Is non-contrast MRI sufficient to detect meningioma residue after surgery?

BACKGROUND: Contrast-enhanced magnetic resonance imaging (MRI) is the imaging modality routinely used to follow up patients who have undergone surgical resection of brain meningiomas. There are growing concerns about the massive use of gadolinium-based contrast agents (GBCA). Our aim was to evaluate the performance of a new imaging protocol, performed without GBCA injection, in the detection of tumoral residue or local recurrence after surgery of parafalcine and convexity meningiomas. MATERIALS AND METHODS: Only adult patients with a documented resected parafalcine or convexity meningioma were included. We performed a dedicated MRI protocol that included non-contrast and post-contrast sequences. The presence or absence of residue on the unenhanced sequences was independently recorded by three observers: first blindly, then in comparison with a baseline enhanced MRI examination. RESULTS: A total of 51 patients were included. 37 of them featured a tumor residue on the reference enhanced sequence. Overall, an average of 32 of 37 (87%) residues were identified on the unenhanced sequences that were blindly reviewed; and more than 34 of 37 (93%) were identified with the help of the comparative baseline enhanced examination, with a high sensitivity. The missed cases were related to small residues. CONCLUSION: Unenhanced MRI sequences are highly sensitive and specific in identifying a tumor residue or a local recurrence in the post operative follow up of brain meningiomas. Sensitivity is even higher with the help of a comparative baseline enhanced MRI examination, whatever the strength of magnetic field.

Pure endoscopic management of epileptogenic hypothalamic hamartomas.

Hypothalamic hamartomas (HH) are rare congenital malformations located in the region of the tuber cinereum and third ventricle. Their usual clinical presentation is characterized by gelastic/dacrystic seizures which often become pharmaco-resistant and progress to secondary focal/generalized intractable epilepsy causing mostly in children cognitive and behavioral problems (particularly in cases of progressive epileptic encephalopathy) and precocious puberty. Whereas gelastic seizures can be surgically controlled either by resection of the lesion or disconnection (tissue-destructive) procedures, aimed at functionally prevent the spreading of the epileptic burst; generalized seizures tend to respond better to HH excision rather than isolated neocortical resections, which generally fail to control them. Prospective analysis of 14 consecutive patients harboring HH treated in an 8-year period; 12 patients had unilateral and two bilateral HH. All patients were managed by pure endoscopic excision of the HH. The mean operative time was 48 min and mean hospital stay was 2 days; perioperative blood loss was negligible in all cases. Two patients showed a transient diabetes insipidus (DI); no transient or permanent postoperative neurological deficit or memory impairment was recorded. Complete HH excision was achieved in 10/14 patients. At a mean follow-up of 48 months, no wound infection, meningitis, postoperative hydrocephalus, and/or mortality were recorded in this series of patients. Eight patients became seizure free (Engel class I), 2 other experienced worthwhile improvement of disabling seizures (Engel class II); 2 patients were cured from gelastic attacks while still experiencing focal dyscognitive seizures; and 2, having bilateral HH (both undergoing unilateral HH excision), did not experience significant improvement and required later on a temporal lobectomy coupled to amygdalohyppocampectomy. Overall, the followings resulted to be predictive factors for better outcomes in terms of seizure control: (1) cases of unilateral, Delalande class B, HH, (2) shorter history of epilepsy. Endoscopic resection of HH proved, in our series, to be effective in achieving complete control or in reducing the frequency of seizures. Furthermore, this approach has confirmed its minimally invasive nature with a very low morbidity rate: of note, it allowed to better preserve short-term memory and hypothalamic function.

Acute toxicities and cumulative dose to the brain of repeated sessions of stereotactic radiotherapy (SRT) for brain metastases: a retrospective study of 184 patients.

BACKGROUND: Stereotactic radiation therapy (SRT) is a focal treatment for brain metastases (BMs); thus, 20 to 40% of patients will require salvage treatment after an initial SRT session, either because of local or distant failure. SRT is not exempt from acute toxicity, and the acute toxicities of repeated SRT are not well known. The objective of this study was to analyze the acute toxicities of repeated courses of SRT and to determine whether repeated SRT could lead to cumulative brain doses equivalent to those of whole-brain radiotherapy (WBRT). MATERIAL AND METHODS: Between 2010 and 2020, data from 184 patients treated for 915 BMs via two to six SRT sessions for local or distant BM recurrence without previous or intercurrent WBRT were retrospectively reviewed. Patients were seen via consultations during SRT, and the delivered dose, the use of corticosteroid therapy and neurological symptoms were recorded and rated according to the CTCAEv4. The dosimetric characteristics of 79% of BMs were collected, and summation plans of 76.6% of BMs were created. RESULTS: 36% of patients developed acute toxicity during at least one session. No grade three or four toxicity was registered, and grade one or two cephalalgy was the most frequently reported symptom. There was no significant difference in the occurrence of acute toxicity between consecutive SRT sessions. In the multivariate analysis, acute toxicity was associated with the use of corticosteroid therapy before irradiation (OR = 2.6; p = 0.01), BMV grade (high vs. low grade OR = 5.17; p = 0.02), and number of SRT sessions (3 SRT vs. 2 SRT: OR = 2.64; p = 0.01). The median volume equivalent to the WBRT dose (VWBRT) was 47.9 ml. In the multivariate analysis, the VWBRT was significantly associated with the total GTV (p < 0.001) and number of BMs (p < 0.001). Even for patients treated for more than ten cumulated BMs, the median BED to the brain was very low compared to the dose delivered during WBRT. CONCLUSION: Repeated SRT for local or distant recurrent BM is well tolerated, without grade three or four toxicity, and does not cause more acute neurological toxicity with repeated SRT sessions. Moreover, even for patients treated for more than ten BMs, the VWBRT is low.

Changes in the characteristics of patients treated for brain metastases with repeat stereotactic radiotherapy (SRT): a retrospective study of 184 patients.

PURPOSE: Brain metastases (BMs) are the leading cause of intracranial malignant neoplasms in adults. WHO, Karnofsky performance status (KPS), age, number of BMs, extracerebral progression (ECP), recursive partitioning analysis (RPA), diagnosis-specific graded prognostic assessment (Ds-GPA) are validated prognostic tools to help clinicians decide on treatment. No consensus exists for repeat stereotactic radiotherapy (SRT) for BMs. The aim of this study was to review the changes in patient characteristics treated with repeated SRTs. METHODS AND MATERIALS: The data of patients treated between 2010 and 2020 with at least two courses of SRT without previous whole brain radiotherapy (WBRT) were reviewed. Age, WHO, KPS, ECP, type of systemic treatment, number of BMs were recorded. RPA, Ds-GPA and brain metastasis velocity (BMV) were calculated. RESULTS: 184 patients were treated for 915 BMs and received two to six SRTs for local or distant brain recurrence. The median number of BMs treated per SRT was 1 (range: 1-6), for a median of 4 BMs treated during all sessions (range: 2-19). WHO, Ds-GPA and RPA were stable between each session of SRT, whereas KPS was significantly better in SRT1 than in the following SRT. The number of BMs was not significantly different between each SRT, but there was a tendency for more BM at SRT1 (p = 0.06). At SRT1, patients had largest BM and undergo more surgery than during the following SRT (p < 0.001). 6.5%, 37.5% and 56% of patients were classified as high, intermediate, and low BMV, respectively, at the last SRT session. There was almost perfect concordance between the BMV-grade calculated at the last SRT session and at SRT2 (r = 0.89; p < 0.001). CONCLUSION: Repeated SRT doesn't lead to a marked alteration in the general condition, KPS was maintained at over 70% for more than 95% of patients during all SRTs. Long survival can be expected, especially in low-grade BMV patients. WBRT shouldn't be aborted, especially for patients developing more than twelve BMs annually.

Is physical activity a trigger factor for subarachnoid hemorrhage?

INTRODUCTION: Subarachnoid hemorrhage (SAH) is a serious pathology, associated with 43% mortality and significant disability. In the absence of relevant guidelines, some teams advocate that patients harboring an unruptured intracranial aneurysm (ICA) abstain from all sports activity, as a prophylactic precaution. The aim of the present study was to evaluate the impact of physical activity as a risk factor for SAH, through a review of the literature. METHOD: A systematic literature review was performed for the period 2000 to 2020 in accordance with the PRISMA guidelines. Prospective and retrospective articles reporting more than 50 patients whose physical activity was associated with onset of SAH were included. The main end-point was prevalence of SAH occurring after physical activity. For comparison purposes, the prevalences of other circumstances were calculated to establish a range of frequency. RESULTS: Physical activity appeared to be quite rarely associated with onset of SAH, with a prevalence of 3%, compared to 30% at rest, 7.3% in association with defecation and 4.5% in association with sexual activity. Age under 60 years, male gender (M/F ratio 1.38) and smoking (67.1%) were associated with onset of SAH during physical activity. CONCLUSION: Physical activity appears to be a rare trigger factor for SAH. These results are in contrast to the idea that physical activity should, as a precaution, be avoided in patients with unruptured ICA. There is at present no scientific evidence of an association with aneurysmal SAH.

Delayed cerebral ischemia after meningioma resection: Literature review and illustrative case.

BACKGROUND: Cerebral vasospasm results from arterial vasoconstriction, mainly following aneurysmal subarachnoid hemorrhage, and may cause delayed cerebral ischemia (DCI). DCI rarely occurs after tumor resection. We performed a systematic review of the literature together with a case report of DCI after meningioma resection. LITERATURE REVIEW: METHODS: A systematic literature review was performed following the PRISMA statement, searching the PubMed, Medline and Cochrane databases using keywords and MESH terms related to "vasospasm/DCI and meningioma resection". RESULTS: In the studies retrieved in the literature, 5 cases of DCI after meningioma surgery were identified. The average age of patients was 52 years. The average onset time of DCI was 9.7 days. Clinical presentation was highly variable: hemiparesis (60%), confusion (60%) and/or aphasia (40%). Meningioma location was most frequently sphenoidal (60%). Most patients had vasospasm in multiple cerebral vessels, involving only the anterior circulation. Various management strategies were used: endovascular treatment (33.3%), antiplatelet therapy (50%) and/or nimodipine (40%). In terms of outcome, there were no deaths, but most patients had variable neurological sequelae (80%): aphasia, visual impairment, hemiparesis. CONCLUSION: The systematic literature review and the present case of DCI following resection of an olfactory meningioma suggested that the main etiologic factors causing this rare pathology are: 1) intraoperative subarachnoid hemorrhagic contamination; 2) microvascular manipulation; 3) and possible dysregulation of hypothalamic function.

Radionecrosis after repeated courses of radiotherapy under stereotactic conditions for brain metastases: Analysis of clinical and dosimetric data from a retrospective cohort of 184 patients.

PURPOSE: Between 10 and 40% of patients with cancer will develop one or more brain metastases (BMs). Stereotactic radiotherapy (SRT) is part of the therapeutic arsenal for the treatment of de novo or recurrent BM. Its main interest is to delay whole brain radiation therapy (WBRT), which may cause cognitive toxicity. However, SRT is not exempt from long-term toxicity, and the most widely known SRT is radionecrosis (RN). The objective of this study was to analyze the occurrence of RN per BM and per patient. MATERIAL AND METHODS: Between 2010 and 2020, data from 184 patients treated for 915 BMs by two to six SRT sessions for local or distant brain recurrence without previous or intercurrent WBRT were retrospectively reviewed. RN was examined on trimestral follow-up MRI and potentially confirmed by surgery or nuclear medicine. For each BM and SRT session plan, summation V12Gy, V14Gy, V21Gy and V23Gy isodoses were collected. Volumes of intersections were created between the 12Gy isodose at the first SRT and the 18Gy isodose of the following SRT (V18-12Gy). RESULTS: At the end of follow-up, 23.0% of patients presented RN, and 6.3% of BM presented RN. Median follow-up of BM was 13.3 months (95%CI 18.3-20.8). The median interval between BM irradiation and RN was 8.7 months (95% CI 9.2-14.7). Six-, 12- and 24-month RN-free survival rates per BM were 75%, 54% and 29%, respectively. The median RN-free survival per patient was 15.3 months (95% CI 13.6-18.1). In multivariate analysis, the occurrence of RN per BM was statistically associated with local reirradiation (P<0.001) and the number of SRTs (P<0.001). In univariate analysis, the occurrence of RN per patient was statistically associated with the sum of all V18-12Gy (P=0.02). No statistical association was found in multivariate analysis. A sum of all V18-12Gy of less than 1.5ml was associated with a 14.6% risk of RN, compared with 35.6% when the sum of all V18-12Gy was superior to 1.5ml. The sum of all V18-12Gy larger than 1.5ml was associated with a 74% specificity and 53% sensitivity of RN (P<0.001). CONCLUSION: Based on these results, a small number of BMs show RN during repeated SRT for local or distant recurrent BMs. Local reirradiation was the most predictive factor of brain RN. A V18-12Gy larger than 7.6ml in the case of local reirradiation or larger than 1.5ml in proximity reirradiation were prognostic factors of RN. The more BM patients need radiation therapy, and the longer they survive after irradiation, the higher their individual risk of developing RN.

[Impact of NGS results on patient outcome with a multiform glioblastoma]. / Analyse de l'impact des résultats du séquençage de nouvelle génération chez les patients atteints de glioblastome.

PURPOSE: Although some genetic alterations in glioblastoma (GBM) have been characterized, the prognostic value of these gene mutations is not yet established in patients treated with standard therapy. PATIENTS AND METHOD: 40 patients with newly diagnosed GBM, treated between July 2017 and December 2019, and who had genomic analysis were analyzed. Next-generation sequencing techniques (NGS) were used with a panel of 26 genes. Patients were grouped according to MGMT status, the presence or absence of at least one mutated gene on the panel, and p53 expression by immunohistochemistry. RESULTS: the median follow-up was 11.5 months (1.0-37). For all patients, the median duration of progression-free survival was 8 months (95% CI, 5.3-10.7) and the median overall survival (OS) was 17 months (95% CI, 7.5-26.5). Progression-free and overall survival were significantly different according to MGMT status but not according to NGS and p53 status. Three groups of patients according to different combined status could be distinguished due to significant differences in overall survival. CONCLUSION: we have shown that the presence of MGMT promoter methylation is a good prognostic factor. By grouping the patients according to their MGMT, NGS and p53 status, three groups of patients could be separated according to their overall survival. However, these results must be confirmed on a larger number of patients.

Surgical management of persistent post-traumatic trans-tentorial brain hernia.

INTRODUCTION: Temporal engagement may persist after etiologic surgical treatment of acute subdural hematoma (ASH) without clinical improvement despite normalized intracranial pressure (ICP). The aim of this study was to assess the feasibility of secondary direct temporal lobe disengagement (DTLD) after surgery for supratentorial ASH and to evaluate clinical outcome. MATERIALS AND METHODS: This was a retrospective analysis of 4 patients undergoing secondary DTLD. Patient data were recorded at admission, pre- and postoperatively and at 6months' follow-up (FU): age, gender, Rotterdam score, Glasgow Coma Scale (GCS), neurological deficits, oculomotor nerve palsy (ONP), ICP, midline shift, complications and Extended Glasgow Outcome Scale (GOS-E). RESULTS: At postoperative evaluation 48h after DTLD, we observed a significant improvement in GCS score (initial 6±3, preoperative 7±3, postoperative 14±1; P=0.02), midline shift (initial 16±3mm, preoperative 13±5mm, postoperative 9±2mm; P=0.049) and ONP (P=0.01). In all cases, early postoperative imaging documented visualization of a patent ipsilateral peri-mesencephalic cistern. At 6-month FU, GOS-E showed 75% good recovery and 25% disability. Complete ONP recovery was observed in 75% of patients (P=0.01). Neurological deficits were present at FU in 25% of patients. No surgery-related complications or mortality were recorded. CONCLUSIONS: In traumatic brain injury, secondary DTLD may allow simple, effective and safe management of trans-tentorial uncal herniation, avoiding more challenging procedures. Clinical results are promising, as this technique seems to favorably influence neurological outcome in this selected subgroup of patients with persistent clinical and radiological signs of temporal engagement after etiological treatment with normal ICP values.

Interventional magnetic-resonance-guided cryotherapy combined with microsurgery for recurrent glioblastoma: An innovative treatment?

BACKGROUND: Glioblastoma invariably recurs after primary Stupp tumor therapy and portends a poor prognosis. Cryoablation is a well-established treatment strategy for extra-cranial tumors. The safety and efficacy of interventional MR-guided cryoablation (iMRgC) has not been explored in recurrent glioblastoma. METHODS: A retrospective analysis of data collected over a period of 24 months was performed. The inclusion criteria were: (I) recurrent glioblastoma despite Stupp protocol; (II) MRI followed by histological confirmation of recurrent glioblastoma; (III) location allowing iMRgC followed by microsurgical resection; and (IV) patient's consent. The primary objective was to assess feasibility in terms of complications. The secondary objective was to analyze progression-free survival (PFS), post-iMRgC survival and overall survival (OS). RESULTS: The study included 6 patients, with a mean age of 67±7.6 years [range, 54-70 years]. No major complications were observed. Median PFS was 7.5 months [IQR 3.75-9.75] and 6-month PFS was 50%. Median post-iMRgC survival was 9 months [IQR 7.5-15.25] and 6-month post-iMRgC survival was 80%. Median OS was 22.5 months [IQR 21.75-30]. CONCLUSION: iMRgC for recurrent glioblastoma demonstrated a good safety profile, with no major complications. Our data suggest improved PFS and OS. TRIAL REGISTRATION NUMBER: No. IRB00011687 retrospectively registred on July 7th 2021.

Glioblastoma multiforme presenting with ischemic stroke: case report and review of the literature.

A 58-year-old woman presented with acute onset of global aphasia. Imaging studies revealed a left frontotemporal enhancing tumor and ischemic stroke in the territory of the middle cerebral artery. The patient was operated on, and the diagnosis of glioblastoma multiforme was confirmed. At the time of surgery, several branches of the left middle cerebral artery were found embedded in the tumor. One branch, which was infiltrated by tumor and completely occluded, was resected to achieve complete resection. Postoperatively, the stroke area within the middle cerebral artery territory increased, together with worsening of the patient's clinical status, thus requiring urgent decompressive craniectomy. Thereafter, the patient gradually improved, and received radiation therapy and chemotherapy with no recurrence after 24 months of follow-up. To our knowledge, glioblastomas presenting with ischemic stroke are rare, and such patients should be considered to be at high surgical risk.

Investigating the real impact of COVID-19 pandemic on the daily neurosurgical practice?

OBJECTIVE: The objective of this study was to relate the neurosurgical activity during a time of sanitary crisis such as experienced during the SARS-CoV-2 pandemic. METHODS: A monocentric retrospective analysis was made based on a prospectively gathered cohort of all patients requiring neurosurgical care between March 15th and May 12th, 2020. Local impact of SARS-CoV-2 was analysed regarding number of patients admitted in ICU. RESULTS: One hundred and sixty patients could benefit from neurosurgical care with a wide-ranging profile of clinical and surgical activities performed during the study that seemed similar to last year profile activity. Surgical indications were restricted to non-deferrable surgeries, leading to a drop in operative volume of 50%. Only 1.3% of patients required transfer to other units due to the impossibility of providing gold standard neurosurgical care in our centre. CONCLUSION: Despite the challenges represented by the SARS-CoV-2 pandemic, it was proven possible to ensure the routine neurosurgical continuity and provide high standards of neurosurgical care without compromising patients' access to the required treatments.

[Choice optimisation of radiation therapy technique for central neurocytomas from literature data]. / Optimisation du choix de la technique d'irradiation des neurocytomes centraux à partir des données de la littérature.

Neurocytomas represent 0,25 to 0,5 of brain tumours. These tumours have neuronal differentiation. It's a young adult disease. The main treatment is neurosurgery. The place of other therapies is still unclear, noticeably with regards to radiotherapy. This review aim is to determine the place and the modalities of radiotherapy in the management of neurocytomas. A literature search using PubMed allowed to select the most relevant studies. Finally, 22 studies were selected according to pre-established criteria to answer the problem. All studies were retrospective studies except one. The analysis conclusion defined radiotherapy as a treatment of choice in selected patients, when surgical resection was incomplete or when tumour was atypical.

[What is the place of surgery in the management of brain metastases in 2020?] / Quelle est la place de la chirurgie dans la prise en charge des métastases cérébrales en 2020 ?

Brain metastases are the most common intracranial tumors and are associated with a dismal prognosis. The management of patients with brain metastases has become more important because of the increased incidence of these tumours, the better treatment of the systemic disease and the improvement of surgical techniques. The treatment requires multidisciplinary approaches and become complex because of new emerging systemic therapy and advancements in neurosurgery and radiation oncology. The surgical treatment has an indispensable role to obtain a tissue diagnosis, in relieving intracranial effect mass and improving neurological status by improving induced encephalopathy. An understanding of the role and indications of the surgery in patients with metastatic brain lesions is essential for the effective management of this growing population.

The Cryo-immunologic effect: A therapeutic advance in the treatment of glioblastomas?

The immunotherapy of cerebral glioblastoma has become a hot topic. Immune checkpoint blockade antibodies have progressively acquired a role in the management of malignant tumors. A multimodal approach using surgery, radiotherapy, chemotherapy in combination with immunotherapy represent a potent weapon against glioblastomas. In parallel, clinical applications of cryotherapy-freezing tumors based on repetition of rapid freeze-slow thaw cycle-for various cancers such as skin, lung, breast, esophagus, hepatic, kidney, prostate and bone tumors were developed. The future immunomodulatory approaches might be combined with brain tumors cryoablation to increase the cryoimmune response. The objective of this study was to analyze from the literature the relationship between cerebral cryosurgery and immunomodulation using PRISMA method. The animals' studies demonstrate the dendritic cells maturation and activation with the enhancement of antigen-presenting function after cryotherapy suggesting the potential usefulness of the association of cryotherapy and immunomodulator in the management of gliomas.

Predictive factors of epilepsy in arteriovenous malformation.

OBJECTIVE: Structural epilepsy related to cerebral arteriovenous malformation (AVM) suggests different epileptogenic mechanisms. The aim of our study was to determine factors associated with epilepsy into a retrospective cohort of AVM patients. PATIENTS AND METHODS: Ruptured and unruptured AVM data retrieved from a prospective single center registry (2009-2016) were retrospectively assessed. Demographic, clinical and radiological features were identified in AVM patients with or without epilepsy according to the International League Against Epilepsy classification. RESULTS: Epilepsy concerned 22 out of 80 consecutive patients with AVM (27.5%). Univariate analysis comparing both groups revealed a significant association of different variables with the structural epilepsy: young age (P=0.02), large nidus size (P=0.02), venous dilation (P=0.02), posterior cerebral artery (PCA) feeder (P<0.001) and Spetzler-Martin grade (P=0.02). Based on multivariate analysis, only the PCA feeder was identified (OR=5.2 [95% CI 1.1-24,5], P=0.04). CONCLUSION: PCA feeder for cerebral AVM was significantly associated with structural epilepsy. The hypothesis of a vascular steal phenomenon to the detriment of internal temporal lobe vascularization could be related to the development of epilepsy.

A combined single-stage procedure to treat brain AVM.

Complete resection of brain arteriovenous malformation (AVM) is a surgical challenge, mainly due to risk of intraoperative rupture. The objective of this feasibility study was to analyze complete resection rate at 3 months and clinical outcome at 6 months after treatment of brain AVM by combined single-stage embolization and surgical resection. A retrospective observational study from July 2015 to February 2019 was conducted at the Department of Neurosurgery of Strasbourg University Hospital, France. Decision to treat was taken on the basis of history of AVM rupture, symptomatic AVM, or morphologic risk factors for rupture. Complete resection rate was assessed on postoperative cerebral subtraction angiography at 3 months and clinical outcome at 6 months was evaluated on the modified Rankin Scale (mRS). In the 16 patients treated for symptomatic brain AVM, the rate of complete resection was 75%, resection with residual shunt 18.7%, and incomplete resection with residual nidus 6.3%. Good clinical outcome (mRS=0 or 1) was achieved in 81.3% of patients at 6 months. The transfusion rate was 7.1%. There were procedural complications in 12.5% of patients but no intraoperative ruptures. This combined single-stage procedure allows extensive preoperative embolization of the AVM, facilitating surgical microdissection by identifying the dissection plane and perforating arteries and allowing the operator to work in close contact with the nidus without fear of intraoperative rupture.

Impact of discontinuation of antithrombotic therapy after surgery for chronic subdural hematoma.

INTRODUCTION: The management of antithrombotic therapy (AT) after surgery for chronic subdural hematoma (cSDH) requires taking account of the balance of risk between hemorrhage recurrence (HR) and the prophylactic thromboembolic effect (TE). The goal of the present study was to evaluate the prevalence of vascular events (VE: TE and/or HR) in the first 3 postoperative months after cSDH evacuation in patients previously treated by AT. The impact of AT resumption was also evaluated. PATIENTS AND METHODS: This observational prospective multicenter collaborative study (14 French neurosurgery centers) included patients with cSDH treated by AT and operated on between May 2017 and March 2018. Data collection used an e-CRF, and was principally based on an admission questionnaire and outcome/progression at 3 months. RESULTS: In this cohort of 211 patients, VE occurred in 58 patients (27.5%): HR in 47 (22.3%), TE in 17 (8%), with mixed event in 6 cases (2%). Median overall time to onset of complications 26 days±31.5, and specifically 43.5 days±29.25 for HR. Non-resumption of AT significantly increased the relative risk of VE [OR: 4.14; 95% CI: 2.08 - 8.56; P <0.001] and especially of TE [OR: 7.5; 95% CI: 1.2 - 42; P<0.001]. The relative risk of HR was significantly increased when AT was resumed at less than 30 days (P=0.015). CONCLUSION: The occurrence of VE in patients operated on for cSDH and previously treated by AT was statistically significant (27.5%). HR was the most common event (22.3%), whereas TE accounted for only the 8%, although with shorter time to onset. In order to prevent TE risk, AT should be restarted after 30 days, as HR risk is greatly decreased beyond this time.