Herniation Of Cerebellar Tonsils Research Articles

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.

Coronavirus disease 2019-associated persistent cough and Chiari malformation type I resulting in acute respiratory failure: illustrative case.

Chiari malformation type I (CM-I) is the herniation of cerebellar tonsils through the foramen magnum, potentially resulting in the obstruction of cerebrospinal fluid flow and brainstem compression. Sleep-disordered breathing (SDB) is common in patients with CM-I, and symptomatic exacerbations have been described after Valsalva-inducing stressors. Acute decompensation in the setting of coronavirus disease 2019 (COVID-19) has not been described. After violent coughing episodes associated with COVID-19 infection, a 44-year-old female developed several months of Valsalva-induced occipital headaches, episodic bulbar symptoms, and worsening SDB, which led to acute respiratory failure requiring mechanical ventilation. Imaging demonstrated 12 mm of cerebellar tonsillar descent below the foramen magnum, dorsal brainstem compression, and syringobulbia within the dorsal medulla. She underwent posterior fossa and intradural decompression with near-complete resolution of her symptoms 6 months postoperatively. Although CM-I can remain asymptomatic, Valsalva-inducing stressors, including COVID-19 infection, can initiate or acutely exacerbate symptoms, placing patients at risk for CM-I-associated brainstem dysfunction and, in rare cases, acute respiratory failure. Worsening Valsalva maneuvers can contribute to further cerebellar tonsil impaction, brainstem compression, syringomyelia/syringobulbia, and worsening CM-I intradural pathology. Ventilator support and timely decompressive surgery are paramount, as brainstem compression can reduce central respiratory drive, placing patients at risk for coma, neurological deficits, and/or death.

Clinical Efficacy of Minimally Invasive Subpial Tonsillectomy (MIST) for Treatment of Chiari Malformation (Type I) with Syringomyelia

Objective: To investigate the clinical efficacy of minimally invasive subpial tonsillectomy (MIST) in the treatment of Chiari malformation (type I) with syringomyelia. Method A total of 209 Chiari malformation (type I) patients with syringomyelia were studied. The patients were grouped based on the syrinx diameter changes: complete disappearance group (48 patients), obvious shrinkage group (147 patients), and non-obvious shrinkage group (14 patients). The Chicago Chiari Outcome Scale (CCOS) was used to compare clinical data of the three groups of patients before treatment. The correlations between disease duration and syrinx diameter changes as well as post-treatment clinical symptoms were analyzed. The related factors of efficacy were analyzed. Results: Age and disease duration were the oldest/longest in the non-obvious shrinkage group, and the youngest/shortest in the complete disappearance group (P < 0.05). The maximum diameter reduction of syrinx was the greatest in the complete disappearance group, and the smallest in the non-obvious shrinkage group ( P < 0.05). The proportions of patients with hypoesthesia, limb weakness, and muscle atrophy were the largest in the non-obvious shrinkage group, and the smallest in the complete disappearance group ( P < 0.05). The CCOS score were the highest in the complete disappearance group, and the lowest in the non-obvious shrinkage group ( P < 0.05). There were statistically significant (P < 0.05) negative correlations between disease duration and maximum diameter reduction of syrinx, CCOS pain score, CCOS non-pain score, CCOS functionality score, and CCOS complication score, disease duration and hypoesthesia, limb weakness, muscle atrophy, and sleep apnea. Result of multivariate stepwise regression analysis indicated that age, disease duration, and preoperative syrinx diameter were the risk factors for efficacy (P < 0.05). Conclusion: For patients with Chiari malformation complicated by syringomyelia, the longer the disease duration, the more difficult it is to achieve syrinx reduction and improve the clinical symptoms. “Minimally invasive subpial tonsillectomy (MIST) and cisterna magna reconstruction” is an improved surgical approach to treat Chiari malformation (cerebellar tonsil herniation). It has the advantages of small incision, less postoperative reaction, and fewer complications, and it emphasizes the reshaping and repair of cerebellar tonsils, reconstruction of cisterna magna, and restoration of cerebrospinal fluid circulation.

Assessing the Prevalence of Ectopic Cerebellar Tonsils and Accompanying Symptoms in Individuals with Various Headaches.

Chiari malformation exhibits well-defined clinical signs, symptoms, and incidence rates in clinical studies. However, cerebellar tonsil ectopia presents with ambiguous symptoms and undetermined incidence rates in numerous studies. Our objective was to determine the incidence of cerebellar tonsil ectopia in individuals with headaches and identify additional clinical symptoms. This aims to improve diagnosis accuracy for clinicians and neurologists, leading to more effective treatment approaches. A cross-sectional study conducted in 2022 included 2305 participants aged 4-78 years presenting with headache. Chiari malformation was diagnosed using magnetic resonance imaging (MRI) scans, with a definition of cerebellar tonsil herniation extending beyond 5mm into the cervical canal. The prevalence of Chiari malformation was 3.4%, with no significant gender difference (p = 0.72). There was a significant correlation between Chiari malformation and headache exacerbation due to the Valsalva maneuver (p < 0.001) and the presence of vertigo (p < 0.001). No significant association was found between Chiari malformation and accompanying symptoms such as nausea (p = 0.43), photophobia (p = 0.2), phonophobia (p = 0.52), and speech disorders (p = 0.45). These findings suggest a notable prevalence of Chiari malformation among headache patients and its association with specific headache characteristics, such as acute and occipital headaches, exacerbation by the Valsalva maneuver, and the co-occurrence of vertigo. These results underscore the need to consider Chiari malformation in the differential diagnosis of patients presenting with these specific headache features.

A Critical Update of the Classification of Chiari and Chiari-like Malformations.

Chiari malformations are a group of craniovertebral junction anomalies characterized by the herniation of cerebellar tonsils below the foramen magnum, often accompanied by brainstem descent. The existing classification systems for Chiari malformations have expanded from the original four categories to nine, leading to debates about the need for a more descriptive and etiopathogenic terminology. This review aims to examine the various classification approaches employed and proposes a simplified scheme to differentiate between different types of tonsillar herniations. Furthermore, it explores the most appropriate terminology for acquired herniation of cerebellar tonsils and other secondary Chiari-like malformations. Recent advances in magnetic resonance imaging (MRI) have revealed a higher prevalence and incidence of Chiari malformation Type 1 (CM1) and identified similar cerebellar herniations in individuals unrelated to the classic phenotypes described by Chiari. As we reassess the existing classifications, it becomes crucial to establish a terminology that accurately reflects the diverse presentations and underlying causes of these conditions. This paper contributes to the ongoing discussion by offering insights into the evolving understanding of Chiari malformations and proposing a simplified classification and terminology system to enhance diagnosis and management.

Treatment of Chiari malformations with craniovertebral junction anomalies: Where do we stand today?

BackgroundChiari malformation type 1 (CM-1) is characterized by cerebellar tonsil herniation through the foramen magnum and can be associated with additional craniovertebral junction anomalies (CVJA). The pathophysiology and treatment for CM-1 with CVJA (CM-CVJA) is debated. ObjectiveTo evaluate the trends and outcomes of surgical interventions for patients with CM-CVJA. MethodsA systematic review of the literature was performed to obtain articles describing surgical interventions for patients with CM-CVJA. Articles included were case series describing surgical approach; reviews were excluded. Variables evaluated included patient characteristics, approach, and postoperative outcomes. ResultsThe initial query yielded 403 articles. Twelve articles, published between 1998-2020, met inclusion criteria. From these included articles, 449 patients underwent surgical interventions for CM-CVJA. The most common CVJAs included basilar invagination (BI) (338, 75.3%), atlantoaxial dislocation (68, 15.1%) odontoid process retroflexion (43, 9.6%), and medullary kink (36, 8.0%). Operations described included posterior fossa decompression (PFD), transoral (TO) decompression, and posterior arthrodesis with either occipitocervical fusion (OCF) or atlantoaxial fusion. Early studies described good results using combined ventral and posterior decompression. More recent articles described positive outcomes with PFD or posterior arthrodesis in combination or alone. Treatment failure was described in patients with PFD alone that later required posterior arthrodesis. Additionally, reports of treatment success with posterior arthrodesis without PFD was seen. ConclusionPatients with CM-CVJA appear to benefit from posterior arthrodesis with or without decompressive procedures. Further definition of the pathophysiology of craniocervical anomalies is warranted to identify patient selection criteria and ideal level of fixation.

Case Report: Cerebral Edema and Tonsillar Herniation Leading to Brain Death After Cocaine Use in a Patient with End-Stage Renal Disease

The effect of cocaine use on the cerebral vasculature is well understood, with potential for ischemic or hemorrhagic stroke. The risk of adverse effects can be prolonged and amplified in patients with renal dysfunction and uremia. Uremia-induced osmotic gradients and upregulation of aquaporin channels along with cocaine-induced blood-brain barrier degradation may act synergistically. We present the first known case of a non-compliant dialysis patient who suffers cerebral edema, tonsillar herniation, and brain death following cocaine use. A 32-year-old female with end-stage renal disease presented with shortness of breath and flu-like symptoms for one week and was alert and oriented with no neurologic deficits. The patient had missed her last 5 dialysis treatments and labs revealed hyperkalemia and uremia. Urine drug screen was positive for cocaine, opiates, and tetrahydrocannabinol (THC). Following dialysis and metabolic correction, she developed an irregular respiratory pattern and stridor and received neck computed tomography (CT). The patient became unresponsive with dilated and nonreactive pupils. CT revealed absent intraluminal carotid and vertebral artery flow at the skull base, cerebellar tonsil herniation, and anoxic brain injury. Vital signs were maintained, and cerebral edema was managed with 45-degree head-of-bed elevation and mannitol. Following cerebral edema treatment, the patient had preserved respiratory drive, fixed and dilated pupils, no corneal reflex, no cough or gag reflex, and negative oculocephalic reflex. Repeat cranial CT angiography revealed bilateral hemispheric edema, basal subarachnoid hemorrhage, and confirmed absent intracranial blood flow. Brain death was diagnosed with a radioisotope cerebral blood flow study. The use of cocaine in patients with renal dysfunction may increase the risk of cerebral edema and tonsillar herniation due to synergistic physiologic effects. Physicians should be aware of this interaction to allow for preventative measures.

Natural History of Chiari 1 Deformity.

Chiari type 1 deformity (Ch1) is associated with bony deformity of the skull base and herniation of cerebellar tonsils more than 5 mm below the foramen magnum. Magnetic resonance imaging (MRI) is used for diagnosis and surgery is advised for symptomatic children. We present a case series using MRI including cerebrospinal fluid (CSF) flow, in children with Ch1 to demonstrate a variety of outcomes, both surgical and spontaneous: spontaneous resolution, spontaneous worsening, postsurgical improvement, and postsurgical deterioration. A 2-week-old female newborn underwent brain MRI demonstrating an ectopic neurohypophysis, under opercularization suggesting brain immaturity and a normal craniocervical junction (CCJ). Follow-up (F/U) MRI at 6 years of age showed interval spontaneous development of Ch1 with decreased CSF spaces at CCJ. A 6-year-old girl referred for imaging with short stature and growth hormone deficiency demonstrated incidental findings of Ch1 without syringomyelia. There was 15-mm protrusion of pointed cerebellar tonsils through the foramen magnum and a reduced CSF space at the craniocervical junction. No surgery was performed, and F/U MRI at the age of 7 years demonstrated spontaneous resolution of the tonsillar ectopia (cerebellar tonsils now 3 mm right and 6 mm left) and expansion of the CSF spaces at CCJ. A 7-year-old boy with headaches and staring spells underwent an MRI demonstrating 6-mm protrusion of pointed cerebellar tonsils and CSF space reduction at CCJ. No surgery was performed, and F/U imaging at the age of 9 years demonstrated spontaneous improvement in cerebellar tonsillar position and increased bidirectional CSF flow at CCJ. A 17-month-old boy underwent brain MRI for unsteady gait and poor vestibular response, which showed Ch1 and narrow CSF spaces at the foramen magnum and with reduced CSF flow. At the age of 3 years, after posterior fossa decompression, F/U MRI showed postsurgical improvement of the position of the cerebellar tonsils and increased CSF space at CCJ. A 4-month-old male infant with a history of 34-week prematurity, prior germinal matrix hemorrhage, and neonatal subdural hemorrhage was referred for MRI of the cervical and thoracic spine for evaluation of developmental delay and hypotonia with torticollis. Magnetic resonance imaging of the spine demonstrated mild protrusion of inferiorly pointed cerebellar tonsils up to the foramen magnum, with visible CSF and without retroflexion of the dens. Follow-up MRI scans demonstrated progressive worsening of the Chiari 1 deformity, even after multiple surgeries. It is important to be aware of a variety of different outcomes with Ch1, including spontaneous resolution, spontaneous worsening, improvement with surgery, and even deterioration after surgery. More research is required to determine objective criteria for predicting outcome, which include both anatomic measures and physiologic measures of CSF flow, so that better surgical decisions can be made and for evaluating patients who have undergone surgery.

A Machine Learning Approach to Support Treatment Identification for Chiari I Malformation

Chiari I malformation is characterized by the herniation of cerebellar tonsils below the foramen magnum. It is often accompanied by syringomyelia and neurosurgical management is still controversial. In fact, it is frequent that some symptomatic patients initially undergo bony decompression of the posterior fossa and need in a short time more invasive surgery with higher morbility (e.g., decompression of posterior fossa with dural plastic, with or without tonsillar coarctation) because of unsatisfactory results at MRI controls. This study proposes a machine learning approach (based on SVM classifier), applied to different morphometric indices estimated from sagittal MRI and some information on the patient (i.e., age and symptoms at diagnosis), to recognize patients with higher risk of syringomyelia and clinical deterioration. Our database includes 58 pediatric patients who underwent surgery treatment. A negative outcome at 1 year from the intervention was observed in 38% of them (accuracy of 62%). Our algorithm allows us to increase the accuracy to about 71%, showing it to be a valid support to neurosurgeons in refining the clinical picture.

Chiari Type 1 malformation: A case report

Type I Chiari malformation (CM) is an acquired or congenital disorder characterized by herniation of the cerebellar tonsils through the foramen magnum and into the spinal canal. The resulting anatomic abnormality impairs the flow of cerebral spinal fluid and results in the Chiari symptoms and signs. The purpose of this study was to report a case of successfully treated CM Type 1 that was discovered accidentally during childhood. A 9-year-old female presented to the emergency department complaining of dizziness and headache. Before her admission, she lost balance and collapsed to the ground fainting. A magnetic resonance imaging (MRI) scan of the brain disclosed herniation of cerebellar tonsils through the foramen magnum at 13 mm below the spinal canal. It is very difficult to determine the true frequency of this disorder early in childhood. A definitive diagnosis is generally made after a MRI, where the abnormal protrusion of the cerebellum toward the spinal cord can be seen.

Brain herniation death in pediatric cerebral lyme borreliosis followed by kidney organ donation

Fatal pediatric patient outcomes in chronic Lyme borreliosis are rarely identified. One sudden cardiac Lyme death in a seventeen-year-old black adolescent has been autopsy confirmed and reported in 2017 from Westchester, New York four years after his death in 2013. Herein is a case report of a pediatric Lyme disease brain death in a nineteen-month-old South Asian infant whose duration of disease was twelve months after sustaining three ixodid tick bites, to his sudden death from cerebellar tonsil herniation. This infant’s kidneys were transplanted into an unknown recipient.

Familial chiari malformation

Chiari malformation type 1 (CM 1) is defined as herniation of cerebellar tonsils 4-5 mm below the foramen magnum. Multiple developmental factors like defective development of pontine flexure and shallow posterior fossa are the proposed factors which predispose the development of this syndrome. These reports on familial occurrence of this syndrome correlates with the embryonal- developmental etiology of Chiari 1 malformation. Recent advances in the understanding of the influence of genes and pathogenesis of familial Chiari malformation are expected to improve management of affected patients and monitoring of at-risk family members.

Resolution of Tonsillar Herniation and Syringomyelia Following Resection of a Large Anterior Frontal Parasagittal Meningioma

Chiari I malformation is the herniation of cerebellar tonsils below the level of the foramen magnum due to congenital or acquired pathologies. Acquired Chiari I malformation (ACM) may occur secondary to space-occupying lesions (SOLs), such as intracranial tumors due to elevated intracranial pressure (ICP), and can be accompanied by syringomyelia. ACM and syringomyelia have been shown to resolve after resection of the SOL, without the need for adjuvant posterior fossa decompression. The vast majority of SOLs leading to ACM have been reported in the posterior fossa, thus exerting a direct mass effect on the cerebellum. Supratentorial SOLs leading to ACM are much less frequent but, when present, are most commonly parieto-occipital. We report a rare case of a large anterior left frontal, parasagittal meningioma causing ACM and syringomyelia. These findings resolved following the resection of the meningioma, with no further surgical intervention. Our case demonstrates that ACM can occur secondary to an anterior supratentorial mass and further supports the idea that decompression of the posterior fossa is not required for the resolution of intracranial tumor-associated ACM and syringomyelia.

Investigation of The Improvement Rate Regarding The Herniation of Cerebellar Tonsils Following Shunting Procedures in Patients with Chiari Malformation and Associated Hydrocephalus

Introduction and Aim: Chiari malformation is a congenital anomaly formed as the result of the herniation of posterior fossa structures through the foramen magnum toward the spinal canal. In this study, we aimed to present the improvement rate regarding the herniation in cerebellar tonsils following shunting procedures in patients with Chiari malformation and associated hydrocephalus. Method: We measured in mm the improvement rate regarding the herniation in cerebellar tonsils in postoperative cervical MRI images obtained following ventriculoperitoneal shunting procedures for hydrocephalus in adult patients with symptoms of Chiari malformation such as balance disorder, dizziness, numbness and loss of muscular strength at the hands who were diagnosed with Chiari malformation and hydrocephalus following cranial and cervical magnetic resonance imaging MRI . Results: A total of fifteen adult patients in whom the cerebellar tonsillar herniation was over 5 mm and accompanied by hydrocephalus were included in our study. The measure of herniation in the patients involved in the study was between 1.11 cm and 8 mm. The amount of improvement in herniation following the shunting procedure was between 7.76 mm and 2.2 mm. Conclusion: In patients with Chiari malformation associated with hydrocephalus, cerebellar tonsillar herniation can regress to 5 mm, which is considered as physiological, and the symptoms related to Chiari malformation can disappear. When Chiari malformation is associated with hydrocephalus, the tonsillar herniation may improve, and symptoms may disappear following the ventriculoperitoneal shunting procedure for hydrocephalus without necessitating posterior decompression for Chiari-related herniation.

Tonsillar herniation spectrum: more than just Chiari I. Update and controversies on classification and management.

Cerebellar tonsil herniation comprises a spectrum of disorders sharing a common neuroimaging finding consisting of downward displacement of the cerebellar tonsils through the foramen magnum and into the upper cervical spinal canal. This not uncommon condition may result from a large host of congenital or acquired causes, and confusion regarding its classification and pathogenesis still exists. Terminology also remains heterogeneous, including inconsistencies in the usage of the "Chiari 1" monicker. In this paper, the hypothesized mechanisms of development of tonsillar herniation are reviewed and strategies of management are discussed, with particular attention to surgical options adapted to the underlying etiology. A focus will be placed on acquired causes of tonsillar herniation.

Impact of morphological measurements on symptoms in Chiari malformation type 1

Aim: Chiari malformation Type 1 (CM1) is a pathology resulting from herniation of cerebellar tonsils or tonsils into the spinal canal. We aimed to examine the impact of the cranium’s morphological measurements on the symptoms with CM1 patients.Methods: This research was designed as a retrospective case-control study in a single-center. 2309 patients aged between 18-70 who underwent brain magnetic resonance imaging (MRI) to confirm or exclude the diagnosis of CM1 as a result of clinical and examination findings were evaluated. Cranium’s morphological measurements, the amount of herniation, patient’s symptoms, and the modified Asgari score were retrospectively assessed. Results: Patients with a final diagnosis of CM1 after the MRI evaluation were classified as study group (n=212), and the others control group (n=2097). The maximum cranial length, maximum cranial height, supra occiput length, posterior cranial fossa (PCF) anteroposterior length, in the study group were shorter, whereas the sagittal diameter of the foramen magnum and the longest anteroposterior diameter of the cerebrum were longer (P&lt;0.001 for all mentioned comparisons). Tentorium cerebelli slope was found to be significantly lower in the study group (P&lt;0.001). The most prevalent symptoms were a headache (92%). The herniation amount had a negative correlation with maximum cranial length and maximum cranial height (r=-0.184, P=0.07; r=-0.158 and P=0.022, respectively) and a positive correlation with the modified Asgari score (r=0.598; P&lt;0.001).Conclusion: The cranium’s morphological measurements have an impact on the symptoms of patients with CM1.

Chiari 1 malformation and raised intracranial pressure.

The pathophysiology of Chiari 1 malformation (CM1) is inextricably related to intracranial pressure (ICP). The characteristic cerebellar tonsil herniation at the foramen magnum may either cause raised ICP by disturbing CSF flow (as observedinidiopathic CM1) or may itself be the effect of raised ICP (as observedinacquired CM1). Distinguishing between these two phenomena, therefore, is of paramount importance in successfully alleviating the symptoms of the condition and preventing serious complications. In this article, we discuss the pathophysiology of raised ICP in CM1 and review the current evidence for its investigation and treatment. We also share our own clinical experience which investigates the utility of ICP monitoring in a series of 26 children with CM1.

Clinical diagnosis-part II: what is attributed to Chiari I.

Chiari malformation type I is identified as radiological appearance of cerebellar tonsil herniation below the foramen magnum. The wide spectrum of clinical manifestations variably associated sometimes encompasses signs and symptoms whose correlation with the malformation remains debatable. However, a correct clinical framework is relevant in tailoring the strategy of management, and in particular, establishing the appropriate surgical intervention. An analysis of relevant articles on this issue was performed, involving both single case reports and case series. The papers were obtained from electronic databases including PubMed/MEDLINE and Google Scholar, as well as direct contact with some authors. This review focuses on those unusual clinical pictures attributed to Chiari malformation type I (CMI), investigating their actual relationship with the morphological condition. Supposed physiopathogenetic mechanisms and clinical relevance are discussed along with an analysis on the surgical indications and results. There is no clear explanation on why some patients may exhibit uncommon symptoms, often in association with the most frequent ones, but even reported as single initial clinical occurrence. Their actual incidence may have been roughly underestimated in the literature so far, because of wide heterogeneity of selection and analysis among different studies. Most of the authors appear sharing the impression that CMI surgical decompression plays a significant role in controlling the majority of these unusual symptoms, stressing their actual occurrence in relation with the malformation. A routinely multidisciplinary clinical approach has become advisable to encompass the diversity of conditions potentially associated with CMI and improve the care of CMI patients.

Acute brainstem compression

A 34-year-old African woman, whose medical history was unremarkable, presented to the emergency room with severe headache and vomiting. Temperature, blood cells count, plasma electrolytes and chest X-ray were normal....

Chiari I malformation: surgical technique, indications and limits.

Chiari malformation type I (CM-I) is a rare disease characterised by herniation of cerebellar tonsils below the foramen magnum with associated anomalies of posterior fossa. We describe here the surgical technique, indications and limits of surgical treatment. The authors describe the surgical technique, including: posterior fossa decompression, opening of the foramen of Magendie and duraplasty in case of CM-I. Posterior fossa decompression plus duraplasty is a safe and effective procedure for patients with CM-I malformation.