Increased abundance of Ruminococcus gnavus in gut microbiota is associated with moyamoya disease and non-moyamoya intracranial large artery disease.

Moyamoya disease (MMD) is a rare cerebrovascular disease endemic in East Asia. The p.R4810K mutation in RNF213 gene confers a risk of MMD, but other factors remain largely unknown. We tested the association of gut microbiota with MMD. Fecal samples were collected from 27 patients with MMD, 7 patients with non-moyamoya intracranial large artery disease (ICAD) and 15 control individuals with other disorders, and 16S rRNA were sequenced. Although there was no difference in alpha diversity or beta diversity between patients with MMD and controls, the cladogram showed Streptococcaceae was enriched in patient samples. The relative abundance analysis demonstrated that 23 species were differentially abundant between patients with MMD and controls. Among them, increased abundance of Ruminococcus gnavus > 0.003 and decreased abundance of Roseburia inulinivorans < 0.002 were associated with higher risks of MMD (odds ratio 9.6, P = 0.0024; odds ratio 11.1, P = 0.0051). Also, Ruminococcus gnavus was more abundant and Roseburia inulinivorans was less abundant in patients with ICAD than controls (P = 0.046, P = 0.012). The relative abundance of Ruminococcus gnavus or Roseburia inulinivorans was not different between the p.R4810K mutant and wildtype. Our data demonstrated that gut microbiota was associated with both MMD and ICAD.

A novel SREBF1::NACC1 gene fusion in an unclassifiable intracranial tumour.

A 39-year-old man had an intracranial tumour without infiltration into the surrounding cerebral tissue. The tumour recurred seven times in 11 years but maintained a well-demarcated character. Histopathological examination of the 4th surgical specimens showed nests of tumour cells surrounding small blood vessels. The tumour cells harboured amphophilic cytoplasm and small round nuclei with fine chromatin, and perinuclear haloes and clear borders were frequently observed, which was unclassifiable histology. By the Deutsches Krebsforschungszentrum methylation classifier, the tumour was not classified into any of the methylation classes. mRNA sequencing identified a novel SREBF1::NACC1 gene fusion. This intracranial tumour could be a novel tumour entity with NACC1 rearrangement showing characteristic histological and diagnostic imaging findings.

Lack of Association between Seropositivity of Vasculopathy-Related Viruses and Moyamoya Disease.

OBJECTIVES: Although the association between genetic factors, such as RNF213 mutations, and moyamoya disease (MMD) has been well investigated, environmental factors are largely undetermined. Thus, we aimed to examine whether viral infection increases the risk of MMD. MATERIALS AND METHODS: To eliminate the effect of presence or absence of the RNF213 p.R4810K mutation, the entire study population was positive for this mutation. We collected whole blood from 111 patients with MMD (45 familial and 66 sporadic cases) and 67 healthy volunteers, and we measured the immunoglobulin G titer of 11 viruses (cytomegalovirus, varicella-zoster virus, measles virus, rubella virus, herpes simplex virus, mumps virus, Epstein-Barr virus, human parvovirus B19, human herpesvirus 6 [HHV6], human herpesvirus 8, and John Cunningham virus) that were presumed to be associated with vasculopathy using the enzyme-linked immunosorbent assay. Positivity for past viral infection was determined by cut-off values obtained from previous reports and the manufacturer's instructions, and the positive rate was compared between cases and age- and sex-matched controls. We performed familial case-specific and sporadic case-specific analyses, as well as a case-control analysis. RESULTS: There was no significant difference in the positive rate between the case group and the control group in any of the analyses. A significant difference was only observed in the combined case-control analysis for HHV6 (p = 0.046), but the viral antibody-positive rate in control individuals was higher than in MMD cases. CONCLUSIONS: Our cross-sectional study suggest that the investigated 11 viruses including HHV6 are unlikely to have an impact on MMD development.

Thrombosis of Large Aneurysm Induced by Flow-Diverter Stent and Dissolved by Direct Factor Xa Inhibitor.

BACKGROUND: Antiplatelet agents are typically administered before and after treatment using flow-diverter stents (FDS) to prevent thrombotic complications, but the effects of anticoagulants are unclear. We present a patient with a giant aneurysm treated with an FDS. The thrombus within the aneurysm was dissolved when a direct factor Xa inhibitor was administered to treat lower limb venous thrombosis that occurred secondary to steroid use. CASE DESCRIPTION: A 60-year-old woman with a 30-mm giant thrombosed aneurysm in the cavernous segment of the right internal carotid artery presenting with headache and right abducens nerve palsy was treated by placing an FDS. Diplopia and increased pain in her right eye appeared on postoperative day 7, and both were alleviated by continuous oral administration of prednisolone. Angiography 3 months postoperatively revealed that the aneurysm thrombosis had progressed, and there were signs of healing. However, at the same time, lower limb venous thrombosis occurred, which was treated by continuous edoxaban. Six months after surgery, her headaches worsened and angiography showed that the aneurysm was again contrast enhanced and that the thrombus within the aneurysm had dissolved. After discontinuing edoxaban 9 months after surgery, the aneurysmal thrombosis had again rapidly progressed. CONCLUSIONS: Administration of a direct factor Xa inhibitor during healing after placing an FDS may cause dissolution of an existing thrombus; therefore factor Xa inhibitors must be used with caution.

A Case of Posterior Reversible Encephalopathy Syndrome After Surgical Clipping of Unruptured Cerebral Aneurysm.

BACKGROUND: Posterior reversible encephalopathy syndrome (PRES) is characterized by reversible edematous lesions on imaging examinations, along with symptoms of altered consciousness disorder and seizures. Various factors associated with PRES have been reported. However, we encountered a very rare case that developed after clipping surgery for unruptured cerebral aneurysm. CASE DESCRIPTION: A 74-year-old man with a history of hypertension presented with an unruptured right middle cerebral artery aneurysm and underwent cranial clipping surgery. After surgery, he developed consciousness disorder and epilepsy after delayed awakening from general anesthesia. Radiological examinations revealed multiple edematous lesions, strongly suggesting PRES, and excluding asymmetry consistent with the area of craniotomy. With conservative treatment, symptoms and radiological findings almost disappeared. Symptoms and imaging findings remaining at the area of craniotomy were attributed to the severe difference in cerebral perfusion pressure due to craniotomy. CONCLUSIONS: Based on the literature, this case was considered to represent PRES caused by rapid blood pressure fluctuations accompanying general anesthesia for clipping surgery. Practitioners must keep PRES in mind as a rare complication after clipping for unruptured cerebral aneurysms. PRES developing after craniotomy shows unilaterality and may become severe in the craniotomy area and leave sequelae.

Dural and Pial Arteriovenous Fistulas Connected to the Same Drainer in the Middle Cranial Fossa: A Case Report.

BACKGROUND: Dural arteriovenous fistulas (AVFs) in the middle cranial fossa are rare. Pial AVFs are similarly rare but differ from dural AVFs in that they derive their arterial supply from pial or cortical arterial vessels and do not lie within the intradural region. We report an extremely rare case of dural and pial AVF connected to the same drainer in the middle cranial fossa. CASE DESCRIPTION: In a 58-year-old man with a subcortical hemorrhage in the right temporal lobe, digital subtraction angiography showed a dural AVF in the middle cranial fossa fed by the middle meningeal artery (MMA) and draining into the sphenopetrosal vein. A combination with a small pial AVF connected to the same sphenopetrosal vein was suspected. Open surgery was performed to directly observe the shunt points. Transarterial indocyanine green (ICG) angiography using the MMA via the superficial temporal artery on a skin flap was performed to repeatedly and distinctly evaluate the dural shunt points and to prevent cerebral thromboembolism. Although the dural supply was completely disconnected, the sphenopetrosal vein remained arterialized. ICG angiography revealed pial AVF, which was fed by the cortical arteries draining into the same drainer. The pial supply was completely disconnected, and disappearance of the dural and pial AVF was confirmed. CONCLUSIONS: We report an extremely rare case of dural and pial AVF connected to the same drainer in the middle cranial fossa. To our knowledge, this is the first such case report described in the literature.