Boron neutron capture therapy delays the decline in neurological function in a mouse model of metastatic spinal tumors.

Metastatic spinal tumors are increasingly prevalent due to advancements in cancer treatment, leading to prolonged survival rates. This rising prevalence highlights the need for developing more effective therapeutic approaches to address this malignancy. Boron neutron capture therapy (BNCT) offers a promising solution by delivering targeted doses to tumors while minimizing damage to normal tissue. In this study, we evaluated the efficacy and safety of BNCT as a potential therapeutic option for spine metastases in mouse models induced by A549 human lung adenocarcinoma cells. The animal models were randomly allocated into three groups: untreated (n = 10), neutron irradiation only (n = 9), and BNCT (n = 10). Each mouse was administered 4-borono-L-phenylalanine (250 mg/kg) intravenously, followed by measurement of boron concentrations 2.5 h later. Overall survival, neurological function of the hindlimb, and any adverse events were assessed post irradiation. The tumor-to-normal spinal cord and blood boron concentration ratios were 3.6 and 2.9, respectively, with no significant difference observed between the normal and compressed spinal cord tissues. The BNCT group exhibited significantly prolonged survival rates compared with the other groups (vs. untreated, p = 0.0015; vs. neutron-only, p = 0.0104, log-rank test). Furthermore, the BNCT group demonstrated preserved neurological function relative to the other groups (vs. untreated, p = 0.0004; vs. neutron-only, p = 0.0051, multivariate analysis of variance). No adverse events were observed post irradiation. These findings indicate that BNCT holds promise as a novel treatment modality for metastatic spinal tumors.

[Usefulness of Preoperative Simulation: Skull Base Approach].

Preoperative simulation images creates an accurate visualization of a surgical field. The anatomical relationship of the cranial nerves, arteries, brainstem, and related bony protrusions is important in skull base surgery. However, an operator's intention is unclear for a less experienced neurosurgeon. Three-dimensional(3D)fusion images of computed tomography and magnetic resonance imaging created using a workstation aids precise surgical planning and safety management. Since the simulation images allows to perform virtual surgery, a déjà vu effect for the surgeon can be obtained. Additionally, since 3D surgical images can be used for preoperative consideration and postoperative verification, discussion among the team members is effective from the perspective of surgical education for residents and medical students. Significance of preoperative simulation images will increase eventually.

Increasing C-reactive protein levels in a patient with glioblastoma with lymph node metastasis: a case report.

BACKGROUND: Glioblastoma usually recurs locally and extracranial metastases are rare. Most patients with extracranial metastases experience recurrence of the primary intracranial tumor. Lymph node metastases are often detected based on lymphadenopathy or symptoms caused by other metastatic sites. CASE PRESENTATION: Herein, we report a case of glioblastoma with lymph node metastasis in which the patient was asymptomatic but exhibited gradually increasing C-reactive protein levels prior to becoming febrile 9 months after the initial C-reactive protein increase. Diagnosis of lymph node metastasis that was delayed because the patient had a fever of unknown origin, no signs of infection, and the primary intracranial tumor did not recur. Chest computed tomography indicated supraclavicular, mediastinal, and hilar lymphadenopathy, and biopsy identified lymph node metastasis of glioblastoma. This is the fifth reported case of lymph node metastasis without intracranial recurrence. CONCLUSIONS: C-reactive protein levels may be a diagnostic marker for lymph node metastasis in patients with glioblastoma. Further evaluation is needed to elucidate the role of CRP in glioblastoma with lymph node metastasis.

Expression and distribution of hypoxia-inducible factor-1α and vascular endothelial growth factor in comparison between radiation necrosis and tumor tissue in metastatic brain tumor: A case report.

We report the case of a 70-year-old woman with metastatic brain tumors who underwent surgical removal of the tumor and radiation necrosis. The patient had a history of colon cancer and had undergone surgical removal of a left occipital tumor. Histopathological evaluation revealed a metastatic brain tumor. The tumor recurred six months after surgical removal, followed by whole-brain radiotherapy, and the patient underwent stereotactic radiosurgery. Six months later, the perifocal edema had increased, and the patient became symptomatic. The diagnosis was radiation necrosis and corticosteroids were initially effective. However, radiation necrosis became uncontrollable, and the patient underwent removal of necrotic tissue two years after stereotactic radiosurgery. Pathological findings predominantly showed necrotic tissue with some tumor cells. Since the vascular endothelial growth factor (VEGF) and hypoxia-inducible factor-1α (HIF-1α) were expressed around the necrotic tissue, the main cause of the edema was determined as radiation necrosis. Differences in the expression levels and distribution of HIF-1α and VEGF were observed between treatment-naïve and recurrent tumor tissue and radiation necrosis. This difference suggests the possibility of different mechanisms for edema formation due to the tumor itself and radiation necrosis. Although distinguishing radiation necrosis from recurrent tumors using MRI remains challenging, the pathophysiological mechanism of perifocal edema might be crucial for differentiating radiation necrosis from recurrent tumors.

[Intraoperative Fluorescence Imaging of Brain Tumors].

Malignant gliomas are highly invasive tumors. Accurate identification of tumor tissue is essential for enabling tumor resection as much as possible without damaging important neurological functions. One of the methods is intraoperative fluorescence imaging. This method visualizes in real time the boundary between the tumor and normal brain, which cannot be identified using conventional surgical microscope under white light. Although many fluorescent dyes have been reported for intraoperative fluorescence imaging of brain tumors, only 5-aminolevulinic acid(5-ALA)is approved by Ministry of Health, Labour and Welfare in Japan. After the oral administration of 5-ALA, fluorescence is emitted by protoporphyrin Ⅸ, a metabolite of 5-ALA in tumor cells(red fluorescence with a peak at 635 nm, induced by an excitation light of 405 nm). The intensity of fluorescence is correlated with tumor cell density, proliferation rate, and vascular density. In a multicenter randomized controlled study in Germany, compared with white light imaging, fluorescence imaging with 5-ALA increased the tumor resection rate and significantly prolonged progression-free survival at 6 months. However, no difference was observed in overall survival. Regarding other fluorescent substances, fluorescein sodium is a dye that leaks from tumor vessels without the blood-brain barrier, like contrast media used for computed tomography and magnetic resonance imaging(green fluorescence with a peak at 520 nm, induced by an excitation light of 493 nm). This dye spreads in the interstitial tissue of the tumor to visualize the tumor area. Indocyanine green emits a near-infrared light of 820-920 nm, induced by an excitation light of 760- 810 nm. This dye was expected to be useful for visualizing deep tumors as it emits light with high tissue permeability; however, it does not leak out of blood vessels because of its large molecular weight. Subsequently, this dye is used for intraoperative angiography of highly vascularized tumors. Talaporfin sodium was originally developed for photodynamic therapy in Japan and is readily taken up by tumor cells. This substance is also used for intraoperative fluorescence imaging because it emits the fluorescence of 672 nm, induced by an excitation light of 664 nm. Here, we review various fluorescent dyes used for intraoperative imaging of brain tumors.

Folate receptor-targeted novel boron compound for boron neutron capture therapy on F98 glioma-bearing rats.

Folic acid (FA) has high affinity for the folate receptor (FR), which is limited expressed in normal human tissues, but over-expressed in several tumor cells, including glioblastoma cells. In the present work, a novel pteroyl-closo-dodecaborate conjugate (PBC) was developed, in which the pteroyl group interacts with FR, and the efficacy of boron neutron capture therapy (BNCT) using PBC was investigated. Thus, in vitro and in vivo studies were performed using F98 rat glioma cells and F98 glioma-bearing rats. For the in vivo study, boronophenylalanine (BPA) was intravenously administered, while PBC was administered by convection-enhanced delivery (CED)-a method for direct local drug infusion into the brain of rats. Furthermore, a combination of PBC administered by CED and BPA administered by intravenous (i.v.) injection was also investigated. In the biodistribution experiment, PBC administration at 6 h after CED termination showed the highest cellular boron concentrations (64.6 ± 29.6 µg B/g). Median survival time (MST) of untreated controls was 23.0 days (range 21-24 days). MST of rats administered PBC (CED) followed by neutron irradiation was 31 days (range 26-36 days), which was similar to that of rats administered i.v. BPA (30 days; range 25-37 days). Moreover, the combination group [PBC (CED) and i.v. BPA] showed the longest MST (38 days; range 28-40 days). It is concluded that a significant MST increase was noted in the survival time of the combination group of PBC (CED) and i.v. BPA compared to that in the single-boron agent groups. These findings suggest that the combination use of PBC (CED) has additional effects.

[The Efficacy of the Emergent Shunt-Clamp System for Secondary Hydrocephalus Associated with Fourth Ventricle Outlet Obstruction Syndrome:A Report of Two Cases].

Endoscopic third ventriculostomy(ETV)is the first-line treatment for fourth ventricle outlet obstruction(FVOO)-associated hydrocephalus. However, because FVOO is difficult to diagnose in the acute stage, ventriculoperitoneal shunt(VPS)is also used. Herein, we report two cases of shunted FVOO resulting in overdrainage or slit ventricle syndrome(SVS)that were treated successfully with the shunt-clamp system. In addition, we discuss the efficacy of the shunt-clamp system for FVOO-associated hydrocephalus. CASE 1:A 79-year-old man complained of severe postural headaches. One year earlier, he underwent VPS for secondary hydrocephalus associated with hemorrhagic cerebellar infarction. CT revealed that the ventricle had become slit-like. Although the shunt valve adjusted the maximum pressure, his complaint and the ventricle shape did not improve. After the on-off valve was inserted in the shunt system and clamped, his symptoms were resolved and the ventricle size was normalized. CASE 2:A 21-year-old man who complained of drowsiness, diplopia, and severe intermittent retroocular pain was admitted to our hospital. One year earlier, he underwent VPS with the shunt-clamp system for a secondary hydrocephalus after surgery for medulloblastoma. CT on admission revealed ventricle dilatation;however, the shape of the ventricle became slit-like 3 days after admission. We made a diagnosis of SVS and planned ETV. Owing to the difficulty in approaching the lateral ventricle, the shunt system was clamped 8 hours before the operation. After confirming ventricle dilatation, ETV was successfully performed. After the operation, the symptoms were resolved, and magnetic resonance imaging confirmed that the ventricle size was normalized.

Continuous Blood Glucose Monitoring May Detect Carotid Occlusion Intolerance during Carotid Artery Stenting.

BACKGROUND: The frequency of the occurrence of adverse events associated with carotid artery stenting (CAS) is usually low, but serious adverse events such as cerebral hyperperfusion syndrome (CHS) may occur. Real-time monitoring is ideal for the early detection of adverse events during the surgical procedure. This study aimed to evaluate continuous blood glucose (BG) monitoring for the detection of adverse events during CAS. METHODS: Forty patients undergoing scheduled CAS were prospectively enrolled. An artificial pancreas was used for continuous BG monitoring (once per minute), using venous blood extracted at a rate of 2 mL/hr during CAS. The primary endpoint was a correlation between BG change and adverse events. RESULTS: CAS was discontinued in 1 patient, and BG was not measured in 5 patients (12.5%) because of the inability to extract blood. Among 34 evaluable patients, no patient developed CHS, but 3 patients (9%) experienced carotid occlusion intolerance. During CAS, BG was significantly higher in patients with carotid occlusion intolerance (median: 5 mg/dL) than in patients without carotid occlusion intolerance (median: 0 mg/dL) (P = 0.0221). A cutoff BG value ≥4 mg/dL during CAS showed 50% sensitivity and 100% specificity for the detection of carotid occlusion intolerance. There was no significant correlation between BG change and other adverse events. CONCLUSIONS: BG elevation may help detect carotid occlusion intolerance although it is still unknown whether BG monitoring can detect CHS. Further studies should validate that a cutoff BG elevation value of ≥4 mg/dL during CAS indicates carotid occlusion intolerance.

Delayed brain radiation necrosis: pathological review and new molecular targets for treatment.

Delayed radiation necrosis is a well-known adverse event following radiotherapy for brain diseases and has been studied since the 1930s. The primary pathogenesis is thought to be the direct damage to endothelial and glial cells, particularly oligodendrocytes, which causes vascular hyalinization and demyelination. This primary pathology leads to tissue inflammation and ischemia, inducing various tissue protective responses including angiogenesis. Macrophages and lymphocytes then infiltrate the surrounding areas of necrosis, releasing inflammatory cytokines such as interleukin (IL)-1α, IL-6, and tumor necrosis factor (TNF)-α. Microglia also express these inflammatory cytokines. Reactive astrocytes play an important role in angiogenesis, expressing vascular endothelial growth factor (VEGF). Some chemokine networks, like the CXCL12/CXCR4 axis, are upregulated by tissue inflammation. Hypoxia may mediate the cell-cell interactions among reactive astrocytes, macrophages, and microglial cells around the necrotic core. Recently, bevacizumab, an anti-VEGF antibody, has demonstrated promising results as an alternative treatment for radiation necrosis. The importance of VEGF in the pathophysiology of brain radiation necrosis is being recognized. The discovery of new molecular targets could facilitate novel treatments for radiation necrosis. This literature review will focus on recent work characterizing delayed radiation necrosis in the brain.

Comparison of outcomes with/without preoperative embolization for meningiomas with diluted N-butyl-2-cyanoacrylate.

BACKGROUND: Preoperative embolization for meningiomas is controversial regarding its effectiveness in reducing intraoperative blood loss and operative time. In contrast, some reports have documented improved surgical outcomes in large meningiomas. In this study, we retrospectively compared the outcomes of craniotomy for meningiomas with/without preoperative embolization with diluted N-butyl-2-cyanoacrylate (NBCA) primarily in a single institution. METHODS: Data (World Health Organization grade, Simpson grade, maximum tumor diameter, intraoperative bleeding, operative time, history of hypertension, and time from embolization to craniotomy) of patients with initial intracranial meningiomas were compared with or without preoperative embolization from January 2015 to April 2022. RESULTS: The embolization group consisted of 56 patients and the nonembolization group included 76 patients. Diluted NBCA (13% concentration for all patients) was used in 51 of 56 patients (91.1%) who underwent transarterial embolization. Permanent neurological complications occurred in 2 (3.6%) patients. Intraoperative bleeding was significantly lower in the embolization group for a maximum tumor diameter ≥40 mm (155 vs. 305 ml, respectively, p < 0.01). In the nonembolization group, for a maximum tumor diameter ≥30 mm, patients with hypertension had more intraoperative bleeding than non-hypertensive ones. CONCLUSIONS: Despite its limitations, the present results showed that, under certain conditions, preoperative embolization for intracranial meningiomas caused less intraoperative bleeding. The safety of treatment was comparable with that reported in the Japan Registry of NeuroEndovascular Therapy 3 (JR-NET3) with a complication rate of 3.7% for preoperative embolization of meningiomas, despite the treatment focused on the liquid embolization material.

Surgical Outcomes and Medical Costs Associated with Spinal Cord Tumors: Comparison of Extramedullary and Intramedullary Tumors.

OBJECTIVE: This study aimed to clarify the differences in the perioperative data of patients with extramedullary and intramedullary tumors and estimate the impact of surgery on medical costs. METHODS: This single-center retrospective study included consecutive patients who underwent spinal tumor resection between September 2020 and December 2022. The perioperative medical information and medical costs for individual patients were obtained from their medical records. RESULTS: Thirty-two patients with extramedullary spinal cord tumors and 18 with intramedullary spinal cord tumors were included in the study. The 2 groups had no difference in surgery-related or major systemic complications. However, the operation time and the length of hospital stay were significantly longer and activities of daily living at discharge tended to worsen in the intramedullary tumor group compared to those in the extramedullary tumor group. As a result, the discharge outcome was significantly different between the 2 groups. The total medical costs for intramedullary tumors were approximately 1.43 times higher than those for extramedullary tumors. Further, a better functional outcome at discharge can save medical costs, regardless of extramedullary or intramedullary tumors. CONCLUSIONS: Surgery for intramedullary tumors can be performed with similar perioperative risks as for extramedullary tumors. However, intramedullary tumors are associated with concerns, such as prolonged hospitalization and worsening of activities of daily living at discharge, which ultimately result in higher medical costs.

Postoperative Airway Management after Anterior Cervical Spine Surgery: Retrospective Neurosurgical Multicenter Study.

Airway complications that occur after anterior cervical spine surgery pose a life-threatening risk, which encompasses complications including prolonged intubation, unplanned reintubation, and/or necessity of tracheostomy. The present study aimed to identify the surgical risks associated with postoperative airway complications in neurosurgical training institutes. A retrospective, multicenter, observational review of data from 365 patients, who underwent anterior cervical spine surgery between 2018 and 2022, at three such institutes was carried out. Postoperative airway complication was defined as either the need for prolonged intubation on the day of surgery or the need for unplanned reintubation. The perioperative medical information was obtained from their medical records. The average age of the cohort was over 60 years, with males comprising approximately 70%. Almost all surgeries predominantly involved anterior cervical discectomy and fusion or anterior cervical corpectomy and fusion, with most surgeries occurring at the level of C5/6. In total, 363 of 365 patients (99.5%) were extubated immediately after surgery, and the remaining two patients were kept under intubation because of the risk of airway complications. Of the 363 patients who underwent extubation immediately after surgery, two (0.55%) required reintubation because of postoperative airway complications. Patients who experienced airway complications were notably older and exhibited a significantly lower body mass index. The results of this study suggested that older and frailer individuals are at an elevated risk for postoperative airway complications, with immediate postoperative extubation generally being safe but requiring careful judgment in specific cases.

Nonclinical pharmacodynamics of boron neutron capture therapy using direct intratumoral administration of a folate receptor targeting novel boron carrier.

Background: Boron neutron capture therapy (BNCT) is a precise particle radiation therapy known for its unique cellular targeting ability. The development of innovative boron carriers is crucial for the advancement of BNCT technologies. Our previous study demonstrated the potential of PBC-IP administered via convection-enhanced delivery (CED) in an F98 rat glioma model. This approach significantly extended rat survival in neutron irradiation experiments, with half achieving long-term survival, akin to a cure, in a rat brain tumor model. Our commitment to clinical applicability has spurred additional nonclinical pharmacodynamic research, including an investigation into the effects of cannula position and the time elapsed post-CED administration. Methods: In comprehensive in vivo experiments conducted on an F98 rat brain tumor model, we meticulously examined the boron distribution and neutron irradiation experiments at various sites and multiple time intervals following CED administration. Results: The PBC-IP showed substantial efficacy for BNCT, revealing minimal differences in tumor boron concentration between central and peripheral CED administration, although a gradual decline in intratumoral boron concentration post-administration was observed. Therapeutic efficacy remained robust, particularly when employing cannula insertion at the tumor margin, compared to central injections. Even delayed neutron irradiation showed notable effectiveness, albeit with a slightly reduced survival period. These findings underscore the robust clinical potential of CED-administered PBC-IP in the treatment of malignant gliomas, offering adaptability across an array of treatment protocols. Conclusions: This study represents a significant leap forward in the quest to enhance BNCT for the management of malignant gliomas, opening promising avenues for clinical translation.

TERT promoter mutations in primary and secondary glioblastomas.

Telomerase reverse transcriptase (TERT) is up-regulated in a variety of human neoplasms. Mutations in the core promoter region of the TERT gene, which increases promoter activity, have been reported in melanomas and a variety of human neoplasms, including gliomas. In the present study, we screened for TERT promoter mutations by direct DNA sequencing in a population-based collection of 358 glioblastomas. TERT promoter mutations (C228T, C250T) were detected in 55 % glioblastomas analysed. Of these, 73 % had a C228T mutation, and 27 % had a C250T mutation; only one glioblastoma had both C228T and C250T mutations. TERT promoter mutations were significantly more frequent in primary (IDH1 wild-type) glioblastomas (187/322; 58 %) than in secondary (IDH1 mutated) glioblastomas (10/36, 28 %; P = 0.0056). They showed significant inverse correlations with IDH1 mutations (P = 0.0056) and TP53 mutations (P = 0.043), and a significant positive correlation with EGFR amplification (P = 0.048). Glioblastoma patients with TERT mutations showed a shorter survival than those without TERT mutations in univariate analysis (median, 9.3 vs. 10.5 months; P = 0.015) and multivariate analysis after adjusting for age and gender (HR 1.38, 95 % CI 1.01-1.88, P = 0.041). However, TERT mutations had no significant impact on patients' survival in multivariate analysis after further adjusting for other genetic alterations, or when primary and secondary glioblastomas were separately analysed. These results suggest that the prognostic value of TERT mutations for poor survival is largely due to their inverse correlation with IDH1 mutations, which are a significant prognostic marker of better survival in patients with secondary glioblastomas.

Bevacizumab treatment for symptomatic radiation necrosis diagnosed by amino acid PET.

Bevacizumab is effective in treating radiation necrosis; however, radiation necrosis was not definitively diagnosed in most previous reports. Here we used amino acid positron emission tomography to diagnose radiation necrosis for the application of bevacizumab in treating progressive radiation necrosis. Lesion/normal tissue ratios of <2.5 on (18)fluoride-labeled boronophenylalanine-positron emission tomography were defined as an indication of effective bevacizumab treatment. Thirteen patients were treated with bevacizumab at a dose of 5 mg/kg every 2 weeks. Two patients were excluded because of adverse events. The median reduction rate in perilesional edema was 65.5%. Karnofsky performance status improved in six patients after bevacizumab treatment. Lesion/normal tissue ratios on (18)fluoride-labeled boronophenylalanine-positron emission tomography (P = 0.0084) and improvement in Karnofsky performance status after bevacizumab treatment (P = 0.0228) were significantly associated with reduced rates of perilesional edema. Thus, (18)fluoride-labeled boronophenylalanine-positron emission tomography could be useful for diagnosing radiation necrosis and predicting the efficacy of bevacizumab in progressive radiation necrosis.

Chronic expanding pituitary hematoma with calcification resulting from pituitary adenoma: illustrative case.

BACKGROUND: Pituitary apoplexy (PA) is characterized by sudden headache, vomiting, visual dysfunction, anterior lobe dysfunction, and endocrine disorder due to bleeding or infarction from a pituitary adenoma. PA occurs in approximately 0.6-10% of pituitary adenomas, more commonly in men aged 50-60 years, and more frequently in nonfunctioning and prolactin-producing pituitary adenomas. Further, asymptomatic hemorrhagic infarction is found in approximately 25% of PA. OBSERVATIONS: A pituitary tumor with asymptomatic hemorrhage was detected on head magnetic resonance imaging (MRI). Thereafter, the patient underwent head MRI every 6 months. After 2 years, the tumor was enlarged and visual dysfunction was noticed. The patient underwent endoscopic transnasal pituitary tumor resection and was diagnosed with a chronic expanding pituitary hematoma with calcification. The histopathological findings were very similar to those of chronic encapsulated expanding hematoma (CEEH). LESSONS: CEEH associated with pituitary adenomas gradually increases in size, causing visual dysfunction and pituitary dysfunction. In case of calcification, total removal is difficult due to adhesions. In this case, calcification developed within 2 years. A pituitary CEEH, even when showing calcification, should be operated on, as visual function can be fully recovered.

Occult Germinoma of the Intramedullary Spinal Cord: A Case Report.

Primary germ cell tumors of the central nervous system (CNS) typically occur in the neurohypophysis, hypothalamus, or pineal gland and rarely in the spinal cord. We report a case of a spinal intramedullary tumor, which was first detected on magnetic resonance imaging (MRI) 41 months after the initial symptoms, with a verified pathological diagnosis of germinoma. The initial symptom was an abnormal sensation in the left plantar region that gradually worsened, resulting in severe sensory disturbance, difficulty in standing, and even bladder rectal disturbance. Repeated MRI after the onset failed to provide an imaging diagnosis. The MRI was performed 41 months after the onset and revealed a previously undiagnosed, contrast-enhancing spinal intramedullary neoplastic lesion at the Th11-12 level. Gross total resection of the tumor was successfully performed, and the pathology confirmed the diagnosis of pure germinoma. Postoperative chemotherapy, followed by local radiation, was successfully administered. Among primary germinomas of the CNS, occult germinoma that lacks imaging findings suggestive of tumors in the early stages of onset and becomes apparent over time is often reported as a primary neurohypophyseal germinoma, particularly in adolescents presenting with diabetes insipidus. In the present case, the lesion appeared to correspond to a primary occult germinoma of the intramedullary spinal cord.

Treatment Outcomes of 94 Cases of Pipeline Embolization Device in a Single Center: Predictive Factors of Incomplete Aneurysm Occlusion.

Objective: This study aimed to report the outcome of an endovascular treatment with a pipeline embolization device (PED) at a single center. We also examined the predictive factors for an incomplete occlusion after the PED placement. Methods: The subjects were 94 patients with 109 aneurysms who underwent the PED placement at our single center from June 2015 to September 2022. As treatment outcomes, we investigated the PED placement success rate, perioperative morbidity and mortality, postoperative cranial nerve improvement rate, and the classification of angiographic result at 6 months after the PED placement. Furthermore, the predictors of an incomplete occlusion were investigated in detail. Results: One hundred nine aneurysms locations were: C1 (9), C2 (30), C3 (15), C4 (53), and C5 (2) in the internal carotid artery segments. Perioperative morbidity, including the asymptomatic ones, occurred in 10 cases (10.6%). Among these 10 cases, the modified Rankin Scale (mRS) improved to preoperative mRS after 90 days in 9 cases except 1 case. On the other hand, no perioperative mortality was observed. The postoperative cranial nerve improvement rate was 84.4%, and 61.7% of patients had a complete occlusion in the follow-up angiography, 6 months after the PED placement. Predictive factors for an incomplete occlusion after the PED placement were the elderly aged 70 years or older (P-value = 0.0214), the elderly aged 75 years or older (P-value = 0.0009), and the use of anticoagulants (P-value = 0.0388) in an univariate analysis. Further, the multivariate analysis revealed that the elderly aged 75 years or older was a predictive factor of an incomplete occlusion in this study. Conclusion: We summarized the outcomes of the PED treatment at our single center. In this study, the elderly aged 75 years or older was a predictive factor of an incomplete occlusion after the PED placement.

Vertebral artery is an anatomical landmark in the posterior unilateral resection of cervical benign nerve sheath tumors with dumbbell extension of Eden type 2 or 3.

Background: In the cervical nerve sheath tumor (NST) surgery with dumbbell extension of Eden type 2 or 3, selection of anterior, posterior, or combined approach remains controversial. Objectives: This technical note aimed to propose possible advantages of the posterior unilateral approach (PUA). Methods: Six patients who underwent the surgical treatment of cervical NSTs with dumbbell extension of Eden type 2 or 3 were included. The critical surgical steps included (1) complete separation of extradural and intradural procedures, (2) careful peeling of the neural membranes (epineurium and perineurium) from the tumor surface in the extradural procedure, (3) complete removal of the extradural tumor within the neural membranes, (4) intradural disconnection of tumor origin, and (5) intentional tumor removal up to the vertebral artery (VA), i.e., the VA line. Results: The tumor location of dumbbell extension was Eden types 2 and 3 in two and four patients. Gross total resection was achieved in two patients and intentional posterior removal of the tumor to the VA line was achieved in the remaining four patients. No vascular or neural injuries associated with surgical procedures occurred. Postoperative neurological assessment revealed no symptomatic aggravation in all patients. No secondary surgery was performed during the study period. Conclusion: PUA was safe and less invasive for functional recovery and tumor resection, if the anatomical relationship between the tumor and VA is clearly understood. The VA line is an important anatomical landmark to limit the extent of tumor resection.

Influence of surgical position and registration methods on clinical accuracy of navigation systems in brain tumor surgery.

The aim of this study was to evaluate the influence of skin distortion due to surgical positioning on the clinical accuracy of the navigation system. The distance errors were measured in four fiducial markers (anterior, posterior, right, and left of the head) after the registration of the navigation system. The distance errors were compared between the surface-merge registration (SMR) method using preoperative imaging and the automatic intraoperative registration (AIR) method using intraoperative imaging. The comparison of the distance errors were performed in various surgical positions. The AIR method had the significant accuracy in the lateral markers than the SMR method (lateral position, 3.8 mm vs. 8.95 mm; p < 0.0001; prone position, 4.5 mm vs. 13.9 mm; p = 0.0001; 5.2 mm vs. 11.5 mm; p = 0.0070). The smallest distance errors were obtained close to the surgical field in the AIR method (3.25-3.85 mm) and in the forehead in the SMR method (3.3-8.1 mm). The AIR method was accurate and recommended for all the surgical positions if intraoperative imaging was available. The SMR method was only recommended for the supine position, because skin distortion was frequently observed in the lateral region.