Effects of radiation on cerebral vasculature: a review

Late-onset vascular complications of radiotherapy for primary brain tumors: a case-control and cross-sectional analysis

PURPOSE

Radiotherapy (RT) is a recognized risk factor for cerebrovascular (CV) disease in children and in adults with head and neck cancer. We aimed to investigate whether cerebral RT increases the risk of CV disease in adults with primary brain tumors (PBT).

METHODS

We retrospectively identified adults with a supratentorial PBT diagnosed between 1975 and 2006 and with at least 10 years follow-up after treatment. We analyzed demographic, clinical, and radiological features with special attention to CV events. We also described CV events, vascular risk factors, and intracranial artery modifications in a cross-sectional study of irradiated patients alive at the time of the study.

RESULTS

A total of 116 patients, treated with RT (exposed group), and 85 non-irradiated patients (unexposed group) were enrolled. Stroke was more frequent in irradiated PBT patients than in the unexposed group (42/116 (36%) vs 7/85 (8%); p < 0.001), with higher prevalence of both ischemic (27/116 (23%) vs 6/85 (7%); p = 0.004) and hemorrhagic (12/116 (10%) vs 1/85 (1%); p = 0.02) stroke. In the irradiated group, patients with tumors near the Willis Polygon were more likely to experience stroke (p < 0.016). Fourty-four alive irradiated patients were included in the cross-sectional study. In this subgroup, intracranial arterial stenosis was more prevalent (11/45, 24%) compared to general population (9%).

CONCLUSIONS

Stroke prevalence is increased in long-surviving PBT patients treated with cranial RT.

IMPLICATIONS FOR CANCER SURVIVORS

CV events are frequent in long survivors of PBT treated with cerebral RT. We propose a check list to guide management of late CV complications in adults treated with RT for PBT.

The Party Wall: Redefining the Indications of Transcranial Approaches for Giant Pituitary Adenomas in Endoscopic Era

The evolution of endoscopic trans-sphenoidal surgery raises the question of the role of transcranial surgery for pituitary tumors, particularly with the effectiveness of adjunct irradiation. This narrative review aims to redefine the current indications for the transcranial approaches for giant pituitary adenomas in the endoscopic era. A critical appraisal of the personal series of the senior author (O.A.-M.) was performed to characterize the patient factors and the tumor's pathological anatomy features that endorse a cranial approach. Traditional indications for transcranial approaches include the absent pneumatization of the sphenoid sinus; kissing/ectatic internal carotid arteries; reduced dimensions of the sella; lateral invasion of the cavernous sinus lateral to the carotid artery; dumbbell-shaped tumors caused by severe diaphragm constriction; fibrous/calcified tumor consistency; wide supra-, para-, and retrosellar extension; arterial encasement; brain invasion; coexisting cerebral aneurysms; and separate coexisting pathologies of the sphenoid sinus, especially infections. Residual/recurrent tumors and postoperative pituitary apoplexy after trans-sphenoidal surgery require individualized considerations. Transcranial approaches still have a critical role in giant and complex pituitary adenomas with wide intracranial extension, brain parenchymal involvement, and the encasement of neurovascular structures.

Microenvironment changes in arteriovenous malformations after stereotactic radiation

Cerebral arteriovenous malformations are dysplastic vascular tangles with aberrant vascular dynamics and can result significant morbidity and mortality. A myriad of challenges are encountered when treating these lesions and are largely based on nidal size, location, and prior hemorrhage. Currently, stereotactic radiosurgery is an accepted form of treatment for small to medium sized lesions and is especially useful in the treatment of lesions in non-surgically assessable eloquent areas of the brain. Despite overall high rates of nidal obliteration, there is relatively limited understand on the mechanisms that drive the inflammatory and obliterative pathways observed after treatment with stereotactic radiosurgery. This review provides an overview of arteriovenous malformations with respect to stereotactic radiosurgery and the current understanding of the mechanisms that lead to nidal obliteration.

Early stage T1-weighted perfusion magnetic resonance imaging: a factor that predicts local control response in patients with meningioma who underwent gamma-knife radiosurgery

BACKGROUND

Gamma-knife radiosurgery (GKRS) is an alternative treatment option for selected intracranial meningiomas. The study's aim is to demonstrate the advantages of T1-weighted perfusion magnetic resonance imaging (T1-PMRI) by measuring the volume transfer coefficient (K^trans) values in the prediction of local response for patients with meningioma who have undergone GKRS consecutively.

METHODS

The data of patients diagnosed radiologically with WHO grade 1 intracranial meningiomas was collected prospectively. The patients who were treated consecutively with GKRS at our institution (September 2017-September 2018) were included. After GKRS, the patients were followed up at the defined periods with routine contrast-enhanced MRI and T1-PMRI by measuring the K^trans. The comparison between the pre-treatment and third-month post-treatment (PO3M) K^trans was done using the Wilcoxon signed-rank test.

RESULTS

Thirty-one patients with 36 tumors have undergone GKRS. Twenty-two patients were female. The mean age was 55.3 years. The mean pre-GKRS volume was 7.67 ccs. The mean 50% radiation isodose was 12.2 Gy. The local tumor control rate was 100%. Fourteen tumors were regressed fully at the last MRI. PO3M K^trans decreased when compared with the pre-GKRS values (p < 0.0001). However, the numerical decrease in tumor volumes on contrast-enhanced MRI was not statistically significant (p = 0.117).

CONCLUSION

Changes between K^trans on PO3M and pre-GKRS T1-PMRI were more useful in determining the early response to GKRS in patients with meningioma than volumetric changes. Therefore, K^trans should be taken as a reference to predict the early response to GKRS in follow-up imaging scans.

Effect of radiotherapy on cardiac-specific death in patients with non-malignant tumors of central nervous system and related clinical features

Importance

Cardiac-specific death from radiation caused by radiation therapy (RT) in patients with malignant tumors has received extensive attention, however, little is known regarding the potential cardiotoxic effects of RT in patients with non-malignant tumors.

Objectives and methods

In this study, we used the SEER data to explore the incidence of post-radiation cardiovascular complications in patients with non-malignant tumors of central nervous system (CNS), and identify the influencing factors of cardiac-specific death.

Results

Ultimately 233, 306 patients were included (97.8% of patients had brain tumors and 2.2% had spinal cord tumors). For patients with non-malignant tumors of CNS, RT {yes (odds ratio [OR] 0.851, 95% confidence interval [CI] 0.774–0.936, p = 0.001, before propensity score matching (PSM); OR 0.792, 95% CI 0.702–0.894, p < 0.001, after PSM) vs. no} was associated with lower risk of cardiac-specific death, other clinical features affecting cardiac death similar to those in patients with non-malignant tumors of CNS receiving RT. For patients with non-malignant tumors of CNS receiving RT, female, married status, Hispanic ethnicity, surgery, and tumor site (brain exclude nerve and endocrine, nervous system) were associated with lower risks of cardiac-specific death, while earlier year of diagnosis, older age of diagnosis, Black, larger tumor and bilateral tumor were risk factors for cardiac-specific death.

Conclusions

Our study shows the influencing factors for cardiac-specific death in patients with non-malignant tumors of CNS, and found RT is associated with lower risk of cardiac-specific death. These results can facilitate the identification of patients with non-malignant tumors of CNS who can benefit from RT while avoiding cardiovascular events. In addition, this study helps to enhance the clinical use of RT in these populations, especially in patients who may have impaired cardiac function due to CNS tumors.

Characteristics of Radiation-Related Intracranial Aneurysms: A Multicenter Retrospective Study

BACKGROUND AND PURPOSE

Intracranial aneurysms, a rare complication of radiation therapy, have been reported mainly in case reports or case series. We performed a multicenter, retrospective cohort study to investigate the characteristics of radiation-induced intracranial aneurysms.

MATERIALS AND METHODS

Data on 2641 patients with intracranial aneurysms were retrospectively collected from 3 hospitals between January 2005 and June 2014. An additional 1519 patients were recruited from a single center between July 2014 and March 2020. Aneurysms in patients with a history of radiation therapy for at least 6 months were defined as radiation-related aneurysms. Patients' demographic profiles, clinical characteristics, and aneurysm parameters detected on CTA were compared between radiation-related and control groups.

RESULTS

Of the 4160 patients, the average age was 57.9 (SD, 13.5) years, 2406 (57.8%) were women, 477 (11.5%) had multiple aneurysms, 3009 (72.3%) had SAH, and 34 (0.8%) had radiation-related aneurysms. The male-to-female ratio in the radiation-related group was significantly higher than that in the control group (2.4:1 versus 0.72:1, P = .001). The mean age of the radiation-related group was significantly younger than in the control group (51.4 [SD, 15.0] years versus 58.2 [SD, 13.5] years, P = .003). More patients in the radiation-related group presented with SAH than in the control group (without age and sex matching, 88.2% versus 72.2%, P = .037; with age and sex matching, 88.2% versus 58.8%, P = .006). Of the 4813 intracranial aneurysms, only 43 (0.9%) aneurysms were categorized as in the radiation-related group, whereas 4770 (99.1%) aneurysms constituted the control group. Compared with the control group, there was a significantly higher proportion of sidewall aneurysms (46.5% versus 32.3%, P = .048) and a predilection for aneurysms involving the ICA and posterior circulation arteries (72.1% versus 52.2%, P = .046) in the radiation-related group.

CONCLUSIONS

Compared with the control group, radiation-related aneurysms are more prone to occur in men and young patients, with a higher percentage of sidewall aneurysms located in the ICA and posterior circulation arteries. Furthermore, SAH is highly prevalent in patients with radiation-induced aneurysms, indicating that dedicated screening for aneurysms after radiation therapy is necessary, but further studies are needed to determine when and how to screen.

Blood-Brain Barrier Permeability Following Conventional Photon Radiotherapy - A Systematic Review and Meta-Analysis of Clinical and Preclinical Studies

Radiotherapy (RT) is a cornerstone treatment strategy for brain tumours. Besides cytotoxicity, RT can cause disruption of the blood–brain barrier (BBB), resulting in an increased permeability into the surrounding brain parenchyma. Although this effect is generally acknowledged, it remains unclear how and to what extent different radiation schemes affect BBB integrity. The aim of this systematic review and meta-analysis is to investigate the effect of photon RT regimens on BBB permeability, including its reversibility, in clinical and preclinical studies. We systematically reviewed relevant clinical and preclinical literature in PubMed, Embase, and Cochrane search engines. A total of 69 included studies (20 clinical, 49 preclinical) were qualitatively and quantitatively analysed by meta-analysis and evaluated on key determinants of RT-induced BBB permeability in different disease types and RT protocols. Qualitative data synthesis showed that 35% of the included clinical studies reported BBB disruption following RT, whereas 30% were inconclusive. Interestingly, no compelling differences were observed between studies with different calculated biological effective doses based on the fractionation schemes and cumulative doses; however, increased BBB disruption was noted during patient follow-up after treatment. Qualitative analysis of preclinical studies showed RT BBB disruption in 78% of the included studies, which was significantly confirmed by meta-analysis (p < 0.01). Of note, a high risk of bias, publication bias and a high heterogeneity across the studies was observed. This systematic review and meta-analysis sheds light on the impact of RT protocols on BBB integrity and opens the discussion for integrating this factor in the decision-making process of future RT, with better study of its occurrence and influence on concomitant or adjuvant therapies.

United States medical preparedness for nuclear and radiological emergencies

With the end of the Cold War in 1991, U.S. Government (USG) investments in radiation science and medical preparedness were phased out; however, the events of 11 September, which involved a terroristic attack on American soil, led to the re-establishment of funding for both radiation preparedness and development of approaches to address injuries. Similar activities have also been instituted worldwide, as the global threat of a radiological or nuclear incident continues to be a concern. Much of the USG's efforts to plan for the unthinkable have centred on establishing clear lines of communication between agencies with responsibility for triage and medical response, and external stakeholders. There have also been strong connections made between those parts of the government that establish policies, fund research, oversee regulatory approval, and purchase and stockpile necessary medical supplies. Progress made in advancing preparedness has involved a number of subject matter meetings and tabletop exercises, publication of guidance documents, assessment of available resources, clear establishment of anticipated concepts of operation for multiple radiation and nuclear scenarios, and identification/mobilization of resources. From a scientific perspective, there were clear research gaps that needed to be addressed, which included the need to identify accurate biomarkers and design biodosimetry devices to triage large numbers of civilians, develop decorporation agents that are more amenable for mass casualty use, and advance candidate products to address injuries caused by radiation exposure and thereby improve survival. Central to all these activities was the development of several different animal constructs, since efficacy testing of these approaches requires extensive work in research models that accurately simulate what would be expected in humans. Recent experiences with COVID-19 have provided an opportunity to revisit aspects of radiation preparedness, and leverage those lessons learned to enhance readiness for a possible future radiation public health emergency.

Microvascular decompression as a second step treatment for trigeminal neuralgia in patients with failed two-isocentre gamma knife radiosurgery

OBJECTIVE

Subsequent microvascular decompression (MVD) might be affected by the previous two-isocentre gamma knife radiosurgery (GKS) due to the tissue changes caused by its higher dose radiation and larger treatment volume. This study aimed to evaluate the safety and efficacy of MVD as a second step treatment after two-isocentre GKS.

METHODS

Between December 2016 and May 2019, data from 19 consecutive trigeminal neuralgia (TN) patients who experienced MVD after failed two-isocentre GKS were collected. The clinical characteristics, intraoperative findings, surgical outcomes and complications were reviewed and compared with 158 patients who underwent MVD as an initial treatment.

RESULTS

Fifteen patients (78.9%) achieved complete pain relief (Barrow Neurological Institute, BNI class I) immediately after surgery and nine patients (47.4%) maintained complete pain relief at the last follow-up, which was similar to patients who underwent initial MVD. The median follow-up period was 36 months. The incidence of new or worsened facial numbness showed no statistical significance between the groups. During surgery, trigeminal nerve atrophy was noted in 9 patients (47.4%), thickened arachnoid in 3 patients (15.8%), atherosclerotic plaque in 3 patients (15.8%) and neurovascular adhesion in 1 patient (5.3%).

CONCLUSIONS

MVD remains an effective and safe rescue therapy for patients who elect the minimally invasive treatment with two-isocentre GKS for the first time, without an increased risk of facial numbness.

Anticoagulation for Radiation-Induced Optic Neuropathy

Radiation-induced optic neuropathy (RION) is a severely disabling complication of radiotherapy, without any known effective treatment. Three patients, one female and two males, aged 60, 34, and 45 years, respectively, developed progressive deterioration in visual acuity over 1 month, 8 years, and 2 months, starting 3, 12, and 9 years after radiotherapy for nasopharyngeal carcinoma. They received 70.15, 60.89, and 56.11 Gy over a period of 6-7 weeks, with fractionated doses of 2, 1.79, and 1.81 Gy, respectively. Ophthalmological examination revealed a relative afferent pupillary defect in the latter 2 patients, best-corrected visual acuity was 6/12 or better in all. Visual field charting showed a superior altitudinal field defect in the first two, and generalised visual loss in the third patient in the symptomatic eyes. Anticoagulation with heparin bridging and oral warfarin with an INR target of 2.0-3.0 was commenced within 2 months of symptom onset. All showed improvement in visual fields within 2 weeks, and remained stable for at least 2 years while on warfarin. Our encouraging findings will need to be confirmed in a randomised controlled clinical trial.

Diffusion and Perfusion MRI Predicts Response Preceding and Shortly After Radiosurgery to Brain Metastases: A Pilot Study

BACKGROUND AND PURPOSE

To determine the ability of diffusion-weighted imaging (DWI) and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) to predict long-term response of brain metastases prior to and within 72 hours of stereotactic radiosurgery (SRS).

METHODS

In this prospective pilot study, multiple b-value DWI and T1-weighted DCE-MRI were performed in patients with brain metastases before and within 72 hours following SRS. Diffusion-weighted images were analyzed using the monoexponential and intravoxel incoherent motion (IVIM) models. DCE-MRI data were analyzed using the extended Tofts pharmacokinetic model. The parameters obtained with these methods were correlated with brain metastasis outcomes according to modified Response Assessment in Neuro-Oncology Brain Metastases criteria.

RESULTS

We included 25 lesions from 16 patients; 16 patients underwent pre-SRS MRI and 12 of 16 patients underwent both pre- and early (within 72 hours) post-SRS MRI. The perfusion fraction (f) derived from IVIM early post-SRS was higher in lesions demonstrating progressive disease than in lesions demonstrating stable disease, partial response, or complete response (q = .041). Pre-SRS extracellular extravascular volume fraction, v_e , and volume transfer coefficient, K^trans , derived from DCE-MRI were higher in nonresponders versus responders (q = .041).

CONCLUSIONS

Quantitative DWI and DCE-MRI are feasible imaging methods in the pre- and early (within 72 hours) post-SRS evaluation of brain metastases. DWI- and DCE-MRI-derived parameters demonstrated physiologic changes (tumor cellularity and vascularity) and offer potentially useful biomarkers that can predict treatment response. This allows for initiation of alternate therapies within an effective time window that may help prevent disease progression.

Giant intracranial aneurysm following radiation therapy: literature review with a novel case discussion

BACKGROUND

The aim of this paper is to report the results of our review of the literature of published cases of intracranial aneurysms appearing after radiotherapy, and to present our case to add it to the current literature, in order to discuss the role of inflammation.

METHODS

We searched the PubMed database using combinations of the following MeSH terms: intracranial aneurysm, radiosurgery, radiotherapy, inflammatory changes in aneurysmal walls from 1967 to 2019.

RESULTS

51 studies, for a total cohort of 60 patients, are described. The median latency between the radiation treatment and the diagnosis was 9,83 years, ranging from a minimum of 0,33 to a maximum of 33. The modality of rays' administration was variable, and the dosage ranged from a minimum of 12 grays to a maximum of 177,2 grays. The anterior circulation appeared to be more frequently involved, and the most compromised vessel was the internal carotid artery. Radiation-induced vascular diseases have already been described in literature as well as RT-induced cellular and structural changes such as necrosis, macrophage or mononuclear cell infiltration, and several data support the role of inflammation in the development and remodelling of intracranial aneurysms, that, on one hand, favours them and, on the other, is necessary to their healing after endovascular treatment.

CONCLUSIONS

Our team suggested a new insight in the management of these vascular lesions, which corresponds to a lower threshold when deciding whether or not to treat, and a longer and stricter follow-up.

Clinical outcome following cerebral AVM hemorrhage

BACKGROUND

A significant difference exists between the published results reporting the clinical outcome following brain arteriovenous malformation (AVM) ruptures. Information about the outcome following hemorrhage in an AVM population treated with radiosurgery could provide additional information to assess the risk of mortality and morbidity following an AVM hemorrhage.

METHODS

Clinical outcome was studied in 383 patients, the largest patient population yet studied, who suffered from a symptomatic hemorrhage after Gamma Knife® surgery (GKS) but before confirmed AVM obliteration. The impact of different patient, AVM, and treatment parameters on the clinical outcome was analyzed. The aim was to generate outcome predictions by comparing our data to and combining them with earlier published results.

RESULTS

No relation was found between clinical outcome and treatment parameters, indicating that the results are applicable also on untreated AVMs. Twenty-one percent of the patients died, 45% developed or experienced worsening of neurological sequelae, and 35% recovered completely after the hemorrhage. Old age was a predictor of poor outcome. Sex, AVM location, AVM volume, and history of prior hemorrhage did not influence the outcome. The mortality rate was comparable to earlier published prospective data, but higher than that found in retrospective studies.

CONCLUSIONS

The mortality rates in earlier published retrospective series as well as in studies focusing on clinical outcome following AVM hemorrhage significantly underestimate the risk for a mortal outcome following an AVM hemorrhage. Based on our findings, an AVM rupture has around 20% likelihood to result in mortality, 45% likelihood to result in a minor or major deficit, and 35% likelihood of complete recovery. The findings are probably applicable also for AVM ruptures in general. The cumulative mortality and morbidity rates 25 years after diagnosis were estimated to be around 40% in a patient with a patent AVM.

Growth hormone therapy in adults with growth hormone deficiency: a critical assessment of the literature

PURPOSE

Growth hormone (GH) therapy has been studied as treatment for clinical manifestations of adult-onset growth hormone deficiency (AO-GHD), including cardiovascular risk, bone health, and quality of life. Patients with AO-GHD typically also have significant history of pituitary pathology and hypopituitarism, which raises the question of what proportion of their clinical presentation can be attributed to GHD alone. Currently, much of the existing data for GH therapy in AO-GHD come from uncontrolled retrospective studies and observational protocols. These considerations require careful reassessment of the role of GH as a therapeutic agent in adult patients with hypopituitarism.

METHODS

We contrast results from placebo-controlled trials with those from uncontrolled and retrospective studies for GH replacement in patients with hypopituitarism. We also examine the evidence for the manifestations of AO-GHD being attributed to GHD alone, as well as the data on adults with congenital, life-long untreated isolated GHD.

RESULTS

The evidence for increased morbidity and mortality in hypopituitary patients with GHD, and for the benefits of GH therapy, are conflicting. There remains the possibility that the described clinical manifestations of AO-GHD may not be due to GHD alone, but may also be related to underlying pituitary pathology, treatment history and suboptimal hormone replacement.

CONCLUSIONS

In the setting of inconsistent data on the benefits of GH therapy, treatment of AO-GHD remains an individualized decision. There is a need for more randomized, placebo-controlled studies to evaluate the long-term outcomes of GH therapy in adults with hypopituitarism.

THE RISK OF MULTIPLE INTRACRANIAL ANEURYSM FORMATION IN PATIENTS WITH MALIGNANT DISEASE UNDERGOING RADIATION THERAPY: A CASE REPORT AND LITERATURE REVIEW

Neoplastic etiology of intracranial cerebral aneurysm is rare. Yet, the risk of its development is higher in malignant tumor patients receiving radiation therapy. Due to the possible negative effects of irradiation on intracranial vessel walls, the risk of aneurysm formation after radiation therapy, which is crucial for some types of breast cancer patients, continues to be a matter of debate. The aim of this study was to evaluate the hazard of multiple intracranial aneurysm development in patients with malignant disease undergoing radiation therapy. It is based on literature review and case report of a 77-year-old female patient who underwent surgery for multifocal invasive hormone-receptor positive ductal breast carcinoma of no special type, followed by chemotherapy, adjuvant radiation and hormone therapy. Her comorbidity included arterial hypertension and type 2 diabetes. Six unruptured intracranial aneurysms of different bilateral locations were diagnosed incidentally by multi-slice computed tomography angiography and digital subtraction angiography of cerebral vessels. Due to the bilateral aneurysm multiplicity, tumor characteristics and prognosis, comorbidity and relatively advanced age, the patient was not selected for active endovascular or microsurgical aneurysm treatment but only periodical clinical, oncologic and radiological follow-up was advised. In conclusion, the risk of multiple intracranial aneurysm formation in patients with breast cancer undergoing radiation therapy is low, but still possible. Long-term follow-up and regular cerebral angiographic check-up studies are necessary in selected malignant patients to decrease such a risk and to evade the worst outcome associated with aneurysm rupture.

Computational Modeling of Interstitial Fluid Pressure and Velocity in Non-small Cell Lung Cancer Brain Metastases Treated With Stereotactic Radiosurgery

Background: Early imaging-based treatment response assessment of brain metastases following stereotactic radiosurgery (SRS) remains challenging. The aim of this study is to determine whether early (within 12 weeks) intratumoral changes in interstitial fluid pressure (IFP) and velocity (IFV) estimated from computational fluid modeling (CFM) using dynamic contrast-enhanced (DCE) MRI can predict long-term outcomes of lung cancer brain metastases (LCBMs) treated with SRS.

Methods: Pre- and post-treatment T₁-weighted DCE-MRI data were obtained in 41 patients treated with SRS for intact LCBMs. The imaging response was assessed using RANO-BM criteria. For each lesion, extravasation of contrast agent measured from Extended Tofts pharmacokinetic Model (volume transfer constant, K^trans) was incorporated into a computational fluid model to estimate tumor IFP and IFV. Estimates of mean IFP and IFV and heterogeneity (skewness and kurtosis) were calculated for each lesion from pre- and post-SRS imaging. The Wilcoxon rank-sum test was utilized to assess for significant differences in IFP, IFV, and IFP/IFV change (Δ) between response groups.

Results: Fifty-three lesions from 41 patients were included. Median follow-up time after SRS was 11 months. The objective response (OR) rate (partial or complete response) was 79%, with 21% demonstrating stable disease (SD) or progressive disease (PD). There were significant response group differences for multiple posttreatment and Δ CFM parameters: post-SRS IFP skewness (mean −0.405 vs. −0.691, p = 0.022), IFP kurtosis (mean 2.88 vs. 3.51, p = 0.024), and IFV mean (5.75e-09 vs. 4.19e-09 m/s, p = 0.027); and Δ IFP kurtosis (mean −2.26 vs. −0.0156, p = 0.017) and IFV mean (1.91e-09 vs. 2.38e-10 m/s, p = 0.013). Posttreatment and Δ thresholds predicted non-OR with high sensitivity (sens): post-SRS IFP skewness (−0.432, sens 84%), kurtosis (2.89, sens 84%), and IFV mean (4.93e-09 m/s, sens 79%); and Δ IFP kurtosis (−0.469, sens 74%) and IFV mean (9.90e-10 m/s, sens 74%).

Conclusions: Objective response was associated with lower post-treatment tumor heterogeneity, as represented by reductions in IFP skewness and kurtosis. These results suggest that early post-treatment assessment of IFP and IFV can be used to predict long-term response of lung cancer brain metastases to SRS, allowing a timelier treatment modification.

Neurosurgery and Manned Spaceflight

There has been a renewed interest in manned spaceflight due to endeavors by private and government agencies. Publicized goals include manned trips to or colonization of Mars. These missions will likely be of long duration, exceeding existing records for human exposure to extra-terrestrial conditions. Participants will be exposed to microgravity, temperature extremes, and radiation, all of which may adversely affect their physiology. Moreover, pathological mechanisms may differ from those of a terrestrial nature. Known central nervous system (CNS) changes occurring in space include rises in intracranial pressure and spinal unloading. Intracranial pressure increases are thought to occur due to cephalad re-distribution of body fluids secondary to microgravity exposure. Spinal unloading in microgravity results in potential degenerative changes to the bony vertebrae, intervertebral discs, and supportive musculature. These phenomena are poorly understood. Trauma is of highest concern due to its potential to seriously incapacitate crewmembers and compromise missions. Traumatic pathology may also be exacerbated in the setting of altered CNS physiology. Though there are no documented instances of CNS pathologies arising in space, existing diagnostic and treatment capabilities will be limited relative to those on Earth. In instances where neurosurgical intervention is required in space, it is not known whether open or endoscopic approaches are feasible. It is obvious that prevention of trauma and CNS pathology should be emphasized. Further research into neurosurgical pathology, its diagnosis, and treatment in space are required should exploratory or colonization missions be attempted.

Pharmacological management of ionizing radiation injuries: current and prospective agents and targeted organ systems

Introduction: There is a limited array of currently available medicinals that are useful for either the prevention, mitigation or treatment of bodily injuries arising from ionizing radiation exposure.Area covered: In this brief article, the authors review those pharmacologic agents that either are currently being used to counter the injurious effects of radiation exposure, or those that show promise and are currently under development.Expert opinion: Although significant, but limited progress has been made in the development and fielding of safe and effective pharmacotherapeutics for select types of acute radiation-associated injuries, additional effort is needed to broaden the scope of drug development so that overall health risks associated with both short- and long-term injuries in various organ systems can be reduced and effectively managed. There are several promising radiation countermeasures that may gain regulatory approval from the government in the near future for use in clinical settings and in the aftermath of nuclear/radiological exposure contingencies.

Prediction of survival and progression in glioblastoma patients using temporal perfusion changes during radiochemotherapy

BACKGROUND

The aim of this study was to investigate changes in structural magnetic resonance imaging (MRI) according to the RANO criteria and perfusion- and permeability related metrics derived from dynamic contrast-enhanced MRI (DCE) and dynamic susceptibility contrast MRI (DSC) during radiochemotherapy for prediction of progression and survival in glioblastoma.

METHODS

Twenty-three glioblastoma patients underwent biweekly structural and perfusion MRI before, during, and two weeks after a six weeks course of radiochemotherapy. Temporal trends of tumor volume and the perfusion-derived parameters cerebral blood volume (CBV) and blood flow (CBF) from DSC and DCE, in addition to contrast agent capillary transfer constant (K^trans) from DCE, were assessed. The patients were separated in two groups by median survival and differences between the two groups explored. Clinical- and MRI metrics were investigated using univariate and multivariate survival analysis and a predictive survival index was generated.

RESULTS

Median survival was 19.2 months. A significant decrease in contrast-enhancing tumor size and CBV and CBF in both DCE- and DSC-derived parameters was seen during and two weeks past radiochemotherapy (p < 0.05). A 10%/30% increase in K^trans/CBF two weeks after finishing radiochemotherapy resulted in significant shorter survival (13.9/16.8 vs. 31.5/33.1 months; p < 0.05). Multivariate analysis revealed an index using change in K^trans and relative CBV from DSC significantly corresponding with survival time in months (r² = 0.843; p < 0.001).

CONCLUSIONS

Significant temporal changes are evident during radiochemotherapy in tumor size (after two weeks) and perfusion-weighted MRI-derived parameters (after four weeks) in glioblastoma patients. While DCE-based metrics showed most promise for early survival prediction, a multiparametric combination of both DCE- and DSC-derived metrics gave additional information.

Role of gamma knife radiosurgery in the treatment of prolactinomas

PURPOSE

Stereotactic radiosurgery is one of the treatment options for prolactinomas, the most commonly used being Gamma Knife Radiosurgery (GKRS). GKRS is indicated mainly in the treatment of dopamine agonist (DA)-resistant prolactinomas. In our study, we report on our experience in treating prolactinoma patients by GKRS.

METHODS

Twenty-eight patients were followed-up after GKRS for 26-195 months (median 140 months). Prior to GKRS, patients were treated with DAs and 9 of them (32.1%) underwent previous neurosurgery. Cavernous sinus invasion was present in 16 (57.1%) patients. Indications for GKRS were (i) resistance to DA treatment (17 patients), (ii) drug intolerance (5 patients), or (iii) attempts to reduce the dosage and/or shorten the length of DA treatment (6 patients).

RESULTS

After GKRS, normoprolactinaemia was achieved in 82.1% of patients, out of which hormonal remission (normoprolactinaemia after discontinuation of DAs) was achieved in 13 (46.4%), and hormonal control (normoprolactinaemia while taking DAs) in 10 (35.7%) patients. GKRS arrested adenoma growth or decreased adenoma size in all cases. Two patients (8.3%) developed hypopituitarism after GKRS. Prolactinoma cystic transformation with expansive behaviour, manifested by bilateral hemianopsia, was observed in one patient.

CONCLUSIONS

GKRS represents an effective treatment option, particularly for DA-resistant prolactinomas. Normoprolactinaemia was achieved in the majority of patients, either after discontinuation of, or while continuing to take, DAs. Tumour growth was arrested in all cases. The risk of the development of hypopituitarism can be limited if the safe dose to the pituitary and infundibulum is maintained.

Intracranial aneurysms formation after radiotherapy for head and neck cancer: a 10-year nationwide follow-up study

Background

Intracranial aneurysms after radiotherapy (RT) have previously been reported. However, the majority of studies were case reports. Therefore, we performed a nationwide study to explore the risk of radiation-induced intracranial aneurysms.

Methods

This study included patients diagnosed with head and neck cancer (ICD9: 140–149, 161). Intracranial aneurysms formation was identified using the following ICD9 codes: nonruptured cerebral aneurysm (ICD9:4373), aneurysm clipping (ICD9:3951). Patients who did not receive curative treatment and those with intracranial aneurysms before the diagnosis of head and neck cancer were excluded.

Results

In total, 70,691 patients were included in the final analysis; they were categorized into the following three groups: nasopharyngeal carcinoma (NPC) with RT, non-NPC with RT, and non-NPC without RT. Patients in the NPC with RT group had the highest risk of developing intracranial aneurysms (hazard ratio (HR) 2.57; P <  0.001). In addition, hypertension was also a risk factor of developing intracranial aneurysms (HR 2.14; P <  0.01). The mean time interval from cancer diagnosis to intracranial aneurysm formation in the NPC with RT group was 4.3 ± 3.1 years.

Conclusions

Compared with the non-NPC with RT and the non-NPC without RT groups, patients with NPC who received RT had a higher risk of developing intracranial aneurysms.

Treatment of Radiation-Induced Cognitive Decline in Adult Brain Tumor Patients

OPINION STATEMENT

Patients with either primary or metastatic brain tumors quite often have cognitive impairment. Maintaining cognitive function is important to brain tumor patients and a decline in cognitive function is generally accompanied by a decline in functional independence and performance status. Cognitive decline can be a result of tumor progression, depression/anxiety, fatigue/sleep dysfunction, or the treatments they have received. It is our opinion that providers treating brain tumor patients should obtain pre-treatment and serial cognitive testing in their patients and offer mitigating and therapeutic interventions when appropriate. They should also support cognition-focused clinical trials.

Early posttreatment assessment of MRI perfusion biomarkers can predict long-term response of lung cancer brain metastases to stereotactic radiosurgery

Background

Imaging criteria to evaluate the response of brain metastases to stereotactic radiosurgery (SRS) in the early posttreatment period remains a crucial unmet need. The aim of this study is to correlate early (within 12 wk) posttreatment perfusion MRI changes with long-term outcomes after treatment of lung cancer brain metastases with SRS.

Methods

Pre- and posttreatment perfusion MRI scans were obtained in patients treated with SRS for intact non-small cell lung cancer brain metastases. Time-dependent leakage (Ktrans), blood plasma volume (Vp), and extracellular extravascular volume (Ve) were calculated for each lesion. Patients were followed longitudinally with serial MRI until death, progression, or intervention (whole brain radiation or surgery).

Results

We included 53 lesions treated with SRS from 41 total patients. Median follow-up after treatment was 11 months. Actuarial local control at one year was 85%. Univariate analysis demonstrated a significant difference (P = 0.032) in posttreatment Ktrans SD between patients with progressive disease (mean = 0.0317) and without progressive disease (mean = 0.0219). A posttreatment Ktrans SD cutoff value of 0.017 was highly sensitive (89%) for predicting progressive disease and no progressive disease. Early posttreatment volume change was not associated with outcome (P = 0.941).

Conclusion

Posttreatment Ktrans SD may be used as an early posttreatment imaging biomarker to help predict long-term response of lung cancer brain metastases to SRS. This can help identify patients who will ultimately fail SRS and allow for timelier adjustment in treatment approach. These data should be prospectively validated in larger patient cohorts and other histologies.

Pseudoprogression successfully treated with bevacizumab in a child with spinal pilocytic astrocytoma

CLINICAL CASE

We report on a 7-year-old female with spinal pilocytic astrocytoma complicated by pseudoprogression 1 month after completion of radiation therapy. Although she was initially treated with high-dose steroids, her clinical symptoms did not completely resolve, and magnetic resonance imaging (MRI) revealed extension of the lesions into the medulla oblongata. Treatment with bevacizumab was commenced, followed by rapid resolution of the clinical symptoms and improvements in the MRI findings.

CONCLUSION

This case highlights the efficacy and tolerability of bevacizumab for the treatment of pseudoprogression in children with spinal low-grade gliomas.

Cardiovascular effects of radiation therapy

Radiation therapy (RT) plays a prominent role in the treatment of many cancers. With increasing use of RT and high overall survival rates, the risks associated with RT must be carefully considered. Of these risks, the cardiovascular and autonomic toxicities have been of significant concern. In fact, cardiovascular disease is the leading cause of nonmalignancy-related death in cancer survivors. The manifestations of radiation induced cardiac injury include the acute toxicities of myopericarditis and late toxicities including constrictive pericarditis, restrictive cardiomyopathy, coronary artery disease, valvular heart disease, heart failure, and conduction abnormalities. Neck and cranial RT have also been associated with significant long-term toxicities including accelerated occlusive carotid artery disease, autonomic dysfunction due to baroreceptor damage, and development of metabolic syndromes due to damage to the hypothalamic-pituitary axis. The clinical manifestations of radiation induced disease may not present until several years following the delivery of radiation. We review the adverse effects of RT on these organ systems and discuss risk reduction strategies that may effectively mitigate some of these adverse outcomes.

Targeted alpha therapy with 212Pb or 225Ac: Change in RBE from daughter migration

Targeted α-therapy (TAT) could be delivered early to patients who are at a high-risk for developing brain metastases, targeting the areas of the vasculature where tumor cells are penetrating into the brain. We have utilized a Monte Carlo model representing brain vasculature to calculate physical dose and DNA damage from the α-emitters ²²⁵Ac and ²¹²Pb. The micron-scale dose distributions from all radioactive decay products were modeled in Geant4, including the eV-scale interactions using the Geant4-DNA models. These interactions were then superimposed on an atomic-scale DNA model to estimate strand break yields. In addition to ²²⁵Ac having a higher dose per decay than ²¹²Pb, it also has a double strand break yield per decay that is 4.7 ± 0.5 times that of ²¹²Pb. However, the efficacy of both nuclides depends on retaining the daughter nuclei at the target location in the brain vasculature. The relative biological effectiveness (RBE) of ²²⁵Ac and ²¹²Pb are similar when the entire decay chains are included, with maxima of 2.7 ± 0.6 and 2.5 ± 0.5 (respectively), and RBE values of about 2 to a depth of 80 μm. If the initial daughter is lost, the RBE of ²¹²Pb is completely reduced to 1 or lower and the RBE of ²²⁵Ac is approximately 2 only for the first 40 μm.

Radiotherapy in acromegaly: Long-term brain parenchymal and vascular magnetic resonance changes

BACKGROUND

Radiation therapy (RT) effectiveness on hormonal reduction is proven in acromegaly; however, collateral long-term effects are still undetermined. This transversal neuroimaging study on a large cohort of acromegalic patients aimed to investigate the rate of parenchymal and vascular changes after RT.

MATERIALS AND METHODS

Thirty-six acromegalic patients underwent RT (RT+) after unsuccessful surgery and were compared to RT- acromegalic patients matched for age, gender, adenoma features, clinical and surgical history. All patients underwent magnetic resonance angiography (MRA) to investigate intracranial artery abnormalities and FLAIR sequence to assess white matter changes according to the Wahlund scale.

RESULTS

RT+ acromegalic patients had a higher rate of controlled disease (29/36 vs. 12/36, P<0.001). RT+ acromegalic patients had MRI/MRA evaluation 15.3±9.6 years after RT. RT+ acromegalic patients had a significantly higher Wahlund score than RT- acromegalic patients (6.03±6.41 vs. 2.53±3.66, P=0.006) due to increased white matter signal abnormalities at the level of the temporal lobes, the basal ganglia (insula) and the infratentorial regions, bilaterally. Among RT+ patients one died because of temporo-polar anaplastic astrocytoma, one suffered from a stroke due to right internal carotid artery occlusion, one presented with cystic degeneration of the temporal poles. Long-dated RT (>10 years before MR evaluation) was associated with a higher rate of RT-related white matter changes (P=0.0004).

CONCLUSIONS

RT seems to have created a cohort of patients with brain parenchymal changes whose clinical and cognitive impact is still unknown. These patients might require a prolonged MRI and MRA follow-up to promptly detect delayed RT-related complications and minimize their clinical consequences.

A role for endothelial cells in radiation-induced inflammation

PURPOSE

To unravel the role of the vasculature in radiation-induced brain tissue damage.

MATERIALS AND METHODS

Postnatal day 14 mice received a single dose of 10 Gy cranial irradiation and were sacrificed 6 h, 24 h or 7 days post-irradiation. Endothelial cells were isolated from the hippocampus and cerebellum using fluorescence-activated cell sorting, followed by cell cycle analysis and gene expression profiling.

RESULTS

Flow cytometric analysis revealed that irradiation increased the percentage of endothelial cells, relative to the whole cell population in both the hippocampus and the cerebellum. This change in cell distribution indicates that other cell types are more susceptible to irradiation-induced cell death, compared to endothelial cells. This was supported by data showing that genes involved in endothelial cell-specific apoptosis (e.g. Smpd1) were not induced at any time point investigated but that genes involved in cell-cycle arrest (e.g. Cdkn1a) were upregulated at all investigated time points, indicating endothelial cell repair. Inflammation-related genes, on the other hand, were strongly induced, such as Ccl2, Ccl11 and Il6.

CONCLUSIONS

We conclude that endothelial cells are relatively resistant to ionizing radiation but that they play an active, hitherto unknown, role in the inflammatory response after irradiation. In the current study, this was shown in both the hippocampus, where neurogenesis and extensive cell death after irradiation occurs, and in the cerebellum, where neurogenesis no longer occurs at this developmental age.

Photon vs. proton radiochemotherapy: Effects on brain tissue volume and perfusion

BACKGROUND AND PURPOSE

To compare the structural and hemodynamic changes of healthy brain tissue in the cerebral hemisphere contralateral to the tumor following photon and proton radiochemotherapy.

MATERIALS AND METHODS

Sixty-seven patients (54.9 ±14.0 years) diagnosed with glioblastoma undergoing adjuvant photon (n = 47) or proton (n = 19) radiochemotherapy with temozolomide after tumor resection underwent T1-weighted and arterial spin labeling MRI. Changes in volume and perfusion before and 3 to 6 months after were compared between therapies.

RESULTS

A decrease in gray matter (GM) (-2.2%, P<0.001) and white matter (WM) (-1.2%, P<0.001) volume was observed in photon-therapy patients compared to the pre-radiotherapy baseline. In contrast, for the proton-therapy group, no significant differences in GM (0.3%, P = 0.64) or WM (-0.4%, P = 0.58) volume were observed. GM volume decreased with 0.9% per 10 Gy dose increase (P<0.001) and differed between the radiation modalities (P<0.001). Perfusion decreased in photon-therapy patients (-10.1%, P = 0.002), whereas the decrease in proton-therapy patients, while comparable in magnitude, did not reach statistical significance (-9.1%, P = 0.12). There was no correlation between perfusion decrease and either dose (P = 0.64) or radiation modality (P = 0.94).

CONCLUSIONS

Our results show that the tissue volume decrease depends on radiation dose delivered to the healthy hemisphere and differs between treatment modalities. In contrast, the decrease in perfusion was comparable for both irradiation modalities. We conclude that proton therapy may reduce brain-volume loss when compared to photon therapy.

Combined use of susceptibility weighted magnetic resonance imaging sequences and dynamic susceptibility contrast perfusion weighted imaging to improve the accuracy of the differential diagnosis of recurrence and radionecrosis in high-grade glioma patients

Purpose was to assess predictive power for overall survival (OS) and diagnostic performance of combination of susceptibility-weighted MRI sequences (SWMRI) and dynamic susceptibility contrast (DSC) perfusion-weighted imaging (PWI) for differentiation of recurrence and radionecrosis in high-grade glioma (HGG). We enrolled 51 patients who underwent radiation therapy or gamma knife surgeryfollowed by resection for HGG and who developed new measurable enhancement more than six months after complete response. The lesions were confirmed as recurrence (n = 32) or radionecrosis (n = 19). The mean and each percentile value from cumulative histograms of normalized CBV (nCBV) and proportion of dark signal intensity on SWMRI (proSWMRI, %) within enhancement were compared. Multivariate regression was performed for the best differentiator. The cutoff value of best predictor from ROC analysis was evaluated. OS was determined with Kaplan-Meier method and log-rank test. Recurrence showed significantly lower proSWMRI and higher mean nCBV and 90th percentile nCBV (nCBV90) than radionecrosis. Regression analysis revealed both nCBV90 and proSWMRI were independent differentiators. Combination of nCBV90 and proSWMRI achieved 71.9% sensitivity (23/32), 100% specificity (19/19) and 82.3% accuracy (42/51) using best cut-off values (nCBV90 > 2.07 and proSWMRI≤15.76%) from ROC analysis. In subgroup analysis, radionecrosis with nCBV > 2.07 (n = 5) showed obvious hemorrhage (proSWMRI > 32.9%). Patients with nCBV90 > 2.07 and proSWMRI≤15.76% had significantly shorter OS. In conclusion, compared with DSC PWI alone, combination of SWMRI and DSC PWI have potential to be prognosticator for OS and lower false positive rate in differentiation of recurrence and radionecrosis in HGG who develop new measurable enhancement more than six months after complete response.

Microvascular decompression for trigeminal neuralgia in patients with failed gamma knife surgery: Analysis of efficacy and safety

OBJECTIVE

Though it is usually successful, failure or delayed pain recurrence may occur after gamma knife surgery (GKS) in patients with trigeminal neuralgia (TN), and additional intervention may be required. This study aimed to investigate whether the safety and efficacy of microvascular decompression (MVD) were influenced by prior GKS.

PATIENTS AND METHODS

The authors retrospectively evaluated 36 consecutive TN patients who underwent MVD after failed GKS from January 2012 to June 2013. The clinical features, operative findings and surgical outcomes were reviewed and statistically analyzed, and the operation results were further compared with a cohort of 60 patients with no prior GKS.

RESULTS

At surgery, atrophy of the trigeminal nerve was observed in 13 patients (36.1%), arachnoid thickening in 6 patients (16.7%), adhesions between vessels and the trigeminal nerve in 8 patients (22.2%), and atherosclerotic plaque in the offending vessels in 3 patients (8.3%). The complete pain relief rates were 83.3% immediately after MVD and 72.2% at last follow-up, which showed no statistical difference when compared with patients without GKS. New or worsened facial numbness occurred in 7 patients (19.4%), which was significantly higher than those without GKS (p=0.02). Univariate analysis suggested that a positive pain response to the prior GKS correlated with better long-term outcome (p=0.015), and the existence of arachnoid adhesions correlated with higher risk of facial numbness (p=0.03).

CONCLUSIONS

MVD remains an appropriate and effective alternative therapy for patients with failed GKS, with no added technical difficulty. However, the risk of facial numbness seems to be higher than those with MVD alone.

A review of radiation countermeasures focusing on injury-specific medicinals and regulatory approval status: part I. Radiation sub-syndromes, animal models and FDA-approved countermeasures

PURPOSE

The increasing global risk of nuclear and radiological accidents or attacks has driven renewed research interest in developing medical countermeasures to potentially injurious exposures to acute irradiation. Clinical symptoms and signs of a developing acute radiation injury, i.e. the acute radiation syndrome, are grouped into three sub-syndromes named after the dominant organ system affected, namely the hematopoietic, gastrointestinal, and neurovascular systems. The availability of safe and effective countermeasures against the above threats currently represents a significant unmet medical need. This is the first article within a three-part series covering the nature of the radiation sub-syndromes, various animal models for radiation countermeasure development, and the agents currently approved by the United States Food and Drug Administration for countering the medical consequences of several of these prominent radiation exposure-associated syndromes.

CONCLUSIONS

From the U.S. and global perspectives, biomedical research concerning medical countermeasure development is quite robust, largely due to increased government funding following the 9/11 incidence and subsequent rise of terrorist-associated threats. A wide spectrum of radiation countermeasures for specific types of radiation injuries is currently under investigation. However, only a few radiation countermeasures have been fully approved by regulatory agencies for human use during radiological/nuclear contingencies. Additional research effort, with additional funding, clearly will be needed in order to fill this significant, unmet medical health problem.

Computational modelling of the cerebral cortical microvasculature: effect of x-ray microbeams versus broad beam irradiation

Microbeam Radiation Therapy is an innovative pre-clinical strategy which uses arrays of parallel, tens of micrometres wide kilo-voltage photon beams to treat tumours. These x-ray beams are typically generated on a synchrotron source. It was shown that these beam geometries allow exceptional normal tissue sparing from radiation damage while still being effective in tumour ablation. A final biological explanation for this enhanced therapeutic ratio has still not been found, some experimental data support an important role of the vasculature. In this work, the effect of microbeams on a normal microvascular network of the cerebral cortex was assessed in computer simulations and compared to the effect of homogeneous, seamless exposures at equal energy absorption. The anatomy of a cerebral microvascular network and the inflicted radiation damage were simulated to closely mimic experimental data using a novel probabilistic model of radiation damage to blood vessels. It was found that the spatial dose fractionation by microbeam arrays significantly decreased the vascular damage. The higher the peak-to-valley dose ratio, the more pronounced the sparing effect. Simulations of the radiation damage as a function of morphological parameters of the vascular network demonstrated that the distribution of blood vessel radii is a key parameter determining both the overall radiation damage of the vasculature and the dose-dependent differential effect of microbeam irradiation.

Bypass surgery to treat symptomatic fusiform dilation of the internal carotid artery following craniopharyngioma resection: report of 2 cases

Fusiform dilation of the internal carotid artery (FDICA) is an infrequent vascular complication following resection of suprasellar lesions in the pediatric population, and its course appears to be benign without apparent clinical symptoms. However, data correlating symptomatic FDICA with bypass surgery are scarce. The authors here report 2 symptomatic cases that were treated using internal maxillary artery bypass more than 5 years after total removal of a craniopharyngioma at an outside institution. Both cases of FDICA were resected to relieve the mass effect and to expose the craniopharyngioma. The postoperative course was uneventful, and radiological imaging revealed graft conduit patency. To the authors' knowledge, this is the first reported use of extracranial to intracranial bypass to treat FDICA following removal of a suprasellar lesion. Their findings suggest that bypass surgery is a useful therapeutic approach for symptomatic cases of FDICA and total removal of recurrent craniopharyngioma. Moreover, the indications for surgical intervention and treatment modalities are discussed in the context of previous relevant cases.

Flow Induced Microvascular Network Formation of Therapeutic Relevant Arteriovenous (AV) Loop-Based Constructs in Response to Ionizing Radiation

BACKGROUND The arteriovenous (AV) loop model enables axial vascularization to gain a functional microcirculatory system in tissue engineering constructs in vivo. These constructs might replace surgical flaps for the treatment of complex wounds in the future. Today, free flaps are often exposed to high-dose radiation after defect coverage, according to guideline-oriented treatment plans. Vascular response of AV loop-based constructs has not been evaluated after radiation, although it is of particular importance. It is further unclear whether the interposed venous AV loop graft is crucial for the induction of angiogenesis. MATERIAL AND METHODS We exposed the grafted vein to a single radiation dose of 2 Gy prior to loop construction to alter intrinsic and angio-inductive properties specifically within the graft. Vessel loops were embedded in a fibrin-filled chamber for 15 days and radiation-induced effects on flow-mediated vascularization were assessed by micro-CT and two-dimensional histological analysis. RESULTS Vessel amount was significantly impaired when an irradiated vein graft was used for AV loop construction. However, vessel growth and differentiation were still present. In contrast to vessel density, which was homogeneously diminished in constructs containing irradiated veins, vessel diameter was primarily decreased in the more peripheral regions. CONCLUSIONS Vascular luminal sprouts were significantly diminished in irradiated venous grafts, suggesting that the interposing vein constitutes a vital part of the AV loop model and is essential to initiate flow-mediate angiogenesis. These results add to the current understanding of AV loop-based neovascularization and suggest clinical implications for patients requiring combined AV loop-based tissue transfer and adjuvant radiotherapy.

Dosimetric Analysis of Neural and Vascular Structures in Skull Base Tumors Treated with Stereotactic Radiosurgery

Objective To examine the relationship between the prescribed target dose and the dose to healthy neurovascular structures in patients with vestibular schwannomas treated with stereotactic radiosurgery (SRS). Study Design Case series with chart review. Setting SRS center from 2011 to 2013. Subjects Twenty patients with vestibular schwannomas treated at the center from 2011 to 2013. Methods Twenty patients with vestibular schwannomas were included. The average radiation dose delivered to healthy neurovascular structures (eg, carotid artery, basilar artery, facial nerve, trigeminal nerve, and cochlea) was analyzed. Results Twenty patients with vestibular schwannomas who were treated with fused computed tomography/magnetic resonance imaging-guided SRS were included in the study. The prescribed dose ranged from 10.58 to 17.40 Gy over 1 to 3 hypofractions to cover 95% of the target tumor volume. The mean dose to the carotid artery was 5.66 Gy (95% confidence interval [CI], 4.53-6.80 Gy), anterior inferior cerebellar artery was 8.70 Gy (95% CI, 4.54-12.86 Gy), intratemporal facial nerve was 3.76 Gy (95% CI, 3.04-4.08 Gy), trigeminal nerve was 5.21 Gy (95% CI, 3.31-7.11 Gy), and the cochlea was 8.70 Gy (95% CI, 7.81-9.59 Gy). Conclusions SRS for certain vestibular schwannomas can expose the anterior inferior cerebellar artery (AICA) and carotid artery to radiation doses that can potentially initiate atherosclerotic processes. The higher doses to the AICA and carotid artery correlated with increasing tumor volume. The dose delivered to other structures such as the cochlea and intratemporal facial nerve appears to be lower and much less likely to cause immediate complications when shielded.

Efficacy and safety of antitumor agents plus radiotherapy compared with radiotherapy alone for brain metastases from lung cancer

The present study aimed to investigate the efficacy and safety of different therapeutic regimens for brain metastases (BMs) from lung cancer (LC). A total of 13 controlled trials (1,783 cases) involving chemotherapy, tyrosine kinase inhibitors or endostatin plus radiotherapy (combination group) vs. radiotherapy alone group were identified from PubMed. Compared with the radiotherapy alone group, the combination group resulted in a significant benefit for objective response rate (ORR) [risk ratio (RR), 1.38; 95% confidence interval (CI), 1.19–1.60; P<0.0001], notably prolonged the time to central nervous system progression [CNS-TTP; hazard ratio (HR), 0.71; 95% CI, 0.57–0.90; P=0.004] and progression-free survival (PFS; HR, 0.60; 95% CI, 0.44–0.83; P=0.002); however, failed in prolonging the overall survival (OS; HR, 0.80; 95% CI, 0.61–1.05; P=0.11) with a higher overall severe adverse events (AEs, Grade ≥3; RR, 2.57; 95% CI, 1.24–5.35; P=0.01). Notably, subgroup analysis demonstrated that targeted therapy plus radiotherapy possessed a superior OS compared with radiotherapy alone (HR, 0.58; 95% CI, 0.37–0.90; P=0.01) with mild non-hematological toxicity and without severe hematotoxicity. The present study demonstrated that targeted agents plus radiotherapy possessed desirable effects with mild adverse events. Secondary to best, chemoradiotherapy is an alternative option for patients without suitable molecular targets.

Analysis of volumetric response of pituitary adenomas receiving adjuvant CyberKnife stereotactic radiosurgery with the application of an exponential fitting model

Tumor control rates of pituitary adenomas (PAs) receiving adjuvant CyberKnife stereotactic radiosurgery (CK SRS) are high. However, there is currently no uniform way to estimate the time course of the disease. The aim of this study was to analyze the volumetric responses of PAs after CK SRS and investigate the application of an exponential decay model in calculating an accurate time course and estimation of the eventual outcome.A retrospective review of 34 patients with PAs who received adjuvant CK SRS between 2006 and 2013 was performed. Tumor volume was calculated using the planimetric method. The percent change in tumor volume and tumor volume rate of change were compared at median 4-, 10-, 20-, and 36-month intervals. Tumor responses were classified as: progression for >15% volume increase, regression for ≤15% decrease, and stabilization for ±15% of the baseline volume at the time of last follow-up. For each patient, the volumetric change versus time was fitted with an exponential model.The overall tumor control rate was 94.1% in the 36-month (range 18-87 months) follow-up period (mean volume change of -43.3%). Volume regression (mean decrease of -50.5%) was demonstrated in 27 (79%) patients, tumor stabilization (mean change of -3.7%) in 5 (15%) patients, and tumor progression (mean increase of 28.1%) in 2 (6%) patients (P = 0.001). Tumors that eventually regressed or stabilized had a temporary volume increase of 1.07% and 41.5% at 4 months after CK SRS, respectively (P = 0.017). The tumor volume estimated using the exponential fitting equation demonstrated high positive correlation with the actual volume calculated by magnetic resonance imaging (MRI) as tested by Pearson correlation coefficient (0.9).Transient progression of PAs post-CK SRS was seen in 62.5% of the patients receiving CK SRS, and it was not predictive of eventual volume regression or progression. A three-point exponential model is of potential predictive value according to relative distribution. An exponential decay model can be used to calculate the time course of tumors that are ultimately controlled.

Intracranial aneurysm formation after radiotherapy for medulloblastoma

Background:

The development of an intracranial aneurysm after radiotherapy is rare but secondary effect of cranial irradiation in a primary disease treatment.

Case Description:

The patient was a 17-year-old male adolescent who was diagnosed as having a posterior fossa medulloblastoma when he was 8 years old. He had undergone tumor resection with radiotherapy and chemotherapy. A distal posterior inferior cerebellar artery aneurysm was identified by magnetic resonance imaging 8 years after radiotherapy and grew rapidly throughout the next 1 year. The patient underwent microsurgical clipping and was discharged without deficit.

Conclusion:

This experience demonstrates that physicians caring for patients who have undergone intracranial radiotherapy should carefully consider the possibility of an aneurysmal formation when conducting follow-up imaging.

Neck Mass Due to Thrombosis of the Jugular Vein in Patients with Cancer

The hypothesis that jugular thrombosis (JT) may cause a mass in the cervical region is usually overlooked. The objective of the present study was to identify the characteristics of neck masses resulting from JT in cancer patients and to analyze the possible reasons for their formation. A retrospective study was conducted on 8 patients with JT affected by 3 types of neoplasia, ie, carcinomas (3 cases), adenocarcinomas (3 cases), and lymphomas (2 cases) located in the breast, digestive apparatus, lymphatic system (2 cases each), lung and an undetermined site (1 case each), diagnosed over the last 12 years. The most frequent symptom of JT was the presence of a mass in the supraclavicular space (62.5% of cases) deeply located on the anterior margin of the sternocleidomastoid muscle and diagnosed by computed tomography and ultrasound. The masses were slightly hardened, with a clearly defined upper limit and an imprecise lower limit and with an irregular surface. The patients also presented with cough, hoarseness, pain during movements, facial edema, and collateral circulation. In one of the patients with a lung cancer, JT symptoms preceded the symptoms of cancer by 2 months. Hypercoagulation, compression, and invasion of a vessel possibly explain the occurrence of JT in these patients.

Cardiovascular Complications of Cranial and Neck Radiation

OPINION STATEMENT

Cancer survivors who receive head and neck radiation are at increased risk for cerebrovascular events. This is mediated via damage to the hypothalamus-pituitary axis leading to the metabolic syndrome and extracranial arterial injury leading to carotid artery stenosis. Head and neck radiation can also lead to intracranial injury that can present as moyamoya, especially in children. Survivors require lifelong periodic follow-up for the development of pan-hypopituitarism or its individual components as well as for dyslipidemia and obesity. Aggressive control of traditional cardiovascular risk factors is recommended to reduce cardiovascular morbidity and mortality. There are no specific guidelines for the surveillance and management of asymptomatic carotid artery disease in cancer survivors. However, regular detailed examination for carotid bruits and neurological symptoms is recommended. Treatment of significant radiation-induced carotid artery disease has not been specifically studied and is based upon recommendations for patients with atherosclerotic carotid stenosis. Carotid endarterectomy can be difficult in radiation patients due to anatomic concerns and the risk of post-operative cranial nerve injury and wound complications but should be considered in patients with suitable anatomy and neck architecture. Carotid artery stenting, while successful, may be associated with greater long-term mortality and neurologic complications. Regardless of the strategy employed, radiation patients are at increased risk for restenosis and should undergo routine surveillance even after revascularization.

Evaluation on efficacy and safety of tyrosine kinase inhibitors plus radiotherapy in NSCLC patients with brain metastases

Objective

The study was designed to evaluate the efficacy and safety of tyrosine kinase inhibitors (TKIs) plus radiotherapy in patients with brain metastases (BM) of non-small cell lung cancer.

Methods

Medline PubMed, Google Scholar, Web of Science, Oxford Journals Collection, clinical trials and current controlled trials were searched to identify relevant publications. After screening literature and undertaking quality assessment and data extraction, the meta-analysis was performed using RevMan5.3 software.

Results

Eight controlled trials (980 participants) were included in the study. Compared with radiotherapy without TKIs (non-TKI-group), TKIs plus radiotherapy (TKI-group) had a significant benefit on objective response rate (ORR) (RR = 1.56, 95%CI [1.25,2.03]; P =0.0008), significantly prolonged the time to central nerves system progression (CNS-TTP) (HR =0.58, 95% CI [0.35, 0.96]; P =0.03) and median overall survival (MOS) (HR =0.68, 95% CI [0.47, 0.98]; P =0.04) of NSCLC patients with BM. There was no significant difference in overall severe adverse events (Grade≥3) (RR = 1.49, 95% CI [0.88,2.54]; P = 0.14) between two groups.

Conclusion

This meta-analysis showed TKI-group produced superior response rate when compared with non-TKI-group. TKIs plus radiotherapy significantly prolong the CNS-TTP and MOS of patients without enhancing overall severe adverse events.

Cancer-treatment-induced neurotoxicity--focus on newer treatments

Neurotoxicity caused by traditional chemotherapy and radiotherapy is widely recognized in patients with cancer. The adverse effects of newer therapeutics, such as biological and immunotherapeutic agents, are less well established, and are associated with considerable neurotoxicity in the central and peripheral nervous systems. This Review addresses the main neurotoxicities of cancer treatment with a focus on the newer therapeutics. Recognition of these patterns of toxicity is important because drug discontinuation or dose adjustment might prevent further neurological injury. Knowledge of these toxicities also helps to differentiate treatment-related symptoms from progression of cancer or its involvement of the nervous system. Familiarity with the neurological syndromes associated with cancer treatments enables clinicians to use the appropriate treatment for the underlying malignancy while minimizing the risk of neurological damage, which might preserve patients' quality of life.

De Novo Aneurysm Formation Following Gamma Knife Surgery for Arteriovenous Malformation: A Case Report

Background Stereotactic radiosurgery plays a critical role in the treatment of central nervous system neoplasm and cerebrovascular malformations. This procedure is purportedly less invasive, but problems occurring later including tumor formation, necrosis, and vasculopathy-related diseases have been reported. Clinical Presentation We report on a 65-year-old man who had experienced a de novo aneurysm in an irradiated field and an acute onset of right hemiparesis and aphasia. He had undergone gamma knife radiosurgery to treat an arteriovenous malformation 15 and 12 years prior, with 18 and 22 Gy marginal doses. At current admission, radiologic studies showed a de novo aneurysm in the irradiated field without recurrence of malformation. The aneurysm was resected. Histologic findings showed a disruption of the internal elastic lamina accompanied by fibrous degeneration. Conclusion Stereotactic radiosurgery is a promising treatment tool, but long-term risks have not been fully researched. The treatment procedure for benign lesions should be chosen prudently.

Angiographic, hemodynamic, and histological changes in an animal model of brain arteriovenous malformations treated with Gamma Knife radiosurgery

OBJECT

Brain arteriovenous malformations (AVMs) are a major cause of stroke. Many AVMs are effectively obliterated by stereotactic radiosurgery, but such treatment for lesions larger than 3 cm is not as effective. Understanding the responses to radiosurgery may lead to new biological enhancements to this treatment modality. The aim of the present study was to investigate the hemodynamic, morphological, and histological effects of Gamma Knife surgery (GKS) in an animal model of brain AVM.

METHODS

An arteriovenous fistula was created by anastomosing the left external jugular vein to the side of the common carotid artery in 64 male Sprague-Dawley rats (weight 345 ± 8.8 g). Six weeks after AVM creation, 32 rats were treated with a single dose of GKS (20 Gy); 32 animals received sham radiation. Eight irradiated and 8 control animals were studied at each specified time point (1, 3, 6, and 12 weeks) for hemodynamic, morphological, and histological characterization.

RESULTS

Two AVMs showed partial angiographic obliteration at 6 weeks. Angiography revealed complete obliteration in 3 irradiated rats at 12 weeks. Blood flow in the ipsilateral proximal carotid artery (p < 0.001) and arterialized jugular vein (p < 0.05) was significantly lower in the irradiated group than in the control group. The arterialized vein's external diameter was significantly smaller in GKS-treated animals at 6 (p < 0.05) and 12 (p < 0.001) weeks. Histological changes included subendothelial cellular proliferation and luminal narrowing in GKS-treated animals. Neither luminal obliteration nor thrombus formation was identified at any of the time points in either irradiated or nonirradiated animals.

CONCLUSIONS

GKS produced morphological, angiographic, and histological changes in the model of AVM as early as 6 weeks after treatment. These results support the use of this model for studying methods to enhance radiation response in AVMs.

Ruptured internal carotid artery aneurysm presenting with catastrophic epistaxis after repeated stereotactic radiotherapies for anterior skull base tumor: case reports and review of the literature

Objectives Radiation-induced aneurysm is a rare complication for head and neck tumors. Only seven cases of an aneurysm after stereotactic radiosurgery and/or stereotactic radiotherapy (SRT) have been described. We report two patients with a ruptured internal carotid artery (ICA) aneurysm presenting with catastrophic epistaxis after repeated SRT for an anterior skull base tumor.

Results Two male patients received repeated SRT in various combinations following surgery for an anterior skull base tumor. They presented with significant epistaxis due to rupture of the aneurysm of the ICA 6 and 77 months after the final SRT, respectively. The aneurysms were located within the radiation field. Preoperative angiography had revealed no aneurysms. Thus the aneurysms in these cases were most likely induced by the repeated SRT.

Conclusions This is a proven report of aneurysm formation following repeated SRT without conventional radiotherapy. SRT may be very effective to control malignant skull base tumors. However, the possible development of radiation-induced aneurysm of the ICA should be considered in the case of repeated SRT. The surviving patients who have received SRT should undergo sequential follow-up for possible vascular involvement.

The biology of radiosurgery and its clinical applications for brain tumors

Stereotactic radiosurgery (SRS) was developed decades ago but only began to impact brain tumor care when it was coupled with high-resolution brain imaging techniques such as computed tomography and magnetic resonance imaging. The technique has played a key role in the management of virtually all forms of brain tumor. We reviewed the radiobiological principles of SRS on tissue and how they pertain to different brain tumor disorders. We reviewed the clinical outcomes on the most common indications. This review found that outcomes are well documented for safety and efficacy and show increasing long-term outcomes for benign tumors. Brain metastases SRS is common, and its clinical utility remains in evolution. The role of SRS in brain tumor care is established. Together with surgical resection, conventional radiotherapy, and medical therapies, patients have an expanding list of options for their care. Clinicians should be familiar with radiosurgical principles and expected outcomes that may pertain to different brain tumor scenarios.