Evolution of cerebral microbleeds after cranial irradiation in medulloblastoma patients

Mitigating Radiotoxicity in the Central Nervous System: Role of Proton Therapy

OPINION STATEMENT

Central nervous system (CNS) radiotoxicity remains a challenge in neuro-oncology. Dose distribution advantages of protons over photons have prompted increased use of brain-directed proton therapy. While well-recognized among pediatric populations, the benefit of proton therapy among adults with CNS malignancies remains controversial. We herein discuss the role of protons in mitigating late CNS radiotoxicities in adult patients. Despite limited clinical trials, evidence suggests toxicity profile advantages of protons over conventional radiotherapy, including retention of neurocognitive function and brain volume. Modelling studies predict superior dose conformality of protons versus state-of-the-art photon techniques reduces late radiogenic vasculopathies, endocrinopathies, and malignancies. Conversely, potentially higher brain tissue necrosis rates following proton therapy highlight a need to resolve uncertainties surrounding the impact of variable biological effectiveness of protons on dose distribution. Clinical trials comparing best photon and particle-based therapy are underway to establish whether protons substantially improve long-term treatment-related outcomes in adults with CNS malignancies.

Complications of Cancer Therapy in Children: A Comprehensive Review of Neuroimaging Findings

ABSTRACT

Complications of cancer therapy in children can result in a spectrum of neurologic toxicities that may occur at the initiation of therapy or months to years after treatment. Although childhood cancer remains rare, increasing survival rates mean that more children will be living longer after cancer treatment. Therefore, complications of cancer therapy will most likely occur with increasing frequency.At times, it is very difficult to differentiate between therapeutic complications and other entities such as tumor recurrence, development of secondary malignancy, and infection (among other conditions). Radiologists often play a key role in the diagnosis and evaluation of pediatric patients with malignancies, and thus, awareness of imaging findings of cancer complications and alternative diagnoses is essential in guiding management and avoiding misdiagnosis. The aim of this review article is to illustrate the typical neuroimaging findings of cancer therapy-related toxicities, including both early and late treatment effects, highlighting pearls that may aid in making the appropriate diagnosis.

Salvage craniospinal irradiation for recurrent intracranial germinoma: a single institution analysis

This study investigated the effectiveness and safety of low-dose salvage craniospinal irradiation (CSI) for recurrent germinoma. We retrospectively reviewed long-term tumor control and late adverse effects in 15 recurrent germinoma patients treated at our hospital between 1983 and 2019. Following the first recurrence of germinoma, seven were treated with 24-30 Gy of salvage CSI, three underwent non-CSI, and five were treated with only chemotherapy. CSI achieved a significantly better recurrence-free survival rate after the first recurrence compared to other strategies (100% vs 33%, p < 0.001: log-rank test). To evaluate the safety of salvage CSI, we assessed the outcomes at the final follow-up of seven patients who received salvage CSI at first recurrence and three patients who received salvage CSI at second recurrence. The median follow-up period was 220 months after initial treatment. Five patients who received 40-50 Gy of radiation therapy or underwent multiple radiation therapy before salvage CSI were classified into Group A, whereas five patients treated with platinum-based chemotherapy and 24-32 Gy of radiation therapy to the primary site, whole ventricle, or whole brain were classified into Group B. In Group A, one had endocrine dysfunction and the other had visual dysfunction. None were socially independent. Meanwhile, in Group B, no endocrine or visual dysfunction was found, and three patients were socially independent. Salvage CSI achieved excellent tumor control in recurrent germinoma and was safe in patients initially treated with low-dose radiation therapy and chemotherapy.

Evolution and implementation of radiographic response criteria in neuro-oncology

Radiographic response assessment in neuro-oncology is critical in clinical practice and trials. Conventional criteria, such as the MacDonald and response assessment in neuro-oncology (RANO) criteria, rely on bidimensional (2D) measurements of a single tumor cross-section. Although RANO criteria are established for response assessment in clinical trials, there is a critical need to address the complexity of brain tumor treatment response with multiple new approaches being proposed. These include volumetric analysis of tumor compartments, structured MRI reporting systems like the Brain Tumor Reporting and Data System, and standardized approaches to advanced imaging techniques to distinguish tumor response from treatment effects. In this review, we discuss the strengths and limitations of different neuro-oncology response criteria and summarize current research findings on the role of novel response methods in neuro-oncology clinical trials and practice.

Glioblastoma Multiforme Survivor With Radiation-Induced Consequences: A Case Report

Glioblastoma multiforme is an aggressive malignant tumor of the brain with a poor prognosis and no known cure. Current treatment options for this aggressive malignancy include surgical resection, adjuvant radiation therapy, and systemic pharmacological therapy. This case report presents one patient's experience with resolved glioblastoma multiforme treated by surgical resection and radiation therapy and discusses her later development and treatment of a radiation-induced meningioma. Despite developing radiation-induced morbidities, the patient experienced an extended life because of the aggressive treatment. It is thought that the young age of this patient at the time of diagnosis may have contributed to her prolonged survival time. When balancing aggressive treatment plans to increase survival time in glioblastoma multiforme patients, risks and potential consequences of treatment, such as post-surgical changes, vascular dementia, strokes, and meningiomas, should be weighed and discussed with the patient. Furthermore, striving for a high quality of life should be kept at the forefront of every treatment plan in all patients with glioblastoma multiforme.

Toxicity and Clinical Results after Proton Therapy for Pediatric Medulloblastoma: A Multi-Centric Retrospective Study

Medulloblastoma is the most common malignant brain tumor in children. Even if current treatment dramatically improves the prognosis, survivors often develop long-term treatment-related sequelae. The current radiotherapy standard for medulloblastoma is craniospinal irradiation with a boost to the primary tumor site and to any metastatic sites. Proton therapy (PT) has similar efficacy compared to traditional photon-based radiotherapy but might achieve lower toxicity rates. We report on our multi-centric experience with 43 children with medulloblastoma (median age at diagnosis 8.7 years, IQR 6.6, M/F 23/20; 26 high-risk, 14 standard-risk, 3 ex-infant), who received active scanning PT between 2015 and 2021, with a focus on PT-related acute-subacute toxicity, as well as some preliminary data on late toxicity. Most acute toxicities were mild and manageable with supportive therapy. Hematological toxicity was limited, even among HR patients who underwent hematopoietic stem-cell transplantation before PT. Preliminary data on late sequelae were also encouraging, although a longer follow-up is needed.

Short and Long-Term Toxicity in Pediatric Cancer Treatment: Central Nervous System Damage

Simple Summary

The purpose of this review is to describe central nervous system side effects in the treatment of pediatric cancer patients. Unfortunately, we must consider that the scarce data in the literature does not allow us to expand on some issues, especially those related to innovative immunotherapy. We have described the major neurotoxicities arising with the various types of treatment to help specialists who approach these treatments recognize them early, prevent them, and treat them promptly.

Abstract

Neurotoxicity caused by traditional chemotherapy and radiotherapy is well known and widely described. New therapies, such as biologic therapy and immunotherapy, are associated with better outcomes in pediatric patients but are also associated with central and peripheral nervous system side effects. Nevertheless, central nervous system (CNS) toxicity is a significant source of morbidity in the treatment of cancer patients. Some CNS complications appear during treatment while others present months or even years later. Radiation, traditional cytotoxic chemotherapy, and novel biologic and targeted therapies have all been recognized to cause CNS side effects; additionally, the risks of neurotoxicity can increase with combination therapy. Symptoms and complications can be varied such as edema, seizures, fatigue, psychiatric disorders, and venous thromboembolism, all of which can seriously influence the quality of life. Neurologic complications were seen in 33% of children with non-CNS solid malign tumors. The effects on the CNS are disabling and often permanent with limited treatments, thus it is important that clinicians recognize the effects of cancer therapy on the CNS. Knowledge of these conditions can help the practitioner be more vigilant for signs and symptoms of potential neurological complications during the management of pediatric cancers. As early detection and more effective anticancer therapies extend the survival of cancer patients, treatment-related CNS toxicity becomes increasingly vital. This review highlights major neurotoxicities due to pediatric cancer treatments and new therapeutic strategies; CNS primary tumors, the most frequent solid tumors in childhood, are excluded because of their intrinsic neurological morbidity.

White matter hyperintensities relate to executive dysfunction, apathy, but not disinhibition in long-term adult survivors of pediatric cerebellar tumor

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Pediatric brain tumor survivors have more executive dysfunction than controls.

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White matter hyperintensities are positively associated with executive dysfunction.

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White matter hyperintensities are positively associated with apathy.

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Multivariate regression supports white matter hyperintensity associations.

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Survivors appear to drive white matter hyperintensities associations.

White matter hyperintensities (WMHs) have been related to executive dysfunction, apathy and disinhibition in a wide range of neurological populations. However, this relationship has not been examined in survivors of pediatric brain tumor. The goal of this study was to investigate how executive dysfunction, apathy, and disinhibition relate to WMHs in 31 long-term survivors of pediatric cerebellar brain tumor and 58 controls, using informant-report data from the Frontal Systems Behavior Scale. Total WMH volume was quantified using the Lesion Growth Algorithm. Further, periventricular, and subcortical volumes were identified based on proximity to custom ventricle masks generated in FSL. A ratio of WMH volume to whole brain volume was used to obtain normalized WMH volumes. Additionally, a multivariate regression analysis was performed. On average, informant-report scores were within normal limits and only executive dysfunction was significantly higher in survivors compared to controls (t(47.9) = -2.4, p=.023). Informants reported clinically significant levels of apathy in 32.3% of survivors. Informants also reported clinically significant executive dysfunction in 19.4 % of survivors and clinically significant disinhibition in, again, 19.4 % of survivors. Increased volume of WMHs was positively correlated with executive dysfunction (r = 0.33, p = 0.02) and apathy (r = 0.23, p = .04). Similarly, multivariate regression demonstrated correlations with executive dysfunction (p=.05, FDR corrected) and apathy (p=.05, FDR corrected). Exploratory analysis demonstrated an interaction wherein the relationship between total WMHs and executive dysfunction and apathy depends on whether the participant was a survivor. The current findings indicate that increased WMH volumes are associated with higher ratings of apathy and executive dysfunction, and that these results are likely unique to cerebellar brain tumor survivors. WMH burden may serve as a useful marker to identify survivors at risk of executive dysfunction or increased apathy.

Cerebral amyloid angiopathy: early presentation in a patient with prior neurosurgical interventions. Case report

BACKGROUND

Cerebral amyloid angiopathy (CAA) has classically been described as a disease of the elderly. Genetic predisposition has been linked to the APOE e3/e3 allele. Evidence suggests that brain insult in the form of injury, prior surgical intervention, or radiation can exacerbate the clearance of toxic proteins in patients susceptible to CAA.

CASE

We describe a unique case of CAA in a 30-year-old male who had prior surgical interventions for spina bifida, Chiari malformation, and hydrocephalus as a child.

CONCLUSIONS

The case is used to teach important components regarding diagnosis, clinical suspicion, and highlight the need for further investigation regarding the emerging role of the glymphatic system and its role in clinical pathology.

Central Nervous System Complications Among Oncology Patients

Cancer treatment related injury to the central nervous system (CNS) is well-recognized in the setting of brain-directed radiation therapies and conventional and novel systemic anticancer therapies. Late-delayed treatment-induced CNS complications frequently result in permanent neurologic disability. Therapeutic options are supportive with limited clinical benefit, whereby alteration or discontinuation of the overall antineoplastic treatment plan is frequently necessary to prevent further neurologic injury. Better identification of patients at high risk for developing late CNS toxicities, neuroprotective strategies with modification of existing antineoplastic treatment regimens, and research efforts directed at earlier recognition and improved treatment of central neurologic complications are paramount.

Combining Low-Dose Radiation Therapy and Magnetic Resonance Guided Focused Ultrasound to Reduce Amyloid-β Deposition in Alzheimer's Disease

Amyloid-β deposition is one of the neuropathological hallmarks of Alzheimer's disease (AD), but pharmacological strategies toward its reduction are poorly effective.Preclinical studies indicate that low-dose radiation therapy (LD-RT) may reduce brain amyloid-β. Animal models and proof-of-concept preliminary data in humans have shown that magnetic resonance guided focused ultrasound (MRgFUS) can reversibly open the blood-brain-barrier and facilitate the delivery of targeted therapeutics to the hippocampus, to reduce amyloid-β and promote neurogenesis in AD. Ongoing clinical trials on AD are exploring whole-brain LD-RT, which may damage radio-sensitive structures, i.e., hippocampus and white matter, thus contributing to reduced neurogenesis and radiation-induced cognitive decline. However, selective irradiation of cortical amyloid-β plaques through advanced LD-RT techniques might spare the hippocampus and white matter. We propose combined use of advanced LD-RT and targeted drug delivery through MRgFUS for future clinical trials to reduce amyloid-β deposition in AD since its preclinical stages.

Stroke-Like Migraine Attacks After Radiation Therapy (SMART) Syndrome: A Comprehensive Review

PURPOSE OF REVIEW

SMART syndrome is a delayed complication of cranial irradiation that can be misconstrued as tumor recurrence or some other intracranial neurological disease. Recognition of this clinical syndrome is imperative as it can obviate the need for invasive diagnostic testing and can provide reassurance to both the patient and their loved ones.

RECENT FINDINGS

SMART syndrome is generally considered a reversible clinical syndrome; however, neurological deficits may become permanent. Pathophysiology of SMART syndrome may involve cerebrovascular autoregulation impairment, neuronal dysfunction leading to trigeminovascular system impairment and/or cortical spreading depression, and seizures. In addition to MRI brain with gadolinium, other imaging modalities, such as CT perfusion, MR perfusion, MR spectroscopy, and FDG PET/CT, aid in arriving to the diagnosis sooner. Patients should also undergo electroencephalogram in order to promptly identify and treat seizures. There are currently no clear guidelines on how to effectively treat SMART syndrome, but treatment may involve anti-seizure medication, anti-hypertensives, anti-platelet, and steroid therapy. This review provides a comprehensive understanding of the clinical characteristics of SMART syndrome from presentation to diagnostic evaluation. We also discuss radiographic features and treatment strategies for this rare disease. With increased radiotherapy utilization, prompt clinical recognition of SMART syndrome and further development of a comprehensive diagnostic approach to SMART syndrome utilizing newer radiographic modalities as well as treatment algorithms to effectively treat this clinical condition will be imperative.

Seizures, Edema, Thrombosis, and Hemorrhages: An Update Review on the Medical Management of Gliomas

Patients affected with gliomas develop a complex set of clinical manifestations that deeply impact on quality of life and overall survival. Brain tumor-related epilepsy is frequently the first manifestation of gliomas or may occur during the course of disease; the underlying mechanisms have not been fully explained and depend on both patient and tumor factors. Novel treatment options derive from the growing use of third-generation antiepileptic drugs. Vasogenic edema and elevated intracranial pressure cause a considerable burden of symptoms, especially in high-grade glioma, requiring an adequate use of corticosteroids. Patients with gliomas present with an elevated risk of tumor-associated venous thromboembolism whose prophylaxis and treatment are challenging, considering also the availability of new oral anticoagulant drugs. Moreover, intracerebral hemorrhages can complicate the course of the illness both due to tumor-specific characteristics, patient comorbidities, and side effects of antithrombotic and antitumoral therapies. This paper aims to review recent advances in these clinical issues, discussing the medical management of gliomas through an updated literature review.

Maintenance of Tight Junction Integrity in the Absence of Vascular Dilation in the Brain of Mice Exposed to Ultra-High-Dose-Rate FLASH Irradiation

Persistent vasculature abnormalities contribute to an altered CNS microenvironment that further compromises the integrity of the blood-brain barrier and exposes the brain to a host of neurotoxic conditions. Standard radiation therapy at conventional (CONV) dose rate elicits short-term damage to the blood-brain barrier by disrupting supportive cells, vasculature volume and tight junction proteins. While current clinical applications of cranial radiotherapy use dose fractionation to reduce normal tissue damage, these treatments still cause significant complications. While dose escalation enhances treatment of radiation-resistant tumors, methods to subvert normal tissue damage are clearly needed. In this regard, we have recently developed a new modality of irradiation based on the use of ultra-high-dose-rate FLASH that does not induce the classical pathogenic patterns caused by CONV irradiation. In previous work, we optimized the physical parameters required to minimize normal brain toxicity (i.e., FLASH, instantaneous intra-pulse dose rate, 6.9 · 106 Gy/s, at a mean dose rate of 2,500 Gy/s), which we then used in the current study to determine the effect of FLASH on the integrity of the vasculature and the blood-brain barrier. Both early (24 h, one week) and late (one month) timepoints postirradiation were investigated using C57Bl/6J female mice exposed to whole-brain irradiation delivered in single doses of 25 Gy and 10 Gy, respectively, using CONV (0.09 Gy/s) or FLASH (>106 Gy/s). While the majority of changes found one day postirradiation were minimal, FLASH was found to reduce levels of apoptosis in the neurogenic regions of the brain at this time. At one week and one month postirradiation, CONV was found to induce vascular dilation, a well described sign of vascular alteration, while FLASH minimized these effects. These results were positively correlated with and temporally coincident to changes in the immunostaining of the vasodilator eNOS colocalized to the vasculature, suggestive of possible dysregulation in blood flow at these latter times. Overall expression of the tight junction proteins, occludin and claudin-5, which was significantly reduced after CONV irradiation, remained unchanged in the FLASH-irradiated brains at one and four weeks postirradiation. Our data further confirm that, compared to isodoses of CONV irradiation known to elicit detrimental effects, FLASH does not damage the normal vasculature. These data now provide the first evidence that FLASH preserves microvasculature integrity in the brain, which may prove beneficial to cognition while allowing for better tumor control in the clinic.

Cerebral microbleeds: from depiction to interpretation

Cerebral microbleeds (CMBs) are defined as hypointense foci visible on T2*-weighted and susceptible-weighted MRI sequences. CMBs are increasingly recognised with the widespread use of MRI in healthy individuals as well as in the context of cerebrovascular disease or dementia. They can also be encountered in major critical medical conditions such as in patients requiring extracorporeal mechanical oxygenation. The advent of MRI-guided postmortem neuropathological examinations confirmed that, in the context of cerebrovascular disease, the vast majority of CMBs correspond to recent or old microhaemorrhages. Detection of CMBs is highly influenced by MRI parameters, in particular field strength, postprocessing methods used to enhance T2* contrast and three dimensional sequences. Despite recent progress, harmonising imaging parameters across research studies remains necessary to improve cross-study comparisons. CMBs are helpful markers to identify the nature and the severity of the underlying chronic small vessel disease. In daily clinical practice, presence and numbers of CMBs often trigger uncertainty for clinicians especially when antithrombotic treatments and acute reperfusion therapies are discussed. In the present review, we discuss those clinical dilemmas and address the value of CMBs as diagnostic and prognostic markers for future vascular events.

Cerebral Autoregulation and Neurovascular Coupling after Craniospinal Irradiation in Long-Term Survivors of Malignant Pediatric Brain Tumors of the Posterior Fossa

INTRODUCTION

Long-term survivors of craniospinal irradiation have an increased risk for stroke which increases with radiation dose and follow-up time. Radiotherapy induces structural changes of the cerebral vasculature, affecting both, large, and small vessels. It is unknown how these structural changes affect functional mechanisms of cerebral blood flow regulation such as cerebral autoregulation and neurovascular coupling.

METHODS

Using the transcranial Doppler, we compared dynamic cerebral autoregulation and neurovascular coupling of 12 patients after long-term survival of craniospinal irradiation due to a malignant pediatric brain tumor of the posterior fossa and 12 age- and sex-matched healthy patients. Mean arterial blood pressure and cerebral blood flow velocities in the middle and posterior cerebral artery were recorded at rest during normal breathing to assess cerebral autoregulation (transfer function parameters phase and gain, as well as the correlation coefficient indices Mx, Sx, and Dx), and during 10 cycles of a visual task to assess neurovascular coupling (parameters time delay, natural frequency, gain, attenuation, and rate time).

RESULTS

Parameters of cerebral autoregulation showed a consistent trend toward reduced cerebral autoregulation in patients that did not reach statistical significance. Neurovascular coupling was not altered after craniospinal irradiation.

CONCLUSION

In this pilot study, we demonstrated a trend toward reduced cerebral autoregulation, and no alteration of neurovascular coupling after irradiation in long-term survivors of malignant pediatric brain tumors of the posterior fossa.

A Case of Occlusive Radiation Vasculopathy Presenting as Bilateral Internal Carotid Artery, Left Middle Cerebral Artery Occlusion and Literature Review

Radiation vasculopathy is one of the rare causes of ischemic stroke. Carotid stenosis with large volume infarction may occur years after radiation therapy for head or neck cancer. We report a case of a patient with bilateral internal carotid artery occlusion presenting with left middle cerebral artery infarct 10 years after receiving treatment for tongue cancer. A literature review and discussion of treatment for such patients are presented.

Neurotoxicity of Cancer Therapies

PURPOSE OF REVIEW

This article reviews neurologic complications associated with chemotherapy, radiation therapy, antiangiogenic therapy, and immunotherapy.

RECENT FINDINGS

Cancer therapies can cause a wide range of neurologic adverse effects and may result in significant patient morbidity and mortality. Although some treatment-associated neurologic complications manifest acutely and are often reversible and transient, others occur with delayed onset, can be progressive, and are uniquely challenging to patient management. With an increase in multimodality and combination therapies, including targeted therapies and immunotherapies, and prolonged patient survival, novel and unique patterns of neurologic complications have emerged.

SUMMARY

Both conventional and novel cancer therapies can adversely affect the nervous system, thereby producing a wide range of neurologic complications. Increased awareness among neurologists and early recognition of cancer therapy-induced neurotoxic syndromes is critically important to minimize patient morbidity, prevent permanent injury, and improve patient outcomes.

Recognizing Radiation-induced Changes in the Central Nervous System: Where to Look and What to Look For

Radiation therapy (RT) continues to play a central role as an effective therapeutic modality for a variety of tumors and vascular malformations in the central nervous system. Although the planning and delivery techniques of RT have evolved substantially during the past few decades, the structures surrounding the target lesion are inevitably exposed to radiation. A wide variety of radiation-induced changes may be observed at posttreatment imaging, which may be confusing when interpreting images. Histopathologically, radiation can have deleterious effects on the vascular endothelial cells as well as on neuroglial cells and their precursors. In addition, radiation induces oxidative stress and inflammation, leading to a cycle of further cellular toxic effects and tissue damage. On the basis of the time of expression, radiation-induced injury can be divided into three phases: acute, early delayed, and late delayed. Acute and early delayed injuries are usually transient and reversible, whereas late delayed injuries are generally irreversible. The authors provide a comprehensive review of the timeline and expected imaging appearances after RT, including the characteristic imaging features after RT with concomitant chemotherapy. Specific topics discussed are imaging features that help distinguish expected posttreatment changes from recurrent disease, followed by a discussion on the role of advanced imaging techniques. Knowledge of the RT plan, the amount of normal structures included, the location of the target lesion, and the amount of time elapsed since RT is highly important at follow-up imaging, and the reporting radiologist should be able to recognize the characteristic imaging features after RT and differentiate these findings from tumor recurrence. ^©RSNA, 2020.

Rate of radiation-induced microbleed formation on 7T MRI relates to cognitive impairment in young patients treated with radiation therapy for a brain tumor

BACKGROUND

Radiation therapy (RT) is essential to the management of many brain tumors, but has been known to lead to cognitive decline and vascular injury in the form of cerebral microbleeds (CMBs).

PURPOSE

In a subset of children, adolescents, and young adults recruited from a larger trial investigating arteriopathy and stroke risk after RT, we evaluated the prevalence of CMBs after RT, examined risk factors for CMBs and cognitive impairment, and related their longitudinal development to cognitive performance changes.

METHODS

Twenty-five patients (mean 17 years, range: 10-25 years) underwent 7-Tesla MRI and cognitive assessment. Nineteen patients were treated with whole-brain or focal RT 1-month to 20-years prior, while 6 non-irradiated patients with posterior-fossa tumors served as controls. CMBs were detected on 7T susceptibility-weighted imaging (SWI) using semi-automated software, a first use in this population.

RESULTS

CMB detection sensitivity with 7T SWI was higher than previously reported at lower field strengths, with one or more CMBs detected in 100% of patients treated with RT at least 1-year prior. CMBs were localized to dose-targeted brain volumes with risk factors including whole-brain RT (p = 0.05), a higher RT dose (p = 0.01), increasing time since RT (p = 0.03), and younger age during RT (p = 0.01). Apart from RT dose, these factors were associated with impaired memory performance. Follow-up data in a subset of patients revealed a proportional increase in CMB count with worsening verbal memory performance (r = -0.85, p = 0.03).

CONCLUSIONS

Treatment with RT during youth is associated with the chronic development of CMBs that evolve with memory impairment over time.

Non-Human Primates Receiving High-Dose Total-Body Irradiation are at Risk of Developing Cerebrovascular Injury Years Postirradiation

Nuclear accidents and acts of terrorism have the potential to expose thousands of people to high-dose total-body iradiation (TBI). Those who survive the acute radiation syndrome are at risk of developing chronic, degenerative radiation-induced injuries [delayed effects of acute radiation (DEARE)] that may negatively affect quality of life. A growing body of literature suggests that the brain may be vulnerable to radiation injury at survivable doses, yet the long-term consequences of high-dose TBI on the adult brain are unclear. Herein we report the occurrence of lesions consistent with cerebrovascular injury, detected by susceptibility-weighted magnetic resonance imaging (MRI), in a cohort of non-human primate [(NHP); rhesus macaque, Macaca mulatta] long-term survivors of high-dose TBI (1.1-8.5 Gy). Animals were monitored longitudinally with brain MRI (approximately once every three years). Susceptibility-weighted images (SWI) were reviewed for hypointensities (cerebral microbleeds and/or focal necrosis). SWI hypointensities were noted in 13% of irradiated NHP; lesions were not observed in control animals. A prior history of exposure was correlated with an increased risk of developing a lesion detectable by MRI (P = 0.003). Twelve of 16 animals had at least one brain lesion present at the time of the first MRI evaluation; a subset of animals (n = 7) developed new lesions during the surveillance period (3.7-11.3 years postirradiation). Lesions occurred with a predilection for white matter and the gray-white matter junction. The majority of animals with lesions had one to three SWI hypointensities, but some animals had multifocal disease (n = 2). Histopathologic evaluation of deceased animals within the cohort (n = 3) revealed malformation of the cerebral vasculature and remodeling of the blood vessel walls. There was no association between comorbid diabetes mellitus or hypertension with SWI lesion status. These data suggest that long-term TBI survivors may be at risk of developing cerebrovascular injury years after irradiation.

Intracranial meningioma and concomitant cavernous malformation: A series description and review of the literature

OBJECTIVES

Intracranial meningioma with concomitant cavernous malformation has been rarely described in the literature. This study aimed to investigate the correct neurosurgical conduct.

PATIENTS AND METHODS

We retrieved clinical and radiological data for 39 outpatients or patients that underwent surgery (mean age: 60 years; n = 25 females) for a single or multiple meningiomas and concomitant single or multiple cavernous malformations. Cavernous malformations were classified according to Zabramski's type scale. Our results were compared to results published in the literature.

RESULTS

All patients had at least one meningioma and at least one concomitant cavernous malformation. Most meningiomas and cavernous malformations were located in the supratentorial region. Nine patients (23 %) had multiple meningiomas and nine had concomitant multiple cavernous malformations. Cavernous malformations were classified as type I (n = 0), type II (n = 9), type III (n = 11), or type IV (n = 19). The surgical priority was meningioma removal. A single patient underwent simultaneous removal of a meningioma and a contiguous cavernous malformation. In the postoperative period and long term follow-up, no complications occurred related to cavernous malformations, intra- or extra-lesional bleeding, or morphology/size changes. Years after surgical treatment, a new type IV cavernous malformation occurred in two patients.

CONCLUSION

Our findings corroborate that meningioma removal should take priority in patients with intracranial meningioma and concomitant cavernous malformation. Concomitant cavernous malformations showed no change in morphology or size; therefore, they should merely be observed during follow-up. In patients that harbor a single meningioma, a type IV cavernous malformation should preferably be considered a concomitant cerebral microbleed.

Neuroprotection of Radiosensitive Juvenile Mice by Ultra-High Dose Rate FLASH Irradiation

Major advances in high precision treatment delivery and imaging have greatly improved the tolerance of radiotherapy (RT); however, the selective sparing of normal tissue and the reduction of neurocognitive side effects from radiation-induced toxicities remain significant problems for pediatric patients with brain tumors. While the overall survival of pediatric patients afflicted with medulloblastoma (MB), the most common type primary brain cancer in children, remains high (≥80%), lifelong neurotoxic side-effects are commonplace and adversely impact patients’ quality of life. To circumvent these clinical complications, we have investigated the capability of ultra-high dose rate FLASH-radiotherapy (FLASH-RT) to protect the radiosensitive juvenile mouse brain from normal tissue toxicities. Compared to conventional dose rate (CONV) irradiation, FLASH-RT was found to ameliorate radiation-induced cognitive dysfunction in multiple independent behavioral paradigms, preserve developing and mature neurons, minimize microgliosis and limit the reduction of the plasmatic level of growth hormone. The protective “FLASH effect” was pronounced, especially since a similar whole brain dose of 8 Gy delivered with CONV-RT caused marked reductions in multiple indices of behavioral performance (objects in updated location, novel object recognition, fear extinction, light-dark box, social interaction), reductions in the number of immature (doublecortin⁺) and mature (NeuN⁺) neurons and increased neuroinflammation, adverse effects that were not found with FLASH-RT. Our data point to a potentially innovative treatment modality that is able to spare, if not prevent, many of the side effects associated with long-term treatment that disrupt the long-term cognitive and emotional well-being of medulloblastoma survivors.

Modern Radiotherapy for Pediatric Brain Tumors

Cancer is a leading cause of death in children with tumors of the central nervous system, the most commonly encountered solid malignancies in this population. Radiotherapy (RT) is an integral part of managing brain tumors, with excellent long-term survival overall. The tumor histology will dictate the volume of tissue requiring treatment and the dose. However, radiation in developing children can yield functional deficits and/or cosmetic defects and carries a risk of second tumors. In particular, children receiving RT are at risk for neurocognitive effects, neuroendocrine dysfunction, hearing loss, vascular anomalies and events, and psychosocial dysfunction. The risk of these late effects is directly correlated with the volume of tissue irradiated and dose delivered and is inversely correlated with age. To limit the risk of developing these late effects, improved conformity of radiation to the target volume has come from adopting a volumetric planning process. Radiation beam characteristics have also evolved to achieve this end, as exemplified through development of intensity modulated photons and the use of protons. Understanding dose limits of critical at-risk structures for different RT modalities is evolving. In this review, we discuss the physical basis of the most common RT modalities used to treat pediatric brain tumors (intensity modulated radiation therapy and proton therapy), the RT planning process, survival outcomes for several common pediatric malignant brain tumor histologies, RT-associated toxicities, and steps taken to mitigate the risk of acute and late effects from treatment.

Posterior reversible encephalopathy syndrome in an oncological normotensive patient: evidence for a pathogenic role of concomitant low magnesium serum levels and chemotherapy treatment

Background:

Posterior reversible encephalopathy (PRES) is a rare syndrome characterized by headache, confusion, seizures, visual changes and white matter edema at radiological imaging. Its pathophysiology is not clarified and different causes, including uncontrolled hypertension, eclampsia, chemotherapy and hypomagnesemia have been suggested.

Case report:

A woman affected by stage IV breast cancer with lower extremity deep vein thrombosis treated with low-molecular-weight-heparin, currently in therapy with Palbociclib/Fulvestrant (antiCDK4 and 6/estrogen receptor antagonist) but previously treated with several other chemotherapy lines (including VEGF inhibitor bevacizumab), was admitted to our Internal Medicine department because of ascites and abdominal pain. She was treated with diuretics (and paracentesis). Recently (six-month earlier) a pan-encephalic radiotherapy was done because of brain and skull metastasis. Among blood tests, low serum levels of hypomagnesemia were observed. She developed PRES that rapidly progressed to lethargy, unresponsiveness till coma without changes in blood pressure. Magnetic Resonance Imaging study showed bilateral parieto-occipital edema and a thrombosis of left transverse and sigmoid sinuses. Anti-edema therapy, intravenous supplementation of magnesium and decoagulation were started, with complete and rapid recovery (within 18 hours) of clinical and radiologic changes.

Conclusions:

PRES diagnosis was based on the rapid clinical recovery after antiedema treatment and magnesium supplementation. Low magnesium level related to both diuretic and Fulvestrant/Palbociclib therapies and recent radiotherapy can represent potential mechanisms favouring PRES development. The previous bevacizumab treatment may also be involved as a PRES predisposing factor. The concomitant occurrence of cerebral thrombosis can have precipitated the clinical situation. (www.actabiomedica.it)

The correlation between serum apolipoprotein B/apolipoprotein A1 ratio and brain necrosis in patients underwent radiotherapy for nasopharyngeal carcinoma

INTRODUCTION

The apolipoprotein B/apolipoprotein A1 (ApoB/ApoA1) ratio is recognized as a clinical indicator of cardiovascular disease and ischemic cerebral disease. Cerebrovascular dysfunction is also involved in head and neck radiotherapy. The aim of this study was to investigate the correlation between ApoB/ApoA1 ratio and the severity of radiation-induced brain necrosis (RN) in patients who underwent radiotherapy after nasopharyngeal carcinoma (NPC).

METHODS

In this retrospective study, 191 NPC patients diagnosed with RN were evaluated. Clinical characteristics, serum lipid, apolipoproteins, and brain magnetic resonance imaging findings were collected. Serum lipid and apolipoproteins were quantified using standard diagnostic assays, and the quality of life (QOL) was assessed by the World Health Organization quality of life abbreviated instrument (WHOQOL-BREF).

RESULTS

ApoB/ApoA1 ratio was positively correlated with lesion volume (r = .18, p = .03) and negatively correlated with WHOQOL-BREF scores (r = -.28, p < .01). The ApoB/ApoA1 ratio and intensity-modulated radiation therapy (IMRT) were independent risk factor of RN volume. Moreover, ApoB/ApoA1 ratio was significantly negatively correlated with physical health (r = -.29, p < .01), psychological (r = -.27, p < .01), social relationships (r = -.17, p = .02), and environment (r = -.27, p < .01) domains of WHOQOL-BREF.

CONCLUSIONS

Serum ApoB/ApoA1 ratio is positively correlated with RN volume, which indicated serum ApoB/ApoA1 ratio as an independent risk factor for lesion volume in patients with RN after radiotherapy for NPC, suggesting a bright intervention target in RN treatment.

Quantifying effects of radiotherapy-induced microvascular injury; review of established and emerging brain MRI techniques

Microvascular changes are increasingly recognised not only as primary drivers of radiotherapy treatment response in brain tumours, but also as an important contributor to short- and long-term (cognitive) side effects arising from irradiation of otherwise healthy brain tissue. As overall survival of patients with brain tumours is increasing, monitoring long-term sequels of radiotherapy-induced microvascular changes in the context of their potential predictive power for outcome, such as cognitive disability, has become increasingly relevant. Ideally, radiotherapy-induced significant microvascular changes in otherwise healthy brain tissue should be identified as early as possible to facilitate adaptive radiotherapy and to proactively start treatment to minimise the influence on these side-effects on the final outcome. Although MRI is already known to be able to detect significant long-term radiotherapy induced microvascular effects, more recently advanced MR imaging biomarkers reflecting microvascular integrity and function have been reported and might provide a more accurate and earlier detection of microvascular changes. However, the use and validation of both established and new techniques in the context of monitoring early and late radiotherapy-induced microvascular changes in both target-tissue and healthy tissue currently are minimal at best. This review aims to summarise the performance and limitations of existing methods and future opportunities for detection and quantification of radiotherapy-induced microvascular changes, as well as the relation of these findings with key clinical parameters.

Management for Different Glioma Subtypes: Are All Low-Grade Gliomas Created Equal?

Following the identification of key molecular alterations that provided superior prognostication and led to the updated 2016 World Health Organization (WHO) Central Nervous System (CNS) Tumor Classification, the understanding of glioma behavior has rapidly evolved. Mutations in isocitrate dehydrogenase (IDH) 1 and 2 are present in the majority of adult grade 2 and 3 gliomas, and when used in conjunction with 1p/19q codeletion for classification, the prognostic distinction between grade 2 versus grade 3 is diminished. As such, the previously often used term of "low-grade glioma," which referred to grade 2 gliomas, has now been replaced by the phrase "lower-grade glioma" to encompass both grade 2 and 3 tumors. Additional molecular characterization is ongoing to even further classify this heterogeneous group of tumors. With such a colossal shift in the understanding of lower-grade gliomas, management of disease is being redefined in the setting of emerging molecular-genetic biomarkers. In this article, we review recent progress and future directions regarding the surgical, radiotherapeutic, chemotherapeutic, and long-term management of adult lower-grade gliomas.

Susceptibility-weighted imaging in malignant melanoma brain metastasis

BACKGROUND

The value of cerebral susceptibility-weighted imaging (SWI) in malignant melanoma (MM) patients remains controversial and the effect of melanin on SWI is not well understood.

PURPOSE

To systematically analyze the spectrum of intracerebral findings in MM brain metastases (BM) on SWI and to determine the diagnostic value of SWI.

STUDY TYPE

Retrospective.

POPULATION/SUBJECTS

In all, 100 patients with melanoma BM (69 having received radiotherapy [RT] and 31 RT-naïve) and a control group of 100 melanoma patients without BM were included. For detailed analysis of signal characteristics, 175 metastases were studied.

FIELD STRENGTH/SEQUENCE

Gradient echo SWI sequence at 1.5, 3.0, and 9.4 T.

ASSESSMENT

Signal characteristics from melanotic and amelanotic BMs on SWI with a focus on blooming artifacts were analyzed, as well as the presence and longitudinal dynamics of isolated SWI blooming artifacts in patients with and without BM.

STATISTICAL TESTS

Chi-squared and Student's t-test were used for contingency table measures and group data of signal and clinical characteristics, respectively.

RESULTS

Melanotic and amelanotic metastases did not show significant differences of SWI blooming artifacts (38% vs. 43%, P = 0.61). Most metastases without an initial SWI artifact developed a signal dropout during follow-up (80%; 65/81). Isolated SWI artifacts were detected more frequently in patients with BM (20 vs. 9, P = 0.03), of which the majority were found in patients who had received RT (17 vs. 3, P = 0.08). None of these isolated SWI blooming artifacts turned into overt metastases over time (median follow-up: 8.5 months). Similar findings persisted as remnants of successfully treated metastases (88%; 7/8).

DATA CONCLUSION

We conclude that SWI provides little additional diagnostic benefit over standard T₁ -weighted imaging, as melanin content alone does not cause diagnostically relevant SWI blooming. Signal transition of SWI may rather indicate secondary phenomena like microbleeding and/or metal scavenging. Our results suggest that isolated SWI artifacts do not constitute vital tumor tissue but represent unspecific microbleedings, RT-related parenchymal changes or posttherapeutic remnants of former metastatic lesions.

LEVEL OF EVIDENCE

3 Technical Efficacy Stage: 5 J. Magn. Reson. Imaging 2019;50:1251-1259.

Risk factors of radiotherapy-induced cerebral microbleeds and serial analysis of their size compared with white matter changes: A 7T MRI study in 113 adult patients with brain tumors

BACKGROUND

Although radiation therapy (RT) contributes to survival benefit in many brain tumor patients, it has also been associated with long-term brain injury. Cerebral microbleeds (CMBs) represent an important manifestation of radiation-related injury.

PURPOSE

To characterize the change in size and number of CMBs over time and to evaluate their relationship to white matter structural integrity as measured using diffusion MRI indices.

STUDY TYPE

Longitudinal, retrospective, human cohort.

POPULATION

In all, 113 brain tumor patients including patients treated with focal RT (n = 91, 80.5%) and a subset of nonirradiated controls (n = 22, 19.5%).

FIELD STRENGTH/SEQUENCE

Single and multiecho susceptibility-weighted imaging (SWI) and multiband, shell, and direction diffusion tensor imaging (DTI) at 7 T.

ASSESSMENT

Patients were scanned either once or serially. CMBs were detected and quantified on SWI images using a semiautomated approach. Local and global fractional anisotropy (FA) were measured from DTI data for a subset of 35 patients.

STATISTICAL TESTS

Potential risk factors for CMB development were determined by multivariate linear regression and using linear mixed-effect models. Longitudinal FA was quantitatively and qualitatively evaluated for trends.

RESULTS

All patients scanned at 1 or more years post-RT had CMBs. A history of multiple surgical resections was a risk factor for development of CMBs. The total number and volume of CMBs increased by 18% and 11% per year, respectively, although individual CMBs decreased in volume over time. Simultaneous to these microvascular changes, FA decreased by a median of 6.5% per year. While the majority of nonirradiated controls had no CMBs, four control patients presented with fewer than five CMBs.

DATA CONCLUSION

Identifying patients who are at the greatest risk for CMB development, with its likely associated long-term cognitive impairment, is an important step towards developing and piloting preventative and/or rehabilitative measures for patients undergoing RT.

LEVEL OF EVIDENCE

3 Technical Efficacy: Stage 4 J. Magn. Reson. Imaging 2019;50:868-877.

The management of childhood cancer survivors at risk for stroke: A Delphi survey of regional experts

BACKGROUND

Evidence is not available to guide management of childhood cancer survivors (CCS) at risk for radiation-associated cerebral vascular disease (CVD) and stroke. We propose to use a consensus-based methodology to describe the collective opinion of regional experts for the care of these patients and identify areas of controversy.

PROCEDURE

Thirty physicians from the New England region who care for CCS participated in a Delphi panel querying their management approach (imaging, laboratory tests, medications, counseling, referrals) to a CCS treated with cranial radiation formatted as five clinical scenarios (asymptomatic, small- and large-vessel CVD, transient ischemia, stroke) in three rounds of anonymous questionnaires. Consensus defined as ≥90% agreement.

RESULTS

Response rate was 100% for all three rounds. Panelists reached consensus on laboratory tests to assess stroke risk factors, stroke risk and prevention counseling, brain imaging to monitor survivors with known CVD, and acute care for stroke symptoms. Only 67% panelists agreed with MRI screening asymptomatic survivors with no history of CVD, 87% endorsed aspirin as stroke prevention for large-vessel CVD and 57% for small-vessel CVD. There was no consensus on specialty referrals. Overall, panelists practicing at large institutions and neurology subspecialists were more likely to advocate for screening, interventions, and referrals.

CONCLUSIONS

Despite lack of evidence to guide stroke prevention in CCS treated with cranial radiation, a panel of regional physicians reached consensus on managing most clinical scenarios. Controversial areas requiring further study are surveillance imaging for asymptomatic survivors, aspirin for stroke prevention, and indications for specialty referral.

Medical Complications of Brain Tumors

PURPOSE OF REVIEW

This article discusses common and emergent medical complications encountered in patients with primary brain tumors.

RECENT FINDINGS

Clinical studies and systematic reviews published in recent years have improved knowledge regarding the incidence of neurologic and medical complications occurring in patients with primary brain tumors. Studies in tumor-related epilepsy and venous thromboembolism provide data for the clinician to make evidence-based decisions about perioperative management, prophylaxis, and therapy. Patients with brain tumors experience unique toxicities related to novel drugs and chemotherapeutics that result in hematologic, infectious, and endocrine disorders. Recent work that has focused on quality of life in patients with brain tumors highlights the importance of good supportive care and optimal medical management of neurobehavioral symptoms and late complications of treatment.

SUMMARY

A thorough understanding of the variety of medical and neurologic complications in patients with primary brain tumors improves the clinician's ability to quickly recognize and manage common and urgent conditions.

Cerebral microbleeds: a magnetic resonance imaging review of common and less common causes

Cerebral microbleeds (CMBs) are small foci of (acute, subacute or chronic) blood products, best seen using magnetic resonance imaging (MRI) techniques sensitive to iron deposits (i.e. gradient-echo T2*-weighted and susceptibility-weighted imaging), frequently encountered in small vessel disease (SVD) (with hypertensive vasculopathy and cerebral amyloid angiopathy as the most frequent conditions) and also in other disorders. In this review, the MRI characteristics of CMBs and the associated MRI abnormalities encountered in common and less common SVD and non-SVD conditions are the main focus. Identification of the origin of CMBs depends on their localization, the presence of other associated MRI abnormalities, and the patient's history and clinical state.

Neuroradiologic Pearls for Neuro-oncology

PURPOSE OF REVIEW

This article reviews key principles in the identification of tumors of the central nervous system (CNS) using standard and advanced imaging modalities. This article highlights the pitfalls and pearls of the imaging evaluation of patients with cancer at time of diagnosis and during cancer therapy and discusses the challenges of the imaging evaluation of treatment-related toxicities.

RECENT FINDINGS

Treatment of CNS tumors with surgery, chemotherapy, or radiation alters the imaging appearance of the tumor and can be associated with a variety of treatment-related toxicities. The clinician must be familiar with how to assess response to treatment and how to differentiate tumor progression from treatment-related effects.

SUMMARY

Management and follow-up of neuro-oncology patients is optimized by a comprehensive radiologic approach to CNS tumors and recognition of the challenges in the assessment of response to treatments.

Recurrent Thromboembolic Events after Ischemic Stroke in Patients with Primary Brain Tumors

BACKGROUND

Stroke mechanisms and the risk of recurrent thromboembolism are incompletely understood in patients with primary brain tumors. We sought to better delineate these important clinical features.

METHODS

We performed a retrospective cohort study of adults with primary brain tumors diagnosed with magnetic resonance imaging-confirmed acute ischemic stroke at the Memorial Sloan Kettering Cancer Center from 2005 to 2015. Study neurologists collected data on patients' cancer history, stroke risk factors, treatments, and outcomes. Stroke mechanisms were adjudicated by consensus. The primary outcome was recurrent thromboembolism (arterial or venous) and the secondary outcome was recurrent ischemic stroke. Kaplan-Meier statistics were used to calculate cumulative outcome rates, and Cox hazards analysis was used to evaluate the association between potential risk factors and outcomes.

RESULTS

We identified 83 patients with primary brain tumors and symptomatic acute ischemic stroke. Median survival after index stroke was 2.2 years (interquartile range, .5-7.0). Tumors were mostly gliomas (72%) and meningiomas (13%). Most strokes were from unconventional mechanisms, particularly radiation vasculopathy (36%) and surgical manipulation (18%). Small- or large-vessel disease or cardioembolism caused 13% of strokes, whereas 29% were cryptogenic. Cumulative recurrent thromboembolism rates were 11% at 30 days, 17% at 180 days, and 27% at 365 days, whereas cumulative recurrent stroke rates were 5% at 30 days, 11% at 180 days, and 13% at 365 days. We found no significant predictors of outcomes.

CONCLUSION

Patients with primary brain tumors generally develop strokes from rare mechanisms, and their risk of recurrent thromboembolism, including stroke, is high.