M eningioMas are the most frequently reported primary intracranial neoplasms in the US. Most of these lesions are benign (i.e., WHO Grade I) with a low tendency for invasion and recurrence and a natural history of slow growth. Within the intracranial space, there is a narrow capacity for mass expansion. The primary approach for large meningiomas has been resection. Despite a dramatic decline in surgical morbidity for abbreviatioNs CN = cranial nerve; CPA = cerebellopontine angle; GKRS = Gamma Knife radiosurgery; HR = hazard ratio; SRS = stereotactic radiosurgery. submitted January 26, 2014. accepted October 14, 2014. iNclude wheN citiNg Published online December 5, 2014; DOI: 10.3171/2014.10.JNS14198. disclosure The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper. obJect Stereotactic radiosurgery (SRS) has become a common treatment modality for intracranial meningiomas. Skull base meningiomas greater than 8 cm 3 in volume have been found to have worse outcomes following SRS. When symptomatic, patients with these tumors are often initially treated with resection. For tumors located in close proximity to eloquent structures or in patients unwilling or unable to undergo a resection, SRS may be an acceptable therapeutic approach. In this study, the authors review the SRS outcomes of skull base meningiomas greater than 8 cm 3 in volume, which corresponds to a lesion with an approximate diameter of 2.5 cm. methods The authors reviewed the data in a prospectively compiled database documenting the outcomes of 469 patients with skull base meningiomas treated with single-session Gamma Knife radiosurgery (GKRS). Seventy-five patients had tumors greater than 8 cm 3 in volume, which was defined as a large tumor. All patients had a minimum follow-up of 6 months, but patients were included if they had a complication at any time point. Thirty patients were treated with upfront GKRS, and 45 were treated following microsurgery. Patient and tumor characteristics were assessed to determine predictors of new or worsening neurological function and tumor progression following GKRS. results After a mean follow-up of 6.5 years (range 0.5-21 years), the tumor volume was unchanged in 37 patients (49%), decreased in 26 patients (35%), and increased in 12 patients (16%). Actuarial rates of progression-free survival at 3, 5, and 10 years were 90.3%, 88.6%, and 77.2%, respectively. Four patients had new or worsened edema following GKRS, but preexisting edema decreased in 3 patients. In Cox multivariable analysis, covariates associated with tumor progression were 1) presentation with any cranial nerve (CN) deficit from III to VI (hazard ratio [HR] 3.78, 95% CI 1.91-7.45; p < 0.001), history of radiotherapy (HR 12.06, 95% CI 2.04-71.27; p = 0.006), and tumor volume greater than 14 cm 3 (HR 6.86, p = 0.066). In those patients with detailed clinical follow-up (n = 64), neurological function was unchanged in 37 patients (58%), improved in 16 patients (25%), and d...

OBJECTIVEThe choice of transsylvian versus transcortical corridors for resection of insular gliomas remains controversial. Functional pathway compromise from transcortical transgression and vascular injury during transsylvian dissection are the primary concerns. In this study, data from a single-center experience with both approaches were compared to determine whether one approach was associated with a higher rate of morbidity than the other.METHODSThe authors identified 100 consecutive patients who underwent resection of pure insular gliomas at the Barrow Neurological Institute. Volumetric analysis was performed using FLAIR and contrast-enhanced T1-weighted MRI for low- and high-grade gliomas, respectively, for extent of resection (EOR) and diffusion-weighted sequences were used to detect for postoperative ischemia. Step-wise logistic regression analysis was performed to identify predictors of neurological morbidity.RESULTSData from 100 patients with low-grade or high-grade insular gliomas were analyzed. Fifty-two patients (52%) underwent a transsylvian approach, and 48 patients (48%) underwent a transcortical approach. The mean (± SD) EOR was 91.6% ± 12.4% in the transsylvian group and 88.6% ± 14.2% in the transcortical group (p = 0.26). Clinical outcome metrics for the 2 groups were similar. Overall, 13 patients (25%) in the transsylvian group and 10 patients (21%) in the transcortical group had evidence of ischemia on postoperative MR images. For both approaches, high-grade histology was associated with permanent morbidity (p = 0.01). For patients with gliomas located within the superior-posterior quadrant of the insula, development of postoperative ischemia was associated with only the transsylvian approach (46% vs 0%, p = 0.02).CONCLUSIONSAreas of restricted diffusion are common on postoperative MRI following resection of insular gliomas, but only a minority of these patients develop permanent neurological deficits. Insular glioma patients with high-grade histology may be at particular risk for developing symptomatic postoperative ischemia. Both the transcortical and transsylvian corridors are associated with reasonable morbidity profiles, although gliomas situated within the superior-posterior quadrant of the insula are more safely accessed with a transcortical approach.

Object The authors evaluate the impact of target location on the rate of pain relief (PR) in patients with intractable trigeminal neuralgia (TN) undergoing stereotactic radiosurgery (SRS). Methods The authors conducted a retrospective review of 99 patients with idiopathic TN who were identified from a prospectively maintained database and were treated with SRS targeting the dorsal root entry zone with a maximum dose of 80 Gy. Targeting of the more proximal portion of a trigeminal nerve with the 50% isodose line overlapping the brainstem was performed in 36 patients (proximal group). In a matched group, 63 patients received SRS targeting the 20% isodose line tangential to the emergence of the brainstem (distal group). The median follow-up time was 33 months (range 6–124 months). Results The actuarial rate of maintenance of Barrow Neurological Institute (BNI) Pain Score I–IIIa was attained in 89% of patients at 1 year, 81% at 2 years, and 69% at 4 years, respectively, after SRS. Kaplan-Meier analysis revealed that durability of PR was only associated with the proximal location of the radiosurgical target (log-rank test, p = 0.018). Radiosurgery-induced facial numbness (BNI Score II or III) developed in 35 patients, which was significantly more frequent in the proximal group (19 patients [53%] compared with 16 [25%] in the distal group [p = 0.015]). Conclusions The radiosurgical target appears to affect the duration of pain relief in patients with idiopathic trigeminal neuralgia with the target closer to the brainstem affording extended pain relief. However, the proximal SRS target was also associated with an increased risk of mild to moderate facial numbness.

OBJECT Stereotactic radiosurgery (SRS) has been shown to offer a high probability of tumor control for Grade I meningiomas. However, SRS can sometimes incite edema or exacerbate preexisting edema around the targeted meningioma. The current study evaluates the incidence, timing, and degree of edema around parasagittal or parafalcine meningiomas following SRS. METHODS A retrospective review was undertaken of a prospectively maintained database of patients treated with Gamma Knife radiosurgery at the University of Virginia Health System. All patients with WHO Grade I parafalcine or parasagittal meningiomas with at least 6 months of clinical follow-up were identified, resulting in 61 patients included in the study. The median radiographic follow-up was 28 months (range 6–158 months). Rates of new or worsening edema were quantitatively assessed using volumetric analysis; edema indices were computed as a function of time following radiosurgery. Statistical methods were used to identify favorable and unfavorable prognostic factors for new or worsening edema. RESULTS Progression-free survival at 2 and 5 years was 98% and 90%, respectively, according to Kaplan-Meier analysis. After SRS, new peritumoral edema occurred or preexisting edema worsened in 40% of treated meningiomas. The median time to onset of peak edema was 36 months post-SRS. Persistent and progressive edema was associated with 11 tumors, and resection was undertaken for these lesions. However, 20 patients showed initial edema progression followed by regression at a median of 18 months after radiosurgery (range 6–24 months). Initial tumor volume greater than 10 cm3, absence of prior resection, and higher margin dose were significantly (p < 0.05) associated with increased risk of new or progressive edema after SRS. CONCLUSIONS Stereotactic radiosurgery offers a high rate of tumor control in patients with parasagittal or parafalcine meningiomas. However, it can lead to worsening peritumoral edema in a minority of patients. Following radiosurgery, transient edema occurs earlier than persistent and progressive edema. Longitudinal follow-up of meningioma patients after SRS is required to detect and appropriately treat transient as well as progressive edema.

OBJECTIVEMeningiomas at the falcotentorial junction represent a rare subgroup of complex meningiomas. Debate remains regarding the appropriate treatment strategy for and optimal surgical approach to these tumors, and surgical outcomes have not been well described in the literature. The authors reviewed their single-institution experience in the management, approach selection, and outcomes for patients with falcotentorial meningiomas.METHODSFrom the medical records, the authors identified all patients with falcotentorial meningiomas treated with resection at the Barrow Neurological Institute between January 2007 and October 2017. Perioperative clinical, surgical, and radiographic data were retrospectively collected. For patients who underwent the supracerebellar infratentorial approach, the tentorial angle was defined as the angle between the line joining the nasion with the tuberculum sellae and the tentorium in the midsagittal plane.RESULTSFalcotentorial meningiomas occurred in 0.97% (14/1441) of the patients with meningiomas. Most of the patients (13/14) were female, and the mean patient age was 59.8 ± 11.3 years. Of 17 total surgeries (20 procedures), 11 were single-stage primary surgeries, 3 were two-stage primary surgeries (6 procedures), 2 were reoperations for recurrence, and 1 was a reoperation after surgery had been aborted because of brain edema. Hydrocephalus was present in 5 of 17 cases, 4 of which required additional treatment. Various approaches were used, including the supracerebellar infratentorial (4/17), occipital transtentorial/transfalcine (4/17), anterior interhemispheric transsplenial (3/17), parietal transventricular (1/17), torcular (2/17), and staged supracerebellar infratentorial and occipital transtentorial/transfalcine (3/17) approaches. Of the 17 surgeries, 9 resulted in Simpson grade IV resection, and 3, 1, and 4 surgeries resulted in Simpson grades III, II, and I resection, respectively. The tentorial angle in cases with Simpson grade I resection was significantly smaller than in those with an unfavorable resection grade (43.3° ± 4.67° vs 54.0° ± 3.67°, p = 0.04). Complications occurred in 10 of 22 approaches (17 surgeries) and included visual field defects (6 cases, 2 permanent and 4 transient), hemiparesis (2 cases), hemidysesthesia (1 case), and cerebellar hematoma (1 case).CONCLUSIONSFalcotentorial meningiomas are challenging lesions. A steep tentorial angle is an unfavorable preoperative radiographic factor for achieving maximal resection with the supracerebellar infratentorial approach. Collectively, the study findings show that versatility is required to treat patients with falcotentorial meningiomas and that treatment goals and surgical approach must be individualized to obtain optimal surgical results.

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Stereotactic radiosurgery (SRS) is not only effective for the prevention of arteriovenous malformation (AVM)-associated hemorrhage, 3,4,6,7,15,16,23,26 but is also effective in the treatment of AVM-associated epilepsy, with estimates ranging from 55% to 80% of patients who are seizure free after SRS (Table 1). 8,9,14,22,23,25 However, detailed seizure outcomes are lacking in the majority of AVM series. Many studies, including a previous one from our Gamma Knife center, 23 outline clinical seizure outcomes broadly without a thorough analysis of factors related to outcome. Additionally, the potentially long-term antiepileptic effects of SRS are not accounted for by most previous studies due to their relatively short follow-up durations.In the current study, we evaluated a cohort of patients with AVM-related epilepsy who were treated with SRS at our institution. Our aims were to classify long-term postoperative seizure outcomes, determine antiepileptic drug abbreviatioNs AED = antiepileptic drug; AVM = arteriovenous malformation; CI = confidence interval; DSA = digital subtraction angiography; GKRS = Gamma Knife radiosurgery; OR = odds ratio; RIC = radiation-induced change; SRS = stereotactic radiosurgery. submitted June 20, 2014. accepted November 25, 2014. iNclude wheN citiNg Published online January 23, 2015; DOI: 10.3171/2014.11.JNS141388. disclosure The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper. Departments of 1 Neurological Surgery, 2 Neurology, and 3 Radiation Oncology, University of Virginia Health System, Charlottesville, Virginia obJect Epilepsy associated with arteriovenous malformations (AVMs) has an unclear course after stereotactic radiosurgery (SRS). Neither the risks of persistent seizures nor the requirement for postoperative antiepileptic drugs (AEDs) are well defined. methods The authors performed a retrospective review of all patients with AVMs who underwent SRS at the University of Virginia Health System from 1989 to 2012. Seizure status was categorized according to a modified Engel classification. The effects of demographic, AVM-related, and SRS treatment factors on seizure outcomes were evaluated with logistic regression analysis. Changes in AED status were evaluated using McNemar's test. results Of the AVM patients with pre- or post-SRS seizures, 73 with pre-SRS epilepsy had evaluable data for subsequent analysis. The median patient age was 37 years (range 5-69 years), and the median follow-up period was 65.6 months (range 12-221 months). Sixty-five patients (89%) achieved seizure remission (Engel Class IA or IB outcome). Patients presenting with simple partial or secondarily generalized seizures were more likely to achieve Engel Class I outcome (p = 0.045). Twenty-one (33%) of 63 patients tapered off of pre-SRS AEDs. The incidence of freedom from AED therapy increased significantly after SRS (p < 0.001, McNemar's test). Of the Engel Class IA patients who continued AED therapy, 54% had patent AVM nidi...

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