Summary: Objective: Preoperative training of surgery is extremely diverse including practice of the microsurgical technique, learning of anatomy, and surgical video observation. The knowledge regarding these is generally evaluated in the board certification test of neurosurgery; however, there are few reports on the objective evaluation of the surgical techniques. In this study, we reported on our evaluation method of the surgical technique.

Materials: We are conducting a technical examination in the form of a contest for the doctors who have been working for 10 years or less by the following method. Till date, more than 50 neurosurgeons have been enrolled, with consistent results, which will be reported.

Method: The total allotted time is 5 min. After the arteriotomy of the 1-mm artificial vessels, suturing is performed with a 10 - 0 suture. We present the basic tasks beforehand through the video. Evaluation items are graded by four stroke surgical supervisors. Evaluation items are the technique of using microscope, tremor of the hand, and ligature suturing technique. The contents of the examination are determined considering reproducibility, cost, objectivity of evaluation, and continuity.

Results: In order to prevent differences in rating by graders, but there was no significant difference in rating by the evaluator.

Conclusion: By objectively evaluating the same surgical technique, it is possible to perform relative evaluation of the individual technique, perform objective evaluation of the individual technological growth, and determine the pros and cons of individual technologies.

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Summary: Although surgery for cerebrovascular disease is an important field for neurosurgeons, the number of enforcements may decrease owing to the development of endovascular intervention. Current neurosurgeons must acquire surgical skills with smaller number of cases. Here, we present our surgical education method with surgical videos and records using information technology to facilitate safe and reliable neurovascular surgery. The author also disclosed the surgical results during their own training period.

We consider that sharing surgical experience with each other is the best way to acquire surgical skills with smaller number of cases, the sharing method being our unique audio-visual training by the effective use of information technology. Our audio-visual training is derived from several records of surgical maneuvers on how each trainee and trainer manipulate the microsurgical instruments and proceed with microsurgery. These audio-visual records are synchronized and edited on the same screen, so that trainees watch it repeatedly and learn neurosurgical techniques efficiently. The author performed 39 clippings (20 cases of unruptured and 19 cases of ruptured cerebral aneurysms) and 31 cerebrovascular anastomoses during the neurosurgical specialist terms of 1st and 2nd year under our education method. All cases were successfully completed. We emphasize the importance of neurosurgical education and sharing surgical experience effectively among current neurosurgeons.

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Summary: Anterior communicating artery aneurysms (AcomANs) are one of the most common types of intracranial aneurysms, accounting for approximately 35% of the latter. Additionally, an AcomAN has been found to be a risk factor for the rupture of unruptured cerebral aneurysms. Therefore, this paper aimed to discuss the clinical features, pterional and interhemispheric approaches to surgery, methods of simulation, and endovascular treatment of AcomANs.

Many prior reports have regarded the location of the Acom as a risk factor for the rupture of unruptured cerebral aneurysms when morphologic and associated anomalies were present. The Acom has many important perforating arteries such as the recurrent artery of Heubner, hypothalamic artery, and subcallosal artery. Therefore, it is crucial to understand the precise anatomical features of these perforating arteries before the surgery.

In our study, the Acom had numerous perforating arteries that terminated in the superior surface of the optic chiasm and above the chiasm in the anterior hypothalamus. Common variants of the Acom, such as a double or triple Acom, triple A-2 segments, and duplication of the A-1 segments, were also encountered.

The advantages and disadvantages of the pterional and interhemispheric approaches for the surgical treatment of AcomANs must also be understood. The pterional approach is popular among neurosurgeons; however, in cases where the AcomAN is large, located very superiorly, or projects posteriorly, the interhemispheric approach should be selected. The surgical tips and pitfalls of each approach have been presented in this paper.

In our study, deep and wide dissection and exposure of the Sylvian fissure were necessary for using the pterional approach. The method used to dissect the interhemispheric fissure, namely the concrete method, involved exposing the parent artery according to the height of the AcomAN. Remarkable advances have been made in terms of the development of information and communication technology, particularly as it relates to imaging diagnostic modalities. Therefore, thorough preoperative simulation is recommended, particularly by the surgeon performing the operation. Moreover, before the surgery, the surgeon should imagine the worst scenarios that could occur with the patient during the procedure. Once the surgeon has hedged all possible risks, the surgery should be confirmed positively.

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Summary: Atherosclerotic carotid stenosis (CS) comprises about 20% of all cerebral infarctions in Western countries, and the number of patients with CS is also likely to increase in Japan due to changes in dietary habits and the unprecedented rate of the aging population. Therefore, the significance of appropriate management of CS will also concomitantly increase.

The risk of future ischemic events in patients with CS has long been assessed mainly by luminal morphology as angiographically determined stenosis and ulceration. However, recent remarkable advances in vessel wall visualization using ultrasound and magnetic resonance imaging (MRI) combined with a deeper understanding of vascular biology have shown that vessel wall characteristics also have considerable influence on the onset of ischemic events. Assessments of plaque characteristics are now important in the management of CS.

Several features of a vulnerable plaque such as intraplaque hemorrhage, large lipid-rich necrotic cores, and ruptured fibrous caps have been precisely demonstrated using MRI.

The current status of carotid plaque characterization using MRI will be briefly outlined in this review. Thereafter, the potential clinical implications and future challenges of analyzing plaque using MRI will be discussed.

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Summary: Following technological advances in endovascular therapy, this approach is preferred over　surgery as the mainstay of treatment for dural arteriovenous fistula (dAVF). However, surgery remains important, and its role should be re-evaluated. In this retrospective study, we investigated the outcomes of surgical treatment for dAVF, focusing on the pitfalls of this approach in 101 patients who underwent surgery for dAVF. We analyzed the characteristics of lesions treated surgically, as well as treatment outcomes including the morbidity, AV shunt occlusion, and recurrence rates. The results included 20 patients who underwent only surgical treatment. The surgical morbidity rate was 5%. All AV shunts were extirpated at radical procedures; however, recurrence occurred in one patient. In conclusion, surgery serves as definitive treatment for specific types of dAVF. Careful decision-making regarding an endovascular vs. an open surgical approach is important, together with preparedness to manage the associated challenges, as observed in this case series.

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Summary: Neuroendoscopic surgery may be more advantageous for patients with a massive intraventricular ematoma (IVH) compared to conventional procedures such as external ventricular drainage erformed alone. We proposed the effectiveness of a combination of flexible and rigid endoscopes hen compared with the use of a single flexible endoscope in hematoma evacuation surgeries for IVH. e studied 26 consecutive patients who had IVH associated with intracerebral hemorrhage between pril 2011 and October 2017. The first 16 patients with IVH were treated using a single flexible endoscope the flexible group). The remaining 10 patients with IVH were treated with a combination of lexible and rigid endoscopes (the combined group). The average postoperative hematoma evacuation atio was higher in the combined group than in the flexible group (combined: 58 ± 9.3% vs. flexible: 6 ± 6.5%). No differences were observed in the duration of intraventricular drainage, additional cerebrospinal luid shunt surgeries, or outcome on discharge between the groups. A rigid endoscope is ffective for rapid removal of a hard hematoma. However, its use in the dry field narrows the operative avity, leading to deterioration of the visibility of the bleeding point. In contrast, the diving technique sing a flexible endoscope in the wet field enables amelioration of the visibility of the bleeding oint or that of the anatomical structures by enlarging the objective cavities. Thus, it enables the removal f deep-seated hematoma in the third ventricle or in the aqueduct. However, hard and large hematomas re sometimes difficult to remove due to their small working channel.

The combined use of a flexible and a rigid endoscope enabled effective and safe hematoma evacuation n patients with casting IVH. It was the most important point to optimize the order and timing of witching, accounting for the respective advantages and disadvantages.

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Summary: This report describes the salvage techniques used to achieve postoperative patency of intraoperative bypass graft obstructions in patients who underwent superficial temporal artery-middle cerebral artery (STA-MCA) bypass surgery. We analyzed 72 patients (79 sides) who underwent STAMCA anastomosis at our hospital between 2006 and 2017. This cohort comprised 35 females and 37 males, whose ages ranged from 9 to 74 years. The incidences of occlusive cerebrovascular disease, moyamoya disease, and cerebral aneurysm were 30 sides in 30 patients, 26 sides in 19 patients, and 23 sides in 23 patients, respectively. In terms of intraoperative bypass occlusion, we evaluated the sites, causes, timing, and type of salvage treatment performed. Intraoperative bypass patency was confirmed using Doppler ultrasonography and indocyanine green video angiography. Postoperative bypass patency was evaluated using three-dimensional computed tomography angiography (3DCTA). Nine patients developed intraoperative acute bypass occlusion (5 occlusive cerebrovascular diseases, 4 moyamoya diseases) were 9, 5, and 4, respectively. Anastomotic thrombus formation was deemed to be the cause of occlusion in 8 patients, while an intraluminal STA thrombus was the cause in 1 patient. Occlusion occurred in the former toward the end of the procedure and it occurred in the latter immediately after anastomosis. In terms of salvage treatment, re-suturing was used for the bypass occlusion in the 8 patients with anastomotic thrombi, while STA reconstruction was used in the patient with the intraluminal STA thrombus. Using 3DCTA, we observed that 8 of the 9 patients who underwent salvage treatment for intraoperative bypass occlusion demonstrated patency after 7 postoperative days. Bypass occlusion during the STA-MCA bypass was attributable to thrombi of the anastomotic sites in a significantly high percentage of patients in whom Doppler ultrasonography revealed a marked reduction in blood flow within a short time. This was true even after confirming graft patency immediately after anastomosis. Patients who developed bypass occlusion secondary to anastomotic site thrombus underwent simultaneous re-suturing and graft patency restoration. We concluded that, in patients undergoing STA-MCA bypasses, Doppler ultrasonography is warranted before wound closure. If poor or diminished blood flow is observed, careful reevaluation and prompt re-suturing are warranted.

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Summary: Introduction: For acute ischemic stroke caused by large artery occlusion, prompt significant reperfusion is essential. Standardization of device selection and surgical techniques may be useful in this regard.

Methods: This was a retrospective cohort study of 82 patients who underwent mechanical thrombectomy for acute ischemic stroke due to a large artery occlusion in the anterior circulation between August 15, 2015, and December 31, 2017. A unified approach was developed in which occlusion of the internal carotid artery or the sphenoidal segment of the middle cerebral artery was treated using a direct aspiration first-pass technique with an aspiration catheter and occlusion of either the insular segment of the middle cerebral artery or the anterior cerebral artery was treated using various stent retrievers. Patient characteristics and various factors associated with mechanical thrombectomy were analyzed.

Results: Thrombolysis in cerebral infarction scores of ≥2b were observed in 85.4% of the patients, the puncture to recanalization time was 59 minutes, and modified Rankin Scale scores of 0-2 were achieved within 90 days in 47.6% of the patients.

Discussion: The use of standardized procedures and equipment for mechanical thrombectomy did not affect the proportion of significant recanalization, but it did shorten the procedure time. The procedures were performed with satisfactory outcomes, in accordance with the results of previous reports. onclusion: It is possible to shorten the puncture to recanalization time while minimizing the number f restarts in mechanical thrombus retrieval therapy by unifying treatment strategies and procedures.

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Summary: Objective: Common carotid artery occlusion (CCAO) is a relatively rare disease with a wide range of collaterals. As CCAO can induce dynamic changes in the angio-architectural conditions, treatment should be modified according to the cerebral hemodynamic conditions. Here, we report the surgical treatment of three patients with symptomatic CCAO.

Material and Methods: Between January 2010 and December 2016, three patients with symptomatic CCAO were surgically treated. Based on the angiographic findings, including the collateral flow and cerebral blood flow studies, appropriate surgical interventions for individual patients were selected. Results: Two-step vascular reconstruction was performed for Case 1 with CCAO, including a carotid bifurcation and a proximal internal carotid artery (ICA). A left subclavian artery to the proximal left external carotid artery (ECA) bypass was performed using an interposition saphenous vein graft, followed by the superficial temporal artery to middle cerebral artery (STA-MCA) bypass. For Case 2 with CCAO including a carotid bifurcation, a well-developed muscle branch of the left VA to M3 of the MCA bypass was made using an interposition saphenous vein graft. For Case 3 with a relatively short segment CCAO extending to the proximal ICA, occlusions of the CCA and ICA were successfully recanalized using two carotid stents. All vascular reconstruction procedures were successfully completed without any complications, with good clinical outcomes in all patients.

Conclusion: Surgical vascular reconstruction for patients with symptomatic CCAO can achieve successful outcomes. Precise preoperative evaluations of the extent of the occlusion and collateral flow re important, with the surgical strategy based on angiography and CBF findings.

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Summary: Carotid artery stenosis with high tortuosity is a known risk factor for carotid artery stenting CAS) and carotid endarterectomy (CEA). We report two cases in which CEA was performed to reat carotid artery stenosis that presented with remarkable tortuous distal internal carotid arteries ICA).

Case 1: A 70-year-old man presented with right transient ischemic attack (TIA) attributable to right arotid artery stenosis. Preoperative angiography revealed 75% stenosis and advanced calcification. ase 2: A 74-year-old man presented with asymptomatic, severe carotid artery stenosis. Preoperative ngiography revealed 80% stenosis and moderate calcification. CAS was deemed too difficult and CEA as performed in both cases. In Case 1, the end-to-end plication technique was used to reconstruct a elatively short segment of the tortuous vessel. In Case 2, a shunt tube was placed intraoperatively in a anner similar to an external shunt, and primary closure was performed. The preoperative modified ankin Scale score did not worsen in both cases. Both patients recovered satisfactorily, with no recurrence. ngenious surgical procedures, such as angioplasty or shunt insertion, are required after plaque emoval when performing CEA.

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Summary: Basilar bifurcation aneurysms (BA ANs) are currently being treated surgically by endovascular procedures in many institutions. However, aneurysm obliteration by clipping remains the most permanent cure for aneurysms. A subtemporal approach for BA AN has been established in many text books. The benefits of the subtemporal approach are short operative times and no need for skull base resection, while the disadvantages are oculomotor nerve palsy and temporal lobe injury due to excessive brain retraction. Here, we describe tips to help avoid temporal lobe damage, including body and head position, skin incision, craniotomy, and operative procedure performed under the microscope; an approach based on clinical experience. This report describes the usefulness of stepwise aspiration f cerebrospinal fluid from the crural cistern, the brain retraction technique using gelatin sponge to inimize intraoperative temporal lobe retraction, and fenestrated clip to obliterate BA AN.

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