Objective : Meningioma is the most common brain tumor. Surgery is the treatment of choice when the tumor is symptomatic and larger than 3cm ; however, it is sometimes challenging, especially when important perforators or cranial nerves are either related to or affected by the tumor. Herein, we summarize our surgical strategy for meningiomas at our institution and review the current research focusing on the intracellular mechanism of development of the tumor.
Methods : Review of recently published studies on meningioma and case presentations at our institution.
Results : In our surgical strategy, the identification of feeding arteries to meningioma with virtual-reality three-dimensional fusion images constructed from multimodality images is crucial to minimize intraoperative bleeding and to ease the following procedures. Recent progress in intracellular mechanisms, such as epigenetics and transcription factors, is enormous. Genetic mutations in NF2, TRAF7, KLF4, AKT1, and SMO have been reported, some of which are reported to be specific locations or pathological types. A new classification of meningioma, besides the WHO classification, based on epigenetics or transcription factors, has been reported with promising results. Based on these studies on the intracellular mechanism of meningiomas, a chemotherapy regimen has also been reported.
Conclusions : Understanding the vascular construction of meningiomas on a case-by-case basis is important for surgical strategy. Research on intracellular mechanisms is marking an epoch whose findings can lead to a new classification of the tumor as well as treatment.
In 2017, the World Health Organization re-classified pituitary adenomas based on hormone-producing ability and pituitary adenohypophyseal cell lineage. Non-functioning pituitary adenomas account for approximately half of all said tumors, often presenting as visual acuity and visual field disturbances. Currently, no effective pharmacologic therapy has been established for non-functioning pituitary adenomas. Therefore, surgical treatment is the first line of treatment, with endoscopic surgery becoming the mainstream choice. The simultaneous combined supra- and infrasellar approach is effective in treating giant pituitary adenomas, while stereotactic radiotherapy is effective in residual and recurrent tumors. Non-functioning pituitary adenomas are benign tumors with a promising long-term prognosis, and appropriate hormone replacement is required to maintain the patient's quality of life.
Functioning pituitary adenomas cause various clinical manifestations due to excess hormones secreted by the tumor. The prevalence is, in order, prolactinoma, acromegaly, and Cushing disease. Surgical treatment is the treatment of choice, except for prolactinoma, while medical therapy is for the patients without endocrinological remission after surgery. Dopamine agonists and somatostatin analogs are the major tumor-target medications, as those receptors are expressed on the majority of the adenoma cells. Also, end-organ-target medications are used as adjuvant therapy for biochemical control.
Prolactinoma is the most common subtype of functioning pituitary adenomas. Some pitfalls exist in the diagnosis, including non-tumor causes of hyperprolactinemia, macroprolactinemia, hook effect, and possibility of plurihormonal adenoma. Medical treatment with dopamine agonists can achieve tumor shrinkage and hormonal control in a majority of patients. The goal of treatment in prolactinoma is different, depending on the patient's age, sex, and situation. Surgical treatment might be considered positively for macroadenoma in young women in whom strict hormonal control will be required.
Dopamine agonists, first and second generation of somatostatin analogs, and GH receptors antagonist are used as medical therapy for acromegaly. Through combinations of those medications as well as recent advancements in surgery, the control rate of IGF-1 has been improved. More “certainty” and “safety” will be required for surgical treatment of acromagely.
Same as acromegaly, surgical treatment is the first choice for Cushing disease. Dopamine agonists and second generation somatostatin analogs as tumor-target medications, and inhibitors of adrenal steroidogenesis or antagonists of glucocorticoid receptors as adjuvant end-organ targets are used as medical treatment. However, the disease control rate is not satisfactory. The presence of MRI-invisible adenoma is an unsolved problem and new imaging modalities are expected.
Some new medical therapies are in development (undergoing clinical trials), including from molecular-target drugs for tumor control to end-organ targeted selective estrogen receptor modulators as adjuvant therapy. Although those medical treatments will progress, surgery is the ideal modality and mainstay of treatment. The future direction will be to maximally remove the tumor and select an effective adjuvant therapy based on the characteristics of the receptor and gene expression.
We have reviewed the recent advances in untreated vestibular schwannoma, hearing preservation after treatment, and stereotactic radiosurgery for postoperative tumor remnants. In small- and medium-sized untreated vestibular schwannomas, the reported incidence of tumor growth varies widely from 17% to 69%, probably because of the different definitions for growth. Tumor size at the initial diagnosis, dysequilibrium, short-term hearing loss, presence of cystic component, and the length of time between the onset of symptoms and diagnosis have been reported as risk factors for tumor growth. Tumor growth is observed within 1-2 years after diagnosis, and frequent follow-up magnetic resonance imaging is required in the early stages. Large tumor volume, hearing loss at diagnosis, and high tumor growth rate have been reported as the risk factors for hearing loss during follow-up. The risk of future hearing deterioration should be considered at the time of diagnosis. Hearing preservation is achieved in 39-87% of the patients with vestibular schwannoma following stereotactic radiosurgery. Good hearing status before treatment is a favorable prognostic factor. Early intervention is required for successful hearing preservation. A large residual tumor volume is a risk factor for postoperative residual tumor growth ; therefore, a planned stereotactic radiosurgery would a reasonable choice.
Craniopharyngiomas are regarded as particularly challenging tumors for safe and complete removal due to their anatomical location and proximity to vital neurovascular structures. Therefore, in several articles, partial tumor removal followed by radiotherapy is recommended to avoid perioperative complications. These reports present sufficient tumor control with acceptable complications. However, tumor recurrence after long follow-up periods or the effects of radiation on the hypothalamus and visual pathway should be considered when determining the appropriate treatment for these tumors. Contrastingly, several clinical articles on the endoscopic endonasal approach (EEA) report satisfactory outcomes in patients with craniopharyngiomas. However, these clinical series do not have adequate follow-up periods. This article presents several treatment options for craniopharyngiomas.
It is generally considered that cerebrospinal fluid leakage is caused by a damaged dura mater that allows its leakage directly into the epidural space. I report a case in which cerebrospinal fluid was thought to have exuded after its infiltration into the sacral nerve root sheath and stagnant retention therein. A 19-year-old woman complained of orthostatic headache and associated symptoms for 7 years. Spinal magnetic resonance (MR) imaging/MR myelography revealed a rope-like water signal lesion with irregular margins without gadolinium enhancement, extending near the bottom of the subarachnoid space and located at the right fourth sacral nerve root sleeve. She was diagnosed as having a probable cerebrospinal fluid leakage in accordance with the diagnostic imaging criteria for cerebrospinal fluid leakage developed by the Cerebrospinal Fluid Hypovolemia Research Group. After the injection of two epidural blood patches, her orthostatic headache was resolved, associated symptoms were diminished, and MR myelography confirmed the disappearance of the lesion. Cerebrospinal fluid infiltration into the spinal nerve root sheath, stagnant retention therein, and exudation from the sheath may have occurred.
The sudden onset of oculomotor nerve (OCN) paralysis is a symptom that suggests the impending rupture of a cerebral aneurysm. The mechanism of such OCN paralysis has been proposed as direct compression by an enlarged aneurysm and/or blood leakage from an aneurysm. In this article, we report a rare case of aneurysm enlargement in the posterior communicating (Pcom) artery direction to compress the OCN. A 60-year-old woman presented with left OCN paralysis with both ptosis and mydriasis. Although CT did not show any intracranial hemorrhage, CT angiography revealed a left internal carotid- Pcom (IC-PC) aneurysm. We diagnosed it as an impending rupture of the aneurysm that required emergency surgery. Intraoperative findings revealed that the fetal Pcom artery, but not the aneurysm, compressed the OCN. We performed neck clipping and partial wrapping of the aneurysm to change the Pcom artery direction to decompress the OCN. Her symptoms improved after surgery. There was a case report in which the Pcom artery compressed the OCN directly instead of the aneurysm, suggesting that it was caused by an abnormal running of the fetal Pcom artery. In this case, aneurysm clipping reduces the volume of the aneurysm to normalize the Pcom artery direction, resulting in neurovascular decompression of the oculomotor nerve.