The 2021 World Health Organization Classification of Tumours of the Central Nervous System (WHO2021) is a fully integrated molecular classification system for diagnosing glial tumors. This revision was a major upgrade from the previous edition (the WHO2016). The WHO2021 now not only requires detailed molecular characterization of the tumor but also drastically changes the philosophy of tumor grading from “across the tumor entity” to “within tumor types.” These changes greatly impact how clinicians should build treatment strategies for individual patients with astrocytoma and oligodendroglioma, as most evidence is based on clinical trials designed during the pre-molecular era. This review aims to clarify the current consensus regarding diagnosis, the role of surgery, and adjuvant therapy for astrocytoma and oligodendroglioma. Controversial and unsolved issues are also discussed. Ultimately, the article will discuss the uncharted territory of using molecular targeting drugs for this malignancy.

  Glioblastoma (GBM) is still an intractable disease with extremely poor prognosis that recurs almost inevitably despite combined modality therapy with maximal resection, radiation therapy, and chemotherapy. Bevacizumab (BEV) has been used as a standard agent for recurrent GBM (re-GBM), while next-line treatments are ineffective after BEV failure. New treatment modalities, such as tumor-treating fields (TTFields) (no reimbursement) and the oncolytic herpes virus G47Δ, have been recently approved for re-GBM in Japan.

  Cancer Genome Profiling testing was approved in June 2019 and thus provides potential opportunities for application to unapproved molecular targeted therapies in a subset of patients with brain tumors, including GBM. Therefore, there is an urgent need for the development of new treatments for re-GBM, including dose-dense TMZ (ddTMZ).

  High-grade meningioma (WHO grades 2 and 3) treatment is challenging due to the tendency of the tumor to recur locally. Surgical removal, the primary treatment modality, has a limited success rate. Radiation therapy, particularly fractionated external-beam X-ray irradiation, has shown efficacy in controlling these tumors when performed early after resection. Stereotactic irradiation and intensity-modulated radiotherapy are used to treat residual and recurrent tumors. Trials using chemotherapeutics against high-grade meningiomas have yielded 6-month progression-free rates (PFS-6) of up to 26%. Boron neutron capture therapy (BNCT) has shown promising results with a reported PFS of 13.7 months, generating significant interest domestically and internationally in its potential for treating high-grade meningiomas.

  Central nervous system germ cell tumors include five histologic types and mixed types, which can be classified into germinomas, malignant germ cell tumors, and other germ cell tumors as a clinical risk category. Internationally, two classifications, germinoma and non-germinomatous germ cell tumor (NGGCT), are used ; however, their validity is questionable due to tumor type complexity. The standard of care for germinomas is platinum-based chemotherapy followed by whole brain ventricular/whole-brain radiation therapy (23.4Gy in 13 fractions). For malignant germ cell tumors, alkylating agents and platinum-based chemotherapy followed by whole-brain whole-spinal cord irradiation and local radiation therapy (50-59.4Gy in 25-33 fractions). The 10-year overall survival (OS) rate of germinoma is good at about 90%, but late recurrence and radiotherapy-related adverse events are problems. The 10-year OS rate of malignant germ cell tumor is poor at about 60%, and late radiotherapy-related adverse events are an additional issue. In 2022, the Brain Tumor Committee of Japan Children's Cancer Group initiated a clinical trial in patients with primary central nervous system germ cell tumors to investigate reduced invasiveness in chemoradiation therapy. Proving of the study hypothesis is expected to establish a treatment that mitigates late adverse events.

  Intravenous recombinant tissue plasminogen activator (rt-PA) therapy for acute ischemic stroke remains a standard treatment, even in the current era in which mechanical thrombectomy is becoming more prevalent. However, in Japan, despite more than 20 years since its approval in 2005, the implementation rate of intravenous rt-PA therapy is lower than in Western countries, and regional disparities remain. In regions with a shortage of stroke specialists, telemedicine-based care models such as “drip and ship” reportedly improve its implementation rate. However, there are regional disparities in establishing such systems. A survey we conducted of stroke core centers in Hokkaido revealed a low implementation rate of “drip and ship” and the need for remote diagnostic support in this large land area. In recent years, with the advancement of information and communication technology, versatile telemedicine applications have become prevalent in neurosurgery. The expectation of improving the implementation rate of intravenous rt-PA therapy and the equalization of stroke healthcare is increasing through remote diagnostic support using these applications.

  Here, we report two cases of patients with bow-hunter's syndrome at the C1-C2 level who underwent anterior decompression of the vertebral artery. Aged in their 70s and 80s, both patients presented with blurred vision or dizziness induced by left neck rotation. Magnetic resonance angiography and computed tomography angiography revealed occlusion or hypoplasia of the left vertebral artery. Left neck rotation produced anteromedial movement of the C1 transverse process and traction of the right vertebral artery, resulting in stenosis of the right vertebral artery in the C2 transverse foramen. Using the anterior cervical approach, the right C3 and C2 transverse processes were exposed by detachment of the longus colli muscle. Following identification of the right vertebral artery between the C2-C3 transverse processes using a Doppler probe, the surface of the right C2 transverse foramen was carefully drilled through and opened. The preoperative symptoms disappeared postoperatively in both cases. The anatomical relationship between the vertebral artery and the C1 transverse process and rotatory stenosis of the vertebral artery at the C1-C2 level will be most effectively prevented by anterior decompression of the C2 transverse foramen rather than posterior decompression of the C1 transverse foramen. Using appropriate surgical techniques, the anterior cervical approach can effectively treat C1-C2 bow-hunter's syndrome with preserved neck motion.

  In this report, we described a case of idiopathic extracranial right internal carotid artery dissection, which was followed by coil embolization with stenting of the aneurysm at the same site 2 years later. A 44-year-old man presented to our outpatient clinic with a chief complaint of right neck pain. He was diagnosed with idiopathic extracranial internal carotid artery dissection. Two years later, an asymptomatic aneurysm was detected in the dissected area, and stent-assisted coil embolization was performed. Few studies have reported aneurysms forming several years following arterial dissection remission. Long-term follow-up is necessary because aneurysm formation may be associated with a chronic course.