Prevention of rebleeding is extremely important for ruptured cerebral aneurysms, and either open surgery or endovascular treatment is recommended as a prophylactic measure. The decision on which treatment strategy to use is based on a comprehensive evaluation of the patient's clinical and cerebral aneurysm findings from both methods.

  Surgical clipping is selected in cases wherein the advantages of open surgery can be utilized and disadvantages of endovascular coiling can be compensated. The advantages of surgical clipping include the ability to control intracranial pressure and perform revascularization, while the disadvantages of endovascular coiling include microaneurysms, large aneurysms, and aneurysms that require stents.

  The surgeon should be familiar with surgical clipping and endovascular treatment and should aim to deepen the understanding of the pathophysiology of ruptured cerebral aneurysms to provide the best treatment for each case.

  Endovascular treatment has remarkably progressed and is important in stroke treatment. Particularly, there are many evidence-based reports on the efficacy of coil embolization for ruptured intracranial aneurysms, and it has become an indispensable treatment procedure. However, endovascular treatment is not suitable for all ruptured intracranial aneurysms, and we should decide the indication based on the treatment certainty, treatment risk, and characteristics of the treatment team.

  Here, we review the evidence of endovascular treatment for ruptured intracranial aneurysms and discuss on patients that should be treated with coil embolization.

  Sidewall aneurysms include most internal carotid and vertebral artery aneurysms. The indications for flow diverters (FD) have been significantly relaxed by Japanese Ministry of Health, Labour and Welfare to include aneurysms with a maximum diameter of 5mm or more. Consequently, almost all sidewall aneurysms now qualify for insurance coverage, greatly expanding the range of treatment options. There is no doubt about the curative efficacy of FDs. They are particularly effective for paraclinoid internal carotid artery aneurysms, especially in younger patients. Therefore, it seems appropriate to consider FDs as the primary choice for such cases. Conversely, FDs are ineffective in some circumstances, such as in older patients or those with fetal-type posterior communicating artery aneurysms. For such cases, a casual choice of FD should be approached with caution, and other standard treatments should be thoroughly considered.

  Cerebral arteriovenous malformation (AVM) treatment aims to eliminate intracranial hemorrhage risks and prevent new neurological deficits. Gamma Knife radiosurgery has been widely used in the treatment of AVM because a steady growth in scientific publications has established the role of Gamma Knife radiosurgery. Most patients with AVM suitable for Gamma Knife radiosurgery have relatively small- to medium-sized AVMs located in critical structures of the brain and high risks for alternative managements, including surgery and endovascular embolization. The author describes the outcomes of patients who underwent Gamma Knife radiosurgery for multiple types of AVM and reports subgroup analyses to evaluate total obliteration, risk of hemorrhage, and complications of AVM Gamma Knife radiosurgery.

  An endoscope is characterized by its ability to enter through a small opening and observe a corner with a wide-viewing angle. In the field of cerebrovascular disorders, this feature is best utilized in endoscopic surgery for cerebral hemorrhage. With the development of transparent sheaths, endoscopic hematoma removal has made great strides in the field of cerebral hemorrhage surgery, and the stability of surgical instruments and techniques has enabled stable surgical results with widespread use of this technique. There are various reports on endoscopic hematoma removal techniques overseas, with differences depending on the instruments used, and all have shown excellent results. However, clear evidence on the effectiveness of endoscopic hematoma removal has not yet been obtained.

  Endoscopic approaches include transnasal and keyhole approaches, as well as cylinder surgery using a transparent sheath. The use of an endoscope as an adjunct to observe blind spots during aneurysm clipping in microsurgery has been shown to be effective in some cases. However, reports on fully endoscopic aneurysm clipping have been limited to craniotomy and transnasal surgery, and the effectiveness and safety of such procedures have not yet been demonstrated. There are also limited reports on fully endoscopic surgery for cerebral arteriovenous malformations and dural arteriovenous fistulas ; however, we believe that there is room for the development of minimally invasive combined endovascular and endoscopic surgery. Based on the literature and our experience, we discuss the use of endoscopic surgery for cerebrovascular disorders.

  While advances in minimally invasive treatments such as endovascular therapy and radiotherapy have decreased the number of direct surgical procedures, there is an increasing need to learn surgical techniques efficiently, given the smaller number of cases. Drawing surgical illustrations as part of training may prove useful ; however, doing it continuously may be difficult due to a busy work schedule, especially when you are not used to drawing illustrations. The recent development of digital devices has made it possible to create digital illustrations efficiently, which may be useful in surgical education. This paper introduces the author's actual method of creating digital illustrations using the iPad Pro and Procreate. The following four points were considered useful in digital illustration : 1. Layer function : After creating the illustrations, changing the positions, and enabling magnification are possible. 2. Time-saving effect : The work common to each drawing can be shared as a template by copying and pasting, which may save time. 3. Expression : Various expressions are possible depending on the creator's ingenuity, such as expressing texture using the brush function or blur tool or adjusting the layer transparency to see through background structures. 4. Use as data : Data can be attached to an e-mail or carried in a flash drive, which may make it easy to use for academic presentations or papers. Deterioration or loss of the illustrations does not pose a problem. Continuous creation of surgical illustrations while saving time and being able to review the surgery while creating the illustrations may lead to self-reflection concerning subsequent surgeries and the improvement of surgical skills. We believe that creating digital illustrations is useful in maximizing the experience gained from a case.

  Fluid attenuated inversion recovery (FLAIR) images often demonstrate cerebrospinal fluid (CSF) flow artifacts in the ventricles and cisterns, reflecting brain pulsation. The brain pulsation of moyamoya disease after revascularization was investigated using the CSF flow artifacts.

  To score the degree of CSF flow artifact, each CSF artifact grade was defined by comparing the highest intensity in a specific region of interest (ROI) to the reference ROIs, as follows ; higher than the intensity of normal white matter in the centrum semiovale=2 points ; equal to or less than the intensity in the centrum semiovale and higher than CSF intensity=1 point ; and equal to CSF intensity=0. CSF flow scores in eight sites, including ventricles and prepontine cisterns, were measured and added to the total score (0-16).

  A 42-year-old man who suffered from a unilateral moyamoya disease with transient ischemic attacks underwent middle cerebral artery-superficial temporal artery anastomosis and myo-synangiosis for blood flow improvement. The CSF flow score was 9 points before the surgical treatment, which increased to 12 points two years postoperatively. The CSF flow score is considered to represent the grade of brain pulsation. Revascularization for moyamoya disease increased cerebral blood flow and might aid the improvement of the glymphatic system, which was driven primarily by brain pulsation and washed out metabolites from the brain.

  A 54-year-old man undergoing chemotherapy for an undifferentiated pleomorphic sarcoma of the left thigh developed sudden-onset altered consciousness. Computed tomography revealed a subcortical hemorrhage in the right frontal lobe. A hemorrhagic lesion was observed at the base of the hematoma during an emergency craniotomy. Histopathologically, spindle-shaped cells, including multinucleated giant cells, and round-shaped tumor cells, infiltrated around the blood vessels, and a brain metastasis of the undifferentiated pleomorphic sarcoma was identified. The patient died five months after the surgery due to the rapid growth of residual tumors. Brain metastases from undifferentiated pleomorphic sarcomas are rare but can cause acute cerebral hemorrhage. Therefore, this should be considered when treating patients with a history of undifferentiated pleomorphic sarcoma.