Introducing next-generation transcranial surgery with the head-mounted 3D View Vision display in extracorporeal microsurgery: illustrative cases.

BACKGROUND: Exoscopy in neurosurgery offers various advantages, including increased freedom of the viewing axis while the surgeon maintains a comfortable upright position. However, the optimal monitor positioning to avoid interference with surgical manipulation remains unresolved. Herein, the authors describe two cases in which a three-dimensional head-mounted display (3D-HMD) was introduced into a transcranial neurosurgical procedure using an exoscope. OBSERVATIONS: Case 1 was a 50-year-old man who presented with recurrent epistaxis and was diagnosed with an olfactory neuroblastoma that extended from the nasal cavity to the anterior cranial base and infiltrated the right anterior cranial fossa. Case 2 was a 65-year-old man who presented with epistaxis and was diagnosed with a left-sided olfactory neuroblastoma. In both cases, en bloc tumor resection was successfully performed via a simultaneous exoscopic transcranial approach using a 3D-HMD and an endoscopic endonasal approach, eliminating the need to watch a large monitor beside the patient. LESSONS: This is the first report of using a 3D-HMD in transcranial surgery. The 3D-HMD effectively addressed issues with the field of vision and concentration while preserving the effectiveness of traditional microscopic and exoscopic procedures when observed on a 3D monitor. Combining the 3D-HMD with an exoscope holds the potential to become a next-generation surgical approach.

2-Hydroxyglutarate magnetic resonance spectroscopy in adult brainstem glioma.

OBJECTIVE: Adult brainstem gliomas (BSGs) are rare tumors of the CNS that are poorly understood. Upregulation of the oncometabolite 2-hydroxyglutarate (2HG) in the tumor indicates the mutation of isocitrate dehydrogenase (IDH), which can be detected by magnetic resonance spectroscopy (MRS). Although histological examination is required for the definitive diagnosis of BSG, 2HG-optimized MRS (2HG-MRS) may be useful, considering the difficult nature of brainstem lesion biopsy. The aim of this study was to evaluate the utility of 2HG-MRS for diagnosing IDH-mutant adult BSG. METHODS: Patients with a radiographically confirmed brainstem tumor underwent 3T MRS. A single voxel was set in the lesion with reference to the T2 or fluid-attenuated inversion recovery image and analyzed according to the 2HG-tailored MRS protocol (point-resolved spectroscopic sequence; echo time 35 msec). All patients underwent intraoperative navigation-guided or CT-guided stereotactic biopsy for histopathological diagnosis. The status of IDH and H3K27M mutations was confirmed by immunohistochemistry and direct DNA sequencing. In addition, the authors examined the relationship between patients' 2HG concentrations and survival time. RESULTS: Ten patients (7 men, 3 women; median age 33.5 years) underwent 2HG-MRS and biopsy. Four patients had an H3K27M mutation and 4 had an IDH1 mutation (1 R132H canonical IDH mutation, 2 R132S and 1 R132G noncanonical IDH mutations). Two had neither H3K27M nor IDH mutations. The H3K27M and IDH mutations were mutually exclusive. Most tumors were located in the pons. There was no significant radiological difference between mutant H3K27M and IDH on a conventional MRI sequence. A 2HG concentration ≥ 1.8 mM on MRS demonstrated 100% (95% CI 28%-100%) sensitivity and 100% (95% CI 42%-100%) specificity for IDH-mutant BSG (p = 0.0048). The median overall survival was 10 months in IDH-wild-type BSG patients (n = 6) and could not be estimated in IDH-mutant BSG patients (n = 4) due to the small number of deaths (p = 0.008). CONCLUSIONS: 2HG-MRS demonstrated high sensitivity and specificity for the prediction of IDH-mutant BSG. In addition, 2HG-MRS may be useful for predicting the prognosis of adult BSG patients.

Late intrathecal retraction of a lumboperitoneal shunt.

Background: Lumboperitoneal (LP) shunt placement is a good option for treating elderly patients with communicating normal pressure hydrocephalus (NPH) who are also on antiplatelet therapy following endovascular treatment of unruptured bilateral internal carotid artery aneurysms. Here, in an 80-year-old male with an LP shunt, the catheter was "pinched" between adjacent spinous processes, resulting in laceration of the catheter and intrathecal catheter migration. Case Description: An 80-year-old male was treated with a LP shunt for NPH 1 year after undergoing endovascular treatment of unruptured bilateral internal carotid artery aneurysms. The lumbar catheter was placed at the L2-3 level. Six months later, when he clinically deteriorated, the follow-up computed tomography showed recurrent ventricular enlargement. Further, studies additionally confirmed intrathecal migration of the lumbar catheter, warranting secondary ventriculoperitoneal shunt placement. Conclusion: Patients with LP shunts may develop lumbar catheter lacerations secondary to a "pinching" effect from adjacent spinous processes, resulting in intrathecal catheter migration.

Glutamic Acid and Total Creatine as Predictive Markers for Epilepsy in Glioblastoma by Using Magnetic Resonance Spectroscopy Before Surgery.

OBJECTIVE: Epilepsy in glioblastoma patients significantly reduces their quality of life; however, little is known about the association between predicting epilepsy and metabolites in tumors. In this study, we used 3.0-T magnetic resonance imaging and 1H-magnetic resonance spectroscopy (MRS) to quantify metabolite concentrations in patients with varying epilepsy histories. METHODS: Fifty-one patients with glioblastoma underwent pretreatment 3.0-T MRI/1H-MRS scanning. Single-voxel (1.5 cm3) MRS, in an enhanced lesion, was acquired using a double-echo point-resolved spectroscopic sequence with chemical-shift selective water suppression. MRS data were quantified with linear combination model (LC-Model) software. We compared the MRS data between groups with and without epilepsy during the postoperative course (EP). RESULTS: The ratios of glutamate (Glu) and glutamate + glutamine (Glx) to total creatine (Glu/tCr and Glx/tCr) in the tumor were associated with epilepsy history. The receiver operating characteristic curve analysis showed that a Glu/tCr value of 1.81 was 70% sensitive and 90% specific for the prediction of EP (area under curve: 0.82). In the analysis excluding patients with preoperative epilepsy, a Glu/tCr value of 1.81 was 75% sensitive and 88% specific for the prediction (area under curve: 0.87). CONCLUSIONS: Intratumoral metabolite concentrations measured using pretreatment 3.0-T MRI/1H-MRS changed characteristically in the group with EP. Our study suggests that the Glu/tCr ratio in tumors has adequate reliability in predicting EP. Pretreatment MRS is a minimally invasive and simple procedure that can provide useful information on glioblastoma patients.

Metabolic changes and anti-tumor effects of a ketogenic diet combined with anti-angiogenic therapy in a glioblastoma mouse model.

The ketogenic diet (KD) is a high fat and low carbohydrate diet that produces ketone bodies through imitation of starvation. The combination of KD and Bevacizumab (Bev), a VEGF inhibitor, is considered to further reduce the supply of glucose to the tumor. The metabolite changes in U87 glioblastoma mouse models treated with KD and/or Bev were examined using gas chromatography-mass spectrometry. The combination therapy of KD and Bev showed a decrease in the rate of tumor growth and an increase in the survival time of mice, although KD alone did not have survival benefit. In the metabolome analysis, the pattern of changes for most amino acids are similar between tumor and brain tissues, however, some amino acids such as aspartic acid and glutamic acid were different between tumors and brain tissues. The KD enhanced the anti-tumor efficacy of Bev in a glioblastoma intracranial implantation mouse model, based on lowest levels of microvascular density (CD31) and cellular proliferation markers (Ki-67 and CCND1) in KD + Bev tumors compared to the other groups. These results suggested that KD combined with Bev may be a useful treatment strategy for patients with GBM.

Multi-marker algorithms based on CXCL13, IL-10, sIL-2 receptor, and ß2-microglobulin in cerebrospinal fluid to diagnose CNS lymphoma.

Tumor biopsy is essential for the definitive diagnosis of central nervous system (CNS) lymphoma. However, the biopsy procedure carries the risk of complications such as bleeding, convulsions, and infection. Cerebrospinal fluid (CSF) ß2-microglobulin (ß2-MG), soluble IL-2 receptor (sIL-2R), and interleukin-10 (IL-10) are known to be useful diagnostic biomarkers for CNS lymphoma. The C-X-C motif chemokine ligand 13 (CXCL13) was recently reported to be another useful biomarker for CNS lymphoma. The purpose of this study is to establish a diagnostic algorithm that can avoid biopsy by combining these diagnostic biomarkers. In the first, we conducted a case-control study (n = 248) demonstrating that the CSF CXCL13 concentration was significantly increased in CNS lymphoma patients compared with various other brain diseases (AUC = 0.981). We established a multi-marker diagnostic model using CSF CXCL13, IL-10, ß2-MG, and sIL-2R from the results of the case-control study and then applied the model to a prospective study (n = 104) to evaluate its utility. The multi-marker diagnostic algorithms had excellent diagnostic performance: the sensitivity, specificity, positive predictive value, and negative predictive value were 97%, 97%, 94%, and 99%, respectively. In addition, CSF CXCL13 was a prognostic biomarker for CNS lymphoma patients. Our study suggests that multi-marker algorithms are important diagnostic tools for patients with CNS lymphoma.

Tumor-associated macrophage related interleukin-6 in cerebrospinal fluid as a prognostic marker for glioblastoma.

Interleukin-6 (IL-6) is one of the pleiotropic cytokines and has received attention as a critical factor implicated in the invasion and the angiogenesis of various cancers. In glioma, IL-6 is known to be associated with the prognosis; however, the roles of IL-6 in cerebrospinal fluid (CSF) has not been studied sufficiently. We examined the concentration of CSF IL-6 using 75 CSF samples of glioma (54 glioblastomas (GBMs) and 21 other grades of gliomas) and analyzed the association CSF IL-6 with infiltration levels of tumor-associated macrophages (TAMs) and prognosis. The concentration of CSF IL-6 in GBM patients was significantly higher than that in other grades of gliomas. CSF IL-6 levels were associated with the infiltration rate of TAMs in GBMs, and IL-6 levels were increased in the GBM cells co-cultured with TAM-like macrophages. The CSF of GBM patients, which contained high concentration of IL-6, promoted the migration ability of GBM cells, and neutralization antibodies of IL-6 inhibited its migration ability. Finally, in both univariate and multivariate analysis, higher CSF IL-6 levels were associated with poorer prognosis in GBM patients. These results indicated that the concentration of CSF IL-6 is associated with TAMs' infiltration level and may be a useful prognostic biomarker for the GBM patients.

MicroRNA regulating stanniocalcin-1 is a metastasis and dissemination promoting factor in glioblastoma.

BACKGROUND: MicroRNAs (miRs) regulate many biological processes, such as invasion, angiogenesis, and metastasis. Glioblastoma (GBM) patients with metastasis/metastatic dissemination have a very poor prognosis; therefore, inhibiting metastasis/metastatic dissemination has become an important therapeutic strategy for GBM treatment. METHODS: Using 76 GBM tissues, we examined the expression levels of 23 GBM-related miRs and compared the miRs' expression levels between GBMs with metastasis/metastatic dissemination and GBMs without metastasis/metastatic dissemination. Using the bioinformatics web site, we searched the target genes of miRs. To analyze the function of target gene, several biological assays and survival analysis by the Kaplan-Meier method were performed. RESULTS: We found that eight miRs were significantly decreased in GBM with metastasis/metastatic dissemination. By the bioinformatics analysis, we identified stanniocalcin-1 (STC1) as the most probable target gene against the combination of these miRs. Four miRs (miR-29B, miR-34a, miR-101, and miR-137) have predictive binding sites in STC1 mRNA, and mRNA expression of STC1 was downregulated by mimics of these miRs. Also, mimics of these miRs and knockdown of STC1 by siRNA suppressed invasion in GBM cells. GBM with metastasis/metastatic dissemination had significantly higher levels of STC1 than GBM without metastasis/metastatic dissemination. Finally, Kaplan-Meier analysis demonstrated that GBMs with high STC1 level had significantly shorter survival than GBMs with low STC1 level. CONCLUSIONS: STC1 may be a novel metastasis/metastatic dissemination promoting factor regulated by several miRs in GBM. Because STC1 is a secreted glycoprotein and functions via the autocrine/paracrine signals, inhibiting STC1 signal may become a novel therapeutic strategy for GBM.

Myo-inositol concentration in MR spectroscopy for differentiating high grade glioma from primary central nervous system lymphoma.

It is sometimes difficult to distinguish gliomas from other tumors on routine imaging. In this study, we assessed whether 3-T magnetic resonance spectroscopy (MRS) with LCModel software might be useful for discriminating glioma from other brain tumors, such as primary central nervous system lymphomas (PCNSLs) and metastatic tumors. A total of 104 cases of brain tumor (66 gliomas, 20 PCNSLs, 6 metastatic tumors, 12 other tumors) were preoperatively investigated with short echo time (35 ms) single-voxel 3-T MRS. LCModel software was used to evaluate differences in the absolute concentrations of choline, N-acetylaspartate, N-acetylaspartylglutamate, glutamate + glutamine, myo-inositol (mIns), and lipid. mIns levels were significantly increased in high-grade glioma (HGG) compared with PCNSL (p < 0.001). In multivariate logistic regression analysis, mIns was the best marker for differentiating HGG from PCNSL (p < 0.0001, odds ratio 1.9927, 95% confidence interval 1.3628-3.2637). Conventional MRS detection of mIns resulted in a high diagnostic accuracy (sensitivity, 64%; specificity, 90%; area under the receiver operator curve, 0.80) for HGG. The expression of inositol 3-phosphate synthase (ISYNA1) was significantly higher in gliomas than in PCNSLs (p < 0.05), suggesting that the increased level of mIns in glioma is due to high expression of ISYNA1, the rate-limiting enzyme in the mIns-producing pathway. In conclusion, noninvasive analysis of mIns using single-voxel MRS may be useful in distinguishing gliomas from other brain tumors, particularly PCNSLs.

Cognard Type V Dural Arteriovenous Fistula Involving the Occipital Sinus.

The Cognard type V dural arteriovenous fistula (dAVF), which has a drainage route into the spinal vein, is a rare subtype of cranial dAVF. Because of typical features such as progressive myelopathy and brainstem dysfunctions, aggressive treatments should be considered. To eliminate venous congestion of the spinal cord, various approaches including surgical interruption of the spinal draining vein or transarterial embolization with cyanoacrylate have been reported. The introduction of nonadhesive Onyx has changed the treatment of dAVF, although little is known about the clinical usefulness of this type of fistula. We describe a case of the Cognard type V dAVF, draining into the spinal vein through the occipital sinus (OS) successfully treated by transarterial double catheter injection of Onyx. We used the alternating injections from 2 microcatheters until the Onyx reached the OS and reflowed into feeders adequately. This technique contributed to the elimination of the remaining afferent flow in an early stage of Onyx injection and achieved enough penetration into the draining vein.

Radiographic occult cerebellar germinoma presenting with progressive ataxia and cranial nerve palsy.

BACKGROUND: Although the usefulness of susceptibility-weighted imaging (SWI) for detecting basal ganglia germinoma has been reported, the technique is not widely used. We recently encountered an unusual case of primary cerebellar germinoma, presenting with progressive ataxia and cranial nerve palsy, characterized by gradually enlarging low-intensity lesions visible with both T2*-weighted imaging (T2*WI), which were the key to the diagnosis. CASE PRESENTATION: A 30-year-old man was referred to our hospital because of slowly progressive dizziness and mild ataxia. Magnetic resonance imaging (MRI) revealed a small, low-intensity spot in the left cerebellar peduncle on the T2*WI and SWI without enhancement. Cerebral angiography revealed no vascular abnormality. The serum α-fetoprotein value was normal. A steroid-pulse was administered as a therapeutic and diagnostic trial, but the symptoms improved little. The patient was discharged from the hospital but soon developed brainstem dysfunction, characterized by dyspnea or hiccups, and he was readmitted. T2*WI imaging revealed expanded and extended spotty lesions in the cerebellum and brainstem, which had not enhanced with contrast agent previously. Targeted stereotactic biopsy of the newly enhanced cerebellar lesion was performed; histopathological examination of the tissue revealed pure germinoma. Serum and cerebral spinal fluid values of beta-human chorionic gonadotropin were not significantly elevated. Chemotherapy with carboplatin and etoposide was initiated. The enhanced lesion disappeared promptly, but the patient continued to require assisted automatic ventilation because of paralysis of respiratory muscles. CONCLUSIONS: We conclude that enlarging low-intensity lesions on T2*WI and SWI may be a reliable clue to the diagnosis of germinomas, irrespective of their location, even without enhancement. Biopsy of the tumor at an early stage is the only way to make the diagnosis conclusively and enable prompt start of treatment.

Cilostazol administration with combination enteral and parenteral nutrition therapy remarkably improves outcome after subarachnoid hemorrhage.

OBJECTIVE: In order to prevent cerebral vasospasm (VS) following aneurysmal subarachnoid hemorrhage (SAH), we introduced combined enteral nutrition (EN) and parenteral nutrition (PN) with oral cilostazol administration to the postoperative patient after SAH and investigated the effect on VS. METHODS: After aneurysmal SAH, 130 postoperative patients were enrolled in this study between April 2008 and March 2012. The patients enrolled before April 2010 were treated by conventional therapy (control group). The patients enrolled after April 2010 were administrated cilostazol 200 mg/day and received EN and PN simultaneously (combined group). RESULTS: The combined group consisted of 62 patients and the control group of 68 patients. Angiographic VS occurred in 33.9 % (n = 21) of the combined group and in 51.5 % (n = 35) of the control group (p = 0.051, Fisher exact test). The incidence of symptomatic VS was significantly lower in the combined group (p = 0.001). The incidence of new cerebral infarctions was also significantly lower in the combined group (p = 0.0006). Clinical outcome at discharge was also significantly better in the combined group than in control group (p = 0.031). CONCLUSIONS: Cilostazol administration with combination EN and PN is remarkably effective in preventing cerebral VS after aneurysmal SAH.