Clinical and genomic features in patients with second primary glioblastoma following first primary renal cell carcinoma.

PURPOSE: To explore the potential pathogenesis and clinical features of second primary glioblastoma (spGBM) following first primary renal cell carcinoma (fpRCC). METHODS: Patients with spGBM after fpRCC were enrolled from our institution and the SEER dataset. Sanger sequencing, whole genome sequencing, and immunehistochemistry were used to detect molecular biomarkers. RESULTS: Four and 122 cases from our institution and the SEER dataset, respectively, were collected with an overall median age of 69 years at spGBM diagnosis following fpRCC. The median interval time between fpRCC and spGBM was 50.7 months and 4 years, for the four and 122 cases respectively. The median overall survival time was 11.2 and 6.0 months for the two datasets. In addition, spGBM patients of younger age (< 75 years) or shorter interval time (< 1 year) had favorable prognosis (p = 0.081 and 0.05, respectively). Moreover, the spGBM cases were molecularly classified as TERT only paired with TP53 mutation, PIK3CA mutation, EGFR alteration, low tumor mutation burden, and stable microsatellite status. CONCLUSIONS: This is the first study to investigate the pathogenesis and clinical features of spGBM following spRCC. We found that spGBMs are old-age related, highly malignant, and have short survival time. Moreover, they might be misdiagnosed and treated as brain metastases from RCC. Thus, the incidence of spGBMs after fpRCC is underestimated. Further studies are needed to investigate the underlying molecular mechanisms and clinical biomarkers for the development of spGBM following fpRCC.

Comparative study of differentiating human pluripotent stem cells into vascular smooth muscle cells in hydrogel-based culture methods.

Vascular smooth muscle cells (VSMCs), which provides structural integrity and regulates the diameter of vasculature, are of great potential for modeling vascular-associated diseases and tissue engineering. Here, we presented a detailed comparison of differentiating human pluripotent stem cells (hPSCs) into VSMCs (hPSCs-VSMCs) in four different culture methods, including 2-dimensional (2D) culture, 3-dimensional (3D) PNIPAAm-PEG hydrogel culture, 3-dimensional (3D) alginate hydrogel culture, and transferring 3-dimensional alginate hydrogel culture to 2-dimensional (2D) culture. Both hydrogel-based culture methods could mimic in vivo microenvironment to protect cells from shear force, and avoid cells agglomeration, resulting in the extremely high culture efficiency (e.g., high viability, high purity and high yield) compared with 2D culture. We demonstrated hPSC-VSMCs produced from hydrogel-based culture methods had better contractile phenotypes and the potential of vasculature formation. The transcriptome analysis showed the hPSC-VSMCs derived from hydrogel-based culture methods displayed more upregulated genes in vasculature development, angiogenesis and blood vessel development, extracellular matrix compared with 2D culture. Taken together, hPSC-VSMCs produced from hydrogel-based culture system could be applied in various biomedical fields, and further indicated the suitable development of alginate hydrogel for industrial production by taking all aspects into consideration.

Identifying Differential Expression Genes and Prognostic Signature Based on Subventricular Zone Involved Glioblastoma.

Background: Studies have suggested that glioblastoma (GBM) cells originate from the subventricular zone (SVZ) and that GBM contact with the SVZ correlated with worse prognosis and higher recurrence. However, research on differentially expressed genes (DEGs) between GBM and the SVZ is lacking. Methods: We performed deep RNA sequencing on seven SVZ-involved GBMs and paired tumor-free SVZ tissues. DEGs and enrichment were assessed. We obtained GBM patient expression profiles and clinical data from the Chinese Glioma Genome Atlas (CGGA) and The Cancer Genome Atlas (TCGA) databases. The least absolute shrinkage and selection operator Cox regression model was utilized to construct a multigene signature in the CGGA cohort. GBM patient data from TCGA cohort were used for validation. Results: We identified 137 (97 up- and 40 down-regulated) DEGs between GBM and healthy SVZ samples. Enrichment analysis revealed that DEGs were mainly enriched in immune-related terms, including humoral immune response regulation, T cell differentiation, and response to tumor necrosis factor, and the MAPK, cAMP, PPAR, PI3K-Akt, and NF-κb signaling pathways. An eight-gene (BCAT1, HPX, NNMT, TBX5, RAB42, TNFRSF19, C16orf86, and TRPC5) signature was constructed. GBM patients were stratified into two risk groups. High-risk patients showed significantly reduced overall survival compared with low-risk patients. Univariate and multivariate regression analyses indicated that the risk score level represented an independent prognostic factor. High risk score of GBM patients negatively correlated with 1p19q codeletion and IDH1 mutation. Immune infiltration analysis further showed that the high risk score was negatively correlated with activated NK cell and monocyte counts, but positively correlated with macrophage and activated dendritic cell counts and higher PD-L1 mRNA expression. Conclusion: Here, a novel gene signature based on DEGs between GBM and healthy SVZ was developed for determining GBM patient prognosis. Targeting these genes may be a therapeutic strategy for GBM.

Maxillary Swing Approach for Central Skull Base Lesions in Extreme Situations: A Single-Institutional Case Series.

OBJECTIVE: Radical resection of complex lesions occupying multiple compartments at the central skull base remains a significant challenge, since surgical outcomes may be compromised by insufficient exposure and inappropriate techniques. However, the efficiency of the maxillary swing approach for these lesions has not been sufficiently evaluated. Careful assessment of lesion characteristics must be performed when selecting the appropriate procedure. METHODS: Between May 2006 and February 2017, 17 patients underwent resection of extensive lesions in the central skull base using the maxillary swing approach. As shown in the representative cases, data regarding clinical findings and technical considerations were reviewed. RESULTS: Complete resection was achieved in all patients. The pathological findings were diverse, and the majority were schwannomas (9 cases, 52.94%), followed by meningiomas (World Health Organization II) (3 cases, 17.65%). Complications were managed as described in the case illustrations, and symptoms improved with time. The follow-up duration ranged from 62 to 192 months (median, 114 months), while 2 patients were lost to the follow-up. No mortality was observed. Two patients who experienced malignancy relapse were still under observation due to their asymptomatic status. CONCLUSIONS: Our preliminary results suggest that the maxillary swing approach can be an alternative option for managing extreme cases, such as large, extensive, hypervascularized masses with fibrous or calcified consistency, or for recurrent lesions in the central skull base. En bloc resection can be successfully obtained, resulting in long-term local control.

Comparative Study of Human Pluripotent Stem Cell-Derived Endothelial Cells in Hydrogel-Based Culture Systems.

Human pluripotent stem cell (hPSC)-derived endothelial cells (ECs) are promising cell sources for drug discovery, tissue engineering, and studying or treating vascular diseases. However, hPSC-ECs derived from different culture methods display different phenotypes. Herein, we made a detailed comparative study of hPSC-ECs from three different culture systems (e.g., 2D, 3D PNIPAAm-PEG hydrogel, and 3D alginate hydrogel cultures) based on our previous reports. We expanded hPSCs and differentiated them into ECs in three culture systems. Both 3D hydrogel systems could mimic an in vivo physiologically relevant microenvironment to protect cells from shear force and prevent cell agglomeration, leading to a high culture efficiency and a high volumetric yield. We demonstrated that hPSC-ECs produced from both hydrogel systems had similar results as 2D-ECs. The transcriptome analysis showed that PEG-ECs and alginate-ECs displayed a functional phenotype due to their higher gene expressions in vasculature development, extracellular matrix, angiogenesis, and glycolysis, while 2D-ECs showed a proliferative phenotype due to their higher gene expressions in cell proliferation. Taken together, both PEG- and alginate-hydrogel systems will significantly advance the applications of hPSC-ECs in various biomedical fields.

Surgical Management of Brain Metastases in the Perirolandic Region.

Brain metastases (BM) are the most frequent intracranial tumors, which may result in significant morbidity and mortality when the lesions involve the perirolandic region. Surgical intervention for BM in the perirolandic region is still under discussion even though prompt relief of mass effect and avoidance of necrosis together with brain edema may not be achieved by radiotherapy. More recently, several researchers attempt to evaluate the benefit of surgery for BM within this pivotal sensorimotor area. Nevertheless, data are sparse and optimal treatment paradigm is not yet widely described. Since the advance in intraoperative neuroimaging and neurophysiology, resection of BM in the perirolandic region has been proven to be safe and efficacious, sparing this eloquent area while retaining reasonably low morbidity rates. Although management of BM becomes much more tailored and multimodal, surgery remains the cornerstone and principles of resection as well as indications for surgery should be well defined. This is the first review concerning the characteristics of BM involving the perirolandic region and the current impact of surgical therapy for the lesions. Future perspectives of advanced neurosurgical techniques are also presented.

Clinial Features, Individualized Treatment and Long-Term Surgical Outcomes of Skull Base Meningiomas With Extracranial Extensions.

Object: Skull base meningiomas with extracranial extensions are rarely described. This study describes the clinical features, surgical management and clinical outcomes of these rare tumors and investigates risk factors associated with progression-free survival (PFS). Methods: The clinical data of 34 consecutive patients who underwent surgery for skull base meningiomas with extracranial extensions from 2007 to 2018 were retrospectively collected and analyzed. Results: The mean patient age was 47.9 ± 13.9 years; 50.0% were male. The most common symptoms on admission were ophthalmic. All patients underwent a multidisciplinary consultation before surgery, and received individualized surgical management. The gross total resection (GTR) rate was 55.9% (19/34). Twelve patients received post-operative adjuvant radiotherapy (RT). Twelve patients experienced tumor recurrence during the follow-up period. The median PFS duration was 54 months. The mean overall survival (OS) duration was 111 months. By univariate analysis, a higher histological grade (WHO grade II and III), Ki-67 LI ≥ 5 and the extent of resection (EOR) were significantly associated with tumor recurrence. Multivariate analysis revealed Ki-67 LI ≥ 5, the EOR and adjuvant RT as prognostic factor of PFS. Conclusions: These relatively rare meningiomas are difficult to resect and have a poor prognosis; they are more common in males and have a higher histological grade than intracranial meningiomas. Multidisciplinary collaboration and individualized surgical strategies are crucial for surgically managing these complex tumors. Total removal of the tumor remains challenging. Subtotal resection (STR) or partial resection (PR) followed by RT is a reasonable strategy when radical resection is infeasible. Adjuvant RT should be recommended especially for tumors with histopathological risk factors (Ki-67 LI ≥ 5 or high histological grade).

Dissociation between urate and blood pressure in mice and in people with early Parkinson's disease.

BACKGROUND: Epidemiological, laboratory and clinical studies have established an association between elevated urate and high blood pressure (BP). However, the inference of causality remains controversial. A naturally occurring antioxidant, urate may also be neuroprotective, and urate-elevating treatment with its precursor inosine is currently under clinical development as a potential disease-modifying strategy for Parkinson's disease (PD). METHODS: Our study takes advantage of a recently completed phase II trial evaluating oral inosine in de novo non-disabling early PD with no major cardiovascular and nephrological conditions, and of three lines of genetically engineered mice: urate oxidase (UOx) global knockout (gKO), conditional KO (cKO), and transgenic (Tg) mice with markedly elevated, mildly elevated, and substantially reduced serum urate, respectively, to systematically investigate effects of urate-modifying manipulation on BP. FINDINGS: Among clinical trial participants, change in serum urate but not changes in systolic, diastolic and orthostatic BP differed by treatment group. There was no positive correlation between urate elevations and changes in systolic, diastolic and orthostatic BP ((p = .05 (in inverse direction), 0.30 and 0.63, respectively)). Between UOx gKO, cKO, or Tg mice and their respective wildtype littermates there were no significant differences in systolic or diastolic BP or in their responses to BP-regulating interventions. INTERPRETATION: Our complementary preclinical and human studies of urate modulation in animal models and in generally healthy early PD do not support a hypertensive effect of urate elevation or an association between urate and BP. FUND: U.S. Department of Defense, RJG Foundation, Michael J. Fox Foundation LEAPS program, National Institutes of Health, American Federation for Aging Research, Parkinson's Disease Foundation Advancing Parkinson's Therapies initiative.

Transcriptome profiling of the subventricular zone and dentate gyrus in an animal model of Parkinson's disease.

Adult neurogenesis in the subventricular zone (SVZ), as well as in the subgranular zone contributes to brain maintenance and regeneration. In the adult brain, dopamine (DA) can regulate the endogenous neural stem cells within these two regions, while a DA deficit may affect neurogenesis. Notably, the factors that regulate in vivo neurogenesis in these subregions have not yet been fully characterized, particularly following DA depletion. In thi study, we performed RNA sequencing to investigate transcriptomic changes in the SVZ and dentate gyrus (DG) of mice in response to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). This analysis identified differentially expressed genes which were involved in the regulation of transcription, immune response, extracellular region, cell junction and myelination. These genes partially displayed different temporal profiles of expression, some of which may participate in the metabolic switch related to neurogenesis. Additionally, the mitogen­activated protein kinase (MAPK) signaling pathway was shown to be been positively regulated in the SVZ, while it was negatively affected in the DG following MPTP administration. Overall, our findings indicate that exposure to MPTP may exert different effects on transcriptome profiling between the SVZ and DG.

Intrastriatal Transplantation of Human Neural Stem Cells Restores the Impaired Subventricular Zone in Parkinsonian Mice.

Cell replacement therapy using neural stem cells (NSCs) transplantation has recently emerged as a promising method of Parkinson's disease (PD) treatment; however, the underlying mechanisms are not fully understood. To gain new insights into the mechanisms of 6-hydroxydopamine (6-OHDA)-induced lesioning and therapeutic efficacy of human NSCs (hNSCs) transplantation, the striatum (ST) of intrastriatal 6-OHDA-injected parkinsonian mice were unilaterally engrafted with undifferentiated hNSCs. A high-throughput quantitative proteomic approach was used to characterize the proteome profiles of PD-related brain regions such as the SN, ST, olfactory bulb, and subventricular zone (SVZ) in these mice. The abundance of more than 5,000 proteins in each region was determined with high confidence in this study, which is the most extensive proteomic study of PD mouse models to date. In addition to disruption of the DA system, the quantitative analysis demonstrated profound disturbance of the SVZ proteome after 6-OHDA insult. After hNSC engraftment, the SVZ proteome was restored and the astrocytes in the ST were greatly activated, accompanied by an increase in neurotrophic factors. Furthermore, bioinformatics analysis demonstrated that the changes in the proteome were not caused by the proliferation of hNSCs or their progeny, but rather by the reaction of endogenous stem cells. Overall, this study elucidates the unexpected role of SVZ cells in PD progress and treatment, thereby providing new therapeutic targets for PD. Stem Cells 2017;35:1519-1531.

The melanoma-linked "redhead" MC1R influences dopaminergic neuron survival.

OBJECTIVE: Individuals with Parkinson disease are more likely to develop melanoma, and melanoma patients are reciprocally at higher risk of developing Parkinson disease. Melanoma is strongly tied to red hair/fair skin, a phenotype of loss-of-function polymorphisms in the MC1R (melanocortin 1 receptor) gene. Loss-of-function variants of MC1R have also been linked to increased risk of Parkinson disease. The present study is to investigate the role of MC1R in dopaminergic neurons in vivo. METHODS: Genetic and pharmacological approaches were employed to manipulate MC1R, and nigrostriatal dopaminergic integrity was determined by comprehensive behavioral, neurochemical, and neuropathological measures. RESULTS: MC1Re/e mice, which carry an inactivating mutation of MC1R and mimic the human redhead phenotype, have compromised nigrostriatal dopaminergic neuronal integrity, and they are more susceptible to dopaminergic neuron toxins 6-hydroxydopamine and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Furthermore, a selective MC1R agonist protects against MPTP-induced dopaminergic neurotoxicity. INTERPRETATION: Our findings reveal a protective role of MC1R in the nigrostriatal dopaminergic system, and they provide a rationale for MC1R as a potential therapeutic target for Parkinson disease. Together with its established role in melanoma, MC1R may represent a common pathogenic pathway for melanoma and Parkinson disease. Ann Neurol 2017;81:395-406.

Human Neural Stem Cell Transplantation Rescues Cognitive Defects in APP/PS1 Model of Alzheimer's Disease by Enhancing Neuronal Connectivity and Metabolic Activity.

Alzheimer's disease (AD), the most frequent type of dementia, is featured by Aß pathology, neural degeneration and cognitive decline. To date, there is no cure for this disease. Neural stem cell (NSC) transplantation provides new promise for treating AD. Many studies report that intra-hippocampal transplantation of murine NSCs improved cognition in rodents with AD by alleviating neurodegeneration via neuronal complement or replacement. However, few reports examined the potential of human NSC transplantation for AD. In this study, we implanted human brain-derived NSCs (hNSCs) into bilateral hippocampus of an amyloid precursor protein (APP)/presenilin 1 (PS1) transgenic (Tg) mouse model of AD to test the effects of hNSC transplantation on Alzheimer's behavior and neuropathology. Six weeks later, transplanted hNSCs engrafted into the brains of AD mice, migrated dispersedly in broad brain regions, and some of them differentiated into neural cell types of central nervous system (CNS). The hNSC transplantation restored the recognition, learning and memory deficits but not anxiety tasks in AD mice. Although Aß plaques were not significantly reduced, the neuronal, synaptic and nerve fiber density was significantly increased in the frontal cortex and hippocampus of hNSC-treated AD mice, suggesting of improved neuronal connectivity in AD brains after hNSC transplantation. Ultrastructural analysis confirmed that synapses and nerve fibers maintained relatively well-structured shapes in these mice. Furthermore, in vivo magnetic resonance spectroscopy (MRS) showed that hNSC-treated mice had notably increased levels of N-acetylaspartate (NAA) and Glu in the frontal cortex and hippocampus, suggesting that neuronal metabolic activity was improved in AD brains after hNSC transplantation. These results suggest that transplanted hNSCs rescued Alzheimer's cognition by enhancing neuronal connectivity and metabolic activity through a compensation mechanism in APP/PS1 mice. This study provides preclinical evidence that hNSC transplantation can be a possible and feasible strategy for treating patients with AD.

Age- and Brain Region-Specific Changes of Glucose Metabolic Disorder, Learning, and Memory Dysfunction in Early Alzheimer's Disease Assessed in APP/PS1 Transgenic Mice Using 18F-FDG-PET.

Alzheimer's disease (AD) is a leading cause of dementia worldwide, associated with cognitive deficits and brain glucose metabolic alteration. However, the associations of glucose metabolic changes with cognitive dysfunction are less detailed. Here, we examined the brains of APP/presenilin 1 (PS1) transgenic (Tg) mice aged 2, 3.5, 5 and 8 months using 18F-labed fluorodeoxyglucose (18F-FDG) microPET to assess age- and brain region-specific changes of glucose metabolism. FDG uptake was calculated as a relative standardized uptake value (SUVr). Morris water maze (MWM) was used to evaluate learning and memory dysfunction. We showed a glucose utilization increase in multiple brain regions of Tg mice at 2 and 3.5 months but not at 5 and 8 months. Comparisons of SUVrs within brains showed higher glucose utilization than controls in the entorhinal cortex, hippocampus, and frontal cortex of Tg mice at 2 and 3.5 months but in the thalamus and striatum at 3.5, 5 and 8 months. By comparing SUVrs in the entorhinal cortex and hippocampus, Tg mice were distinguished from controls at 2 and 3.5 months. In MWM, Tg mice aged 2 months shared a similar performance to the controls (prodromal-AD). By contrast, Tg mice failed training tests at 3.5 months but failed all MWM tests at 5 and 8 months, suggestive of partial or complete cognitive deficits (symptomatic-AD). Correlation analyses showed that hippocampal SUVrs were significantly correlated with MWM parameters in the symptomatic-AD stage. These data suggest that glucose metabolic disorder occurs before onset of AD signs in APP/PS1 mice with the entorhinal cortex and hippocampus affected first, and that regional FDG uptake increase can be an early biomarker for AD. Furthermore, hippocampal FDG uptake is a possible indicator for progression of Alzheimer's cognition after cognitive decline, at least in animals.

Transplantation of Human Neural Stem Cells in a Parkinsonian Model Exerts Neuroprotection via Regulation of the Host Microenvironment.

Parkinson's disease (PD) is characterized by a progressive loss of dopaminergic neurons and consequent dopamine (DA) deficit, and current treatment still remains a challenge. Although neural stem cells (NSCs) have been evaluated as appealing graft sources, mechanisms underlying the beneficial phenomena are not well understood. Here, we investigate whether human NSCs (hNSCs) transplantation could provide neuroprotection against DA depletion by recruiting endogenous cells to establish a favorable niche. Adult mice subjected to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) were transplanted with hNSCs or vehicle into the striatum. Behavioral and histological analyses demonstrated significant neurorescue response observed in hNSCs-treated animals compared with the control mice. In transplanted animals, grafted cells survived, proliferated, and migrated within the astrocytic scaffold. Notably, more local astrocytes underwent de-differentiation, acquiring the properties of NSCs or neural precursor cells (NPCs) in mice given hNSCs. Additionally, we also detected significantly higher expression of host-derived growth factors in hNSCs-transplanted mice compared with the control animals, together with inhibition of local microglia and proinflammatory cytokines. Overall, our results indicate that hNSCs transplantation exerts neuroprotection in MPTP-insulted mice via regulating the host niche. Harnessing synergistic interaction between the grafts and host cells may help optimize cell-based therapies for PD.

The sirtuin-2 inhibitor AK7 is neuroprotective in models of Parkinson's disease but not amyotrophic lateral sclerosis and cerebral ischemia.

Sirtuin deacetylases regulate diverse cellular pathways and influence disease processes. Our previous studies identified the brain-enriched sirtuin-2 (SIRT2) deacetylase as a potential drug target to counteract neurodegeneration. In the present study, we characterize SIRT2 inhibition activity of the brain-permeable compound AK7 and examine the efficacy of this small molecule in models of Parkinson's disease, amyotrophic lateral sclerosis and cerebral ischemia. Our results demonstrate that AK7 is neuroprotective in models of Parkinson's disease; it ameliorates alpha-synuclein toxicity in vitro and prevents 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced dopamine depletion and dopaminergic neuron loss in vivo. The compound does not show beneficial effects in mouse models of amyotrophic lateral sclerosis and cerebral ischemia. These findings underscore the specificity of protective effects observed here in models of Parkinson's disease, and previously in Huntington's disease, and support the development of SIRT2 inhibitors as potential therapeutics for the two neurodegenerative diseases.

A proposed scheme for the classification and surgical planning of falcine meningioma treatment.

Falcine meningiomas (FM) represent a surgical challenge even in the microsurgical era. An individualised surgical approach to different FM is indispensable, but there have been few reports in this regard. Thus, based on our series of 20 patients with FM who underwent surgery between October 2001 and June 2010, we propose a classification scheme for FM removal and demonstrate its effectiveness. FM in our series were classified into four types, according to tumour growth patterns on coronal MRI: Type I, hemispheroid-shaped tumours invaginating deeply into one hemisphere without shifting the falx (10 patients); Type II, olive-shaped tumours shifting the falx substantially to the contralateral side (six patients); Type IIIA, globular- or dumbbell-shaped tumours extending into both hemispheres, but to different extents (one patient); and Type IIIB, globular- or dumbbell-shaped tumours extending into both hemispheres to approximately equal extent (three patients). An ipsilateral interhemispheric approach was performed for Type I tumours, and a contralateral transfalcine approach for Type II. Type IIIA tumour was approached from the side where the smaller tumour was located. Type IIIB tumours were approached from the non-dominant hemisphere. Simpson grade I resection was achieved in all 20 patients. The follow-up ranged from 12 months to 114 months. There was no postoperative mortality, serious neurological deficits, or tumour recurrence. The preliminary results suggest that the proposed scheme can facilitate surgical planning and accomplish complete tumour resection with minimal invasion.

[Microneurosurgical treatment of massive tuberculum sellae meningiomas].

OBJECTIVE: To summarize the characteristics of the pathological anatomy and blood supply model of massive tuberculum sellae meningiomas (MTSM) and explore its corresponding microneurosurgical strategies. METHODS: The clinical data of 16 MTSM patients were reviewed retrospectively. From January 1998 to January 2010, according to their unique pathological anatomy and blood supply model, all patients underwent microneurosurgical removal with induced hypotension through tumor corridor by the bi-subfrontal anterior longitudinal fission (n = 14), right frontolateral approach (n = 1) and pterional approach (n = 1). There were 5 males and 11 females with a mean age of 48.5 years old (range: 26 - 65). But the mean follow-up period was 74.9 months (range: 4 - 132) in 2/4 cases. RESULTS: Among all cases, the mean tumor diameter was 58.9 mm (range: 51.1 - 76.2 mm). Simpson grade I, II, III, IV removal of MTSMs were accomplished in 3, 9, 3 and 1 case respectively. One case died within 4 postoperative days. Visual acuity improved in 10 patients, remained unchanged in 2 and deteriorated in 2. Transient postoperative diabetes insipidus occurred in 9 cases. CONCLUSION: It is critical to understand the unique characteristics of pathological anatomy and blood supply model of MTSM so as to adopt proper microneurosurgical strategies to remove it in situ.