A comparative analysis of neuroendoscopic foramen magnum decompression versus traditional open surgery for Chiari Malformation Type I.

PURPOSE: Chiari Malformation Type I (CM1) is characterized by the downward displacement of the cerebellar tonsils below the foramen magnum. The standard surgical treatment for CM1 is foramen magnum decompression and atlas laminectomy (FMD-AL). However, there is a growing interest in exploring minimally invasive techniques, such as neuroendoscopically assisted FMD-AL, to optimize surgical outcomes. The aim is to present the results of the less invasive neuroendoscopic-assisted system application as an alternative to decompression surgery in patients with CM-1 with/without syringomyelia. PATIENTS AND METHODS: A retrospective analysis was conducted on 76 patients with CMI who underwent either neuroendoscopic-assisted FMD-AL (n = 23) or open surgery (n = 53). Preoperative and postoperative assessments were performed, including pain levels, functional assessment, outcome and serum creatinine kinase (CK) levels. Surgical parameters and radiological imaging were also evaluated and compared. RESULTS: Both surgical groups showed improvements in pain levels and increase in postoperative CK levels. There were no statistically significant differences between the groups in terms of postoperative JOA scores, VAS scores, CCOS, or syrinx resolution. However, the neuroendoscopic group had significantly lower CK levels, shorter hospital stays, less blood loss, and shorter operation times compared to the open surgery group, indicating reduced muscle damage and potential benefits of the neuroendoscopic assisted approach. CONCLUSION: Both neuroendoscopy and open surgery groups can effectively alleviate symptoms and improve outcomes in patients with CM1. The neuroendoscopic assisted technique offers the advantage of reduced muscle damage and shorter hospital stays. The choice of surgical technique should be based on individual patient characteristics and preferences. LEVEL OF EVIDENCE: 3 (Retrospective case-control study) according to using the Oxford Centre for Evidence-Based Medicine (CEBM) Table.

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

PURPOSE: The 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. METHODS: In 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. RESULTS: The 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. CONCLUSION: This 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.

Duraplasty using a combination of a pedicled dural flap and collagen matrix in posterior fossa decompression for pediatric Chiari malformation type 1 with syrinx.

PURPOSE: In posterior fossa decompression for pediatric Chiari malformation type 1 (CM-1), duraplasty methods using various dural substitutes have been reported to improve surgical outcomes and minimize postoperative complications. To obtain sufficient posterior fossa decompression without cerebrospinal fluid-related complications, we developed a novel duraplasty technique using a combination of a pedicled dural flap and collagen matrix. The objective of this study was to describe the operative nuances of duraplasty using a combination of a pedicled dural flap and collagen matrix in posterior fossa decompression for pediatric CM-1. METHODS: We reviewed the clinical and radiographic records of 11 consecutive pediatric patients who underwent posterior fossa decompression with duraplasty using a combination of a pedicled dural flap and collagen matrix followed by expansile cranioplasty for CM-1. The largest area of the syrinx and the size of the posterior fossa were calculated. RESULTS: The maximum syrinx area was reduced by a mean of 68.5% ± 27.3% from preoperatively to postoperatively. Four patients (36.4%) had near-complete syrinx resolution (> 90%, grade III reduction), five (45.5%) had 50% to 90% reduction (grade II), and two (18.2%) had < 50% reduction (grade I). The posterior fossa area in the midsagittal section increased by 8.9% from preoperatively to postoperatively. There were no postoperative complications, including cerebrospinal fluid leakage, pseudomeningocele formation, or infection. CONCLUSION: Duraplasty using a combination of a pedicled dural flap and collagen matrix in posterior fossa decompression is a promising safe and effective surgical technique for pediatric CM-1 with syrinx.

Chiari Malformation Type 1 and Syringomyelia: Why Do Patients Claim for International Guidelines? Commentary on the 2021 Chiari and Syringomyelia Consensus Document.

The diagnosis of Chiari malformation type 1 (CM1) and Syringomyelia (Syr) has become increasingly common during the past few years. Contemporarily, the body of literature on these topics is growing, although randomized controlled studies on significant case series to drive guidelines are missing in the pediatric and adult populations. As a result of the different opinions about surgical indications and techniques raised by CM1-Syr, an increasing number of well-informed but disoriented patients is emerging. To bridge this gap, an International Consensus Conference on CM1-Syr held in Milan in November 2019 aimed to find a consensus among international experts, to suggest some recommendations that, in the near future, could lead to guidelines. Here, we comment on the most relevant recommendations about the definition, diagnosis, surgical management, failures and re-intervention, and outcome. We also focus on some "wrong" indications or techniques that, although widely disapproved by the experts, and negatively experienced by many patients, are still largely in use.

Evaluation of Adult and Pediatric Chiari Type 1 Malformation Patients: Do Consensus Documents Fit Everyday Practice?

The management of Chiari 1 malformation (CM1) and Syringomyelia (Syr) has shown many changes in surgical indications and techniques over time. The dedicated neurosurgical and neurological community recently planned to analyze the state of the art and find conduct uniformity. This led to international consensus documents on diagnostic criteria and therapeutic strategies. We aimed to evaluate, in a large, monocentric surgical series of adult and children CM1 patients, if the daily clinical practice reflects the consensus documents. Our series comprises 190 pediatric and 220 adult Chiari patients submitted to surgery from 2000 to 2021. The main indications for the treatment were the presence of Syr and symptoms related to CM1. While there is great correspondence with the statements derived from the consensus documents about what to do for Syr and symptomatic CM1, the accordance is less evident in CM1 associated with craniosynostosis or hydrocephalus, especially when considering the early part of the series. However, we think that performing such studies could increase the homogeneity of surgical series, find a common way to evaluate long-term outcomes, and reinforce the comparability of different strategies adopted in different referral centers.

Surgical Management of Chiari Malformation Type I in the Pediatric Population: A Single-Center Experience.

Background: Chiari malformation type 1 (CM-1) involves the cerebellar tonsils' descent below the foramen magnum. In Chiari malformation type 1.5 (CM-1.5), both the cerebellar tonsils and the brainstem are herniated. Common symptoms include headaches and cervical pain, often associated with conditions like syringomyelia and hydrocephalus. Surgical treatment is not performed in asymptomatic patients, while the presence of syringomyelia represents an indication for surgery. Methods: This study retrospectively examined pediatric patients with CM-1 and CM-1.5 at Giannina Gaslini Hospital from 2006 to 2020, analyzing demographics, radiological findings, surgical interventions, and outcomes. Results: Out of 211 patients who underwent surgery, 83.9% were diagnosed with CM-1 and 16.1% with CM-1.5. Headaches were prevalent (69%) and cerebellar signs were noted in 29% of patients. Syringomyelia and hydrocephalus were present in 28.4% and 8% of cases, respectively. Intraoperative ultrasonography guided interventions, with 59.8% requiring bony and ligamentous decompression, and 27.1% undergoing duraplasty. Conclusions: The surgical treatment of CM-1/CM-1.5 involves posterior cranial fossa decompression. Choosing between bony decompression alone and its combination with duraplasty has always been controversial in the pediatric population. If we consider as surgical endpoint the restoration of cerebrospinal fluid (CSF) flux, intraoperative ultrasound may be a real-time helpful tool in orienting the surgical strategy, yet refinement with quantitative measures is needed.

Neuroendoscopy-Assisted Minimal Invasive Management of Chiari 1 Malformation.

Objective The aim this study is to present the results of the minimal invasive neuroendoscopic-assisted system application as an alternative to traditional surgery in patients with Chiari malformation type 1 (CM type 1) with/without syringomyelia. Design, Setting, and Participants In the study, data of 22 symptomatic patients were prospectively collected. Before and after the operation, patient characteristics, computed tomography, magnetic resonance imaging (MRI), cerebrospinal fluid (CSF) flow dynamics MRI, and outcome scales scores were recorded. Foramen magnum decompression and C1 total laminectomy were performed. The fibrous band at the craniocervical junction was opened and a durotomy was performed. In patients with a syrinx, the pre- and postoperative axial and sagittal lengths of the syrinx were measured and compared. Results The mean age of the patients was 32 ± 5 years. There were eight male patients. Ten patients had syrinx. The mean visual analog scale (VAS) score before and after surgery was 8 ± 1.06 and 2.18 ± 1.13, respectively. When evaluated according to the Chicago Chiari Outcome Scale, there was improvement in 20 patients, while there was no change in 2 patients. Syrinx resolved completely in 3 of 10 (13.6%) patients with syringomyelia, and the syrinx volume decreased in 3 patients (13.6%). In 4 of 10 (18.1%) patients, there was no significant change in the syrinx volume. The average operation time was 105 minutes (80-150 minutes). The average blood loss was 40 mL (20-110 mL). Conclusion Although the study was limited due to the small number of patients with a short follow-up, endoscopic decompression was a safe and effective technique for surgery in CM type 1 patients.

Surgical Management of Chiari 1.5 in Children: A Truly Different Disease?

Background: In patients with Chiari 1.5 malformation (CM1.5), a more aggressive disease course and an increased association with craniovertebral junction (CVJ) anomalies has been suggested. The best management of this subgroup of patients is not clearly defined, also due to the lack of specific series elucidating this anomaly's peculiar characteristics. Methods: We evaluated a series of 33 patients (25 females, 8 males; mean age at surgery: 13 years) fulfilling the criteria for Chiari 1.5 diagnosis who underwent posterior fossa decompression and duraplasty (PFDD) between 2006 and 2021. Results: Headache was present in all children, five presented central apnea, five had dysphagia, and three had rhinolalia. Syringomyelia was present in 19 (58%) children. Twenty patients (61%) showed various CVJ anomalies, but only one child presented instability requiring arthrodesis. The mean tonsil displacement below the foramen magnum was 19.9 mm (range: 12-30), without significant correlation with the severity of symptoms. Syringomyelia recurred or was unchanged in three patients, and one needed C1-C2 fixation. The headache disappeared in 28 children (84%). Arachnoid opening and tonsil coagulation or resection was necessary for 19 children (58%). Conclusions: In our pediatric CM series, the need for tonsil resection or coagulation was higher in CM1.5 children due to a more severe crowding.

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

OBJECTIVE: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: Using a large-scale nationwide dataset, machine learning models for the prediction of both 30-day readmissions and reoperations were developed and achieved high accuracy. This highlights the utility of machine learning in risk stratification and surgical decision-making for pediatric CM-I.

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

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

Predictors of poor functional outcomes in adults with type I Chiari Malformation: Clinical and surgical factors assessed with the Chicago Chiari Outcome Scale over long-term follow-up.

OBJECTIVE: This study aimed to identify clinical and surgical features associated with poor long-term postoperative outcomes in patients diagnosed with Type I Chiari Malformation (CMI) treated with posterior fossa decompression with duroplasty (PFDD), with or without tonsillar coagulation. METHODS: This retrospective, single-center study included 107 adult patients with CMI surgically treated between 2010 and 2021. The surgical technique involved a midline suboccipital craniectomy, C1 laminectomy, durotomy, arachnoid dissection, duroplasty, and tonsillar coagulation until 2014, after which tonsillar coagulation was discontinued. Postoperative outcomes were assessed using the Chicago Chiari Outcome Scale (CCOS) at a median follow-up of 35 months. Clinical, surgical, and neuroimaging data were analyzed using the Wilcoxon signed-rank test, Cox regression analysis, and Kaplan-Meier survival curves to identify predictors of poor functional outcomes. RESULTS: Of the 107 patients (mean age 43.9 years, SD 13), 81 (75.5 %) showed functional improvement, 25 (23.4 %) remained unchanged, and 1 (0.9 %) experienced worsened outcomes. Cephalalgia, bilateral motor weakness, and bilateral paresthesia were the most frequent initial symptoms. Tonsillar coagulation was performed in 31 cases (28.9 %) but was clinically associated with higher rates of unfavorable outcomes. The Wilcoxon signed-rank test indicated that long-term follow-up CCOS was significantly higher than postoperative CCOS (Z = -7.678, p < 0.000). Multivariate Cox analysis identified preoperative bilateral motor weakness (HR 6.1, 95 % CI 1.9-18.9; p = 0.002), hydrocephalus (HR 3.01, 95 % CI 1.3-6.9; p = 0.008), and unilateral motor weakness (HR 2.99, 95 % CI 1.1-8.2; p = 0.033) as significant predictors of poor outcomes on a long-term follow-up. CONCLUSION: This study highlights the high rate of functional improvement in CMI patients following PFDD. Preoperative motor weakness and hydrocephalus were significant predictors of poor long-term outcomes. Tonsillar coagulation did not demonstrate a clear clinical benefit and may be associated with worse outcomes. Our findings suggest that careful preoperative assessment and selection of surgical techniques are crucial for optimizing patient outcomes.

Individualized Functional Decompression Options for Adult Chiari Malformation With Syringomyelia and A Novel Scale for Syringomyelia Resolution: A Single-Center Experience.

OBJECTIVE: To compare outcomes of posterior fossa bony decompression alone (PFD) versus PFD with duraplasty (PFDD) versus PFDD with additional obex exploration (PFDDO) in patients with Chiari malformation type I (CMI) combining syringomyelia. METHODS: Clinical records of adult patients who underwent decompressions from 2014 to 2022 were retrospectively analyzed. The decompression procedure was individualized based on the cerebrospinal fluid pulse in the surgical field. The Chicago Chiari Outcome Scale (CCOS) was used to assess the prognosis of the patients and a novel syringomyelia resolution scale, based on 3-dimensional volume, was introduced. The percentage change in the cervical syrinx volume was classified as follows by resolution: ≥ 70%, 30%-70%, and < 30%. RESULTS: Seventy-eight individuals were enrolled, of which 22, 20, and 36 underwent PFD, PFDD, and PFDDO, respectively. The three decompression groups had no significant difference in the preoperative characteristics and postoperative prognosis. Multivariate analyses revealed that better CCOS was significantly correlated with younger age at surgery (p = 0.018), syrinx originated from lower cervical levels (p = 0.037), narrower preoperative cerebral aqueduct (p = 0.005), and better syrinx volume resolution (p = 0.004). Additionally, a better cervical syrinx volume resolution was significantly correlated with higher CCOS (p = 0.017), narrower cerebral aqueduct (p = 0.035), and better tonsillar descent resolution (p = 0.007). CONCLUSION: Individualized functional decompression induced an equal effect on CCOS and syrinx volume resolution for all CMI patients with syringomyelia. Our syringomyelia resolution scale facilitates communication and prediction of CMI prognosis.

Descompresión de fosa posterior sin duroplastia expansiva en adulto con malformación de Chiari tipo 1-siringomielia

Introducción: La malformación de Chiari tipo 1 incluye un grupo heterogéneo de malformaciones congénitas, caracterizadas por el descenso caudal del cerebelo a través del foramen magno. En un 30-70 % de los casos tiene siringomielia asociada. Existen controversias en torno a la técnica quirúrgica ideal. Objetivo: Presentar un caso de MC-1 asociada a siringomielia en el que no se aplica una duroplastia expansiva. Presentación de caso: Paciente femenina de 43 años, con antecedentes de hipertensión arterial. Acudió a consulta neuroquirúrgica por dolor cervical irradiado al miembro superior derecho. Al examen neurológico mostró signos de afectación de primera y segunda motoneurona. La resonancia magnética confirmó el diagnóstico de MC-1. Se intervino quirúrgicamente mediante descompresión de fosa posterior sin duroplastia expansiva. La paciente evolucionó sin complicaciones y egresó a las 48 horas. Durante el seguimiento mejoraron las manifestaciones parestésicas; sin embargo, el examen neurológico se mantuvo igual. A los seis meses, la resonancia magnética indicó una marcada disminución de la siringomielia y la reconformación de la cisterna magna. Hasta los 18 meses del tratamiento, los síntomas no habían empeorado y la capacidad funcional resultaba aceptable (Karnofsky 90/100). Conclusiones: La descompresión de fosa posterior sin duroplastia expansiva, seguida de re-permeabilización microquirúrgica del foramen de Magendie, tuvo resultados favorables en este caso.

Introduction: Chiari malformation type 1 includes a heterogeneous group of congenital malformations, characterized by caudal descent of the cerebellum through the foramen magnum. It has associated syringomyelia in 30-70% of cases. Controversies exist regarding the ideal surgical technique. Objective: To present a case of MC-1 associated with syringomyelia in which an expansive duroplasty is not applied. Case report: Female patient, 43 years old, with history of arterial hypertension. She went to the neurosurgical consultation for cervical pain radiating to the right upper limb. On neurological examination, she showed signs of first and second motor neuron involvement. MRI confirmed the diagnosis of MC-1. She underwent surgery by decompression of the posterior fossa without expansive duroplasty. The patient evolved without complications and she was discharged after 48 hours. During the follow-up, the paresthetic manifestations improved; however, the neurological examination remained the same. At six months, MRI indicated a marked decrease in syringomyelia and reshaping of the cisterna magna. Until 18 months after treatment, symptoms had not worsened and functional capacity was acceptable (Karnofsky 90/100). Conclusions: Posterior fossa decompression without expansive duroplasty, followed by microsurgical re-permeabilization of Magendie's foramen, had favorable results in our case.

Impacted cisterna magna without syringomyelia associated with lancinating headache, throbbed nuchal pain and paraparesis treated byposterior fossa decompression

A 29-year-old woman with acute lancinating headache, throbbed nuchal pain and subacute paraparesis underwent brain MRI in supine position that depicted: the absence of the cisterna magna, filled by non herniated cerebellar tonsils and compression of the brain stem and cisternae of the posterior fossa, which are aspects of the impacted cisterna magna without syringomyelia and without hydrocephalus. During eight days, pain was constant and resistant to drug treatment. Osteodural-neural decompression of the posterior fossa, performed with the patient in sitting position, revealed: compression of the brainstem, fourth ventricle and foramen of Magendie by herniated cerebellar tonsils, which were aspirated. Immediately after surgery, the headache and nuchal pain remmited. MRI depicted the large created cisterna magna and also that the cerebellar tonsils did not compress the fourth ventricle, the foramen of Magendie and the brainstem, besides the enlargement of posterior fossa cisternae. Four months after surgery, headache, nuchal pain and paraparesis had disappeared but hyperactive patellar and Achilles reflexes remained.

Uma paciente de 29 anos de idade com quadro agudo de cefaléia lancinante, dor terebrante na nuca e paraparesia subaguda foi submetida a RM do encéfalo, em posição supina, que revelou: ausência da cisterna magna, preenchida por tonsilas cerebelares não herniadas e compressão do tronco encefálico e das cisternas da fossa posterior, compatíveis com o diagnóstico de cisterna magna impactada sem siringomielia e sem hidrocefalia. Por oito dias a dor foi constante e resistente aos analgésicos. Com a paciente em posição sentada, foi realizada descompressão osteodural-neural da fossa posterior associada a aspiração das tonsilas cerebelares. Os achados perioperatórios foram caracterizados por herniação das tonsilas cerebelares que comprimiam o tronco cerebral, o quarto ventrículo e o forame de Magendie. No pós-operatório imediato houve remissão da cefaléia e da dor na nuca. A RM evidenciou a cisterna magna recém-criada, alargamento do quarto ventrículo e das cisternas do tronco encefálico. Quatro meses depois, a paciente continuava sem cefaléia, sem dor na nuca e sem paraparesia. Entretanto, permaneceu a hiperatividade dos reflexos patelares e aquileus.