%) (Pdiff = 0.01 and 0.18, respectively). Additionally, obex position was significantly associated with occipital headaches, CSI grade, syringomyelia, and scoliosis, independent of tonsil position. Tonsil position was associated with each of these traits when analyzed alone but did not remain significantly associated with use of PFD when included in multivariate analyses with obex position. Compared with tonsil position alone, obex position is more strongly associated with symptomatic CM-I, as measured by presence of a syrinx, scoliosis, or use of PFD surgery. These results support the role of obex position as a useful radiological measurement to inform the evaluation and potentially the management of CM-I.

Management of Chiari I malformations: a paradigm in evolution

Despite decades of experience and research, the etiology and management of Chiari I malformations (CM-I) continue to raise more questions than answers. Controversy abounds in every aspect of management, including the indications, timing, and type of surgery, as well as clinical and radiographic outcomes. This review aims to outline past experiences, consolidate current evidence, and recommend directions for the future management of the Chiari I malformation. A review of recent literature on the management of CM-I in pediatric patients is presented, along with our experience in managing 1073 patients who were diagnosed with CM-I over the past two decades (1998-2018) at Children's National Medical Center (CNMC) in Washington DC. The general trend reveals an increase in the diagnosis of CM-I at younger ages with a significant proportion of these being incidental findings (0.5-3.6%) in asymptomatic patients as well as a rise in the number of patients undergoing Chiari posterior fossa decompression surgery (PFD). The type of surgical intervention varies widely. At our institution, 104 (37%) Chiari surgeries were bone-only PFD with/without outer leaf durectomy, whereas 177 (63%) were PFD with duraplasty. We did not find a significant difference in outcomes between the PFD and PFDD groups (p = 0.59). An analysis of failures revealed a significant difference between patients who underwent tonsillar coagulation versus those whose tonsils were not manipulated (p = 0.02). While the optimal surgical intervention continues to remain elusive, there is a shift away from intradural techniques in favor of a simple, extradural approach (including dural delamination) in pediatric patients due to high rates of clinical and radiographic success, along with a lower complication rate. The efficacy, safety, and necessity of tonsillar manipulation continue to be heavily contested, as evidence increasingly supports the efficacy and safety of less tonsillar manipulation, including our own experience.

Chiari I malformation and altered cerebrospinal fluid dynamics-the highs and the lows.

This paper reviews the altered cerebrospinal fluid dynamics that can be associated with paediatric Chiari I malformation and we present our own institutional experience. We conducted a thorough review of the literature and retrospectively analyzed all cases of operatively managed paediatric Chiari 1 malformation at our institution between February 2006 and February 2019. Acquired Chiari malformation (ACM) can radiologically mimic Chiari I and has been associated with both intracranial hypotension (either secondary to lumboperitoneal shunting or spontaneous CSF hypotension) and idiopathic intracranial hypertension (IIH). At our institution, 61 paediatric cases (range, 2-15years) underwent foramen magnum decompression (FMD) for Chiari I malformation. Whilst 80% (50/61) of cases underwent FMD with no preceding or post-operative problems of CSF dynamics, 8% (5/61) of cases had hydrocephalus at initial presentation requiring CSF diversion followed by FMD for persistent Chiari, and 10% (6/61) developed hydrocephalus following FMD and required long-term CSF diversion. In paediatric ACM, the management of intracranial hypotension involves thorough radiological assessment and inclusion/adjustment of a valve in the case of lumboperitoneal shunting or epidural blood patch or interventional techniques in the case of spontaneous CSF leak. Thereby, unwarranted posterior fossa decompression surgery is avoided. In the case of IIH and Chiari I malformation, children who have recurrent symptoms despite adequate posterior fossa decompression surgery (failed Chiari), there is a strong role for intracranial pressure monitoring as raised intracranial pressure may indicate long-term CSF diversion.

Quantification of changes in brain morphology following posterior fossa decompression surgery in women treated for Chiari malformation type 1.

While 84% of patients surgically treated for Chiari malformation type 1 (CM1) demonstrate improved quality of life after posterior fossa decompression surgery, there are many risks associated with this surgery. Surgical planning to identify candidates likely to improve postoperatively may benefit from an improved understanding of morphological changes after decompression surgery. To evaluate these changes, we quantified 59 morphological parameters on 42 CM1 adult female patients before and after CM1 decompression surgery. Fifty-nine morphological parameters in the posterior cranial fossa, cranio-cervical, and intracranial regions in the midsagittal plane were evaluated using 42 T1-weighted magnetic resonance images of female CM1 patients before and after surgery, and 42 healthy female controls. Morphological differences before and after surgery were compared through the development of a technique to establish the opisthion location, a key reference point not present after surgery. In addition to the expected reduction of the cranio-caudal dimension of the cerebellum, objective analyses showed a significant increase in the area of the cerebrospinal fluid spaces, posterior (6×) and inferior (2.6×) to the cerebellum (+ 112 ± 102 and + 140 ± 127mm2, respectively). This increased area was primarily impacted by an average reduction in the occipital bone length of 24.5 ± 7.3mm following surgery. Based on multiple angles, results demonstrated a 2°-4° anterior rotation of the cerebellum after surgery. Our results show that decompression surgery results in significant changes in the cerebellum and cerebrospinal fluid spaces. Further investigation should determine how these morphological changes impact clinical outcomes.

Craniometrical imaging and clinical findings of adult Chiari malformation type 1 before and after posterior fossa decompression surgery with duraplasty

Background: Posterior fossa decompression both with and without duraplasty are accepted treatments for symptomatic adult patients with Chiari Malformations Type 1 (CM-1). There is still debate of the superiority of one technique over the other. The purpose of this study was to determine the clinical and craniometrical imaging outcomes of a series of patients who underwent posterior fossa decompression with duraplasty.Materials and methods: All adult patients with symptomatic CM-1 operated at a single institution with a minimum of 6 months follow-up were enrolled prospectively. Clinical outcomes and craniometrical parameters based upon MR imaging pre- and post-surgery were analyzed.Results: A series of 33 consecutive patients who met the inclusion criteria were enrolled; mean age of 33.93 ± 10 years (range 14–56 years). The most common preoperative complaint was headache. The most common clinical sign was sensory dysfunction which was relieved or improved in 63% of patients. The mean syringomyelia size had a significant reduction after the surgery (p = .01). The mean tonsillar descent also had significant reduction (p = .00). The mean McRae line length before the surgery and after that were 33.4 and 53.1 mm respectively that this change was not statistically significant (p = .42). The odontoid process parameters had no significant changes after surgery.Conclusions: Posterior fossa decompression surgery with duraplasty can improve both clinical and imaging outcomes such as syringomyelia size and tonsillar descent for patients with symptomatic CM-1. However, no significant difference was found in craniometrical parameters before and after the surgery.

Chiari I - Idiopathic Intracranial Hypertension Association After Failed Posterior Fossa Surgery. Case Report

Objectives: Several papers have been published relating the Idiopathic Intracranial Hypertension Syndrome (HTII) to the Arnold Chiari type I malformation (AC1M). Both entities have clinical and demographic similarities, a poorly defined etiology and, sometimes common therapeutic posibilities. A correlation between both entities has been suggested, especially in a subgroup of patients in whom posterior fossa decompression surgery fails. With regard to a case, we reviewed the literature and proposed our hypothesis about the origin of Chiari-HTII syndrome and its therapeutic possibilities. Case presentation: A 41year-old patient with mild obesity, menstrual abnormalities and empty Sella Turcicae, was operated on with an AC1M associating basilar impression and syringomyelia causing all together a centromedullary syndrome. After posterior fossa decompression surgery and successful arthrodesis, she improved in the immediate postoperative period. Nevertheless, she soon developed symptoms of intracranial hypertension (ICH), and showed increased opening pressure in lumbar puncture compatible with HTII syndrome. A ventriculoperitoneal shunt (VPS) was implanted with clinical improvement and 12 months later the syringomyelia was absent on in the magnetic resonance (MRI). Conclusion: The Chiari I-HTII syndrome is described as the coexistence of ICH symptoms after failed posterior fossa surgery, in patients with no flow MRI anomalies, and increased opening pressure at the lumbar puncture. In our experience, both entities seem to overlap in a common syndrome and must be taken into account, especially in patients with atypical onset of symptoms or patients in whom conservative treatment fails.

Study on the risk factors for hemorrhagic transformation of cerebellar infarction after posterior fossa decompression surgery

Objective: To investigate the related risk factors for hemorrhagic transformation (HT) of cerebellar infarction after posterior fossa decompression surgery. Methods: A total of 91 patients with cerebellar infarction were treated by posterior fossa decompression surgery in Department of Neurosurgery of Jinhua Municipal Central Hospital from Jan 2010 to Jan 2018, were selected as study subjects. The HT group included 17 cases, while the Non-HT group included 74 cases. The clinical data of the two groups were analyzed retrospectively, the univariate and non-conditional lgistic regression analysis were performed to detect the relevant risk factors for hemorrhagic transformation of cerebellar infarction after posterior fossa decompression surgery. Results: By univariate analysis, the differences of these seven risk factors, the large area cerebellar infarction (the diameter of area was larger than 5 cm), pre-op thrombolysis, pre-op mild HT, oral anticoagulants, atrial fibrillation, hyperglycemia and fluctuation of BP in post-op, between two groups were statistically significant (P<0.05). By multivariate logistic analysis, the large area cerebellar infarction (P<0.05), pre-op thrombolysis(P<0.01), pre-op mild HT (P<0.01), oral anticoagulants (P<0.01) were the independent risk factors for post-op HT. Conclusions: The large area cerebellar infarction (the diameter of area was more than 5 cm), pre-op thrombolysis, pre-op mild HT, oral anticoagulants, atrial fibrillation, hyperglycemia and fluctuation of BP in post-op are important risk factors for post-op HT. The large area cerebellar infarction, pre-op thrombolysis, pre-op mild HT, oral anticoagulants are the independent risk factors for post-op HT. A proper pre-op evaluation of these risk factors and an individualized treatment for post-op HT would help a lot with balancing operational risk and improving prognosis.

Comparison between decompressed and non-decompressed Chiari Malformation type I patients: A neuropsychological study

BackgroundPrevious studies have suggested an association of Chiari Malformation type I (CM-I) and cognitive deficits. CM-I is a neurological disorder characterized by a descent of cerebellar tonsils into the foramen magnum, resulting in overcrowding of the upper cervical spine region. Posterior fossa decompression (PFD) is the surgical treatment of choice, however, the literature on the consequences for patients is mainly reduced to the assessment of physical symptoms. MethodsData from a neuropsychological assessment of 76 patients with CM-I, both with PFD (n = 37) and without PFD (n = 39) surgery, and 76 healthy controls, matched by gender, age and years of education are reported. ResultsCM-I patients show a generally lower cognitive performance in executive function, verbal fluency, spatial cognition, language (naming), verbal memory, processing speed, emotional facial recognition and theory of mind, compared to control group. The results are maintained even after statistically controlling for the influence of perceived physical pain and the presence of anxious-depressive symptomatology. Data also illustrate a similar cognitive profile between both groups with CM-I. ConclusionThese findings provide evidence of a deficient cognitive profile associated with CM-I, regardless of the PFD surgery. According to these results, both physical and cognitive consequences must be considered in the treatment of CM-I.

Early analysis of operative management of Chiari I malformation in pediatric cystic fibrosis patients.

Chiari I malformation, defined as herniation of the cerebellar tonsils at least 5mm below the foramen magnum, can result from congenital or acquired pathology. While the mechanism is not well understood, an association between Chiari I and cystic fibrosis has been described in the literature. The lifelong respiratory status management necessitated by cystic fibrosis creates a greater risk of Chiari symptomatology as well as post-operative CSF-related complications in the setting of duraplasty secondary to recurrent transient increases in intracranial pressure. We will review the literature, describe our experience with these patients, and propose bony decompression as an approach to treatment. A retrospective review of pediatric patients treated at our institution with both cystic fibrosis and Chiari I was performed. Since our first case in 2016, our department has evaluated four patients carrying that dual diagnosis. All four underwent posterior fossa decompression surgery. Two patients had incidental pathology. Two symptomatic patients exhibited headaches and/or coordination difficulty. Half of the patients had associated syringomyelia. All patients were offered posterior fossa decompression utilizing intraoperative ultrasound. All four patients underwent posterior fossa decompression without duraplasty. Average operative time was 128min. There were no complications post-operatively. Average hospital stay was 3.8days. Average surgical length of stay was 2.3days. Morbidity and mortality were 0%. The longest follow-up to date is 20months. The two asymptomatic patients remained so post-operatively. The child with headaches and imbalance had complete resolution of his symptoms after surgery, as did the toddler with headaches. Both patients with syringomyelia demonstrated significant decrease in the size of their syrinxes on imaging performed at least 3months post-operatively. Based on the literature and our experience, we recommend considering posterior fossa decompression without duraplasty as treatment for pediatric cystic fibrosis patients with Chiari I malformation. This approach can be effective for symptomatic and prophylactic cases in this particular patient demographic because their comorbidities predispose them to Chiari pathology and symptomatology as well as certain post-operative complications.