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Background: Meningiomas are the most common benign intracranial tumors. Gamma Knife® stereotactic radiosurgery (GKSRS) has become a preferred management for recurrent or residual meningiomas. This study focuses on the relationship between tumor control and the time interval between resection of a World Health Organization (WHO) grade 1 meningioma and GKSRS., Methods: This single institution retrospective analysis reviewed our experience in 238 patients who underwent GKSRS after a pathologically confirmed WHO grade 1 meningioma resection. The median follow-up was 7.4 years. The median aggregate tumor volume at GKSRS was 6 cm3 and a median margin dose of 13 Gy was utilized. Neurological symptoms were evident in 60% of patients at the time of procedure., Results: Overall actuarial tumor control rates achieved were 91.3% at 5 years, 83.4% at 10 years, and 76% at 15 years. There were 35 patients (15%) who developed tumor progression within or directly adjacent to the GKSRS treatment field. The median time until progression was 6.3 years. The duration between surgical intervention and GKSRS did not show statistical significance at 3 months (p = 0.9), 6 months (p = 0.8), 12 months (p = 0.5), or 24 months (p = 0.9). Fifteen patients (6%) had tumor progression at an anatomically distinct location outside the GKSRS target volume. Neurological symptomatic improvement was more likely with early radiosurgery intervention (p = 0.007)., Conclusion: Postoperative GKSRS was associated with excellent long-term tumor control for WHO grade 1 meningiomas, regardless of the interval after initial surgery. In addition, earlier radiosurgery was associated with superior symptom improvement., (© 2021 S. Karger AG, Basel.)

Tremor is the most prevalent movement disorder in adults. Patients who are refractory to medical management can explore surgical intervention. Deep-brain stimulation (DBS) and radiofrequency thalamotomy (RFT) are surgical procedures for intractable tremor that target the ventralis intermedius (VIM) nucleus to relieve contralateral tremor. For patients who are not candidates for surgical procedures, stereotactic radiosurgery (SRS) is a minimally invasive management option for tremor relief. SRS has been used for the elderly, those considered high surgical risk for other surgical procedures, those who are unresponsive to either DBS or RFT, and those who prefer a less invasive option. Radiosurgical thalamotomy is performed using a central dose of 130-140 Gy delivered to the VIM nucleus of the thalamus. The critical aspect of the dose planning procedure is the selection of the target, which requires a neurosurgeon experienced with movement disorder surgery. More than 90% of patients experience improvements in their tremor and quality of life after radiosurgical thalamotomy. Adverse radiation effects rates are low (4%). In selected cases, staged bilateral procedure can also be performed to relieve bilateral refractory tremor. In patients with tremor-predominant Parkinson's disease, VIM thalamotomy is also effective., (© 2019 S. Karger AG, Basel.)

Management of craniopharyngiomas remains challenging due to the tumor's often intimate relationship with the optic apparatus, the hypothalamus, and the pituitary gland. Often multimodal management is needed to achieve the best treatment outcome: tumor control coupled with endocrine, visual, and neurocognitive preservation. Many surgeons favor initial subtotal resection followed by adjunctive therapy to improve quality of life in a tumor with potentially long-term survival even if coupled with a need for periodic new interventions. During the patient's subsequent follow-up, solid or cystic tumor recurrence or progression often require additional management options. Leksell stereotactic radiosurgery (SRS) is a valuable adjuvant strategy that enhances long-term outcomes in patients with residual or recurrent craniopharyngiomas. Tumor control rates of 70-90% have been reported using 11- to 13-Gy tumor margin doses delivered using the Gamma Knife. Smaller tumors are associated with better radiosurgery outcomes. SRS is an effective management for residual or recurrent solid craniopharyngiomas with a favorable benefit-to-risk profile., (© 2019 S. Karger AG, Basel.)

Stereotactic radiosurgery (SRS) is an effective treatment for patients with multiple brain metastases. Three decades of increasingly powerful scientific studies have shown that SRS improves outcomes and reduces toxicity when it replaces whole-brain radiation therapy (WBRT). Expert opinion surveys of clinicians have reported that the total intracranial tumor volume rather than the number of brain metastases is related to outcomes. As a result, an increasing number of treating and referring physicians have replaced the reflex use of WBRT with SRS, unless the patient has miliary disease or carcinomatous meningitis. In the current era of immunotherapy and targeted therapies with potentially increased systemic disease survival, 10 or more tumors are routinely treated with SRS alone at most academic medical centers. In a single SRS session we routinely treat patients with cumulative tumor volumes of 25 cm3 even if they have ≥10 metastases., (© 2019 S. Karger AG, Basel.)

Stereotactic radiosurgery using the Leksell Gamma Knife has proven to be a valuable alternative to orbital enucleation or fractionated radiation therapy for primary tumors of the orbit, metastatic tumors to the choroid, and primary uveal melanomas. With this approach in a single outpatient setting, the eye is immobilized by a local block after which high-definition MRI or CT is performed to define the target. After rapid dose planning, radiation delivery is completed before the local block dissipates. The tumor response is often dramatic. The risk of acute narrow-angle glaucoma, radiation-related retinopathy, or cataract formation has been relatively low. Other worldwide centers have confirmed that this approach is superior to either enucleation or fractionated radiation therapy for these relatively rare problems., (© 2019 S. Karger AG, Basel.)

The most common primary cancers that metastasize to the brain are lung cancer, breast cancer, and melanoma. The established management approaches for brain metastasis include stereotactic radiosurgery, fractionated radiation therapy, and surgical resection. In the past the role of medical therapies in brain metastases was limited. In the last decade, our understanding of molecular drivers of brain metastases and CNS penetration of drugs across the blood-brain barrier has improved. The molecular targeted tyrosine kinase inhibitors have shown effectiveness in brain metastases with activating mutations from non-small cell lung cancer, breast cancer, and melanoma. More recently, immunotherapies have also shown efficacy in the management of these patients. These agents can be effective for both intracranial as well as extracranial disease and are being actively employed in this patient population., (© 2019 S. Karger AG, Basel.)

The outcome of patients with malignant gliomas has not substantially improved, even with advances in imaging, neurosurgery, molecular subtyping, and radiation, and newer oncologic options. Maximal safe resection when feasible remains the initial treatment of choice for most malignant gliomas. These tumors often recur and require additional therapy to control the tumor growth. Leksell stereotactic radiosurgery (SRS) is offered as salvage therapy in patients with recurrent or residual malignant gliomas. SRS is well tolerated and is associated with a relatively low risk of adverse radiation effects in malignant glial tumor patients who otherwise have relatively few options. SRS allows the surgeon more flexibility in terms of surgical options and may enhance quality of life for patients postoperatively. Although randomized controlled studies are lacking in the use of salvage SRS after the failure of initial standard of care management, preliminary data suggest that radiosurgery improves tumor control and overall survival for patients with recurrent malignant gliomas., (© 2019 S. Karger AG, Basel.)

Vestibular schwannomas (VS) are benign tumors predominantly originating from the balance portion of cranial nerve VIII. These tumors have an incidence of 1-2 per 100,000 people. The growth of these tumors is approximately 1-2 mm per year. A VS can result in significant neurologic dysfunction from continued growth or the management paradigms designed to control this predominantly benign tumor. The impacts on the critical space within the auditory canal and cerebellopontine angle can lead to hearing deficits, tinnitus, vestibular dysfunction, facial nerve deficits, and brain stem compression., (© 2019 S. Karger AG, Basel.)

Low-grade gliomas represent a heterogeneous group of tumors. The goals of treatment include prolonged survival and reduced morbidity. Treatment strategies vary depending upon tumor histology, anatomic location, age, and the general medical condition of the patient. Safe surgical resection remains the first choice for the treatment of resectable tumors. In cases of unresectable lesions, adjuvant radiotherapy and chemotherapy are considered. Several reports in recent years have documented the safety and effectiveness of stereotactic radiosurgery (SRS) in controlling tumor growth and improving patients' survival for patients with low-grade gliomas. Patients with progressive, pilocytic, or grade 2 fibrillary astrocytomas, located in critical or deep areas of the brain, are ideal candidates for radiosurgery. The use of SRS as part of multimodal therapy for progressive, recurrent, or unresectable pilocytic or WHO grade 2 fibrillary astrocytomas is a safe and promising therapeutic modality. Gamma Knife radiosurgery has progressively gained more relevance in the management of low-grade gliomas., (© 2019 S. Karger AG, Basel.)

Stereotactic radiosurgery (SRS) has become a standard management option for less common glial tumors. When imaging defines a recurrent or progressive ependymoma after initial resection in a child who has completed adjuvant fractionated radiation therapy, SRS may be used as a boost or salvage strategy. For patients with oligodendrogliomas diagnosed by biopsy or after cytoreductive surgery, SRS may be used as a primary option in smaller volume tumors, or as an adjuvant option for tumors that have progressed after initial surgery, chemotherapy, or fractionated radiation therapy. Currently the increasing use of molecular markers in both tumors helps to define the prognosis, risk of recurrence, and perhaps response to boost or salvage SRS. This report examines the role of SRS in these less common glial tumors., (© 2019 S. Karger AG, Basel.)

A decision to develop a stereotactic radiosurgery center and install the first 201 cobalt-60 Gamma Knife in Pittsburgh was made in 1981 after gathering regional and leadership support. This was part of a 7-year quest that required overcoming barriers to a new technology unfamiliar to US regulatory authorities and insurance companies. The first patient was treated in August 1987. Since that time our center has installed each succeeding Gamma Knife device developed. During an initial 30-year experience we performed more than 14,750 patient procedures. In addition to patient care our Center's goal was to develop a major teaching and clinical research program that eventually led to the training of more than 2,500 physicians and medical physicists, the publication of more than 600 peer-reviewed clinical outcome research studies, and 4 books. This report summarizes the rationale for acquisition, the challenges and the early years, and then the evolution of our center which installed the first US 201 source Gamma Knife., (© 2019 S. Karger AG, Basel.)

Leksell stereotactic radiosurgery has proven to be effective for less common tumors encountered in the brain, including hemangiomas of the orbit or cavernous sinus, recurrent hemangiopericytomas, and both sporadic hemangioblastomas as well as those encountered in the context of von Hippel-Lindau (VHL) disease. While all three tumors are responsive to single-session radiosurgery, hemangiomas and hemangiopericytomas are the most likely to demonstrate tumor regression. Hemangiopericytomas that recur after initial resection can be lower grade or anaplastic and have both higher local as well as distant recurrence risks. Sporadic hemangioblastomas undergo Leksell radiosurgery at the time of recurrence after initial surgery. In the context of VHL, growing or recurrent tumors are treated with tumor control rates exceeding 90%. Tumor control improves with higher dose delivery, typically >15 Gy at the margin. Dose-limiting structures may include the optic apparatus for hemangiomas and brain stem locations for hemangioblastomas., (© 2019 S. Karger AG, Basel.)

For more than 65 years localization of brain targets suitable for stereotactic radiosurgery has been performed after application of an intracranial guiding device to the cranial vault. After imaging and dose planning the same frame is used to secure the target at the focus of the intersection of the ionizing radiation beams that create the radiobiological effect. Non-invasive immobilization systems first proposed for linear accelerator or proton radiation technologies have now been developed for the Leksell Gamma Knife ICON radiosurgical system. The ICON technology adds a cone-beam computed tomography (CBCT) scan to the original Perfexion radiosurgical device in order to define the brain stereotactic space. Marketed since 2015, the ICON can be used for standard radiosurgical procedures, most of which remain frame based, but also coupled with a non-invasive thermoplastic mask for carefully selected patients who undergo standard single-session radiosurgical procedures, as well as multisession procedures using repeat mask fixation. Both at UPMC as well as worldwide, mask immobilization has to date been used for approximately 10% of patients with specific characteristics: relatively simple dose plans, short radiation delivery times, and non-anxious patients, most of whom have metastatic or primary brain cancers. In certain cases, multisession radiosurgery is also performed using the mask. The workflow of frame versus frameless procedures is often altered, and is reliant on high-definition imaging, mostly MRI, done prior to dose planning. Since each CBCT takes 10-12 min to set up and acquire, co-register, and review with the treatment plan, and two CBCT scans are necessary to initiate the treatment plan, this workflow must be added to the beam on time. Although frame-based immobilization remains the predominant method to secure target fixation for problems suitable for single-session radiosurgery, the advent of a mask immobilization technique has proven valuable for a select group of patients. It also provides a non-invasive method to perform multisession or fractionated radiation in patients for whom traditional single-session radiosurgery is not feasible., (© 2019 S. Karger AG, Basel.)

The classification of central neurocytoma (CN) by the WHO was upgraded to grade 2 in 1993 as it was recognized that at least some of these tumors can exhibit more aggressive behavior. Currently, as of 2016, CN is classified as WHO grade 2. Indeed, some atypical variants have been reported and residual postsurgical tumor is believed to have the potential for malignant transformation. Although gross total resection is usually curative for CN (5-year survival rate 99%), it is achieved in nearly 30-50% of cases due to its central location. Adjuvant treatments should be deliberately considered for the optimal management of CN. Recently, stereotactic radiosurgery is increasingly proposed as an adjuvant treatment for CN., (© 2019 S. Karger AG, Basel.)

Chordomas and chondrosarcomas are rare locally aggressive skull base tumors with high progression or recurrence rates. Ultimately, they have high mortality rates unless they respond to multimodality management options that include one or more surgical resections, fractionated radiation therapy, and stereotactic radiosurgery (SRS). SRS has become a standard management option for recurrent or residual chordomas and chondrosarcomas after failed surgical resection and fractionated radiation therapy. This report examines the role of SRS in these skull base tumors., (© 2019 S. Karger AG, Basel.)

Cavernous malformations (CM) represent a distinct subgroup of brain vascular malformations that are characterized by small sinusoidal vascular channels with hyaline degeneration and old blood pigments. Because of the increasing availability of magnetic resonance imaging (MRI) they are detected much more frequently in the present era. CM may be solitary or found in the context of a familial variant that results in an increasing number of CM developing as the patient ages. Because of the variable risk of subacute bleeding, their management options have been controversial. The annual risk of an incidentally detected CM bleeding is <0.5% each year. Leksell radiosurgery is used for a subgroup of patients who have repeatedly bled. In general, CM best considered for stereotactic radiosurgery are deep seated and do not pre-sent to a pial or ependymal surface where microsurgical corridors for removal are feasible. When radiosurgery is used for patients at high risk for both re-bleeding as well as microsurgical resection, the risk of bleeding can be reduced from as high as 33% each year to <0.5% each year after a 2-year latency interval. The target lies within the hemosiderin rim detected during the MRI that is part of planning. Marginal doses are significantly less than those used for angiographically visible arteriovenous malformations., (© 2019 S. Karger AG, Basel.)

The first surgical procedures for abnormal movement disorders began in the 1930s, when surgeons first proposed ablative techniques of the caudate nucleus or transection of motor (pyramidal) pathways to reduce involuntary movements in patients with Parkinson's related tremor. During the 50-year interval between 1945 and 1995, the development of precise intracranial guiding devices, brain maps, and advanced imaging led to the refinement of appropriate deep brain targets affecting extrapyramidal pathways. Lesional surgery and subsequent neuroaugmentation using deep brain stimulation extended the role of deep brain surgery for a wider group of patients with tremor, rigidity, dyskinesia, and other involuntary movement disorders. Stereotactic radiosurgery has had wide application for tremor. The history of movement disorder surgery reads like a who's who of brilliant and resourceful surgeons who pushed the frontiers of neurosurgery. Even today, practitioners of functional brain surgery are among the most innovative practicing neurosurgeons., (© 2018 S. Karger AG, Basel.)

Management options for residual or recurrent glioblastoma multiforme (GBM) are limited despite advances in surgical, chemotherapeutic, and radiotherapeutic techniques. Stereotactic radiosurgery (SRS) is often beneficial in such cases providing improved survival of patients, but still remains underutilized as part of the multimodality management of malignant gliomas. During the last 20 years, 297 patients with histologically proven residual or recurrent GBM underwent Gamma Knife surgery in the University of Pittsburgh. Retrospective analysis of outcomes revealed median survival after initial diagnosis of 18 months, and 1- and 2-year survival rates of 72.5 and 29.5%, respectively. Median survival from the time of SRS was 9 months. The use of modified RPA (recursive partitioning analysis) classification demonstrated superior survival in our series in comparison with historical data. Important prognostic variables include tumor volume <14 cm3, marginal radiation dose of ≥15 Gy, and younger age of the patients (<60 years). Adverse radiation effects (ARE) were noted in 23% of cases and were mainly controlled with corticosteroids. Combining SRS with bevacizumab resulted in further improvement of the overall and progression-free survival and decreased incidence of ARE. Nevertheless, for future application of SRS in patients with GBM, evaluation of its efficacy in a well-designed prospective controlled clinical trials seems mandatory., (© 2018 S. Karger AG, Basel.)

Tremor is a common movement disorder that can be disabling, and its initial treatment is in the form of medical therapies. Often patients are refractory and seek surgical intervention. Treatment options for these patients include surgical radiofrequency thalamotomy and deep brain stimulation. There are a subset of patients who, for various reasons, are not candidates for open surgical procedures, or who opt to avoid them. For these patients, radiosurgical thalamotomy is a safe and useful alternative. Herein, we provide a review of the use of radiosurgical thalamotomy for the treatment of medically refractory tremor by discussing its history, defining the technique and its indications, evaluating its efficacy, and exploring its complications and shortcomings., (© 2018 S. Karger AG, Basel.)

Objective: Trigeminal neuralgia (TN) related to a brainstem cavernous malformation (CM) is a rare entity. We present the first radiosurgical management of a patient with TN secondary to a CM., Clinical Presentation: An 80-year-old female presented with a 33-year history of progressively severe TN refractory to medications. Imaging confirmed a solitary CM located at the pontine dorsal root entry zone of cranial nerve 5., Treatment: Stereotactic radiosurgery of the trigeminal nerve was performed using the Leksell gamma knife. A single 4-mm isocenter of radiation was focused on the trigeminal nerve and a maximum dose of 80 Gy (40 Gy at the 50% isodose line) was delivered to the nerve., Results: At 1 year, the patient noted that the severe pain attacks had been reduced by 75%, although a background lingering discomfort persisted. Pain suppression medications had been significantly reduced to lamotrigine 100 mg twice daily. Her preoperative distribution of sensory dysfunction mildly increased., Conclusion: For medically refractory TN related to a CM, radiosurgery of the afferent nerve may ameliorate pain without a major decrease in sensation. The more than 30-year history of pain in our patient may have reduced the chance of more significant pain relief., (© 2019 S. Karger AG, Basel.)

Object: In this report, we discuss the development of a new, comprehensive, Health Insurance Portability and Accountability Act-compliant electronic quality assurance (QA) registry for Gamma Knife (GK) radiosurgery patients. This registry can be used to query outcomes, link with current hospital electronic medical records, and share data with future corporate or national professional society registries under development., Methods: A clinical task force comprising physicians and regulatory, legal, and information technology (IT) experts was created to define the nomenclature, regulatory requirements, hosting site, and required capabilities of the proposed system. A team of physicians and IT experts defined the clinical parameters and designed the query functions for the registry., Results: The UPMC GK Registry was established as a QA registry exempt from Institutional Review Board oversight. In order to facilitate subsequent query functions (analytics), data entry was created for 3 main categories: brain tumors, vascular malformations, and functional disorders. A Microsoft SQL-based database infrastructure was employed., Conclusions: We developed a new UPMC GK QA registry and successfully migrated our previous data on 13,000 patients into the registry. This simplified and user-friendly registry offers clinicians the opportunity to participate in national registries and to contribute to multicenter evidence-based outcome analyses., (© 2017 S. Karger AG, Basel.)

Background: Further investigation is needed to look at the impact of vestibular schwannoma (VS) on the health-related quality of life (QOL) of participants who undergo Gamma Knife® radiosurgery (GKRS)., Objectives: Investigators compared the QOL for VS participants to reported US population norms in order to evaluate disease burden and long-term QOL several years after GKRS., Methods: This cross-sectional study surveyed participants to assess hearing status, tinnitus, imbalance, vertigo, as well as the Short-Form 36-item Health Questionnaire (SF-36). The data were normalized, age adjusted, and functional status was correlated to determine clinically significant differences., Results: A total of 353 participants who underwent GKRS between 1997 and 2007 were included in this study with a median postoperative period of 5 years. SF-36 scores were very similar to population norms, and age-adjusted scores for participants followed the US population curve. Frequent vertigo and balance problems had the largest statistically and clinically significant effect on physical and mental component summary scores followed by nonuseful hearing in the tumor ear., Conclusions: Participants reported a good long-term QOL that was very similar to the QOL of US population norms. Of the common VS symptoms, vertigo had the greatest impact on QOL followed by imbalance and then hearing loss., (© 2017 S. Karger AG, Basel.)

Background: Management of older patients with medically refractory trigeminal neuralgia (TN) is yet a matter of debate., Objective: We sought to determine the benefit of stereotactic radiosurgery (SRS) as the sole surgical management in older patients (≥70 years)., Methods: One hundred and twenty-seven patients (≥70 years) with typical TN underwent SRS as initial surgical management. The median maximum dose for the first procedure was 80 Gy. Repeat SRS was performed in 46 patients who developed recurrent pain., Results: After the first SRS, the initial pain control was achieved in 91% of patients. Complete pain relief (Barrow Neurological Institute [BNI] score I) developed in 75 patients (59%) and was maintained in 59, 39, and 22% of patients at 1, 3, and 5 years. Following repeat SRS, the rate of complete pain relief was 79, 55, and 41% at 1, 3, and 5 years. The chance of BNI I preservation was greater after repeat SRS compared to initial SRS (hazards ratio: 2.02, p < 0.0001). The incidence of trigeminal sensory loss was 17% after initial SRS but increased to 39% after repeat SRS., Conclusions: SRS alone was used effectively in older TN patients to achieve pain control. Recurrent pain responded to retreatment but was associated with an increased risk of sensory dysfunction., (© 2017 S. Karger AG, Basel.)

Objective: The purpose of this study was to retrospectively analyze the outcomes of stereotactic radiosurgery for patients suffering from medically refractory Parkinson disease (PD) tremor., Methods: We retrospectively studied the outcomes of 33 patients who were treated with gamma knife thalamotomy (GKT) over a 19-year period. Twelve patients were ≥80 years. A median dose of 140 Gy (range, 130-150 Gy) was delivered to the nucleus ventralis intermedius through a single 4-mm isocenter. We used the Fahn-Tolosa-Marin clinical tremor rating scale to score tremor, handwriting, drawing, and ability to drink fluids. The median time to the last follow-up was 23 months (range, 9-144 months)., Results: After GKT, 31 patients (93.9%) experienced improvement in tremor. Twenty-three patients (70.0%) had complete or nearly complete tremor arrest. Nine patients (27.2%) noted tremor arrest and resolution of impairment in writing, drawing, and ability to drink fluids. One patient (3%) improved in bradykinesia, 3 patients (9%) improved in rigidity, and 3 patients (9%) decreased their dosage of dopa after GKT. Tremor relief was fully maintained in the last follow-up for 96.8% of responding patients. Two patients (6%) experienced temporary adverse radiation effects., Conclusions: GKT is a safe and effective treatment for medically refractory PD tremor, especially for the elderly or those not suitable for deep brain stimulation or thermal thalamotomy., (© 2017 S. Karger AG, Basel.)

Background: Trigeminal neuralgia (TN) is mostly caused by vascular compression of the nerve's root entry zone due to an ectatic artery. Rarer causes include compression from tumors, vascular malformations or multiple sclerosis plaques. Developmental venous anomalies (DVAs) are benign, aberrantly appearing venous structures that drain normal cerebral tissue. DVAs are a rare etiology of TN. The management of TN caused by a DVA is controversial as disruption of the DVA can be catastrophic. Methods: We report a case of a young man with severe medically refractory TN related to a brachium pontis DVA who was successfully treated by gamma knife stereotactic radiosurgery (GKSR) to the trigeminal nerve. Results: Within 2 weeks of GKSR, the patient reported experiencing 60% pain relief; 5 years postoperatively, he remains completely pain free with some mild sensory loss in the V2 and V3 areas. Conclusions: GKSR has an established role in the management of TN. This is the first reported case of using GKSR to treat TN caused by a DVA. In the setting of a DVA, GKSR should be an initial consideration for TN therapy after medical failure because of the high surgical risk related to disrupting the DVA. © 2015 S. Karger AG, Basel.

Background: Magnetoencephalography (MEG) can delineate critical regions of the cortex and facilitate conformal stereotactic radiosurgery (SRS) dose planning. Despite the substantial role of Gamma Knife® SRS in arteriovenous malformation (AVM) management, MEG-generated maps of critical regions have never been utilized to improve dose planning., Purpose: To assess the value of integrating functional brain mapping using MEG with dose planning during treatment of brain AVMs with SRS., Methods: This case series encompassed 5 patients with motor region AVMs. Noninvasive eloquent cortex mapping was achieved using a whole-head 306-channel Neuromag® Vectorview MEG System 5-10 days before SRS. On the day of SRS, the functional brain maps were integrated onto the intraoperative dose planning magnetic resonance imaging for Leksell GammaPlan® version 10. The median AVM volume treated was 12.7 cm(3), and 18 Gy was the median margin dose., Results: Functional image integration of MEG improved the recognition of critical brain structures adjacent to the AVM. This facilitated anatomical planning designed to reduce the dose to adjacent critical structures while maintaining a therapeutic dose to the AVM target. The 5 patients had no adverse radiation effects during the follow-up., Conclusion: Coregistration of MEG data improves the accuracy and dose sparing needed for optimal planning during Gamma Knife SRS., (© 2014 S. Karger AG, Basel.)

Ice hockey is an aggressive and fast-paced sport which has a high risk of injury, concussions in particular. Although serious head injury has been recognized for nearly 50 years, an increase in mainstream media attention in recent years has led to unprecedented public awareness. As a result, the National Hockey League (NHL) and other professional leagues around the world have initiated concussion protocols in order to better prevent, recognize, and treat concussions. With over 1,000,000 youth hockey participants in Canada and the USA combined, concussion is an issue that reaches beyond the professional level. In this report we review the incidence, evaluation, treatment, return-to-play protocol, and prevention efforts related to concussion in ice hockey., (© 2014 S. Karger AG, Basel.)

Background: Repeat Gamma Knife stereotactic radiosurgery (GKSR) procedures are becoming common, especially for brain metastases. It is important to identify tumors requiring treatment at repeat GKSR and it can be challenging to distinguish treated tumors, tumor progression and new tumors. Using the image co-registration tool within the Leksell Gamma Plan software, we developed a technique to aid in the identification of tumors needing treatment., Objectives: The objective was to explore a new co-registration technique to identify tumors requiring treatment at repeat GKSR procedures., Methods: Ten patients who underwent repeat GKSR for brain metastases were identified. Contrast-enhanced volumetric T1 magnetic resonance images (MRI) from the previous GKSR were co-registered with the new images and the resulting two-color format image was used to evaluate tumor status., Results: Using the co-registered images, tumors were characterized as: resolved, regressed, stable, larger or new. Overall, 13.6% of tumors completely resolved, 26.2% regressed, 13.1% remained stable, while 7.9% progressed. Thirty-nine percent of tumors were new., Conclusions: The co-registration technique makes clinically relevant changes conspicuous on MRI. It distinguishes between tumors potentially requiring treatment and those that have been treated successfully. It can be used with tumors other than metastases and for evaluating tumor response at follow-up., (© 2014 S. Karger AG, Basel.)

Treatment options for dural arteriovenous fistulas (DAVFs) have expanded with the application of stereotactic radiosurgery (SRS). Our objective was to provide guidelines about the use of SRS in symptomatic patients with imaging-identified DAVFs of the brain. The authors reviewed evidence-based medicine and clinical experience with radiosurgery for DAVFs of the brain and developed guidelines and provided a scientific foundation for patients and physicians. Major recommendations include the definition of DAVF patients suitable for various management strategies ranging from observation to surgical excision to endovascular embolization and SRS. Combined SRS and embolization is an effective management strategy for DAVFs, including those that have recurred after initial embolization. The effect of prior embolization has been evaluated. SRS before embolization facilitates the better recognition of the entire target. For selected DAVF patients who are not eligible for embolization or surgery, SRS alone is an effective treatment option. The dose range for DAVFs is similar to that of arteriovenous malformations. A clinical algorithm for the potential role of SRS for a symptomatic brain DAVF was defined. These guidelines provide a framework for professional judgment and treatment selection alternatives for the management of DAVFs., (Copyright © 2013 S. Karger AG, Basel.)

Widespread availability of magnetic resonance imaging has helped our understanding of the natural history of cavernous malformations (CMs) of the brain. CMs present with diverse clinical manifestations. Supratentorial CMs are often identified incidentally. The clinical presentation corresponds with lesion location. Symptomatic, hemorrhagic CMs of the brainstem pose a challenging clinical problem as they are often associated with high surgical morbidity. In order to study the natural history of CM, we performed a prospective analysis on a series of patients who were sent to us for management. During the mean prospective follow-up interval of 34 months, 9 hemorrhages occurred. History of prior hemorrhage was the most important risk factor for subsequent hemorrhage. The annual hemorrhage was 0.6% in patients who never had a symptomatic hemorrhage. Patients who had prior hemorrhage have a higher (4.5%) annual hemorrhage rate., (Copyright © 2013 S. Karger AG, Basel.)

Selection of the prescription dose for arteriovenous malformation (AVM) radiosurgery is the final step in treatment planning. Physicians need to choose a prescription dose that provides an optimal middle ground between optimizing AVM obliteration with high radiation doses and limiting complication risks with the lowest doses. Accurately predicting complication risks for individual patients is a complex process that is highly dependent on the radiosurgery treatment volume, the target location and the nature of the target tissue. This article reviews the principles and data guiding dose selection for AVM radiosurgery., (Copyright © 2013 S. Karger AG, Basel.)

We sought to define the long-term outcomes and risks of arteriovenous malformation (AVM) management using 2 or more stages of stereotactic radiosurgery (SRS) for symptomatic large-volume AVMs unsuitable for surgery. Two decades ago, we prospectively began to stage anatomical components in order to deliver higher single doses to AVMs>10 cm3 in volume. Forty-seven patients with large AVMs underwent volume-staged SRS. The median interval between the two SRS procedures was 4.9 months (range, 3-14 months). The median nidus volume was 11.5 cm3 (range, 4.0-26 cm3) in the first stage of SRS and 9.5 cm3 in the second. The median margin dose was 16 Gy (range, 13-18 Gy) for both SRS stages. The actuarial rates of total obliteration after 2-staged SRS were 7, 20, 28 and 36% at 3, 4, 5 and 10 years, respectively. Sixteen patients needed additional SRS at a median interval of 61 months (range, 33-113 months) after the 2-staged SRS. After repeat procedure(s), the eventual obliteration rate was 66% at 10 years. The cumulative rates of AVM hemorrhage after SRS were 4.3, 8.6, 13.5 and 36.0% at 1, 2, 5 and 10 years, respectively. Symptomatic adverse radiation effects were detected in 13% of patients. Successful prospective volume-staged SRS for large AVMs unsuitable for surgery requires 2 or more procedures to complete the obliteration process. Patients remain at risk for hemorrhage if the AVM persists., (Copyright © 2013 S. Karger AG, Basel.)

Treatment options for symptomatic dural arteriovenous fistulas (DAVFs) include surgery, embolization and stereotactic radiosurgery (SRS). We reviewed our DAVF experience at the University of Pittsburgh and assessed the role of SRS. We evaluated 40 consecutive patients who underwent Gamma Knife SRS for 44 DAVFs. Twenty-eight patients had upfront SRS before or after embolization performed at our institution, and 12 patients underwent delayed SRS for recurrent or residual DAVFs after initial embolization. The median SRS target volume was 2.0 cm3, and the median marginal dose was 21.0 Gy. At a median follow-up of 45 months (range, 23-116 months), a total of 28 patients with 32 DAVFs had obliteration. The obliteration rate was 83% for patients who had upfront SRS and embolization. The obliteration rate was lower (67%) for patients managed with SRS alone. The obliteration rate was 71% for patients who had delayed SRS for recurrent or residual DAVFs following prior embolization. In our experience cavernous/carotid fistulas were associated with higher rates of obliteration and symptomatic improvement compared to transverse/sigmoid sinus region fistulas. Our experience suggests that successful DAVF obliteration is possible in most patients with upfront SRS in conjunction with embolization. SRS alone is an effective treatment for selected patients with a small-volume, low-risk DAVF., (Copyright © 2013 S. Karger AG, Basel.)