Long-term outcomes of stereotactic radiosurgery for intracranial schwannoma in neurofibromatosis type 2: a genetic analysis perspective.

PURPOSE: Neurofibromatosis type 2 (NF2) is intractable because of multiple tumors involving the nervous system and is clinically diverse and genotype-dependent. Stereotactic radiosurgery (SRS) for NF2-associated schwannomas remains controversial. We aimed to investigate the association between radiosurgical outcomes and mutation types in NF2-associated schwannomas. METHODS: This single-institute retrospective study included consecutive NF2 patients with intracranial schwannomas treated with SRS. The patients' types of germline mutations ("Truncating," "Large deletion," "Splice site," "Missense," and "Mosaic") and Halliday's genetic severity scores were examined, and the associations with progression-free rate (PFR) and overall survival (OS) were analyzed. RESULTS: The study enrolled 14 patients with NF2 with 22 associated intracranial schwannomas (median follow-up, 102 months).　The PFRs in the entire cohort were 95% at 5 years and 90% at 10-20 years. The PFRs tended to be worse in patients with truncating mutation exons 2-13 than in those with other mutation types (91% at 5 years and 82% at 10-20 years vs. 100% at 10-20 years, P = 0.140). The OSs were 89% for patients aged 40 years and 74% for those aged 60 years in the entire cohort and significantly lower in genetic severity group 3 than in the other groups (100% vs. 50% for those aged 35 years; P = 0.016). CONCLUSION: SRS achieved excellent PFR for NF2-associated intracranial schwannomas in the mild (group 2A) and moderate (group 2B) groups. SRS necessitates careful consideration for the severe group (group 3), especially in cases with NF2 truncating mutation exons 2-13.

[Basic and Advanced Techniques of Anastomosis in Deep Surgical Fields:STA-SCA Anastomosis].

This article detailly describes the subtemporal-transtentorial STA-SCA bypass technique. Through temporal base drilling, copious cerebrospinal fluid evacuation before retraction, and sufficient retraction of the temporal lobe preserving the veins of the temporal base would be primodial to obtain an appropriate surgical field. Refrection of the tentrial free edge and identification of recipient SCA posterior to the entry point of the trochlear nerve into the cavernous sinus is a micro-anatomical key. Bilateral bayonet-type needle holders and forceps should be used not to shadow the surgical corridor with one's hands.

Fractionated versus staged gamma knife radiosurgery for mid-to-large brain metastases: a propensity score-matched analysis.

PURPOSE: To compare treatment results between fractionated gamma knife radiosurgery (f-GKRS) and staged gamma knife radiosurgery (s-GKRS) for mid-to-large brain metastases (BMs). METHODS: We retrospectively analyzed data of patients with medium (4-10 mL) to large (> 10 mL) BMs who underwent s-GKRS or f-GKRS between March 2008 and September 2022. Patients were treated with (i) s-GKRS before May 2018 and (ii) f-GKRS after May 2018. Patients who underwent follow-up magnetic resonance imaging at least once were enrolled. Case-matched studies were conducted by applying propensity score matching to minimize treatment selection bias and potential confounding. Local control (LC) was set as the primary endpoint and overall survival (OS) as the secondary endpoint. RESULTS: This study included 129 patients with 136 lesions and 70 patients with 78 lesions who underwent s-GKRS and f-GKRS, respectively. Overall, 124 lesions (62 lesions in each group) were selected in the case-matched group. No differences were observed in the 6-month and 1-year cumulative incidences of LC failure between the s-GKRS and f-GKRS groups (15.6% vs. 15.9% at 6 months and 25.6% vs. 25.6% at 1 year; p = 0.617). One-year OS rates were 62.6% (95% confidence interval [CI]: 45.4-75.7%) and 73.9% (95% CI: 58.8-84.2%) in the s-GKRS and f-GKRS groups, respectively. The post-GKRS median survival time was shorter in the s-GKRS group than in the f-GKRS group (17 vs. 36 months), without significance (p = 0.202). CONCLUSIONS: This is the first study to compare f-GKRS and s-GKRS in large BMs. Fractionation is as effective as staged GKRS for treating mid-to-large BMs.

VEGFR-TKI treatment for radiation-induced brain injury after gamma knife radiosurgery for brain metastases from renal cell carcinomas.

OBJECTIVE: Antiangiogenic vascular endothelial growth factor receptor tyrosine kinase inhibitors play an essential role in systemic therapy for renal cell carcinoma. Given the anti-edematous effect of bevacizumab, an antiangiogenic antibody targeting vascular endothelial growth factor, vascular endothelial growth factor receptor tyrosine kinase inhibitors should exert therapeutic effects on radiation-induced brain injury after stereotactic radiosurgery. This preliminary study aimed to investigate the therapeutic effect of vascular endothelial growth factor receptor tyrosine kinase inhibitor against radiation-induced brain injury. METHODS: Magnetic resonance images for six patients treated with vascular endothelial growth factor receptor tyrosine kinase inhibitors who were diagnosed with radiation-induced brain injury following gamma knife radiosurgery were retrospectively reviewed. RESULTS: The median brain edema volume and tumour mass volume in the pre-tyrosine kinase inhibitor period were 57.6 mL (range: 39.4-188.2) and 3.2 mL (range: 1.0-4.6), respectively. Axitinib, pazopanib (followed by cabozantinib) and sunitinib were administered in four, one and one cases, respectively. The median brain edema volume and tumour mass volume in the post-tyrosine kinase inhibitor period were 4.8 mL (range: 1.5-27.8) and 1.6 mL (range: 0.4-3.6), respectively. The median rates of reduction in brain edema volume and tumour mass volume were 90.8% (range: 51.9-97.6%) and 57.2% (range: 20.0-68.6%), respectively. The post-tyrosine kinase inhibitor values for brain edema volume (P = 0.027) and tumour mass volume (P = 0.008) were significantly lower than the pre-tyrosine kinase inhibitor values. Changes in volume were correlated with tyrosine kinase inhibitor use. CONCLUSION: This study is the first to demonstrate the therapeutic effects of vascular endothelial growth factor receptor tyrosine kinase inhibitors on radiation-induced brain injury in patients with brain metastases from renal cell carcinoma treated via gamma knife radiosurgery.

Stereotactic radiosurgery for recurrent pleomorphic adenoma of the lacrimal gland: a case report.

Lacrimal gland pleomorphic adenomas (LGPAs) are common, benign, and intraorbital tumours that cause exophthalmos, ptosis, and visual disturbances. The curative treatment for LGPAs is gross total resection, and radiotherapy is considered adjunctive for recurrence or an alternative for inoperable LGPAs. Stereotactic radiosurgery (SRS) can be used for precise delivery of high radiation doses to the tumour, crucial in the treatment of intra-and extracranial neoplasms. Here, we present a 95-year-old woman who had a rapidly growing, recurrent LGPA and was successfully treated with SRS. The tumour was controlled without any adverse events over 21 months following SRS. SRS is a potential alternative treatment for recurrent LGPA.

Interfractional change of tumor volume during fractionated stereotactic radiotherapy using gamma knife for brain metastases.

PURPOSE: Fractionated stereotactic radiotherapy (FSRT) using gamma knife is useful for brain metastases. However, several uncertainties derived from fractionation pose issues for maintaining high-level accuracy. This study analyzed interfractional tumor change by performing radiological reassessment at the midterm of FSRT with ≥ 10 fractions, and the significance of replanning was evaluated. METHODS: Data of FSRT using gamma knife with ≥ 10 fractions were retrospectively collected. Interfractional volume changes in MRI at the midterm of the irradiation period were analyzed. Radiological changes after FSRT and final outcomes were also investigated. RESULTS: Overall, 114 lesions in 74 treatments from 66 patients were included, with previously irradiated lesions accounting for 46%. The median interval between planning and the interfractional MRI was 7 days. The interfractional change rates of tumor volume ranged from - 48 to + 72%. Significant interfractional enlargement was observed in 16 lesions (14%); evident regression was confirmed in 17 lesions (15%). Predictive factors for interfractional enlargement were small tumor and cystic lesion; high biologically effective dose was associated with regression. After FSRT, most lesions regressed within 6 months despite interfractional change type. The incidences of tumor control and radiation necrosis indicated no differences between interfractionally-regressed lesions and others. CONCLUSION: This is the first study to evaluate interfractional tumor change in FSRT using gamma knife with ≥ 10 fractions, indicating significant volume changes in 29% of the lesions. These preliminary results suggest that interfractional reassessment of a treatment plan in FSRT with irradiation periods exceeding a week is necessary for more adaptive treatment.

Long-term outcomes of stereotactic radiosurgery for skull base tumors involving the cavernous sinus.

PURPOSE: Stereotactic radiosurgery (SRS) is an effective and less invasive therapeutic option for cavernous sinus (CS) tumors. However, its long-term effectiveness and neurological outcomes have yet to be fully elucidated. We aimed to examine the long-term outcomes of SRS for CS tumors. METHODS: Overall, a cohort of 113 patients with benign CS tumors, including 91 with meningioma, 14 with trigeminal schwannoma (TS), and eight with cavernous hemangioma, treated with SRS at our institution from 1990 to 2018, was included. Tumor control and functional preservation/recovery were evaluated in detail. RESULTS: The median post-SRS follow-up period was 77 months (interquartile range, 39-177). Progression-free survival (PFS) was 97% at 5 years, 89% at 10 years, and 87% at 15 years for the entire cohort; 96% at 5 years and 87% at 10 years for meningiomas; and 100% at 10 years for the other tumors. No significant difference was observed between meningiomas and non-meningiomas (log-rank test, p = 0.107). Improvement in cranial nerve (CN) function was observed in 35 (27%) patients. TSs tended to show CN improvements more often than meningiomas did (total improvements, 62% vs. 23%; p = 0.004; eye movement function, 100% vs. 20%; p = 0.002). CN deterioration or development of new CN deficits was observed in 11 (10%) patients. CONCLUSION: SRS provides good tumor control and acceptable long-term outcome with sufficient preservation of CN function in patients with benign CS tumors.

Stereotactic radiosurgery ensures an effective and safe long-term control of Koos grade IV vestibular schwannomas: a single-center, retrospective, cohort study.

PURPOSE: Stereotactic radiosurgery (SRS) is a standard treatment modality for vestibular schwannomas (VSs). However, there is a paucity of data on tumor control and neurological preservation for larger VSs. We aimed to investigate the long-term effectiveness of SRS for Koos grade IV compared with I-III VSs. METHODS: We included 452 patients with VSs (50 Koos grade IV and 402 Koos grade I‒III) who were treated with SRS at our institution from 1990 to 2021. Tumor control and functional preservation were calculated using the Kaplan-Meier method and compared between groups with the log-rank test. RESULTS: The median post-SRS follow-up period was 68 months. Progression-free survival rates were 91% at 5 and 10 years for Koos grade IV VSs, and 95% and 92%, respectively, for Koos grade I‒III VSs (p = 0.278). In Koos grade IV VSs, functional preservation rates of the facial and trigeminal nerves were both 96% at 5 years (both 98% for Koos grade I‒III VSs; facial, p = 0.410; trigeminal, p = 0.107). Hearing preservation rates were 61% at 5 years for Koos grade IV VSs and 78% for Koos grade I-III VSs (p = 0.645). Symptomatic transient tumor expansion was more common with Koos grade IV VSs (8.0% vs. 2.5%, p = 0.034), although all related symptoms diminished in accordance with tumor shrinkage. CONCLUSION: SRS may contribute to long-term tumor control and adequate neurological preservation in the treatment of Koos grade IV VSs, comparable to those in the treatment of Koos grade I‒III VSs.

Fractionated Gamma Knife radiosurgery after cyst aspiration for large cystic brain metastases: case series and literature review.

Tumor cyst aspiration followed by Gamma Knife radiosurgery (GKRS) for large cystic brain metastases is a reasonable and effective management strategy. However, even with aspiration, the target lesion tends to exceed the dimensions of an ideal target for stereotactic radiosurgery. In this case, the local tumor control rate and the risk of complication might be a critical challenge. This study is aimed to investigate whether fractionated GKRS (f-GKRS) could solve these problems. Between May 2018 and April 2021, eight consecutive patients with nine lesions were treated with f-GKRS in five or ten sessions after cyst aspiration. The aspiration was repeated as needed throughout the treatment course to maintain the cyst size and shape. The patient characteristics, radiologic tumor response, and clinical course were reviewed using medical records. The mean follow-up duration was 10.2 (2-28) months. The mean pre-GKRS volume and maximum diameter were 16.7 (5-55.8) mL and 39.0 (31-79) mm, respectively. The mean tumor volume reduction achieved by aspiration was 55.4%. The tumor volume decreased for all lesions, and symptoms were alleviated in all patients. The median overall survival was 10.0 months, and the estimated 1-year survival rate was 41.7% (95% CI: 10.9-70.8%). The local tumor control rate was 100%. No irradiation-related adverse events were observed. f-GKRS for aspirated cystic brain metastasis is a safe, effective, and less invasive management option for large cystic brain metastases.

Hemodynamic changes during the obliteration process for cerebral arteriovenous malformations after radiosurgery.

OBJECTIVE: The process of cerebral arteriovenous malformation (AVM) obliteration following radiosurgery is poorly understood. Authors of this retrospective study aimed to assess the changes in AVM hemodynamics after stereotactic radiosurgery (SRS) by using 3D flow magnetic resonance imaging (MRI) to elucidate the process of AVM obliteration. METHODS: Twenty-four patients with AVMs treated with SRS between July 2015 and December 2017 were included in this study and classified into two groups depending on the duration of AVM obliteration: group A, obliteration within 3 years (n = 15); and group B, obliteration taking more than 3 years or no obliteration (n = 9). Blood flow (ml/min) in the largest feeding artery was measured before and after SRS by using time-averaged 3D flow MRI. The decreasing rate of blood flow in the feeding artery after SRS was calculated as the percent change from baseline blood flow. A Wilcoxon rank-sum test was used to compare the decreasing blood flow rate between the two groups at 4 and 12 months after SRS. RESULTS: For the entire cohort, the mean decrease in blood flow in the feeding artery from baseline was 29% at 4 months and 71% at 12 months after SRS. In general, blood flow after SRS decreased faster in group A and slower in group B. The decreasing rates in blood flow at 4 and 12 months after SRS were significantly different between the two groups (p = 0.02 and < 0.001, respectively). CONCLUSIONS: Tracking changes in AVM hemodynamics after SRS may be useful for assessing the progress of AVM obliteration and the therapeutic effects of SRS, possibly contributing to the prediction of subsequent obliteration outcome.

Superficial temporal artery lengthening technique to prevent postoperative wound complications in direct revascularization to the anterior cerebral artery for Moyamoya disease.

BACKGROUND: Neurocognitive dysfunctions or psychomotor symptoms of Moyamoya disease may improve after direct revascularization to the anterior cerebral artery (ACA). However, long-distance harvest of the frontal branch of the superficial temporal artery (STA) is needed to reach the cortical ACA, frequently resulting in postoperative wound complications. To solve this problem, we devised a novel method (STA lengthening technique). In this study, we compared the STA lengthening technique and the conventional method regarding postoperative wound complications. METHODS: Twenty-five patients who underwent STA-ACA direct bypass from December 2016 to October 2021 were retrospectively reviewed, and postoperative wound complications were recorded. Magnetic resonance angiography was performed to evaluate the patency of the bypass to the ACA and postoperative development of collaterals to the skin flap. RESULTS: Thirty-eight hemispheres (new method [n = 12] vs. conventional method [n = 26]) were treated. Wound complications occurred in 12 surgeries (46%) of the conventional method, and none (0%) of the new method. The anastomosis with the cortical ACA was patent in all surgeries. Postoperative development of collaterals to the skin flap was confirmed after all surgeries (100%) in the new method, whereas after only five surgeries (20%) in the conventional method. CONCLUSION: The STA lengthening technique can enable to preserve the collateral circulation to the skin flap postoperatively, resulting in good wound healing.

Outcomes of stereotactic radiosurgery in young adults with vestibular schwannomas.

PURPOSE: Vestibular schwannomas (VSs) are comparatively rare in younger patients, and stereotactic radiosurgery (SRS) outcome data are limited. We aimed to evaluate long-term SRS outcomes concerning sporadic VSs in patients aged ≤ 40 years. METHODS: Of 383 patients with VS who had undergone SRS at our institution between 1990 and 2017, we retrospectively compared younger and older patients' tumor control and radiation-induced complication rates using case-control propensity score (PS) matching. RESULTS: The mean follow-up was 83 and 92 months in older and younger patients, respectively. Compared with older patients, younger patients were more likely to have a history of resection (20% vs. 39%, p = 0.006) and be treated with higher marginal doses (median, 12 Gy vs. 14 Gy; p = 0.014). Cumulative 5- and 10-year tumor control rates were higher in older patients (97.7% and 93.9%, respectively) than in younger patients (90.2% and 85.4%, respectively, p = 0.024). After PS matching, younger patients' cumulative tumor control rates (93.6%, 85.4%, and 85.4% at 5, 10, and 15 years, respectively) were similar to those of older patients (p = 0.411). No significant between-cohort differences in hearing preservation rates or other cranial nerve complications were observed. Two younger patients had malignant tumors several years post-SRS, with one patient having confirmed histological transformation. CONCLUSIONS: SRS is equally effective for younger and older patients. Complications other than hearing deterioration are uncommon. However, malignant transformation is possible, and long-term post-SRS surveillance MRI is important. These data are useful for decision-making involving young adults with VSs.

Stereotactic radiosurgery as a primary treatment for metastatic skull base alveolar soft part sarcoma: a case report.

Alveolar soft part sarcoma (ASPS) is a rare malignancy that typically arises in the trunk or extremities and preferentially metastasises to the brain. Radical resection is generally recommended for cranial metastatic ASPS, but stereotactic radiosurgery (SRS) is a recognised alternative for tumours in surgically challenging locations. Here, we present the case of a 22-year-old female, who underwent SRS and systemic therapy with pazopanib for a metastatic ASPS in the left temporal bone. The tumour was successfully controlled without further intervention over 23 months following SRS, which should be considered for metastatic ASPS when surgical resection is not appropriate.

Impact of breast cancer subtype on clinical outcomes after Gamma Knife radiosurgery for brain metastases from breast cancer: a multi-institutional retrospective study (JLGK1702).

INTRODUCTION: Brain metastasis (BM) is one of the most important issues in the management of breast cancer (BC), since BMs are associated with neurological deficits. However, the importance of BC subtypes remains unclear for BM treated with Gamma Knife radiosurgery (GKS). Thus, we conducted a multicenter retrospective study to compare clinical outcomes based on BC subtypes, with the aim of developing an optimal treatment strategy. METHODS: We studied 439 patients with breast cancer and 1-10 BM from 16 GKS facilities in Japan. Overall survival (OS) was analyzed by the Kaplan-Meier method, and cumulative incidences of systemic death (SD), neurologic death (ND), and tumor progression were estimated by competing risk analysis. RESULTS: OS differed among subtypes. The median OS time (months) after GKS was 10.4 in triple-negative (TN), 13.7 in Luminal, 31.4 in HER2, and 35.8 in Luminal-HER2 subtype BC (p < 0.0001). On multivariate analysis, poor control of the primary disease (hazard ratio [HR] = 1.84, p < 0.0001), active extracranial disease (HR = 2.76, p < 0.0001), neurological symptoms (HR 1.44, p = 0.01), and HER2 negativity (HR = 2.66, p < 0.0001) were significantly associated with worse OS. HER2 positivity was an independent risk factor for local recurrence (p = 0.03) but associated with lower rates of ND (p = 0.03). TN histology was associated with higher rates of distant brain failure (p = 0.03). CONCLUSIONS: HER2 positivity is related to the longer OS after SRS; however, we should pay attention to preventing recurrence in Luminal-HER2 patients. Also, TN patients require meticulous follow-up observation to detect distant metastases and/or LMD.

Salvage pemetrexed for brain metastases from ALK-positive lung cancer after Gamma Knife radiosurgery: illustrative case.

BACKGROUND: Systemic therapy for cancer treatment has improved, and therapeutic options for intracranial lesions are increasing. Combinations of treatment modalities are required in certain difficult cases. Gamma Knife radiosurgery (GKS) is effective for the treatment of brain metastases, especially for lesions that are inoperable because of their anatomical or functional location. OBSERVATIONS: The authors report a case of brain metastases in anaplastic lymphoma kinase (ALK)-positive lung adenocarcinoma initially treated with GKS followed by the combination of repeat GKS and ALK tyrosine kinase inhibitors (ALK-TKIs) for tumor recurrence. During the clinical course, acquired resistance to ALK-TKIs due to the long exposure period was suspected. After a great deal of thought and discussion with the oncologist responsible for the treatment of the pulmonary lesions, the authors successfully controlled the lesion for the next 17 months by salvage pemetrexed administration. LESSONS: This is the first report on the effectiveness of pemetrexed for recurrent brain metastasis from ALK-positive lung adenocarcinoma resistant to both radiosurgery and ALK inhibitors. Salvage pemetrexed showed a favorable therapeutic effect in this specific case.

Spontaneous Regression of an Unruptured Arteriovenous Malformation Due to Drainer Vein Thrombosis in a Patient with Protein S Deficiency: A Case Report and Literature Review.

Spontaneous regression of an arteriovenous malformation (AVM) is a rare condition observed in 0.3%-1.3% of patients with AVMs and is most likely caused by hemorrhagic events. The regression of an unruptured AVM is rarer than that of a ruptured AVM. Moreover, due to its low frequency of occurrence, the etiology and natural course of spontaneous regression of an AVM is still unclear. This is the first report presenting a case of a spontaneous regression of an unruptured AVM caused by a gradual drainer vein thrombosis that was suspected to result from hypercoagulability due to protein S deficiency.

Comparing Fractionated and Single-Fraction Gamma Knife Radiosurgery for Brain Metastases From Non-Small-Cell Lung Cancer With a Focus on Driver Alterations.

Background As the overall survival in non-small-cell lung cancer has increased, safer, long-term treatments for brain metastases are increasingly needed. This study aimed to analyze the outcomes of fractionated and single-fraction gamma knife radiosurgery for brain metastases from non-small-cell lung cancer, focusing on driver alteration status. Methodology Patients who underwent gamma knife radiosurgery as their first local treatment for brain metastases from non-small-cell lung cancer between May 2018 and December 2021 at our institution were retrospectively enrolled. Results Among the 98 patients (287 lesions), 45 (130 lesions) harbored driver alterations, including epidermal growth factor receptor mutations in 35 patients and anaplastic lymphoma kinase or ROS1 rearrangement in 10 patients. Overall, 64 and 34 patients underwent single-fraction and fractionated radiosurgery (3-15 fractions), respectively. Large tumor size was a risk factor for recurrence, while fractionated radiosurgery (subdistribution hazard ratio (sHR) = 16.47; confidence interval (CI) = 3.58-75.77; p < 0.001) and small tumor size (sHR = 1.15; CI = 1.04-1.28; p = 0.008) independently protected against radiation necrosis. In the case-matched analyses, the cumulative radiation necrosis rates were significantly lower in the fractionated group than in the single-fraction group among all lesions (p = 0.017) and among those with driver alterations (p = 0.046), whereas no significant difference was confirmed among wild-type lesions (p = 0.382). Conclusions Fractionated gamma knife radiosurgery may be an alternative therapeutic approach for reducing the risk of radiation necrosis, particularly for patients with driver alterations, even when the tumors are small. Further research is necessary to determine the optimal indications for fractionated gamma knife radiosurgery and fractionation methods.

Prognosis of Rotational Angiography-Based Stereotactic Radiosurgery for Dural Arteriovenous Fistulas: A Retrospective Analysis.

BACKGROUND: Cerebral dural arteriovenous fistulas (DAVFs) are intracranial vascular malformations with fine, abnormal vascular architecture. High-resolution vascular imaging is vital for their visualization. Currently, rotational angiography (RA) provides the finest 3-dimensional visualization of the arteriovenous shunt with high spatial resolution; however, the efficacies of the integration of RA have never been studied in stereotactic radiosurgery (SRS) for DAVFs until now. Since 2015, our institution has integrated RA into SRS (RA-SRS) to provide more conformal planning, thereby decreasing overtreatment and undertreatment. OBJECTIVE: To analyze the outcomes of RA-SRS for DAVFs. METHODS: We retrospectively analyzed the outcomes of 51 patients with DAVFs and compared those of 20 DAVFs treated with RA-SRS with those of 31 DAVFs treated with conventional SRS (c-SRS). RESULTS: The time to obliteration was shorter in the RA-SRS group (median, 15 months vs 26 months [cumulative rate, 77% vs 33% at 2 years, 77% vs 64% at 4 years]; P = .015). Multivariate Cox proportional hazards analysis demonstrated that RA-SRS (hazard ratio 2.39, 95% CI 1.13-5.05; P = .022) and the absence of cortical venous reflux (hazard ratio 2.12, 95% CI 1.06-4.25; P = .034) were significantly associated with obliteration. The cumulative 5-year post-SRS stroke-free survival rates were 95% and 97% in the RA-SRS and c-SRS groups, respectively ( P = .615). Neurological improvement tended to occur earlier in the RA-SRS group than in the c-SRS group (median time to improvement, 5 months vs 20 months, log-rank test; P = .077). CONCLUSION: RA-based SRS may facilitate earlier fistula obliteration and may contribute to early neurological improvement.

Endoscopic Extended Transsphenoidal Surgery Aiming for Radical Resection of Skull Base Tumors Involving Cavernous Sinus: Assessment of Resectability and Risks of Complications.

BACKGROUND AND OBJECTIVES: Surgical resection of tumors invading the cavernous sinus (CS) still shows therapeutic challenges. For "nonadenomatous" skull base tumors invading in CS, there were only a few reports showing the outcomes of radical resection. Therefore, the outcomes of endoscopic transsphenoidal surgery (ETS) aiming for radical resection thus remain largely unknown regarding resectability and functional results of the cranial nerves. METHODS: We performed ETS aiming for radical resection in 35 skull base tumors involving CS (17 chondrosarcomas, 12 chordomas, 3 meningiomas, and 3 trigeminal schwannomas; median follow-up 36.5 months ranging from 12 to 91 months). Gross total resection (GTR) is attempted in all the cases for real-time findings from electrophysiological monitoring of the cranial nerves. When the tumor was strongly adherent to the cranial nerves or internal carotid artery, maximum volume reduction of the tumor was attempted. RESULTS: GTR was achieved in 28 patients (80.0%), subtotal resection in 3 (8.6%), and partial resection in 4 (11.4%). One patient experienced internal carotid artery injury during surgery. After ETS, 15 patients showed symptom improvement (51.7% in all 29 patients with preoperative cranial nerve symptoms, CNS). Four (11.4%) transiently developed abducens nerve palsy, and one required repair surgery for cerebrospinal leakage. In univariate analyses, extension to the lateral compartment of CS ( P = .04) was significantly associated with reduced achievement of GTR. Previous transcranial surgery was associated with reduced possibility of improvement and worsening in CNS. Eleven patients underwent stereotactic radiosurgery, at a median of 12 months after ETS. 32 patients (91.4%) did not show recurrence at the final follow-up. CONCLUSION: ETS can achieve sufficient surgical resection in most of the patients, with acceptable neurological complications. For patients with CNS, ETS may offer the opportunity for improving CNS. We should also always prioritize avoidance of critical situations by preventing internal carotid artery injury.

Age-Dependent Hemorrhage Risk and Obliteration Benefit After Radiosurgery for Brain Arteriovenous Malformation.

PURPOSE: Because patients with untreated brain arteriovenous malformations (BAVMs) are at variable risks of cerebral hemorrhage and associated mortality and morbidity, it is essential to identify patient populations who benefit most from prophylactic interventions. This study aimed to examine age-dependent differences in the therapeutic effect of stereotactic radiosurgery (SRS) on BAVMs. METHODS AND MATERIALS: This retrospective observational study enrolled patients with BAVMs who underwent SRS at our institution between 1990 and 2017. The primary outcome was post-SRS hemorrhage, and the secondary outcomes included nidus obliteration, post-SRS early signal changes, and mortality. To investigate age-related differences in outcomes after SRS, we performed age-stratified analyses using the Kaplan-Meier analysis and weighted logistic regression with the inverse probability of censoring weighting (IPCW). To address significant differences in patient baseline characteristics, we also performed inverse probability of treatment weighting (IPTW) adjusted for possible confounders to investigate age-related differences in outcomes after SRS. RESULTS: A total of 735 patients with 738 BAVMs were stratified by age. Age-stratified analysis using a weighted logistic regression model with IPCW showed a direct correlation between patient age and post-SRS hemorrhage (odds ratio [OR], 95% confidence interval [CI], and P value: 2.20, 1.34-3.63, and .002 at 18 months; 1.86, 1.17-2.93, and .008 at 36 months; and 1.61, 1.05-2.48, and .030 at 54 months, respectively). The age-stratified analysis also showed an inverse relationship between age and obliteration over the first 42 months after SRS (OR, 95% CI, and P value: 0.05, 0.02-0.12, and <.001 at 6 months; 0.55, 0.44-0.70, and <.001 at 24 months; and 0.76, 0.63-0.91, and .002 at 42 months, respectively). These results were also confirmed with the IPTW analyses. CONCLUSIONS: Our analysis demonstrated that patients' age at SRS is significantly associated with hemorrhage and the nidus obliteration rate after treatment. In particular, younger patients are more likely to exhibit reduced cerebral hemorrhages and achieve earlier nidus obliteration compared with older patients.