Neurological Surgery最新文献

For treating ruptured cerebral aneurysms, it is important to understand the setup and basic technique of coil embolization. Safe and effective embolization relies on preoperative considerations that determine the treatment strategy, guide the optimization of the therapeutic environment, and help in the selection of appropriate device systems. Moreover, during aneurysmal embolization, basic techniques for microcatheter shaping and navigation, safe coil introduction, and precise use of occlusion balloons are indispensable. Microcatheter shaping should be based on three-dimensional digital subtraction angiography findings as well as the axes of the parent artery and aneurysm. The operator must understand the advantages and disadvantages of the two methods for navigating the microcatheter into the aneurysm. Furthermore, it is essential to preoperatively simulate and understand the approaches for managing aneurysmal embolization-related complications, such as intraoperative aneurysmal rupture and thromboembolism. Mastery of these steps is mandatory before undertaking embolization of ruptured cerebral aneurysms.

The debate regarding the role and clinical impact of radiotherapy for meningiomas remains underdeveloped due to insufficient evidence. However, following recent revisions in the WHO classification and the integration of molecular diagnostics, there has been a substantial shift in the stratification of recurrence risks. Nevertheless, the specific circumstances under which radiotherapy proves crucial remain unclear. As risk stratification becomes more refined, the effectiveness of radiotherapy in treating high-risk meningiomas continues to be a contentious issue. Concurrently, there is vigorous discussion regarding the management of 'brain invasion in otherwise benign'(BIOB)meningiomas. The incorporation of PET imaging alongside MRI for defining radiation targets is increasingly acknowledged as advantageous. Boron neutron capture therapy(BNCT), which specifically targets the biological characteristics of tumor cells in invasive regions, is also gaining significant traction as a promising therapeutic approach for meningiomas with infiltrative components.

The jugular foramen, also known as the foramen magnum, is a highly intricate region of the skull base through which numerous critical blood vessels and nerves traverse. Meningiomas, the most common tumors in neurosurgical pathology, can arise at any location where the meninges are present, posing significant challenges. Meningiomas involving the jugular foramen and sublingual neural tube are particularly notable for their potential to extend from intracranial to extracranial sites, necessitating familiarity with extracranial anatomy, which is not typically encountered in clinical practice. A comprehensive understanding of anatomical characteristics, along with an ample field of view and working space, is crucial for handling the cerebellum, brainstem, and nerves meticulously. The use of surgical support tools such as neuromonitoring and navigation is essential for enhancing the safety of the procedure. Furthermore, preparedness for treatment options, rehabilitation, and adjunctive therapies is vital in the event of neurological symptoms such as those affecting the glossopharyngeal, vagal, or hypoglossal nerves.

Biological molecular studies of meningiomas have also developed with the development of molecular biological methods. In 2013, Clark et al. reported that driver genetic mutations other than NF2, including TRAF7, KLF4, AKT1, and SMO, were associated with meningioma development. In 2017, Sahm et al. proposed a classification of meningiomas based on global methylation status, which was more accurate in predicting prognosis than conventional WHO grading. In 2022, based on this classification, various groups reported an integrated classification that comprehensively included some biological molecular abnormalities, such as DNA mutations, copy number alterations, and RNA sequences. This field is expected to elucidate the mechanism of meningioma development and further research is expected to lead to the development of effective molecularly targeted therapeutics and biomarkers of radiosensitivity in the future. In this article, we summarize the current status and prospects of these biological molecular studies.

Most meningiomas are benign, slow growing tumors, which rarely progress to a higher grade. The incidence rate of malignant progression is estimated to be 2.98/1000 patient-year. However, non-skull base location is a significant risk factor for progression. The median time to malignant progression is 4.3 years; however, the cumulative rate of progression approaches a plateau after 10 years. Although radiosurgery does not appear to increase the incidence rate(0.5/1000 patient-year), exact comparisons have been difficult because of differences in study populations. The median time to progression is 7.0 years from initial diagnosis and 5.0 years from radiosurgery. The cumulative rate appears to increase even after 10 years. The risk of malignant transformation after radiotherapy may increase in patients with tumor-prone syndromes, with some controversies regarding patients with neurofibromatosis type 2. Although short term follow-up in patients with meningioma suggests that radiosurgery is safe, there is uncertainty regarding its use in pediatric patients, and those with tumor-prone syndromes.

Preoperative embolization(POE)of intracranial meningioma is performed worldwide. Although clear evidence of the effectiveness of POE has not been reported in the literature, the technique plays an important role in open surgery, especially for large or skull base meningiomas. The purposes of embolization include: 1)induction of tumor necrosis, resulting in a safer operation, 2)reduction in intraoperative bleeding, and 3)decrease in operative time. Knowledge of the functional vascular anatomy, embolic materials, and endovascular techniques is paramount to ensure safe embolization. Our standard procedure is as follows: 1)embolization is performed several days before open surgery; 2)in cases with strong peritumoral edema, steroid administration or embolization may be performed immediately prior to surgery; 3)patients undergo the procedure under local anesthesia; 4)the microcatheter is inserted as close as possible to the tumor; 5)particulate emboli are the first-line material; 6)embolization is occasionally performed with N-butyl cyanoacrylate(NBCA)glue; and 7)if possible, additional proximal feeder occlusion with coils is performed. The JR-NET study previous showed the situation regarding intracranial tumor embolization in Japan. Endovascular neurosurgeons should fully discuss the indications and strategies for POE with tumor neurosurgeons to ensure safe and effective procedures.

The concept of translational research, which emphasizes the importance of applying research findings to clinical practice, was first introduced in the early 21st century. Since then, Japan has actively promoted translational research through government and academic institutions, fostering collaboration between basic scientists and clinicians. Despite this, Japan's academic competitiveness has declined globally, particularly in fields such as neurosurgery, due to unique training systems and reduced time for research and education amidst physician work reforms. Herein, we discuss the significance of academic pursuits among clinicians, particularly in Japan's neurosurgery landscape, alongside future challenges.

In contrast to other cancer research areas, the development of chemotherapy and radiotherapy for meningiomas has been challenging, lacking standardized criteria for assessing treatment response and progression. Although efforts by RANO have proposed evaluation criteria, a consensus on effective evaluation parameters for meningiomas remains elusive. This paper underscores the importance of establishing efficacy endpoints in clinical trials, compares efficacy assessment in meningioma research with other solid tumor areas, and outlines the challenges ahead in meningioma research. Recent analyses revealed the absence of consensus on efficacy endpoints in meningioma trials, complicating trial design and hindering cross-trial comparisons. The unique anatomical constraints and histological variability of meningiomas pose challenges in determining appropriate efficacy measures. To address these challenges, future research must focus on accumulating prognostic data, standardizing evaluation criteria, and considering multiple endpoints in trial designs. Akin to other cancer areas, investigating targeted therapies and establishing international consensus on efficacy endpoints are crucial steps forward.

Recent advances in endovascular treatment have improved the safety and efficacy of this procedure, and the number of cases in which preoperative embolization is performed is likely to increase. Preoperative tumor embolization is still a controversial treatment, and as long as it carries a risk of complications, its primary benefit of reducing blood loss during surgery may not be sufficient to justify treatment. We recently reported that preoperative embolization does not significantly increase complications, but may prolong recurrence-free survival. However, currently, tumor embolization is only a preoperative adjunctive therapy, and there is no evidence that it is a stand-alone option for meningioma treatment. Nevertheless, the possibility that tumor embolization alone can promote tumor shrinkage and reduce peripheral oedema has been reported, although the number of cases is small. Further research is needed, but in the future, tumor embolization may become an in-office treatment under certain conditions, such as in cases of poor general condition, multiple meningiomas, recurrent and refractory cases, difficult surgery and cases where re-irradiation is difficult after post-radiation therapy.

Considering that most meningiomas are pathologically benign, tumors located in the cerebellopontine angle and petroclival area should be reduced as much as possible, and radiation therapy should be administered if necessary. Consequently, relatively good preservation of cranial nerve function and local lesion control can be expected. However, because the lesions are generally located deep, and are surrounded by various important structures, performing surgical procedures is difficult, and careful management of the surgical strategy is important to avoid complications. Surgical outcomes have dramatically improved with the development of skull base and microsurgical techniques. The main surgical approaches for cerebellopontine angle meningiomas and petroclival meningiomas currently include the anterior and posterior combined transpetrosal, anterior transpetrosal, and lateral suboccipital approaches. Furthermore, with the recent developments in endoscopic surgery, minimally invasive surgery for skull base meningiomas has gradually been introduced. In this article, we explain the preoperative checkpoints, selection of the surgical approach, and surgical techniques for the resection of cerebellopontine angle meningiomas and petroclival meningiomas.