Neurological Surgery最新文献

The basics of meningioma surgery are represented in the '4Ds': Detachment, Devascularization, Debulking, and Dissection. When considering the 4Ds, surgical simulation using 3D images is useful, as it allows the surgeon to understand the 3D relationship between the tumor, feeding vessels, and surrounding tissues. However, the hardness of the tumor and the degree of adhesion between the tumor and surrounding tissue are difficult to determine based on 3D images, and must therefore be confirmed using MRI, such as T2-weighted images.

Meningiomas are the most common primary intracranial tumors. As the number of incidentally discovered meningiomas has increased with the widespread access and use of neuroimaging, treatment strategies for meningiomas have become more important. Close observation is the first choice for asymptomatic lesions; however, the natural history of meningiomas remains unclear. It is necessary to recognize the characteristics of meningiomas that are likely to grow, such as high signal intensity on MRI T2WI. It is also important to examine the growth rates and patterns using multiple neuroimaging examinations during the follow-up period. The authors suggested a relationship between the various observed growth patterns and the length of the follow-up period based on the assumed development of tumor volume. Less than 10% of patients with asymptomatic meningiomas develop symptoms and require treatment. However, it remains unclear which lesions become symptomatic, and further studies are required. Lesions with a sustained growth pattern undergo preventive treatment interventions, but the need for and appropriate timing of these interventions are continuously under debate. Further studies will help elucidate the natural history of meningiomas.

Meningiomas constitute the most common primary tumors of the central nervous system. Despite maximum treatment, grade 2/3 meningiomas are associated with a high risk of recurrence. Stereotactic radiosurgery is the treatment of choice as adjuvant treatment for grade 2/3 meningiomas. Currently, pharmacotherapies, including molecular targeted therapy for various growth factors, their receptors, and the associated pathways, have shown limited effectiveness for management of refractory or recurrent meningiomas. Therefore, novel systemic treatment approaches are urgently required in such cases. Recent advances in genetics and epigenetics and the identification of specific genetic alterations have led to new classifications of these tumors and the development of therapeutic targets. Identification of targeted gene mutations may lead to precision-based medicine. Other therapeutic approaches such as immune checkpoint inhibitors rarely elicit a significant response in meningiomas with a high tumor mutation burden. Combination therapies that affect these multiple targets are also considered adjuvant therapeutic options. Comprehensive/in-depth research is warranted to investigate the safety and efficacy of other treatment strategies, including chimeric antigen receptor T-cells, oncolytic virus immunotherapy, and gene therapy. In this article, we review the current evidence regarding the efficacy of systemic treatments available in the literature and discuss recent and ongoing trials for meningiomas.

Patients with parasellar meningiomas often initially present with visual impairment. Understanding the surrounding anatomy is essential when preparing for surgery of parasellar meningiomas, as this region includes various crucial neurovascular structures. Historically, invasive craniotomy, such as the orthozygomatic approach or zygotomy, has often been attempted to access the region; however, the use of these invasive approaches has become less common, because of the accumulation of anatomical knowledge, as well as the development of surgical techniques and devices, including the endonasal endoscopic approach. Herein, we summarize how we perform surgery for parasellar meningiomas, and outline tips and pitfalls that could be useful for young residents and trainees who are new to the skull base field.

The need for resection of the meningioma capsule has long been debated and remains controversial. Even the definition of a capsule does not seem to have been established. We described the histopathological findings of the so-called capsule and the necessity for resection, considering tumor cell invasion and recurrence, based on a literature review.

Malignant forms of meningioma, such as atypical and anaplastic meningiomas, commonly relapse. Recently, there have been many reports elucidating the molecular biological mechanisms underlying meningioma recurrence. Tumors with loss of CDKN(cyclin dependent kinase)2A and 2B or lack of the tri-methylation of lysine 27 on histone H3 protein have a particularly high recurrence rate. In general, primary treatment for recurrent meningiomas comprises stereotactic radiosurgery(SRS)or stereotactic radiotherapy(SRT). However, re-operation is recommended for SRS-, SRT-refractory tumors. One of the benefits of reoperation is that it allows tumor control while decompressing the normal tissue, and changing the tumor microenvironment. Another is that it facilitates the acquisition of pathological and molecular genetic information, which can enable clinicians to recommend precision medicine. However, during reoperation, it is often difficult to detach the tumor from the surrounding brain tissue and cranial nerves because of severe adhesion. In cases of malignant meningiomas with multiple relapses, it is important to share the purpose and goal of the surgery with the patients and their families. In other words, which is being prioritized more, a high resection rate or functional outcomes? Furthermore, salvage surgery should also be a consideration.

During surgery for meningioma, basic surgical techniques and strategies required for the removal of the tumor are common, particularly for tumors located superficially, such as convexity, parasagittal, and falx meningiomas. Four basic surgical techniques, including detachment; devascularization; debulking; and dissection should be combined and repeated in appropriate sequence, tailored to the specific conditions of each tumor. This eventually enables the total circumferential dissection of the tumor from the surrounding tissues. It is essential to retract the tumor towards the space created at the tumor center through internal debulking, rather than retracting the normal brain, to avoid damage to the surrounding brain tissue. During surgery for parasagittal meningioma with venous sinus occlusion, it is crucial to preserve the cortical veins that have developed as collateral pathways to prevent venous complications. During surgery for falx meningioma, the selection of a surgical approach including a contralateral approach based on factors such as the development of bridging veins and significant peritumoral brain edema is required. In this article, detailed surgical procedures for convexity meningioma, parasagittal meningioma, and falx meningioma were described focusing on the application of fundamental surgical techniques tailored to each tumor type.

Recent advancements in endoscopic transnasal surgery(ETS)have expanded the application of this technique to meningiomas in the central skull base area, offering a less invasive alternative with a potentially lower physical burden on patients than conventional microscopic skull base surgery. Notably, while ETS allows surgeons to reach tumors without traversing the brain and nerves, thus theoretically reducing the risk of cranial nerve damage, it requires a high level of proficiency to avoid inadequate resection and tumor recurrence. In this article, we discuss the various surgical considerations, including preoperative imaging, surgical setting, nasal cavity expansion, skull base opening, tumor removal, and skull base reconstruction, as general procedures for specific meningiomas. We further describe the concept and details of our multi-layer fascial closure technique for dural repair in ETS, underlining the importance of skilled dural reconstruction in preventing postoperative complications. In conclusion, while ETS for skull base meningiomas presents a promising and less invasive treatment option, its success relies heavily on the surgeon's experience and understanding of the skull base anatomy, stressing the need for careful approach selection.

Meningiomas, renowned for their histological diversity, are one of the most prevalent brain tumors. Some meningiomas show unusual histomorphology, especially in intraoperative rapid diagnosis. Therefore, clinical and radiological information is crucial for pathological diagnosis. Before the 2021 World Health Organization Classification of Tumors of the Central Nervous System(5th edition), pathological diagnosis relied solely on histopathological features. However, this classification introduced new diagnostic criteria for anaplastic meningiomas, which now include TERT promoter mutations and the homozygous deletion of CDKN2A/B, indicating the necessity of genetic analysis. Some rhabdoid and papillary meningiomas have BAP1 alterations, which tend to demonstrate an aggressive clinical course and may represent a phenotype of BAP1-related tumor predisposition syndrome. Heterozygous deletion of CDKN2A/B and loss of H3 p.K28me3(K27me3)are also associated with poor prognosis. Although some immunohistochemical markers like MTAP may serve as surrogates for the homozygous deletion of CKKN2A/B, genetic analysis is required to confirm TERT promoter mutations. Therefore, in routine clinical practice, neurosurgeons and pathologists prioritize appropriate formalin fixation to facilitate genetic analysis using pathological specimens.

The frequency of identification of asymptomatic meningiomas is increasing owing to the advancement and widespread use of CT and MRI. The first choice for asymptomatic meningiomas is observation. Approximately 70% of asymptomatic meningiomas increase in volume on long term follow-up. More than half of them reportedly exhibit a self-limiting pattern, in which growth eventually stops. Imaging findings related to increased meningioma volume include no calcification, large tumor size, high signal intensity inside the tumor on T2-weighted images, high brightness within the tumor on diffusion-weighted images, and perifocal edema. We also highlighted the presence of hypo-intensity of the surface layer on T2-weighted imaging, indicating growth arrest in a self-limiting growth pattern of meningioma. In this article, literature reports on image prediction using CT and MRI regarding the growth of asymptomatic meningiomas were reviewed, along with our report.