The brain-machine interface (BMI) is an interface between brain signals and external devices and can be divided into output-type BMI, input-type BMI, bidirectional-type BMI, replacement part BMI, etc. In recent years, the rapid development of neural decoding and neural sensing technology has accelerated the medical applications of BMI. In addition, neuromodulation based on BMI is expected to be applied in clinical situations to treat neuropsychiatric disorders by inducing plastic changes in neural activity. In this paper, we outline the status of BMI development and its clinical application and introduce our efforts in this area.

  Despite globalization, the world has not become homogeneous, and research that takes advantage of local characteristics and strengths still has great potential to provide global benefits. One example is Japan's basic clinical research on malignant brain tumors. Many Japanese researchers specializing in brain tumors have been active overseas and have produced remarkable research. Good models of ‘global’ contributions from Japan are the series of studies on germ cell tumors that predominantly occur in East Asia and the acquisition of practical evidence for use in stereotactic radiosurgery of metastatic brain tumors. Many unique R & D projects continue in Japan. Examples include a clinical trial to explore biomarkers that predict the efficacy of the anti-VEGF drug bevacizumab in primary glioblastoma ; a clinical trial to evaluate the efficacy of ACNU for malignant glioma ; drug and device development for photodynamic therapy with talaporfin sodium ; and drug discovery and clinical trials of tirabrutinib, a BTK inhibitor, in primary CNS lymphoma. Success is anticipated for these research undertakings, and the results are expected to benefit patients worldwide. However, Japanese researchers find themselves working under increasingly demanding conditions, and it is essential to improve the research environment to enable them to demonstrate their abilities fully. There is also a need to promote further international collaboration.

  There is hope for neural regeneration through stem cell-derived neural cell transplantation. In particular, the reconstruction of neural circuits has a different mode of action from that of conventional medical treatment or gene therapy and is expected to have more fundamental effects. However, there are many issues to overcome, such as producing appropriate donor cells, controlling neural connections after transplantation, and establishing tumor formation. Cell-based therapy has been developed mainly for Parkinson's disease, and transplantation of ES/iPS cell-derived dopaminergic neurons is already in clinical trials. In addition, developmental research for treating stroke is underway, and further developments using brain organoids are expected.

  Moyamoya disease (MMD) is a rare cerebrovascular disease with unknown etiology which is characterized by progressive stenosis at the internal carotid artery terminus and an abnormal vascular network formation at the base of the brain. Recent genetic analysis in East Asian patients identified RNF213 as an important susceptibility gene. The RNF213 c.14576G＞A (p. R4810K) variant was identified in approximately 80% of MMD patients in Japan. The variant was significantly correlated to disease onset at a younger age and the clinical severity. More recently, RNF213 appears to be associated with negative remodeling of the intracranial arteries, such as outer diameter narrowing and vessel wall thinning. Direct revascularization surgery prevents cerebral ischemic attack by improving cerebral blood flow. Recent evidence further suggested that direct revascularization reduces the risk of re-bleeding in MMD patients with posterior hemorrhage, who have extremely high annual re-bleeding rate. Intensive perioperative management should promptly avoid surgical complications including cerebral hyperperfusion syndrome and perioperative ischemia.

  Neonatal intracranial pial arteriovenous fistula is rare. Heart failure may occur in patients with high blood flow in the shunts. Cerebral hemorrhage, seizures, and focal cerebral symptoms can also occur. Congestive heart failure during the neonatal period can lead to death and must be urgently treated. However, no standardized treatment methods have been established. Transarterial embolization (TAE) and transvenous embolization (TVE) using coils and n-butyl cyanoacrylate (NBCA) have been performed in selected patients. We report a neonatal case of pial arteriovenous fistula treated with transarterial embolization using NBCA and coils.

  Common carotid artery occlusion with a patent ipsilateral internal carotid artery is a very rare condition, and revascularization is required in such cases.

  Here, we report the case of a 73-year-old man with diabetes mellitus in whom MR angiography and 3D-CT angiography showed that the left internal and external carotid arteries were patent but failed to visualize the left common carotid artery. Carotid ultrasonography demonstrated a very slow flow in the proximal portion of the left common carotid artery, rapid antegrade flow in the left internal carotid artery, and complete occlusion of the left common carotid artery near the bifurcation. Left carotid angiography showed the slow passage of the contrast material just proximal to the bifurcation of the left common carotid artery. Left vertebral angiography showed anastomosis between the muscle branches of the left vertebral artery and occipital artery. The left internal carotid artery was retrogradely visualized through the narrow space near the common carotid bifurcation. In this case, revascularization was performed using carotid endarterectomy without ischemic complications.

  Revascularization by carotid endarterectomy is possible even in cases of common carotid artery occlusion if the occluded portion is located near the bifurcation of the common carotid artery.