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Objective: Various risk factors for recanalization after coil embolization have been reported, but the indications for retreatment of recanalized aneurysms have not been determined.The aim of this study was to identify risk factors indicating the need for retreating recanalization during long-term follow-up (approximately 1 year). Methods: A total of 172 unruptured saccular aneurysms in 155 patients treated by initial coil embolization between February 2012 and July 2019 were retrospectively analyzed. Intraluminal thrombosed aneurysms, aneurysms treated with stent assistance, and aneurysms followed without digital subtraction angiography (DSA) were excluded. Recanalization was identified in 31 aneurysms. Recanalized aneurysms (Meyer grade ≥2) were defined as major recanalization (MA); those that worsened to Meyer grade 1 were defined as minor recanalization (MI). Age, sex, aneurysm location, shape, five morphological variables (neck, height, width, dome-to-neck ratio, aspect ratio), aneurysm volume, endovascular technique, immediate Meyer grade, and volume embolization ratio (VER) were compared between MI (n = 18) and MA (n = 13). Predictors of MA were determined using logistic regression and receiver operating characteristic (ROC) curve analyses. Results: On multivariate logistic regression analysis, spherical shape (odds ratio (OR) 11.9; 95% confidence interval (CI) 1.28–111) and VER (OR 1.92; 95% CI 1.13–3.28) were independent predictors of MA. On ROC curve analysis, the optimal cut-off value for the VER was 20.8% (sensitivity, 76.9%; specificity, 77.8%). Conclusions: Lower VER and non-spherical shape appear to be independent risk factors for progression to MA in recanalized aneurysms, and packing with a VER >20.8% is expected to prevent progression to MA.

Background: Reconstruction the skull base defect of an widely opened frontal sinus following extensive tumor resection in the anterior cranial fossa needs to be addressed to prevent postoperative cerebrospinal fluid (CSF) leakage or tension pneumocephalus. Case description: A 51-year-old man presented with headache and epileptic seizure. Magnetic resonance imaging (MRI) showed a cystic and solid extra-axial tumor with homogenous enhancement adhering the planum sphenoidale. Since the frontal sinus was widely opened following gross total resection of the tumor, the sinus was filled and covered with the adipose tissue. Thereafter, DuraGen overlaid the adipose tissue and was covered with the vascularized pericranium. Additionally, the edge of the pericranium flap was sutured to the dura, and further DuraGen overlaid by “sandwich” technique to protect against CSF leakage and tension pneumocephalus. Three months after operation, CT revealed that complete obliteration of the frontal sinus was confirmed and neither CSF leakage nor meningitis were observed. Conclusion: The present study demonstrated that closure of the widely opened frontal sinus using DuraGen inserted between the skull and the pericranium flap is an effective and promising method for the frontal sinus isolation. Keywords: DuraGen, Anterior cranial fossa, Frontal sinus, Skull base surgery, Duraplasty, Cerebrospinal fluid leakage

Background: Radiation-induced aneurysms have been previously reported; however, multiple and repeated de novo aneurysm formation chronologically and anatomically during long-term follow-up have not yet been observed. The pathogenesis of persistent radiation-induced vasculopathy is not fully understood. Case Description: A 31-year-old woman presented with intraventricular hemorrhage due to rupture of a right internal carotid artery (ICA) aneurysm that developed 17 years after surgical resection of a low-grade glioma in the right frontal lobe and postoperative radiotherapy (focal, 50 Gy/25 fractions). During glioma follow-up, salvage surgery with adjuvant gamma knife therapy and chemotherapy (ranimustine, vincristine, temozolomide) were performed for recurrence of the glioma. The aneurysm was treated with endovascular coil embolization. However, she experienced repeated intraventricular hemorrhages, and angiography revealed a de novo ICA aneurysm. The de novo aneurysms were treated with endovascular surgery using coil embolization and stenting. At 2 years after the third hemorrhage, the surgical wound became dehiscent, probably due to wound infection, thus epicranial soft tissue reconstruction using vascularized skin flap was performed. Despite multistaged endovascular surgery for the ICA aneurysm, she experienced repeated subarachnoid and intraventricular hemorrhages. Angiography revealed a de novo aneurysm of the right posterior cerebral artery and basilar trunk. She underwent coil embolization and stenting. Despite active management with endovascular surgery and close follow-up, she died after an eighth consecutive intraventricular and intracerebral hemorrhage caused by a de novo large aneurysm of the posterior cerebral artery. Conclusions: To the best of our knowledge, the present study is the first to report on of refractory and recurring de novo aneurysms treated by multistaged endovascular surgery during a long-term follow-up after radiotherapy and multistaged craniotomy for glioma. Key words: De novo aneurysm, Low-grade glioma, Multistaged craniotomy, Occult wound infection, Radiation-induced aneurysm