Neurological Surgery最新文献

Facial nerve schwannomas (FNSs) are rare, benign tumors that can arise along segments of the facial nerve, including the cerebellopontine angle, internal auditory canal, middle fossa, and temporal bones. Although traditionally managed with gross total resection and facial nerve reconstruction, the resulting facial nerve palsy has prompted a paradigm shift toward functional preservation. Based on>70 surgical cases, we established a tailored strategy based on preoperative facial nerve function and intraoperative facial nerve electromyograms. Patients with mild-to-moderate palsy underwent facial nerve preservation surgery with subtotal resection and osseous decompression under continuous intraoperative monitoring to preserve and improve facial nerve function. Patients with severe palsy underwent total resection with nerve reconstruction. We proposed a practical five-type classification based on the primary tumor location to guide the surgical approach. Cerebellopontine angle-type FNSs may present without facial symptoms, mimicking vestibular schwannomas, particularly if the labyrinthine segment or geniculate ganglion is not involved. In such cases, radical resection should be avoided to ensure functional preservation. To balance long-term tumor control with optimal facial nerve function, comprehensive surgical expertise is required, including detailed anatomical knowledge, diverse skull-base approaches, intraoperative monitoring, nerve reconstruction techniques and flexible surgical planning that allows for intraoperative modification.

Moyamoya disease(MMD) is a rare cerebrovascular disease characterized by progressive stenosis of the internal carotid artery terminus and an abnormal formation of a vascular network at the base of the brain. Superficial temporal artery-middle cerebral artery(STA-MCA) bypass, either as a direct or combined revascularization procedure, is a reasonable management choice for patients with symptomatic MMD. STA-MCA bypass prevents cerebral ischemic attacks by improving cerebral blood flow. Recent evidence further suggests that direct revascularization reduces the potential risk of rebleeding in patients with MMD with posterior hemorrhage who have an extremely high annual rebleeding rate. Despite the favorable long-term outcomes of STA-MCA bypass, cerebral hyperperfusion syndrome is a potential complication of this procedure that can result in focal neurologic deficits and/or delayed intracerebral hemorrhage. Therefore, recent guideline recommendations indicate that STA-MCA bypass is a reasonable choice for symptomatic patients with MMD, together with intensive perioperative care for blood pressure control.

We reviewed the historical aspects of the diagnostic criteria for moyamoya disease since 1978. Based on novel knowledge of moyamoya disease, the diagnostic criteria have been revised in 1988, 1995, 2009, 2015, and 2021. The most recent diagnostic criteria emphasize the importance of arterial shrinkage, which can be observed in moyamoya disease, and have also reorganized the critical comorbid disorders of quasi-moyamoya disease(moyamoya syndrome). We also discussed the future perspectives on the diagnosis of moyamoya disease.

Genetic research on moyamoya disease(MMD) has advanced significantly following the identification of RNF213 as a susceptibility gene. Approximately 80% of Japanese patients with MMD harbor the RNF213 p.Arg4810Lys variant, which has been increasingly linked to variations in clinical phenotypes, including disease progression, mode of onset, and postoperative outcomes. Of note, this variant is also associated with intracranial arterial stenosis that does not meet the diagnostic criteria for MMD, as well as with systemic vascular conditions such as non-cardioembolic ischemic stroke, coronary artery disease, and pulmonary hypertension. Despite its strong association with the disease, the p.Arg4810Lys variant is present in approximately 2% of the general population, suggesting incomplete penetrance and the involvement of additional pathogenic factors. In parallel, researchers have examined the clinical relevance of RNF213 variants other than p.Arg4810Lys and have identified rare mutations that may contribute to disease severity. Moreover, large-scale genetic analyses have identified additional susceptibility genes, such as DIAPH1 and ANO1, whose roles in MMD pathogenesis remain under investigation. Although substantial advances have been made in elucidating the genetic architecture of MMD, the precise mechanisms underlying disease onset remain elusive and represent an important area of ongoing research.

Emerging evidence obtained as a result of recent advancements in non-invasive diagnostic modalities indicates that the incidence of asymptomatic moyamoya disease may be much higher than previously reported. However, there are currently no established guidelines for managing asymptomatic moyamoya disease because of the lack of sufficient information regarding its clinical features, prognosis, and treatment strategies. To address these issues, we conducted a multicenter prospective cohort study, the Asymptomatic Moyamoya Registry(AMORE), in Japan. The interim analysis of the AMORE revealed that affected hemispheres may carry a 1.0% annual risk of stroke, mainly hemorrhagic stroke, in asymptomatic moyamoya disease. Grade-2 choroidal anastomosis was found to be an independent predictor of stroke, whereas microbleeds and Grade-2 choroidal anastomosis were independent predictors of hemorrhagic stroke. The annual risk of disease progression, transient ischemic stroke(TIA), and de novo microbleeds were 5.9%, 2.3%, and 2.3%, respectively. Younger age and hypercholesterolemia were predictors of disease progression; disease progression prior to TIA was a significant predictor of TIA, and microbleeds at the time of enrollment were significant predictors of de novo microbleeds. Further research on the impact of genetic mutations and cerebral hemodynamics on the prognosis of asymptomatic moyamoya disease is warranted.

The p.R4810K variant of the RNF213 gene was identified as the founder variant of East Asian moyamoya disease. The association of the p.R4810K variant with non-moyamoya intracranial arterial stenosis has been demonstrated, and the concept of RNF213-related vasculopathy has been proposed, suggesting a continuous spectrum of moyamoya disease. Additionally, moyamoya disease is occasionally accompanied by polyvascular disease involving intracranial and neck vessels, coronary arteries(especially vasospastic angina), pulmonary arteries, aorta, abdominal visceral arteries, and peripheral arteries, which are associated with RNF213 variants, mainly p.R4810K. The severity of vascular diseases caused by the RNF213 variant is inconsistent, and some environmental and genetic factors are believed to jointly define the phenotype. RNF213 variants confer the greatest risk of cardiovascular diseases in East Asia. Therefore, successful targeting of these variants is essential for controlling cardiovascular diseases, including stroke, in East Asian countries.

Rare RNF213 variants other than p.R4810K(rs112735431) have been identified in Asian and European patients with moyamoya disease. Several studies have consistently demonstrated that putative functional variants are significantly more prevalent in patients than in the general population, with the aid of bioinformatics tools, such as Combined Annotation-Dependent Depletion. Among these rare susceptibility variants, p.R4062Q(rs1555676035) has been repeatedly reported in severe pediatric cases with moyamoya disease. Three-dimensional structural analysis suggested that this may cause a loss of polar contact with the D4003 residue, leading to instability of the E3 ligase module in RNF213. Rare susceptibility variants tend to accumulate in this E3 module in pediatric cases, which may influence the severity of the clinical manifestations. Further research, including in vitro and in vivo functional analyses of the variants, is required to develop precision medicine.

Currently, no randomized clinical trials have investigated the use of antiplatelet drugs to prevent stroke in patients with Moyamoya disease(MMD). Notably, most of these studies were retrospective observational or prospective with small cohorts. Although the effectiveness of antiplatelet drug administration for ischemic MMD is limited, patients with microembolic signals detected using transcranial Doppler ultrasound may benefit from the prevention of cerebral infarction. There are no data that the administration of antiplatelet drugs increases the risk of hemorrhagic stroke in patients with MMD. However, administration of antiplatelet drugs may increase the patency rate of bypass blood vessels after bypass surgery. Among antiplatelet drugs, cilostazol has a clinically beneficial effect in patients with MMD through its multifaceted effects, such as increasing cerebral blood flow and inhibiting cognitive decline.

Moyamoya disease is a chronic cerebrovascular disorder characterized by progressive stenosis or occlusion of the terminal portion of the internal carotid artery around the circle of Willis, thereby forming fragile collateral vessels(moyamoya vessels). Although ischemic symptoms predominate in pediatric cases, adult cases often involve ischemic and hemorrhagic events. Surgical revascularization effectively improves long-term outcomes; however, perioperative complications, such as ischemic events, hyperperfusion syndrome, and hemorrhagic complications, remain challenging. Perioperative management aims to minimize the risk of ischemia and hemorrhage by stabilizing blood pressure, maintaining fluid and electrolyte balance, and implementing optimal ventilation strategies. Intraoperative management aims to prevent ischemic events by ensuring careful hemodynamic and respiratory monitoring and maintaining adequate cerebral perfusion during bypass procedures. Postoperative care emphasizes the early detection and management of hyperperfusion syndrome using imaging modalities, such as PET and SPECT, together with tailored blood pressure control and pharmacological interventions. Meta-analyses and systematic reviews have underscored the importance of selecting the appropriate surgical technique(direct, indirect, or combined bypass) to minimize complications. Although combined bypass techniques may offer long-term outcomes, particularly in pediatric patients, individualized management strategies are essential to address the complex perioperative risks associated with moyamoya disease. Further research is needed to refine surgical approaches and optimize patient outcomes.

Pregnancy and delivery management in patients with moyamoya disease requires careful attention because of the increased risk of cerebrovascular events. Prepregnancy evaluation, including radiological imaging, neurological assessment, and medication adjustment, is essential. During pregnancy, blood pressure(BP) should be monitored closely to prevent complications, because patients are prone to developing high BP. Delivery should be planned based on the patient's cerebrovascular condition, with vaginal delivery under epidural analgesia management or cesarean section in high-risk cases. Postpartum care includes managing BP and monitoring stroke symptoms. Multidisciplinary collaboration between obstetricians, neurologists, and anesthesiologists is crucial for optimizing outcomes.