Characterization of carotid plaques using chemical exchange saturation transfer imaging.

PURPOSE: The preoperative assessment of carotid plaques is necessary to render revascularization safe and effective. The aim of this study is to evaluate the usefulness of chemical exchange saturation transfer (CEST)-MRI, particularly amide proton transfer (APT) imaging as a preoperative carotid plaque diagnostic tool. METHODS: We recorded the APT signal intensity on concentration maps of 34 patients scheduled for carotid endarterectomy. Plaques were categorized into group A (APT signal intensity ≥ 1.90 E-04; n = 12) and group B (APT signal intensity < 1.90 E-04; n = 22). Excised plaques were subjected to histopathological assessment and, using the classification promulgated by the American Heart Association, they were classified as intraplaque hemorrhage-positive [type VI-positive (tVI+)] and -negative [no intraplaque hemorrhage (tVI-)]. RESULTS: Of the 34 patients, 22 (64.7%) harbored tVI+- and 12 (35.3%) had tVI- plaques. The median APT signals were significantly higher in tVI+- than tIVI- patients (2.43 E-04 (IQR = 0.98-4.00 E-04) vs 0.54 E-04 (IQR = 0.14-1.09 E-04), p < .001). Histopathologically, the number of patients with tVI+ plaques was significantly greater in group A (100%, n = 12) than group B (45%, n = 22) (p < .01). The number of symptomatic patients or asymptomatic patients with worsening stenosis was also significantly greater in group A than group B (75% vs 36%, p < .01). CONCLUSION: In unstable plaques with intraplaque hemorrhage and in patients with symptoms or progressive stenosis, the ATP signals were significantly elevated. CEST-MRI studies has the potential for the preoperative assessment of the plaques' characteristics.

Nonconvulsive status epilepticus in patients with acute subarachnoid hemorrhage is associated with negative arterial spin labeling on peri-ictal magnetic resonance images.

Purpose: Non-convulsive status epilepticus (NCSE) is characterized by repetitive or continuous seizures without convulsions. Arterial spin labeling (ASL) is useful for assessing hyperperfusion due to neurovascular unit coupling in patients with NCSE; subarachnoid hemorrhage (SAH) impairs the neurovascular unit. We hypothesized that the sensitivity of ASL in detecting NCSE is low in patients with SAH during the acute phase. Methods: Based on ASL findings obtained within 48 h after the clinical suspicion of focal-onset NCSE, we divided 34 patients into ASL-negative (no hyperperfusion; n = 10) and ASL-positive (confirmed hyperperfusion; n = 24) groups. We further divided the two groups according to the NCSE etiology: patients who were diagnosed with NCSE within 14 days after SAH onset (acute SAH, n = 11) and patients with NCSE due to factors other acute SAH (n = 23) and compared their characteristics. Results: In 10 of the 34 patients (29.4 %) the ASL findings were normal. The rate of acute SAH was significantly higher in ASL-negative- (n = 8, 80.0 %) than ASL-positive patients (n = 3, 12.5 %). The rate of patients in aphasic status was significantly lower in ASL-negative patients (n = 1, 10 %) than in ASL-positive patients (n = 12, 50.0 %). Conclusion: Normal ASL findings alone should not be used to exclude a diagnosis of NCSE particularly in patients in the acute phase of SAH with deterioration or no improvement in consciousness.

Coexistence of anterior choroidal artery and posterior cerebral artery retia mirabilia presenting with subarachnoid hemorrhage: illustrative case.

BACKGROUND: A rete mirabile is a rare vascular anomaly, with posterior cerebral artery (PCA) involvement being especially rare. Its pathogenesis has been speculated as a remnant of "distal annexation" between the primitive anterior choroidal artery (AchA) and the PCA at this site, but the exact mechanisms remain unclear. OBSERVATIONS: A 29-year-old man presented with subarachnoid hemorrhage. Arteriovenous malformation in the medial temporal lobe was initially suspected, but an arteriovenous shunt was not detected. First, conservative treatment was administered; however, rebleeding occurred 1 month later. Carotid angiography revealed a network-like cluster of blood vessels at the choroidal point of the AchA, suggesting a rete mirabile; these vessel clusters led to the persistent temporo-occipital branch of the AchA. Furthermore, an aneurysm was detected at the junction between the rete mirabile and the persistent temporo-occipital branch of the AchA. Additionally, vertebral angiography demonstrated a rete mirabile at the P2 segment. These findings suggested the coexistence of AchA and PCA retia mirabilia. Consequently, the aneurysm was clipped using a subtemporal approach to prevent re-rupture, and the postoperative course was uneventful. LESSONS: This first report of coexisting AchA and PCA retia mirabilia supports the remnant of distal annexation between the primitive AchA and the PCA as the reason for rete formation at this site.

Experience of using coronary perfusion balloon catheter for acute middle cerebral artery occlusion.

Background: We present the case of an individual with acute occlusion of the middle cerebral artery caused by atherosclerosis. The patient underwent angioplasty using a coronary perfusion balloon, which resulted in a favorable clinical outcome. Case Description: A 66-year-old male patient presented with an acute onset of right hemiplegia and dysarthria. Magnetic resonance imaging revealed an occlusion of the left middle cerebral artery, and alteplase was administered, followed by a mechanical thrombectomy and intracranial balloon catheter angioplasty. Due to restenosis, a coronary perfusion balloon catheter was used for a 15-minute angioplasty procedure while maintaining the perfusion. This treatment approach led to the recanalization of the artery and favorable clinical outcomes. Conclusion: The coronary perfusion balloon may represent a viable therapeutic alternative for the management of refractory intracranial atherosclerotic large vessel occlusion.

Stent retrieval for free-floating thrombus attached to carotid artery stenosis: A report of two cases.

Background: We report two cases who underwent mechanical thrombectomy using a stent retriever in advance of urgent carotid artery stenting (CAS) for carotid artery stenosis with free-floating thrombus (FFT). Case Description: Two patients showing symptomatic carotid artery stenosis with FFT underwent urgent endovascular surgery due to progressive neurological symptoms. The first case showed an FFT with 70% internal carotid artery (ICA) stenosis. After the completion of the common and external carotid artery balloon and distal ICA filter protection, we deployed a 6-mm-diameter stent retriever in the distal part of the stenosis. The white thrombus was retrieved; the angiographic shadow of the FFT disappeared; and CAS was performed. In the second case, due to a 90% severe stenosis lesion with FFT, balloon angioplasty was performed on the lesion using the push wire of the stent retriever. After angioplasty, the stent retriever was smoothly retrieved, and CAS was performed. Postoperative magnetic resonance imaging showed an increase in cerebral embolism in the first case; however, the patient's neurological symptoms improved. The second case showed in-stent plaque protrusion and required two additional stent placements; the patient showed no worsening of his neurological symptoms. Conclusion: In cases of carotid artery stenosis with FFT, it is technically possible to retrieve a thrombus with a stent retriever. Although thrombus removal may help reduce the risk of ischemic complications in a series of urgent CAS procedures, there are concerns such as mechanical irritation to the carotid artery plaque, and its indications and alternative treatments should be carefully considered.

Evaluation of Serial Intra-Arterial Indocyanine Green Videoangiography in the Surgical Treatment of Cranial and Craniocervical Junction Arteriovenous Fistulae: A Case Series.

BACKGROUND AND OBJECTIVES: Intravenous indocyanine green (IV-ICG) videoangiography is commonly performed to detect blood flow in the microscopic view. However, intra-arterial ICG (IA-ICG) videoangiography provides high-contrast imaging, repeatability within a short period of time, and clear-cut separation of the arterial and venous phases compared with IV-ICG. These features are useful for detecting retrograde venous drainage (RVD) and shunt occlusion in arteriovenous fistulae (AVF) surgery. This study aimed to investigate whether IA-ICG videoangiography can be repeatable within a short period of time and be useful for detecting RVD and shunt occlusion in cranial- and craniocervical junction (CCJ)-AVF surgery. METHODS: Between January 2012 and December 2022, 50 patients were treated with endovascular or surgical intervention for cranial- and CCJ-AVF at Tokushima University Hospital. Of these, 5 patients (6 lesions) underwent open surgery with IA-ICG videoangiography in a hybrid operating room. We analyzed the data of these 5 patients (6 lesions). RESULTS: There were 4/patient (median, range 2-12) and 3.5/lesion (median, range 2-10) intraoperative IA-ICG runs. IA-ICG videoangiography detected RVD in all patients. Clearance of IA-ICG-induced fluorescence was achieved within 30 seconds in all patients at each region of interest. After the disconnection of the fistulae, IA-ICG videoangiography and intraoperative digital subtraction angiography (DSA) confirmed the disappearance of RVD in all patients. There were no complications associated with IA-ICG videoangiography. CONCLUSION: This study showed that IA-ICG videoangiography is repeatable within a short period of time before and after obliteration and can be useful for detecting RVD and shunt occlusion in cranial- and CCJ-AVF surgery. IA-ICG videoangiography also allows intraoperative DSA studies in a hybrid operating room. Considering the recent advancements in hybrid operating rooms, combining IA-ICG videoangiography with intraoperative DSA is a useful strategy for cranial- and CCJ-AVF surgery.

Prognostic factors for acute large vessel occlusion with NIHSS 5 or lower.

BACKGROUND: Intravenous recombinant tissue plasminogen activator (IV rt-PA) and endovascular treatment have been performed for severe large vessel occlusion (LVO) and the results have been reported at high levels of evidence. However, acute treatment for LVO with mild symptom remains controversial. We retrospectively examined prognostic factors for LVO with mild symptoms. METHOD: We studied retrospectively the patients within 24 h of onset with large vessel occlusion with NIHSS score ??5. Outcomes were evaluated by modified Rankin Scale (mRS) at 90 days, with 0?2 defined as a good outcome and 3?6 as a poor outcome. Clinical characteristics of each case were examined. RESULT: Participants comprised 76 patients. Of the 76 patients. ICA occlusion showed good outcome in 17?/?19 cases (90%), whereas MCA occlusion showed good outcome in 36?/?54 cases (67%). Among the 14 cases showing positive results for distal intraarterial signal (d-IAS), outcomes were good in 6 cases (43%). On the other hand, the 32 d-IAS-negative cases showed good outcome in 28 cases (88%). Outcomes were thus significantly poorer for d-IAS-positive cases. CONCLUSION: MCA occlusion is associated with poor prognosis, even with NIHSS score ??5, and d-IAS may provide a predictor. J. Med. Invest. 70 : 22-27, February, 2023.

Long-sheath Introducer-assisted Revascularization (L-SHARE) Technique for Treating Large-vessel Occlusion by a Giant Clot.

Revascularization for common carotid artery (CCA) occlusion might be difficult. We reported our strategy for revascularizing CCA occlusion by giant clots. A 94-year-old woman was transferred to our hospital because of right hemiparesis and aphasia. CCA occlusion and giant clots were detected on ultrasonography. We performed mechanical thrombectomy using a 9-Fr balloon-guiding catheter, stent retriever, and aspiration catheter through a 9-Fr long-sheath introducer [long-sheath introducer-assisted revascularization (L-SHARE) technique]. We successfully recanalized CCA occlusion using this method. The L-SHARE technique might be useful for recanalization of CCA occlusion.

Efficacy of Utilizing Both 3-Dimensional Multimodal Fusion Image and Intra-Arterial Indocyanine Green Videoangiography in Cerebral Arteriovenous Malformation Surgery.

OBJECTIVE: An understanding of the complex morphology of an arteriovenous malformation (AVM) is important for successful resection. We have previously reported the utility of intra-arterial indocyanine green (ICG) videoangiography for this purpose, but that method cannot detect the angioarchitecture covered by brain tissue. 3-dimensional (3D) multimodal fusion imaging is reportedly useful for this same purpose, but cannot always visualize the exact angioarchitecture due to poor source images and processing techniques. This study examined the results of utilizing both techniques in patients with AVMs. METHODS: Both techniques were applied in 12 patients with AVMs. Both images were compared with surgical views and evaluated by surgeons. RESULTS: Although evaluations for identifying superficial feeders by ICG videoangiography were high in all cases, the more complicated the AVM, the lower the evaluation by 3D multimodal fusion imaging. Conversely, evaluation of the estimated range of the nidus was high in all cases by 3D multimodal fusion imaging, but low in all but one case by ICG videoangiography. Nidus flow reduction was recognized by Flow 800 analysis obtained after ICG videoangiography. CONCLUSIONS: These results showed that utilizing both techniques together was more useful than each modality alone in AVM surgery. This was particularly effective in identifying superficial feeders and estimating the range of the nidus. This technique is expected to offer an optimal tool for AVM surgery.

Efficacy of intraarterial indocyanine green videoangiography in surgery for arteriovenous fistula at the craniocervical junction in a hybrid operating room: illustrative cases.

BACKGROUND: Sufficient understanding of the angioarchitecture of an arteriovenous fistula (AVF) at the craniocervical junction (CCJ) is crucial to surgical treatment but is often difficult because of the complex vascular anatomy. Intraarterial indocyanine green (ICG) videoangiography has emerged as a more useful option for understanding the vascular anatomy than intravenous ICG videoangiography. This report describes two cases of CCJ AVFs successfully treated by surgery using intraarterial ICG videoangiography and describes the efficacy of this technique. OBSERVATIONS: Case 1 involved a 71-year-old man presenting with tetraparesis after sudden onset of severe headache due to subarachnoid hemorrhage (SAH). Digital subtraction angiography (DSA) demonstrated CCJ epidural AVF. Intraarterial ICG videoangiography revealed the drainer, which had been difficult to identify. The AVF disappeared after disconnection of the drainer. Case 2 involved a 68-year-old man presenting with severe headache due to SAH. DSA showed multiple AVFs at the CCJ and cerebellar tentorium. Intraarterial ICG videoangiography demonstrated concomitant perimedullary AVF and dural AVF at the CCJ. All AVFs disappeared postoperatively. LESSONS: Intraarterial ICG videoangiography was useful for definitive diagnosis of CCJ AVF, facilitating identification of feeders and drainers with bright and high phase contrast and allowing repeated testing to confirm flow direction.

Single-session hematoma removal and transcortical venous approach for coil embolization of an isolated transverse-sigmoid sinus dural arteriovenous fistula in a hybrid operating room: illustrative case.

BACKGROUND: Dural arteriovenous fistula (DAVF) can present with massive hematoma, which sometimes requires emergent removal. Therefore, a surgical strategy for single-session hematoma removal and shunt occlusion in the same surgical field is important. OBSERVATIONS: A 73-year-old man was transferred to the authors' hospital with a headache. Brain computed tomography (CT) revealed an intracerebral hematoma in the right temporoparietal lobe (hematoma volume 12 ml). A cerebral angiogram revealed a right isolated transverse-sigmoid sinus (TSS)-DAVF fed by the occipital artery and middle meningeal artery. There was cortical venous reflux into the Labbé vein and posterior parietal vein. Percutaneous transarterial and transvenous embolization were unsuccessful. The following day, his consciousness level acutely declined with a headache, and brain CT showed hematoma expansion (hematoma volume 41 ml) with a midline shift. Therefore, the authors performed single-session hematoma removal and a transcortical venous approach for coil embolization of an isolated TSS-DAVF in a hybrid operating room. His postoperative course was uneventful. No recurrence was observed 3 months postoperatively on cerebral angiography. LESSONS: Single-session hematoma removal and a transcortical venous approach for coil embolization of an isolated TSS-DAVF is considered in cases with massive hematoma. This strategy is useful, considering recent developments in hybrid operating rooms.

The claw sign predicts first-pass effect in mechanical thrombectomy for cerebral large vessel occlusion in the anterior circulation.

BACKGROUND: Mechanical thrombectomy (MT) is an effective treatment for acute cerebral large vessel occlusion (LVO). Complete recanalization of vessels in a single procedure is defined as the first-pass effect (FPE) and is associated with good prognosis. In this study, angiographic clot protruding sign termed the "claw sign," was examined as candidate preoperative imaging factor for predicting the FPE. METHODS: We retrospectively analyzed data from 91 consecutive patients treated for acute LVO in the anterior circulation by MT between January 2014 and December 2019. The claw sign was defined as a thrombus that protruded proximally by more than half of the diameter of the parent artery. Radiological findings such as claw sign, clinical and etiological features, and outcomes were compared between groups with and without successful FPE. Multivariate analysis was conducted to evaluate perioperative factors associated with FPE. RESULTS: FPE was achieved in 26 of 91 (28.6%) patients and the claw sign was observed in 34 of 91 (37.4%) patients. The claw sign was significantly more frequent in the successful FPE group than in the failed FPE group (53.8% vs. 30.8%; P = 0.040). After the multivariate analysis, the claw sign was the only pretreatment parameter that could predict FPE (odds ratio, 2.67; 95% confidence interval, 1.01-7.06; P = 0.047). CONCLUSION: The claw sign is an angiographic imaging factor that might predict FPE after MT for anterior circulation acute ischemic stroke.

Percutaneous Transluminal Angioplasty and Stenting Using an Aspiration Catheter.

Objective: During percutaneous transluminal angioplasty (PTA) for the vertebral artery, occlusion of the subclavian artery using a balloon guiding catheter may be useful to prevent embolism of clots and/or debris distal to an atherosclerotic lesion. However, when placing a balloon guiding catheter at the intended vessels is difficult, it may be useful to use an aspiration catheter (AC) for mechanical thrombectomy as an intermediate catheter to suction way clots and/or debris. We report two cases in which PTA was performed for an atherosclerotic lesion at the intracranial vertebral artery using an AC, which ended without complications. Case Presentations: Case 1: A 74-year-old man presented with dysarthria and was admitted to our hospital. MRI revealed severe left vertebral artery stenosis and diffuse cerebral infarct areas at the territory of the posterior circulation. The patient had an abdominal aortic aneurysm and abnormally shaped left tortuous subclavian artery. Therefore, we performed PTA and stenting via the left brachial artery. We guided a 6-Fr long sheath to the left subclavian artery, and a 6-Fr AC for thrombectomy was guided through the long sheath to the V4 portion of the left vertebral artery. Thereafter, PTA was carried out under manual aspiration from the AC. As restenosis at the atherosclerotic lesion occurred after PTA, we performed stenting using a coronary stent system for this lesion under manual aspiration from the AC. No new infarct areas were observed on post-procedural MRI. Case 2: A 74-year-old woman presented with dysarthria and was admitted to our hospital. MRI demonstrated basilar artery occlusion and diffuse cerebral infarct areas at the territory of the posterior circulation. As her symptom worsened after admission, we performed urgent mechanical thrombectomy. We first performed thrombectomy using a stent retriever and then performed PTA and stenting (PTAS) for residual basilar artery stenosis via the AC under manual aspiration. Conclusion: When it is difficult to place a guiding catheter at the intended vessels during PTA, an AC may be useful to prevent distal embolization.

Chronic subdural hematoma associated with dural metastasis leads to early recurrence and death: A single-institute, retrospective cohort study.

The prevalence of chronic subdural hematoma (CSDH) associated with dural metastasis is uncertain, and appropriate treatment strategies have not been established. This study aimed to investigate the characteristics of and appropriate treatment strategies for CSDH associated with dural metastasis. We retrospectively reviewed the charts of 214 patients who underwent surgery for CSDH. The patients were divided into the dural metastasis group (DMG; n = 5, 2.3%) and no dural metastasis group (No-DMG; n = 209, 97.3%). Patient characteristics, treatment, and outcomes were compared between the two groups. Active cancer was detected in 31 out of 214 patients, 5 of whom (16.1%) had dural metastasis. In-hospital death (80.0% vs. 0%; p < 0.001) and recurrence within 14 days (80.0% vs. 2.9%; p < 0.001) and 60 days (80.0% vs. 13.9%; p = 0.002) were significantly prevalent in the DMG. All patients in the DMG developed subdural hematoma re-accumulation requiring emergent surgery because of brain herniation, and patients in the DMG had significantly worse recurrence-free survival (p < 0.001). This relationship remained significant (p < 0.001) even when the analysis was limited to the active cancer cohort (n = 31). CSDH associated with dural metastasis leads to early recurrence and death because of the difficulty in controlling subdural hematoma re-accumulation by common drainage procedures. Depending on the primary cancer status, withdrawal of active treatment and change to palliative care should be discussed after diagnosing CSDH associated with dural metastasis.

Involvement of Neutrophil Extracellular Traps in Cerebral Arteriovenous Malformations.

BACKGROUND: Cerebral arteriovenous malformations (cAVMs) represent tangles of abnormal vasculature without intervening capillaries. High-pressure vascular channels due to abnormal arterial and venous shunts can lead to rupture. Multiple pathways are involved in the pathobiology of cAVMs including inflammation and genetic factors such as KRAS mutations. Neutrophil release of nuclear chromatin, known as neutrophil extracellular traps (NETs), plays a multifunctional role in infection, inflammation, thrombosis, intracranial aneurysms, and tumor progression. However, the relationship between NETs and the pathobiology of cAVMs remains unknown. We tested whether NETs play a role in the pathobiology of cAVMs. METHODS: We analyzed samples from patients who had undergone surgery for cAVM and immunohistochemically investigated expression of citrullinated histone H3 (CitH3) as a marker of NETs. CitH3 expression was compared among samples from cAVM patients, epilepsy patients, and normal human brain tissue. Expressions of thrombotic and inflammatory markers were also examined immunohistochemically in samples from cAVM patients. RESULTS: Expression of CitH3 derived from neutrophils was observed intravascularly in all cAVM samples but not other samples. Nidi of AVMs showed migration of many Iba-I-positive cells adjacent to the endothelium and endothelial COX2 expression, accompanied by expression of IL-6 and IL-8 in the endothelium and intravascular neutrophils. Unexpectedly, expression of CitH3 was not necessarily localized to the vascular wall and thrombus. CONCLUSIONS: Our results offer the first evidence of intravascular expression of NETs, which might be associated with vascular inflammation in cAVMs.

Coil embolization with overlapping horizontal low-profile stents to treat a giant thrombosed fetal posterior cerebral artery aneurysm using contralateral approach through anterior communicating artery: Case report.

BACKGROUND: The treatment of internal carotid artery (ICA) - posterior communicating artery aneurysms (ICPC aneurysms) is challenging when a fetal posterior cerebral artery (PCA) arises from the saccular neck. This complex angioarchitecture renders endovascular approaches difficult. Giant thrombosed IC-PC aneurysms are also hard to treat by endovascular coiling because its flow-diversion effect is insufficient. CASE DESCRIPTION: We report the first case of a ruptured giant thrombosed IC-PC aneurysm associated with a fetal PCA that was successfully treated by coil embolization with retrograde overlap horizontal stenting using low-profile stents introduced through the contralateral ICA. The aneurysm was completely occluded and follow-up MRI scans demonstrated the reduction of the aneurysmal size. CONCLUSION: Our technique is advantageous because low-profile stents can be used to treat lesions not accessible with flow-diverter stents due their presence in complex angioarchitectures, and overlap stenting may have flow-diversion effects that can result in the complete occlusion of giant thrombosed aneurysms.

Efficacy of Intra-arterial Indocyanine Green Videoangiography in Hemangioblastoma Surgery: A Case Report.

Intravenous indocyanine green (ICG) videoangiography is reportedly useful for vascular neurosurgery, and for treating hemangioblastoma due to its high vascularity. Videoangiography obtained after intra-arterial ICG injection has emerged as a more useful option than that after intravenous injection. This report offers the first description of a case of hemangioblastoma successfully treated using intra-arterial ICG videoangiography, and describes the efficacy of this technique. A 20-year-old man presented with progressive cerebellar ataxia and dysphagia. Magnetic resonance imaging (MRI) revealed an enhanced solid tumor in the medulla oblongata. Digital subtraction angiography (DSA) showed a highly vascularized tumor. Surgery was performed to remove the tumor in a hybrid operating room. A catheter was introduced into the vertebral artery (VA) for intra-arterial ICG videoangiography. Superficial feeders and drainers were identified and flow dynamic changes in the tumor were assessed by intra-arterial ICG videoangiography. The tumor was removed after confirming lack of flow in the drainer. Intra-arterial ICG videoangiography was more useful than intravenous ICG videoangiography in hemangioblastoma surgery for identifying feeders and drainers and assessing flow dynamics in the tumor. Use of Flow 800 made these findings simpler and easier to evaluate.

Gelatin-thrombin Hemostatic Matrix-related Cyst Formation after Cerebral Hematoma Evacuation: A Report of Two Cases.

The gelatin-thrombin matrix, Floseal, is an excellent novel hemostatic agent that is used in various surgical fields. Thrombin is a serine protease, and the conversion of prothrombin to thrombin is an essential step in the coagulation cascade. However, thrombin can induce blood-brain barrier (BBB) disruption and vasogenic brain edema. This report describes two cases of gelatin-thrombin matrix-related cyst formation after cerebral hematoma evacuation. An 82-year-old man with a gelatin-thrombin matrix-related cyst was treated by cyst drainage and fenestration to the lateral ventricle. Histological evaluation of the cyst wall showed a gelatin-thrombin matrix reserve, marked infiltration of inflammatory cells, and foam cell accumulation. In addition, an 85-year-old woman with a gelatin-thrombin matrix-related cyst was treated with steroids and responded well. In both cases, the post-treatment course was uneventful. Cyst shrinkage and no recurrence were observed. The gelatin-thrombin matrix can cause cyst formation with brain edema. This is the first report demonstrating the cyst wall pathology and the steroid responsivity on cyst shrinkage. The mechanism of cyst formation is thought to be thrombin-induced BBB disruption. Excess gelatin-thrombin matrix should be carefully removed from the surgical beds, particularly those having a blinded space from the neurosurgical microscope.

Transarterial Sinus Coiling for Dural Arteriovenous Fistula: Two Case Reports.

Objective: We report two cases of dural arteriovenous fistula (DAVF) treated by coil embolization of the affected sinus and fistula via a feeding artery instead of transvenous embolization (TVE) due to the difficulty of the transvenous approach. Case Presentation: An 82-year-old man was diagnosed with transverse sinus (TS) DAVF. A microcatheter was inserted into the isolated TS through the fistula via the middle meningeal artery (MMA), which was the feeding artery of the DAVF. The DAVF was occluded by coil embolization of the isolated sinus and fistula. A 79-year-old man was diagnosed with cavernous sinus (CS) DAVF. A microcatheter was inserted into the CS through the fistula via an accessory meningeal artery (AMA), which was the feeding artery of the DAVF. The DAVF was occluded by coil embolization of the affected sinus and fistula. Conclusion: These cases suggested that transarterial sinus coiling is one of the effective treatment options for DAVF.

A Patient with Moyamoya Disease Who Underwent Recanalization Therapy for Acute Intracranial Internal Carotid Artery Occlusion.

Objective: We report a case of acute internal carotid artery occlusion in a patient with adult-onset moyamoya disease who underwent mechanical thrombectomy and had a good outcome. Case Presentation: A 73-year-old woman was diagnosed with moyamoya disease by asymptomatic right middle cerebral artery occlusion at 59 years of age. The patient was transported for stroke symptoms. Magnetic resonance imaging (MRI) demonstrated left terminal internal carotid artery occlusion and low-intensity signal on T2*-weighted imaging at the occlusion site. Alteplase was administered and endovascular treatment was subsequently performed. A small-diameter microcatheter was guided to the distal end of the occlusion and angiography after deployment of a stent retriever revealed irregular stenosis. Severe stenosis remained after thrombectomy, and balloon angioplasty was added. The treatment resulted in recanalization and good outcome. Conclusion: Adults with moyamoya disease may have accompanying atherosclerotic intracranial artery occlusion. Angiography after deployment of a stent retriever was useful for clarifying the etiology of occlusion. It is important to determine the etiology of occlusion based on the medical history or imaging findings and to select an appropriate treatment.