A meningioma is the most common benign tumor in the central nervous system. Asymptomatic small (<2 cm) meningiomas should be treated conservatively, whereas symptomatic large (>3 cm) tumors and asymptomatic tumors with rapid growth must be removed surgically or treated with radiation therapy. During surgery, surgeons should determine the ideal dissection plane to prevent injury to surrounding structures. If the meningioma has a capsule, it should be removed with subcapsular dissection because there are no tumor cells inside the tumor capsule. Radiation therapy, particularly stereotactic radiosurgery (SRS), is a proven alternative to surgical removal for small benign meningiomas, and the outcomes of subtotal resection with adjuvant SRS are comparable with those of gross total resection. In addition, gross total resection is desirable for atypical and malignant meningiomas, and postoperative adjuvant radiation is necessary for subtotally resected atypical meningiomas and malignant (World Health Organization [WHO] grade Ⅲ) meningiomas in any Simpson grades. In elderly patients, the treatment strategy must be much more individualized depending not only on age but also on frailty assessed by the meningioma-specific scoring system (e. g., SKALE score). Recent molecular analyses have demonstrated that molecular classification is a predictor of postoperative progression, and it is a more precise predictor than the WHO histological grade. In the near future, molecular diagnosis may become essential, and it will bring a paradigm shift in the treatment of meningioma.
Transnasal surgery for pituitary adenoma has become much more effective since the introduction of endoscopy. Endoscopic surgery facilitates wider removal of skull base bone and improves surgical freedom. Endoscopy can provide visual confirmation of the boundary between the pituitary adenoma capsule and the surrounding tissues, thus enabling extracapsular removal, which is widely used at present. Although improvement of visual function is the main goal of treatment for nonfunctioning adenomas, large multilobular pituitary adenomas carry particularly high risks for surgery, necessitating further improvements in treatment strategies. On the other hand, endocrinological cure is the main goal of treatment for functional adenomas. Expertise in medical therapy, including cooperation with endocrinologists and radiation oncologists, is also essential for successful treatment of these tumors. Surgical indications and treatment strategies should be based on adequate knowledge and experience with endonasal surgical methods and endocrinology.
[Purpose] To summarize the surgical indications and strategies for hemangioblastoma. [Methods] The subjects were 79 consecutive patients with hemangioblastoma who underwent surgery between 1996 and 2017. There were 11 cases of hemangioblastoma of the medulla oblongata, five cases of hemangioblastoma of the endolymphatic sac, 13 cases of hemangioblastoma of the spinal cord, and 50 cases of hemangioblastoma of the cerebellum. There were 24 patients (31%) with von Hippel-Lindau disease. Visualization of the vascular anatomy of both the feeders and the drainers of hemangioblastomas by preoperative three-dimensional computer graphics image (3DCG) has been used jointly since 2010. [Indications for treatment] Surgery is recommended even in the absence of symptoms for spinal cord tumors that are 1 cm or more in diameter or are enlarging. In principle, we recommend “wait and see” for asymptomatic tumors of the cerebellum. If they become symptomatic, surgery is indicated. However, we recommend intervention for cerebellar tumors, even though asymptomatic, if they are 2 cm or more in diameter or for cerebellar tumors or cysts that show rapid enlargement on serial imaging. Asymptomatic tumors that are located on the surface of the brainstem are also considered for early surgery. (VHL Clinical Practice Guideline 2016) [Surgical strategy] 3DCG is useful for determining the number, location, and course of perforating vessel-type feeders and drainers of hemangioblastomas. 3DCG is also effective for preoperative determination of the proximity of the lesion to the pyramidal tract, spinothalamic tract, and spinocerebellar tract.
Various histological tumors occur in the lateral and third ventricles, and they are usually slow-growing tumors. Representative lateral intraventricular tumors include central neurocytoma, ependymoma, subependymoma, choroid plexus tumor, subependymal giant cell astrocytoma, and meningioma. Representative third ventricular tumors include chordoid glioma, craniopharyngioma, optic pathway glioma, germinoma, and pineal tumors. Treatment strategies need to be determined by tumor histology, and a consensus has not been reached for the treatment of some types of tumors. There are some discussions about whether complete tumor removal needs to be pursued or whether surgical decompression followed by adjuvant therapy should be considered because these tumors are located deep in the brain or close to the vital neurovascular structure. Recently, new treatment modalities, such as neuroendoscopy and stereotactic radiosurgery, have been introduced, and the treatment options for these tumors have thus widened. In this article, the authors present an overview of the current status of the treatment for representative lateral intraventricular and third ventricle tumors and discuss further problems to be solved in the future.
The rate of long-term tumor control after stereotactic irradiation (STI) for vestibular schwannomas exceeds 90%. However, transient enlargement and associated symptoms occur within 2 years after treatment in 20% of cases. Early intervention is considered appropriate for preservation of hearing. Early intervention is also appropriate to obtain symptomatic improvement in cases of nonvestibular schwannoma. Stereotactic irradiation is effective against meningioma, although the optimal timing of intervention for meningioma is still controversial. Next to STI, tumor size is the most important factor for the control of both schwannomas and meningiomas.
A 36-year-old woman suffered from a sudden onset of consciousness disturbance and left hemiparesis. Fifteen days later, the latter symptom persisted. Arterial spin labeling (ASL) imaging revealed hyperperfusion in the right cerebral hemisphere and hypoperfusion in the left cerebellar hemisphere when compared with the left cerebral hemisphere and the right cerebellar hemisphere, respectively. Electroencephalography showed an abnormal slow wave in the right cerebral hemisphere. When the left hemiparesis improved on the 43th hospital day, hyperperfusion in the right cerebral hemisphere and left-to-right cerebellar asymmetry on ASL imaging resolved. The patient might be suspected of having nonconvulsive status epilepticus with transient focal hyperperfusion in the cerebral hemisphere and crossed cerebellar hypoperfusion.