Over the past decade, neuropathological diagnosis has undergone significant changes, integrating morphological features with molecular biomarkers. The molecular era has successfully refined neuropathological diagnostic accuracy; however, a substantial number of CNS tumor diagnoses remain challenging, particularly in children. DNA methylation classification has emerged as a powerful machine learning approach for clinical decision-making in CNS tumors. The aim of this study is to share our experience using DNA methylation classification in daily routine practice, illustrated through clinical cases. We employed a classification system to evaluate discrepancies between histo-molecular and DNA methylation diagnoses, with a specific focus on adult versus pediatric CNS tumors. In our study, we observed that 40% of cases fell into Class I, 47% into Class II, and 13% into Class III among the "matched cases" (>= 0.84). In other words, DNA methylation classification confirmed morphological diagnoses in 63% of adult and 23% of pediatric cases. Refinement of diagnosis was particularly evident in the pediatric population (65% vs. 21% for the adult population, p = 0.006). Additionally, we discussed cases classified with low calibrated scores. In conclusion, our study confirms that DNA methylation classification provides significant added-value for CNS tumors diagnosis, particularly in pediatric cases.

Background and Objectives: Central Nervous System (CNS) pediatric tumors represent the most common solid tumors in children with a wide variability in terms of survival and therapeutic response. By contrast to their adult counterpart, the mutational landscape of pediatric CNS tumors is characterized by oncogenic fusions rather than multiple mutated genes. CNS pediatric tumors associated with oncogenic fusions represent a complex landscape of tumors with wide radiological, morphological and clinical heterogeneity. In the fifth CNS WHO classification, there are few pediatric CNS tumors for which diagnosis is based on a single oncogenic fusion. This work aims to provide an overview of the impact of rare oncogenic fusions (NTRK, ROS, ALK, MET, FGFR, RAF, MN1, BCOR and CIC genes) on pathogenesis, histological phenotype, diagnostics and theranostics in pediatric CNS tumors. We report four cases of pediatric CNS tumors associated with NTRK (n = 2), ROS (n = 1) and FGFR3 (n = 1) oncogenic fusion genes as a proof of concept. Cases presentation and literature review: The literature review and the cohort that we described here underline that most of these rare oncogenic fusions are not specific to a single morpho-molecular entity. Even within tumors harboring the same oncogenic fusions, a wide range of morphological, molecular and epigenetic entities can be observed. Conclusions: These findings highlight the need for caution when applying the fifth CNS WHO classification, as the vast majority of these fusions are not yet incorporated in the diagnosis, including grade evaluation and DNA methylation classification.

IntroductionCraniopharyngiomas (CPs) are benign brain tumors accounting for 5 - 11% of intracranial tumors in children. These tumors often recur and can cause severe morbidity. Postoperative radiotherapy efficiently controls and prevents progression and recurrence. Despite advancements in neurosurgery, endocrinological, visual, and neuropsychological complications are common and significantly lower the quality of life of patients.MethodsWe performed a retrospective study, including all patients younger than sixteen diagnosed with CP between July 1989 and August 2022 and followed up in Hôpital Universitaire de Bruxelles.ResultsNineteen children with CP were included, with median age of 7 years at first symptoms and 7.5 at diagnosis. Common symptoms at diagnosis were increased intracranial pressure (63%), visual impairment (47%), growth failure (26%), polyuria/polydipsia (16%), and weight gain (10.5%). As clinical signs at diagnosis, growth failure was observed in 11/18 patients, starting with a median lag of 1 year and 4 months before diagnosis. On ophthalmological examination, 27% of patients had papillary edema and 79% had visual impairment. When visual disturbances were found, the average preoperative volume was higher (p=0.039). Only 6/19 patients had gross total surgical resection. After the first neurosurgery, 83% experienced tumor recurrence or progression at a median time of 22 months. Eleven patients (73%) underwent postsurgical radiotherapy. At diagnosis, growth hormone deficiency (GHD) was the most frequent endocrine deficit (8/17) and one year post surgery, AVP deficiency was the most frequent deficit (14/17). Obesity was present in 13% of patients at diagnosis, and in 40% six months after surgery. There was no significant change in body mass index over time (p=0.273) after the first six months post-surgery.ConclusionCP is a challenging brain tumor that requires multimodal therapy and lifelong multidisciplinary follow-up including hormonal substitution therapy. Early recognition of symptoms is crucial for prompt surgical management. The management of long-term sequelae and morbidity are crucial parts of the clinical path of the patients. The results of this study highlight the fundamental importance of carrying out a complete assessment (ophthalmological, endocrinological, neurocognitive) at the time of diagnosis and during follow-up so that patients can benefit from the best possible care.

Importance A potential relationship between meningioma and breast cancer was suggested 70 years ago. However, to date, no conclusive evidence is available on this topic. Objective To provide a comprehensive review of the literature on the association of meningioma with breast cancer, supported by a meta-analysis. Data Sources A systematic PubMed search was performed up to April 2023 to identify articles on the association of meningioma with breast cancer. The following key words were used strategically: meningioma , breast cancer , breast carcinoma , association , relation . Study Selection All studies reporting women diagnosed with meningioma and breast cancer were identified. The search strategy was not limited by study design or publication date but only included articles in English. Additional articles were identified via citation searching. Studies reporting a complete population of meningiomas or breast cancer patients throughout a specific study period and a proportion of patients with a second pathology could be used for the meta-analysis. Data Extraction and Synthesis Data extraction was performed by 2 authors in accordance with the Preferred Reporting Items for Systematic Reviews (PRISMA) statement. Meta-analyses regarding both populations were performed using a random-effects model. Risk of bias was assessed. Main Outcomes and Measures The main measures were whether there was an increased prevalence of breast cancer in female patients with meningioma and whether there was an increased prevalence of meningioma in female patients with breast cancer. Results A total of 51 retrospective studies (case reports, case series, and cancer registry reports) describing 2238 patients with both diseases were identified; 18 studies qualified for prevalence analyses and meta-analysis. The random-effects meta-analysis (13 studies) revealed a significantly greater prevalence of breast cancer in female patients with meningioma than in the overall population (odds ratio [OR], 9.87; 95% CI, 7.31-13.32). Meningioma incidence in patients with breast cancer (11 studies) was greater than that in the baseline population; however, the difference according to the random-effects model was not statistically significant (OR, 1.41; 95% CI, 0.99-2.02). Conclusions and Relevance This large systematic review and the meta-analysis on the association between meningioma and breast cancer found nearly 10-fold higher odds of breast cancer in female patients with meningioma compared with the general female population. These findings suggest that female patients with meningioma should be screened more intensively for breast cancer. Further research is required to identify the factors causing this association.

Purpose To determine the possible relation between cervical sagittal balance and neck pain in patients having anterior cervical spine (ACS) surgery. Materials and methods Retrospective monocentric study on 85 patients who underwent ACS surgery between 2014 and 2016. Clinically, all patients were assessed using the Neck Disability Index (NDI). Radiological assessment was achieved by MRI or CT-scan of the cervical spine allowing measurement of radiological parameters for preoperative cervical sagittal balance. These same criteria were measured postoperatively using X-rays. Results There is a statistically significant increase in the Cobb angle postoperatively (10.34 degrees) compared to preoperatively (6.68 degrees) (p < 0.05). Concomitantly, there is a statistically significant decrease in NDI postoperatively (22.69%) compared to preoperatively (42.31%) (p < 0.01). There is a negative correlation between Cobb angle and NDI (r= -0.31) (p < 0.05). Conclusion An improvement in the cervical sagittal balance after ACS surgery is accompanied by a reduction of neck pain. Radiological parameters of cervical sagittal balance may be taken into account when planning surgery in order to maintain cervical alignment and thereby limit the occurrence of neck pain.

Central Nervous System (CNS) embryonal tumors represent a heterogeneous group of highly aggressive tumors occurring preferentially in children but also described in adolescents and adults. In 2021, the CNS World Health Organization (WHO) classification drastically changed the diagnosis of the other CNS embryonal tumors including new histo-molecular tumor types. Here, we report a pediatric case of a novel tumor type among the other CNS embryonal tumors classified within the methylation class "CNS Embryonal Tumor with BRD4-LEUTX Fusion". The patient was a 4-year girl with no previous history of disease. For a few weeks, she suffered from headaches, vomiting and mild fever associated with increasing asthenia and loss of weight leading to a global deterioration of health. MRI brain examination revealed a large, grossly well-circumscribed tumoral mass lesion located in the left parietal lobe, contralateral hydrocephalus and midline shift. Microscopic examination showed a highly cellular tumor with a polymorphic aspect. The majority of the tumor harbored neuroectodermal features composed of small cells with scant cytoplasm and hyperchromatic nuclei associated with small "medulloblastoma-like" cells characterized by syncytial arrangement and focally a streaming pattern. Tumor cells were diffusely positive for Synaptophysin, CD56, INI1 and SMARCA4 associated with negativity for GFAP, OLIG-2, EMA, BCOR, LIN28A and MIC-2. Additional IHC features included p53 protein expression in more than 10% of the tumor's cells and very interestingly, loss of H3K27me3 expression. The Heidelberg DNA-methylation classifier classified this case as "CNS Embryonal Tumor with BRD4:LEUTX Fusion". RNA-sequencing analyses confirmed the BRD4 (exon 13)-LEUTX (exon 2) fusion with no other molecular alterations found by DNA sequencing. Our case report confirmed that a new subgroup of CNS embryonal tumor with high aggressive potential, loss of H3K27me3 protein expression, BRDA4-LEUTX fusion, named "Embryonal CNS tumor with BRD4-LEUTX fusion", has to be considered into the new CNS WHO classification.

Introduction: The incidence of intramedullary spinal cord tumors ranges from 2 to 4% of all central nervous system tumors. Only 6-8% are astrocytomas. The gold standard to diagnose a spinal cord tumor is the spinal cord MRI in toto. Specific radiological criteria orient the diagnosis of the intradural intramedullary lesion. Most of the authors studied adult populations of astrocytomas. However, pediatric astrocytomas present certain particularities.Research question: This work aims to determine if the usual radiological criteria of intramedullary astrocytomas (IMAs) are different depending on the patient's age. Material & methods: We evaluated the radiological features of IMAs in adult and pediatric groups through a retrospective study.Results: We collected 31 patients with IMAs (11 children and 20 adults). We observed some trends but we did not highlight any statistically significant difference between all the radiological criteria studied (sagittal and axial spinal cord localization, T1-and T2-weighted characteristics, contrast uptake, infiltrating character, presence of necrosis, heterogeneous lesion, necrotic, hemorrhagic, presence of edema) and the patient's age.Discussion & conclusion: Given the rarity of IMAs and the lack of large specific pediatric studies, it seems essential to routinely report all cases encountered and create multicentric pediatric databases to draw more robust conclusions.

Introduction: Cervical disc arthroplasty (CDA) is mainly used in young patients with soft herniated discs and seems to have several advantages over anterior cervical discectomy and fusion (ACDF). Severe spondylosis is common and represents a contraindication for performing CDA. Research question: Is it possible to expand the indications for the implantation of cervical prostheses by adapting the surgical technique, particularly for severe spondylosis, to benefit from the advantages of prostheses over ACDF ? Materials and methods: We propose a prospective two-center study to compare the possible clinical benefit of the placement of a cervical prosthesis with systematic total bilateral uncuscectomy (or uncinectomy) compared to the classical technique of ACDF, particularly for severe spondylosis. Visual analog scales for brachialgia, cervicalgia, and neck disability index were measured before and one year after surgery. Odom's criteria were assessed one year after surgery. Results: We compared 81 patients treated with CDA and systematic total bilateral uncuscectomy versus 42 patients treated with ACDF for symptomatic radicular or medullary compression. Patients treated with CDA and uncuscectomy showed greater improvements in VASb, VASc, NDI, and Odom's criteria than those treated with ACDF, with statistically significant results. Moreover, no difference was found between the severe spondylosis subgroup and the non-severe spondylosis subgroup treated with CDA and uncuscectomy. Discussion and conclusion: This study assessed the value of systematic total bilateral uncuscectomy for cervical arthroplasty. Our prospective clinical results suggest a surgical technique to reduce cervical pain and improve function one year after surgery, even in cases of severe spondylosis.

ImportanceA potential relationship between meningioma and breast cancer was suggested 70 years ago. However, to date, no conclusive evidence is available on this topic. ObjectiveTo provide a comprehensive review of the literature on the association of meningioma with breast cancer, supported by a meta-analysis. Data SourcesA systematic PubMed search was performed up to April 2023 to identify articles on the association of meningioma with breast cancer. The following key words were used strategically: meningioma, breast cancer, breast carcinoma, association, relation. Study SelectionAll studies reporting women diagnosed with meningioma and breast cancer were identified. The search strategy was not limited by study design or publication date but only included articles in English. Additional articles were identified via citation searching. Studies reporting a complete population of meningiomas or breast cancer patients throughout a specific study period and a proportion of patients with a second pathology could be used for the meta-analysis. Data Extraction and SynthesisData extraction was performed by 2 authors in accordance with the Preferred Reporting Items for Systematic Reviews (PRISMA) statement. Meta-analyses regarding both populations were performed using a random-effects model. Risk of bias was assessed. Main Outcomes and MeasuresThe main measures were whether there was an increased prevalence of breast cancer in female patients with meningioma and whether there was an increased prevalence of meningioma in female patients with breast cancer. ResultsA total of 51 retrospective studies (case reports, case series, and cancer registry reports) describing 2238 patients with both diseases were identified; 18 studies qualified for prevalence analyses and meta-analysis. The random-effects meta-analysis (13 studies) revealed a significantly greater prevalence of breast cancer in female patients with meningioma than in the overall population (odds ratio [OR], 9.87; 95% CI, 7.31-13.32). Meningioma incidence in patients with breast cancer (11 studies) was greater than that in the baseline population; however, the difference according to the random-effects model was not statistically significant (OR, 1.41; 95% CI, 0.99-2.02). Conclusions and RelevanceThis large systematic review and the meta-analysis on the association between meningioma and breast cancer found nearly 10-fold higher odds of breast cancer in female patients with meningioma compared with the general female population. These findings suggest that female patients with meningioma should be screened more intensively for breast cancer. Further research is required to identify the factors causing this association.

Bevacizumab’s use in recurrent high-grade glioma is controversial. This study evaluates outcomes in recurrent high-grade glioma patients receiving bevacizumab alone or combined with chemotherapy as a late-line treatment. We retrospectively analyzed patients treated with bevacizumab alone or combined with chemotherapy for high-grade gliomas who showed tumor progression after multiple treatment attempts. Overall survival (OS) and progression-free survival (PFS) were analyzed with Kaplan–Meier curves. Predictors of PFS according to prognostic variables were assessed with regression analysis. Between 2010 and 2022, 31 consecutive patients received bevacizumab alone or combined with chemotherapy as a late-line treatment for recurrent high-grade gliomas. Of these patients, 14 (45.2

Introduction: Severe spondylosis is common and represents contraindication to achieve cervical disc arthroplasty (CDA). Research question: Is it possible to restore cervical sagittal alignment using an adequate prosthetic model and performing systematic bilateral total uncuscectomy (or uncinectomy), even in cases of severe spondylosis ? Material and methods: We propose a prospective clinical and radiological study comparing the evolution of preoperative and postoperative cervical sagittal balance 1 year after the interposition of a prosthesis with mobile bearing and systematic total uncuscectomy. VAS for brachialgia and cervicalgia, NDI, Odom's criteria, C2-C7 Cobb angle, C2-C7 SVA, T1 slope, C2 slope, C1-C2 Cobb angle, and segmental Cobb angle were analyzed preoperatively and 1 year postoperatively. Results: 73 patients for a total of 129 levels treated were analyzed. Patients showed significant improvements in VASb, VASc, NDI, and Odom's criteria one year after surgery without clinical differences in the severe spondylosis subgroup (41 patients for 77 levels treated). Our results showed an increase in the C2-C7 Cobb angle postoperatively and a better correlation between T1 slope and C2-C7 Cobb angle postoperatively than preoperatively. Postoperative radiological results were similar between the spondylosis and non-spondylosis subgroups. However preoperative C2-C7 Cobb angle and preoperative ROM were lower in the severe spondylosis subgroup. Discussion and conclusion: This study showed the possibility of restoring cervical sagittal balance by performing cervical disc arthroplasty with systematic uncuscectomy, even in cases of severe spondylosis. Moreover, we propose a simplified mathematical formula to preoperatively evaluate the lack of angulation to restore sagittal cervical alignment.

Introduction COVID-19-infected patients harbour neurological symptoms such as stroke and anosmia, leading to the hypothesis that there is direct invasion of the central nervous system (CNS) by SARS-CoV-2. Several studies have reported the neuropathological examination of brain samples from patients who died from COVID-19. However, there is still sparse evidence of virus replication in the human brain, suggesting that neurologic symptoms could be related to mechanisms other than CNS infection by the virus. Our objective was to provide an extensive review of the literature on the neuropathological findings of postmortem brain samples from patients who died from COVID-19 and to report our own experience with 18 postmortem brain samples. Material and methods We used microscopic examination, immunohistochemistry (using two different antibodies) and PCR-based techniques to describe the neuropathological findings and the presence of SARS-CoV-2 virus in postmortem brain samples. For comparison, similar techniques (IHC and PCR) were applied to the lung tissue samples for each patient from our cohort. The systematic literature review was conducted from the beginning of the pandemic in 2019 until June 1st, 2022. Results In our cohort, the most common neuropathological findings were perivascular haemosiderin-laden macrophages and hypoxic-ischaemic changes in neurons, which were found in all cases (n = 18). Only one brain tissue sample harboured SARS-CoV-2 viral spike and nucleocapsid protein expression, while all brain cases harboured SARS-CoV-2 RNA positivity by PCR. A colocalization immunohistochemistry study revealed that SARS-CoV-2 antigens could be located in brain perivascular macrophages. The literature review highlighted that the most frequent neuropathological findings were ischaemic and haemorrhagic lesions, including hypoxic/ischaemic alterations. However, few studies have confirmed the presence of SARS-CoV-2 antigens in brain tissue samples. Conclusion This study highlighted the lack of specific neuropathological alterations in COVID-19-infected patients. There is still no evidence of neurotropism for SARS-CoV-2 in our cohort or in the literature.

Posterior pituitary tumors (PPT) expressing thyroid transcription factor-1 (TTF-1) are extremely rare low-grade neoplasms. The recent discovery of BRAF mutations in these tumors offers a potential alternative treatment using targeted therapies. We present the case of a 57-year-old female with recurrent BRAFV600E-mutated TTF-1-positive PPT treated with a BRAF inhibitor monotherapy (dabrafenib) leading to tumor regression. After 18 months of uninterrupted treatment, ongoing radiological tumor regression was observed and the patient remained asymptomatic without any significant adverse event. BRAF inhibitor is potentially a valuable treatment option for recurrent TTF-1-positive PPT with BRAF mutation.

BACKGROUND:The mainstay of treatment for symptomatic or large chronic subdural hematoma (CSDH) is surgery, but controversy still exists regarding the best surgical technique. Three different techniques are commonly used: burr hole craniostomy (BHC), minicraniotomy (MC), and twist drill craniostomy (TDC).OBJECTIVE:To determine which surgical technique for drainage of CSDH offers best results.METHODS:We set up a multicenter prospective randomized trial (Comparison of Chronic Subdural Hematoma Treatment [COMPACT] trial) comparing BHC, MC, and TDC for the surgical treatment of CSDH. The primary end point was reoperation rate, and secondary end points included complication rates and clinical outcome. Patients were considered to have good outcome when they did not undergo reoperation, suffered no surgical or medical complication, and had no related mortality. Clinical outcome was also evaluated by evolution of the Markwalder score and the modified Rankin score.RESULTS:Two-hundred forty-five patients were included in the final analysis: 79 BHC, 84 MC, and 82 TDC. Mean duration of surgery was shorter for TDC than for BHC and MC ( P < .001). Reoperation rate was 7.6% for BHC, 13.1% for MC, and 19.5% for TDC ( P = .07). This trend toward better results for BHC was not statistically significant in logistic regression analysis. The proportion of patients with good outcome was 78.5% for BHC group, 76.2% for MC, and 69.5% for TDC ( P = .4). Evolution of the Markwalder score and modified Rankin score were not significantly different between treatment groups.CONCLUSION:All 3 techniques are effective at treating patients with CSDH with eventual 6-month outcome being similar. Although not reaching statistical significance in our study, BHC offers the lowest recurrence rate combined with manageable complication rate.

Various surgical methods to prevent postoperative cerebrospinal fluid (CSF) leaks during transsphenoidal surgery have been reported. However, comparative studies are scarce. We aimed to compare the efficacy of a fibrin-coated collagen fleece (TachoSil) versus a dural sealant (DuraSeal) to prevent postoperative CSF leakage. We perform a retrospective study comparing two methods of sellar closure during endoscopic endonasal transsphenoidal surgery (EETS) for pituitary adenoma resection: TachoSil patching versus DuraSeal packing. Data concerning diagnosis, reconstruction technique, and surgical outcomes were analyzed. The primary endpoint was postoperative CSF leak rate. We reviewed 198 consecutive patients who underwent 219 EETS for pituitary adenoma from February 2007 and July 2018. Intraoperative CSF leak occurred in 47 cases (21.5%). A total of 33 postoperative CSF leaks were observed (15.1%). A reduction of postoperative CSF leaks in the TachoSil application group compared to the conventional technique using Duraseal was observed (7.7% and 18.2%, respectively; p = 0.062; Pearson exact test) although non-statistically significant. Two patients required lumbar drainage, and no revision repair was necessary to treat postoperative CSF rhinorrhea in Tachosil group. Fibrin-coated collagen fleece patching may be a valuable method to prevent postoperative cerebrospinal fluid (CSF) leaks during EETS for pituitary adenoma resection.

Introduction: We report a case of a Kernohan notch phenomenon caused by an acute life-threatening intracranial subdural hematoma due to a cerebrospinal fluid (CSF) leak following lumbar surgery.Case report: A 71-year-old patient underwent decompressive lumbar surgery for refractory neurogenic claudication. Intraoperatively, a dural tear was noted and repaired. Two days later, the patient presented a sudden loss of consciousness following a CSF outflow in the subfascial lumbar drain. A head CT revealed an acute intracranial subdural hematoma with mass effect. A craniotomy was performed to evacuate the hematoma. The lumbar operative site was inspected and revealed a CSF leakage due to a dural defect which was subsequently repaired. The patient subsequently developed a Kernohan's notch phenomenon which partially recovered after two months of rehabilitation.Conclusion: We report a rare and dramatic case of Kernohan notch phenomenon due to an acute intracranial subdural hematoma occurring in the setting of a CSF leak following lumbar spine surgery. This case demonstrates the need to be aware of this potentially fatal complication after spine surgery and the importance of early diagnosis and appropriate treatment.

Primary angiitis of the central nervous system (PACNS) is a rare inflammatory disease affecting central nervous system vessels. The diagnosis, which requires confirmation by brain biopsy, remains challenging due to unspecific clinical presentation and low specificity of imaging and laboratory exams. In these two pediatric biopsy-proven cases of svPACNS we demonstrate that brain positron emission tomography (PET) show a high metabolic activity that extends beyond brain MRI abnormalities. Therefore, combining MRI and PET abnormalities to adequately guide brain biopsy might increase the diagnostic yield of this rare condition.

Purpose Embolization of arteriovenous malformations (AVMs) before radiosurgery has been reported to negatively impact the obliteration rate. This study aims to assess treatment outcomes in a series of 190 patients treated by Gamma Knife radiosurgery (GKRS) for previously embolized AVMs. Methods The institutional database of AVMs was retrospectively reviewed between January 2004 and March 2018. The clinical and radiological data of patients treated with GKRS for previously embolized AVMs were analyzed. Predicting factors of obliteration and hemorrhage following GKRS were assessed with univariate and multivariate regression analyses. Results The mean AVM size was significantly reduced after embolization (p < 0.001). The obliteration rate was 78.4%. Multivariate analyses showed that a lower Spetzler-Martin grade (p = 0.035) and a higher marginal dose (p = 0.007) were associated with obliteration. Post-GKRS hemorrhages occurred in 14 patients (7.4%). A longer time between diagnosis and GKRS was the only factor associated with post-GKRS hemorrhages in multivariate analysis (p = 0.022). Complications related to the combined treatment were responsible for a new permanent neurological disability in 20 patients (10.5%), and a case of death (0.5%). Conclusions This study shows that the embolization of AVMs does not have a negative impact on the obliteration rate after radiosurgery. Embolization reduces the AVM size to a treatable volume by GKRS. However, the combined treatment results in an increased complication rate related to the addition of the risks of each treatment modality.

Spine surgery and spinal fusion surgery are rising. Revision rates following initial surgery are between 8 and 45%. Epidural fibrosis is a common response to spine surgery for most patients and increases complications in revision surgery. Previous research suggests using MESNA (Sodium 2-mercaptoethane sulfonate) in combination with mechanical blunt dissection safely reduces surgical complications. MESNA is a mucolytic agent which selectively cleaves disulphide bonds involved in the adherence and strength of fibrosis, meaning cutting in-struments are not needed. The Chemically Assisted DISSection (CADISS (R)) System is an optimised non-cutting surgical device, consisting of a reconstitution cartridge for MESNA preparation, irrigated surgical instruments, and a footswitch to control MESNA release. This is the first study to investigate the use of the CADISS (R) System in revision spine surgery.Methods: This was a prospective, open label, observational case study. We enrolled 21 patients for revision spine surgery with the CADISS (R) System at two Belgium sites. The primary assessment was the number of successful removals of epidural fibrosis without cutting. The amount of MESNA used, total dissection and procedure time were recorded. For secondary criterion, the surgeons assessed global satisfaction, facilitation of dissection, quickness of action, usability, bleeding reduction and visualisation of the cleavage plane using an 11-point Likert scale (0-10). Due to the exploratory nature, no formal statistical analysis was planned. We calculated the per-centage and confidence interval of successful procedures, the medians and corresponding interquartile range of the Likert criterion, and the mean (+/- SD) of the amount of MESNA used, CADISS (R) dissection time and total procedure time.Results: 24 fibrosis dissections were performed in 19 patients and 23 were successful (95.8%, CI: 78.9%; 99.9%). The mean amount of MESNA used, mean dissection time and procedure time were 16 ml (+/- 4.94), 16.5 min (+/- 16.1) and 86.3 min (+/- 25.1), respectively. No dural tears were reported. The mean global satisfaction score was 9.0 (8.0-9.0). All other Likert criterion had scores of 8.0 or 9.0, excluding quickness of action, which scored 7.0 (6.0-9.0).Conclusions: The CADISS (R) System in revision spine surgery has potential to effectively reduce dissection complications.