Temporal Cerebral Microbleeds Are Associated With Radiation Necrosis and Cognitive Dysfunction in Patients Treated for Nasopharyngeal Carcinoma

Total-Body Irradiation Alters White Matter Volume and Microstructural Integrity in Rhesus Macaques

PURPOSE

Long-term survivors of brain irradiation can experience irreversible injury and cognitive impairment. T1-weighted and diffusion tensor magnetic resonance imaging (MRI) are used to evaluate brain volume and white matter (WM) microstructure in neurodevelopmental and neurodegenerative conditions. The goal of this study was to evaluate the long-term effects of single-dose total-body irradiation (TBI) or TBI with 5% partial-body sparing on brain volumetrics and WM integrity in macaques.

METHODS AND MATERIALS

We used MRI scans from a cohort of male rhesus macaques (age range, 3.6-22.8 years) to compare global and regional brain volumes and WM diffusion in survivors of TBI (T1-weighted, n = 137; diffusion tensor imaging, n = 121; dose range, 3.5-10 Gy) with unirradiated controls (T1-weighted, n = 48; diffusion tensor imaging, n = 38).

RESULTS

In all regions of interest, radiation affected age-related changes in fractional anisotropy, which tended to increase across age in both groups but to a lesser extent in the irradiated group (interaction P < .01). Depending on the region of interest, mean diffusivity decreased or remained the same across age in unirradiated animals, whereas it increased or did not change in irradiated animals. The increases in mean diffusivity were driven by changes in radial diffusivity, which followed similar trends across age. Axial diffusivity did not differ by irradiation status. Age-related changes in relative volumes in controls reflected normal trends in humans, with increasing WM and decreasing gray matter until middle age. Cerebrospinal fluid (CSF) volume did not differ across age in controls. WM volume was lower and CSF volume was higher in young irradiated macaques. WM volume was similar between groups, and CSF volume lower in older irradiated macaques. Gray matter volume was unaffected by radiation.

CONCLUSIONS

TBI results in delayed WM expansion and long-term disruption of WM integrity. Diffusion changes suggest that myelin injury in WM is a hallmark of late-delayed radiation-induced brain injury.

Progression of cognitive dysfunction in NPC survivors with radiation-induced brain necrosis: A prospective cohort

BACKGROUND AND PURPOSE

The evidence of longitudinal changes in cognition in nasopharyngeal carcinoma (NPC) survivors with radiation-induced brain necrosis (RIBN) after radiotherapy (RT) remained insufficient. We aimed to estimate the clinical progression rate of cognitive decline and identify patients with differential decline rates.

MATERIALS AND METHODS

Based on an ongoing prospective cohort study, NPC patients aged ≥18 years old and diagnosed with RIBN were included in this current analysis if they finished the time frame of 3-year follow-up and had at least twice cognition assessments. The Chinese version of the Montreal Cognitive Assessment (MoCA) was used to assess the cognitive state. Linear mixed-effect models were used to analyze the annual progression rates of MoCA total and seven sub-items scores.

RESULTS

Among 134 patients in this study, the transition probability from normal to mild/moderate cognitive dysfunction were 14.2 % (19/134) and 1.49 % (2/134) respectively during the median follow-up time of 2.35 years. The total MoCA score declined by -0.569 (SE 0.208) points annually (p = 0.008). Patients with ≤6 years of duration from RT to RIBN have higher annual progression rate of total scores [-0.851 (SE 0.321), p = 0.013; p for interaction = 0.041].

CONCLUSION

Our findings of the annual decline rate of cognition in NPC patients with RIBN from a 3-year longitudinal data, particularly for those who developed RIBN rapidly after RT, have important implications for the upcoming clinical trials designed to prevent or decrease cognitive decline in NPC patients with RIBN, regarding the selection of study patients and the calculation of sample size.

Neurocognitive function following (chemo)radiotherapy for nasopharyngeal cancer and other head and neck cancers: A systematic review

When radiotherapy is used in the treatment of head and neck cancers, the brain commonly receives incidental doses of radiotherapy with potential for neurocognitive changes and subsequent impact on quality of life. This has not been widely investigated to date. A systematic search of MEDLINE, EMBASE, Psycinfo Info and the Cochrane Central Register of Controlled Trials (CENTRAL) electronic databases was conducted. Of 2077 records screened, 20 were eligible comprising 1308 patients. There were no randomised studies and 73.3% of included patients were from single center studies. IMRT was delivered in 72.6% of patients, and chemotherapy used in 61%. There was considerable heterogeneity in methods. Narrative synthesis was therefore carried out. Most studies demonstrated inferior neurocognitive outcomes when compared to control groups at 12 months and beyond radiotherapy. Commonly affected neurocognitive domains were memory and language which appeared related to radiation dose to hippocampus, temporal lobe, and cerebellum. Magnetic Resonance Imaging could be valuable in the detection of early microstructural and functional changes, which could be indicative of future neurocognitive changes. In studies investigating quality of life, the presence of neurocognitive impairment was associated with inferior quality of life outcomes. (Chemo)radiotherapy for head and neck cancer appears to be associated with a risk of long-term neurocognitive impairment. Few studies were identified, with substantial variation in methodology, thus limiting conclusions. High quality large prospective head and neck cancer studies using standardised, sensitive, and reliable neurocognitive tests are needed.

Risk of temporal lobe necrosis between proton beam and volumetric modulated arc therapies in patients with different head and neck cancers

BACKGROUND

To investigate the frequency of temporal lobe necrosis (TLN) soon after radiotherapy (RT) and identify differences among patients with various types of head and neck cancer (HNC) and between different RT methods.

METHODS

We retrospectively reviewed 483 patients with HNC who had completed RT in our hospital after January, 2015. These patients were followed-up at the radio-oncology department and received contrast-enhanced magnetic resonance imaging (MRI) or computed tomography (CT) to identify metastases or recurrence of cancer at regular intervals. Meanwhile, the occurrence of TLN, graded according to the Common Terminology Criteria for Adverse Events V5.0, was recorded. We categorized the patients into nasopharyngeal carcinoma (NPC) and non-NPC groups and compared the cumulative occurrence of TLN between the groups using Kaplan-Meier and Cox regression analyses. We further compared the cumulative occurrence of TLN between proton beam therapy (PBT) and volumetric modulated arc therapy (VMAT) in patients with any HNC, NPC, and non-NPC HNC.

RESULTS

Compared with the non-NPC group, the NPC group had a higher frequency of TLN (5.6% vs. 0.4%,  p < 0.01) and were more commonly associated with TLN in the Kaplan-Meier analysis (p < 0.01) and the Cox regression model after covariates were adjusted for (adjusted hazard ratio: 13.35, 95% confidence interval: 1.37-130.61) during the follow-up period. Furthermore, the frequency of TLN was similar between patients receiving PBT and those receiving VMAT (PBT vs. VMAT: 4.7% vs. 6.3%, p = 0.76). Kaplan-Meier analysis revealed that the accumulated risks of TLN were similar between PBT and VMAT in patients with any HNC (p = 0.44), NPC (p = 0.84), and non-NPC HNC (p = 0.70).

CONCLUSION

Our study demonstrated that patients with NPC are susceptible to TLN during the early period after RT. In addition, PBT may be associated with an equivalent risk of TLN when compared with VMAT in patients with NPC or other HNCs.

Spatial distribution of cerebral microbleeds and FLAIR hyperintensities on follow-up MRI after radiotherapy for lower grade glioma

Background and purpose

Cerebral microbleeds (CMBs) and fluid-attenuated-inversion recovery (FLAIR) hyperintensities on brain MRI scans after radiotherapy (RT) are considered markers for microvascular damage and related cognitive changes. However, the spatial distribution using existing scoring systems as well as colocation of these imaging biomarkers remain unclear, hampering clinical interpretation. This study aims to elucidate the distribution and colocation of these markers in patients with lower grade glioma (LGG).

Materials and methods

CMBs were spatially classified on retrospective 1.5 T susceptibility weighted MRI scans according to the existing Microbleed Anatomical Rating Scale (MARS) and were additionally scored for being located in hippocampus, amygdala, cortex, white matter (WM), grey matter (GM), WM/GM junction and for their spatial relation to FLAIR hyperintensities. Scoring was performed for whole, ipsilateral and contralateral cerebrum (with respect to tumour bulk).

Results

Fifty-one scans were included of which 28 had at least one CMB. The majority of CMBs were localized in the lobar area and in deep and periventricular white matter (DPWM) - generally in WM. Only few CMBs were found in GM. In scans obtained up to 7 years after RT completion the majority of CMBs were not colocalized with FLAIR hyperintensities.

Conclusion

CMBs and FLAIR hyperintensities appear to be separate imaging biomarkers for radiation therapy induced microvascular damage, as they are not colocalized in patients with LGG, especially not early on after completion of RT.

Microglia drive transient insult-induced brain injury by chemotactic recruitment of CD8+ T lymphocytes

The crosstalk between the nervous and immune systems has gained increasing attention for its emerging role in neurological diseases. Radiation-induced brain injury (RIBI) remains the most common medical complication of cranial radiotherapy, and its pathological mechanisms have yet to be elucidated. Here, using single-cell RNA and T cell receptor sequencing, we found infiltration and clonal expansion of CD8⁺ T lymphocytes in the lesioned brain tissues of RIBI patients. Furthermore, by strategies of genetic or pharmacologic interruption, we identified a chemotactic action of microglia-derived CCL2/CCL8 chemokines in mediating the infiltration of CCR2⁺/CCR5⁺ CD8⁺ T cells and tissue damage in RIBI mice. Such a chemotactic axis also participated in the progression of cerebral infarction in the mouse model of ischemic injury. Our findings therefore highlight the critical role of microglia in mediating the dysregulation of adaptive immune responses and reveal a potential therapeutic strategy for non-infectious brain diseases.

Treatment of Radiation-Induced Brain Necrosis

Radiation-induced brain necrosis (RBN) is a serious complication of intracranial as well as skull base tumors after radiotherapy. In the past, due to the lack of effective treatment, radiation brain necrosis was considered to be progressive and irreversible. With better understanding in histopathology and neuroimaging, the occurrence and development of RBN have been gradually clarified, and new treatment methods are constantly emerging. In recent years, some scholars have tried to treat RBN with bevacizumab, nerve growth factor, and gangliosides and have achieved similar results. Some cases of brain necrosis can be repairable and reversible. We aimed to summarize the incidence, pathogenesis, and treatment of RBN.

Cognitive Decline following Radiotherapy of Head and Neck Cancer: Systematic Review and Meta-Analysis of MRI Correlates

Radiotherapy for head and neck cancers exposes small parts of the brain to radiation, resulting in radiation-induced changes in cerebral tissue. In this review, we determine the correlation between cognitive deterioration in patients with head and neck cancer after radiotherapy and magnetic resonance imaging (MRI) changes. Systematic searches were performed in PubMed, Scopus, and Cochrane databases in February 2021. Studies of head and neck cancer patients treated with radiotherapy and periodical cognitive and MRI assessments were included. Meta-analysis was performed to analyse the correlation of Montreal Cognitive Assessment (MoCA) scores to MRI structural and functional changes. Seven studies with a total of 404 subjects (irradiated head and neck patients, n = 344; healthy control, n = 60) were included. Most studies showed the significance of MRI in detecting microstructural and functional changes in association with neurocognitive function. The changes were seen in various brain areas, predominantly the temporal region, which also shows dose dependency (6/7 studies). An effect size (r = 0.43, p < 0.001) was reported on the correlation of MoCA scores to MRI structural and functional changes with significant correlations shown among patients treated with head and neck radiotherapy. However, the effect size appears modest.

Medical and Neurological Management of Brain Tumor Complications

PURPOSE OF REVIEW

The diagnosis of brain tumors often leads to complications that are either related to the tumor itself or the tumor-directed and supportive therapies, increasing the burden on the patients' quality of life and even survival. This article reviews the medical and neurological conditions that commonly complicate the disease course of brain tumors patients.

RECENT FINDINGS

Various mechanisms have been newly identified to be involved in the pathophysiology of seizures and brain edema and can help advance the treatment of such complications. There have also been new developments in the management of thromboembolic disease and cognitive impairment. Medical and neurological complications are being identified more often in brain tumor patients with the improved survival provided by therapeutic advances. Early and proper identification and management of such complications are crucial for a better survival and quality of life.

Research progress on mechanism and imaging of temporal lobe injury induced by radiotherapy for head and neck cancer

Radiotherapy (RT) is an effective treatment for head and neck cancer (HNC). Radiation-induced temporal lobe injury (TLI) is a serious complication of RT. Late symptoms of radiation-induced TLI are irreversible and manifest as memory loss, cognitive impairment, and even temporal lobe necrosis (TLN). It is currently believed that the mechanism of radiation-induced TLI involves microvascular injury, neuron and neural stem cell injury, glial cell damage, inflammation, and the production of free radicals. Significant RT-related structural changes and dose-dependent changes in gray matter (GM) and white matter (WM) volume and morphology were observed through computed tomography (CT) and magnetic resonance imaging (MRI) which were common imaging assessment tools. Diffusion tensor imaging (DTI), dispersion kurtosis imaging (DKI), susceptibility-weighted imaging (SWI), resting-state functional magnetic resonance (rs-fMRI), magnetic resonance spectroscopy (MRS), and positron emission tomography (PET) can be used for early diagnosis and prognosis evaluation according to functional, molecular, and cellular processes of TLI. Early diagnosis of TLI is helpful to reduce the incidence of TLN and its related complications. This review summarizes the clinical features, mechanisms, and imaging of radiation-induced TLI in HNC patients. KEY POINTS: • Radiation-induced temporal lobe injury (TLI) is a clinical complication and its symptoms mainly include memory impairment, headache, and cognitive impairment. • The mechanisms of TLI include microvascular injury, cell injury, and inflammatory and free radical injury. Significant RT-related structural changes and dose-dependent changes in TL volume and morphology were observed through CT and MRI. • SWI, MRS, DTI, and DKI and other imaging examinations can detect anatomical and functional, molecular, and cellular changes of TLI.

Functional Connectivity Density for Radiation Encephalopathy Prediction in Nasopharyngeal Carcinoma

The diagnostic efficiency of radiation encephalopathy (RE) remains heterogeneous, and prediction of RE is difficult at the pre-symptomatic stage. We aimed to analyze the whole-brain resting-state functional connectivity density (FCD) of individuals with pre-symptomatic RE using multivariate pattern analysis (MVPA) and explore its prediction efficiency. Resting data from NPC patients with nasopharyngeal carcinoma (NPC; consisting of 20 pre-symptomatic RE subjects and 26 non-RE controls) were collected in this study. We used MVPA to classify pre-symptomatic RE subjects from non-RE controls based on FCD maps. Classifier performances were evaluated by accuracy, sensitivity, specificity, and area under the characteristic operator curve. Permutation tests and leave-one-out cross-validation were applied for assessing classifier performance. MVPA was able to differentiate pre-symptomatic RE subjects from non-RE controls using global FCD as a feature, with a total accuracy of 89.13%. The temporal lobe as well as regions involved in the visual processing system, the somatosensory system, and the default mode network (DMN) revealed robust discrimination during classification. Our findings suggest a good classification efficiency of global FCD for the individual prediction of RE at a pre-symptomatic stage. Moreover, the discriminating regions may contribute to the underlying mechanisms of sensory and cognitive disturbances in RE.

Late vascular complications after cranial radiotherapy: A report of two illustrative cases

Cranial radiotherapy (CRT) is used to treat a large variety of benign and malignant disorders. We present two cases of late neurological complications after CRT and briefly discuss its diagnosis and their shared pathophysiological aspects. The first case is a patient with cognitive impairment associated to mineralizing microangiopathy ten years after CRT for nasopharyngeal carcinoma and the second one is a woman with Stroke-like Migraine Attacks after Radiation Therapy (SMART) syndrome two years after CRT for anaplastic meningioma. Nowadays, higher survival rates might cause an increase in appearance of late neurological complications after CTR. These reported cases show that late complications can mimic a wide variety of neurological conditions and the importance of magnetic resonance image (MRI) to get a diagnosis.

Connexin43 Expression and Associated Chronic Inflammation Presages the Development of Cerebral Radiation Necrosis

Cerebral radiation necrosis (CRN) is a delayed complication of radiosurgery that can result in severe neurological deficits. The biological changes leading to necrotic damage may identify therapeutic targets for this complication. Connexin43 expression associated with chronic inflammation may presage the development of CRN. A mouse model of delayed CRN was used. The left hemispheres of adult female mice were irradiated with single-fraction, high-dose radiation using a Leksell Gamma Knife. The brains were collected 1 and 4 days, and 1-3 weeks after the radiation. The expression of connexin43, interleukin-1β (IL-1β), GFAP, isolectin B-4, and fibrinogen was evaluated using immunohistochemical staining and image analysis. Compared with the baseline, the area of connexin43 and IL-1β staining was increased in ipsilateral hemispheres 4 days after radiation. Over the following 3 weeks, the density of connexin43 gradually increased in parallel with progressive increases in GFAP, isolectin B-4, and fibrinogen labeling. The overexpression of connexin43 in parallel with IL-1β spread into the affected brain regions first. Further intensified upregulation of connexin43 was associated with escalated astrocytosis, microgliosis, and blood-brain barrier breach. Connexin43-mediated inflammation may underlie radiation necrosis and further investigation of connexin43 hemichannel blockage is merited for the treatment of CRN.

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.

Cognitive dysfunction in patients with nasopharyngeal carcinoma after induction chemotherapy

OBJECTIVE

This prospective study aimed to assess the incidence, details of the change of cognitive dysfunction, and predictive factors of cognitive function impairment associated with induction chemotherapy (IC) in nasopharyngeal carcinoma (NPC) patients.

METHOD

We prospectively included NPC patients who treated with IC from December 2018 to January 2020. Montreal cognitive assessment (MoCA) was used to measure cognitive function, and score less than 26 was defined as cognitive dysfunction. Multivariate logistic regression analysis was applied to assess the independent predictors associated with cognitive function impairment.

RESULTS

A total of 76 patients were recruited, 10 patients were excluded due to refusal or unable to finish the questionnaire, and 66 patients were analyzed in this study. The median age of the patients was 48.5 years (range, 24-69 years). There was 89.4% of patients received ≥3 circles of IC. For the entire group, 27.3% had cognitive dysfunction, of which attention, language, short-term memory, and orientation showed significant downward trends, while visuospatial/executive function, naming, and abstraction demonstrated no prominent decrease. In patients having cognitive function impairment, 77.8% of them occurred after the first circle of IC. Gender (P = 0.039) and education (P = 0.03) were significant predictors for cognitive dysfunction. Female patients (female vs. male: 50% vs. 20%) and patients with lower educational levels (lower vs. higher: 37.8% vs. 11.8%) were more likely to suffer cognitive dysfunction. In addition, age (P = 0.572) and chemotherapy circles (P = 0.68) had no association with cognitive dysfunction.

CONCLUSION

Approximately 25% of NPC patients suffered cognitive dysfunction after IC, especially in female patients and patients with lower educational levels.

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.

A cross sectional study in cognitive and neurobehavioral impairment in long-term nasopharyngeal cancer survivors treated with intensity-modulated radiotherapy

PURPOSE/OBJECTIVES

To determine neurocognitive and neurobehavioral impairment in long-term nasopharyngeal cancer survivors (NPC) treated with intensity-modulated radiotherapy (IMRT).

MATERIALS/METHODS

A cross-sectional cohort of NPC ≥4 years (y) following IMRT was assessed. Objective cognitive function was measured using the Montreal Cognitive Assessment (MoCA) and patient-reported memory was assessed with the MDASI-HN problems remembering item. Patient and family ratings of patients' neurobehavioral symptoms of apathy, disinhibition and executive dysfunction were assessed with the Frontal Systems Behavior Scale (FrSBe). Other patient-reported symptoms (MDASI-HN), mood (HADS), and quality of life (FACT-H&N) were also collected.

RESULTS

Among 102 participants: M:F = 66:36; median age 56y (32-77); median time since IMRT 7.5y (4.2-11.1). Impaired MoCA scores (<23) were observed in 33 (32%). Patient and family ratings of pre-illness neurobehavioral symptoms were in the normal range (total FrSBe T-scores 53.3 and 59.0 respectively). In contrast, post-treatment patient and family T-scores were clinically impaired (64.7, 71.3 respectively), with apathy, disinhibition and executive dysfunction post-treatment ratings all significantly worse than pre-treatment (p < 0.001). Prevalence of clinically significant post-treatment disturbance was high by patient and family ratings (48%/66% apathy, 35%/53% disinhibition, 39%/56% executive dysfunction). Post-treatment neurobehavioral symptoms strongly correlated with lower quality of life (r = -0.62) and higher anxiety (r = 0.62) and depression scores (r = 0.67, all p < 0.001). Total MoCA scores did not correlate with RT dose. However, greater declines in apathy, disinhibition and executive dysfunction were associated with receiving >75 Gy to temporal lobes.

CONCLUSION

NPC treated with IMRT had moderate to high rates of neurocognitive impairment and clinically significant apathy, disinhibition, and executive dysfunction.

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.

Radiation-Induced Cerebral Microbleeds in Pediatric Patients With Brain Tumors Treated With Proton Radiation Therapy

PURPOSE

Proton beam radiation therapy (PBT) has been increasingly used to treat pediatric brain tumors; however, limited information exists regarding radiation-induced cerebral microbleeds (CMBs) among these patients. The purpose of this study was to evaluate the incidence, risk factors, and imaging appearance of CMBs in pediatric patients with brain tumors treated with PBT.

MATERIALS AND METHODS

A retrospective study was performed of 100 pediatric patients with primary brain tumors treated with PBT. CMBs were diagnosed by examination of serial magnetic resonance imaging scans, including susceptibility-weighted imaging. Radiation therapy plans were analyzed to determine doses to individual CMBs. Clinical records were used to determine risk factors associated with the development of CMBs in these patients.

RESULTS

The mean age at time of PBT was 8.1 years. The median follow-up duration was 57 months. The median time to development of CMBs was 8 months (mean, 11 months; range, 3-28 months). The percentage of patients with CMBs was 43%, 66%, 80%, 81%, 83%, and 81% at 1 year, 2 years, 3 years, 4 years, 5 years, and >5 years from completion of proton radiation therapy. Most of the CMBs (87%) were found in areas of brain exposed to ≥30 Gy. Risk factors included maximum radiation therapy dose (P = .001), percentage and volume of brain exposed to ≥30 Gy (P = .0004, P = .0005), and patient age at time of PBT (P = .0004). Chemotherapy was not a significant risk factor (P = .35). No CMBs required surgical intervention.

CONCLUSIONS

CMBs develop in a high percentage of pediatric patients with brain tumors treated with proton radiation therapy within the first few years after treatment. Significant risk factors for development of CMBs include younger age at time of PBT, higher maximum radiation therapy dose, and higher percentage and volume of brain exposed to ≥30 Gy. These findings demonstrate similarities with CMBs that develop in pediatric patients with brain tumor treated with photon radiation therapy.

Optimization of cervical lymph node clinical target volume delineation in nasopharyngeal carcinoma: a single center experience and recommendation

Nasopharyngeal carcinoma (NPC) are characterized by distinct lymph node metastasis patterns. In order to minimize cervical lymph node irradiation volume, 379 NPC patients with metastatic cervical lymph nodes were eligible for geographic mapping. All lymph nodes were mapped into simulation computed tomography images of a template lymph node negative patient. The proportions of retropharyngeal lymph nodes (RLNs), Level Ib, II, III, IV, Va, Vb and supraclavicular (SCV) lymph nodes were 6.9%, 0.5%, 55.25%, 20.4%, 8.2%, 4.9%, 3.1% and 0.75%, respectively. Based on their distribution profile, we proposed the following modifications: 1. the lateral border of RLNs clinical target volume (CTV) be the medial edge of the internal carotid artery above the level of mastoid process, the medial border be adjacent to the cervical vessels below the free edge of the soft palate; 2. the submandibular gland should not be included in Level Ib; 3. Level II should include the posterior belly of digastric muscle, and the space between the posterior edge of submandibular gland and the anterior edge of sternocleidomastoid muscle; 4. the anterior border of Level III and IV should gradually shift backwards and the CTV only include part of the cervical vessels below the level where the thyroid gland appears; 5. the space of the posterior edge of trapezius muscle also should be included if there are metastatic lymph nodes in the transverse cervical vessle plexus. Our recommendations might adequately encompass metastatic lymph nodes while sparing the organs at risk and reducing adverse events.

Radiation-induced cerebellar-cerebral functional connectivity alterations in nasopharyngeal carcinoma patients

The current study aimed to investigate the altered cerebellar-cerebral functional connectivity (FC) induced by radiotherapy to nasopharyngeal carcinoma (NPC) patients. Twenty-four NPC patients without treatment, and 35 NPC patients receiving radiotherapy underwent functional MRI scanning. Montreal cognitive assessment (MoCA) was performed to evaluate the cognitive status of all participants. FC between 10 predefined cerebellar seeds, which were demonstrated to be involved in different brain functional networks, and all brain voxels was obtained for each participant. Using a second-level two-sample t-test, three significantly different FCs between the two patient groups were found, including the connections between the left lobule VIII and the right medial frontal gyrus, the left lobule VIII and the right crus I, and the right lobule VIIb and the right fusiform gyrus. The altered cerebellar-cerebral FCs were also significantly correlated to the MoCA score, as well as the attention score, one of the seven subscores in MoCA. We suggested that the altered cerebellar-cerebral FCs may underlie the radiation-induced cognitive deficits in NPC patients, especially in the domain of attention. Furthermore, considering the functional networks in which the altered connections involved, the anticorrelation between the default network and dorsal attention network may be impaired, and the mediating function of the frontoparietal network to dorsal attention network may be disrupted. The significantly altered cerebellar-cerebral FC may serve as the potential biomarker in revealing the radiation-induced functional abnormalities and may help in the early intervention to the cognitive impairment.

Relationship between radiation dose and microbleed formation in patients with malignant glioma

BACKGROUND

Cranial irradiation is associated with long-term cognitive changes. Cerebral microbleeds (CMBs) have been identified on susceptibility-weighted MRI (SWI) in patients who have received prior cranial radiation, and serve as radiographic markers for microvascular injury thought to contribute to late cognitive decline. The relationship between CMB formation and radiation dose has not previously been quantified.

METHODS

SWI was performed on 13 patients with stable WHO grade III-IV gliomas between 2 and 4 years after chemoradiotherapy to 60 Gy. The median age at the time of treatment was 41 years (range 25 - 74 years). CMBs were identified as discrete foci of susceptibility on SWI that did not correspond to vessels. CMB density for low (<30 Gy), median (30-45 Gy), and high (>45 Gy) dose regions was computed.

RESULTS

Twelve of 13 patients exhibited CMBs. The number of CMBs was significantly higher for late (>3 years from treatment) compared to early (<3 years) timepoints (early median 6 CMBs; late median 27 CMBs; p = 0.001), and there were proportionally more CMBs at lower doses for late scans (p = 0.006). 88% of all CMBs were observed in regions receiving at least 30 Gy, but the CMB density within medium and high dose regions was not significantly different (p = 0.33 and p = 0.9, respectively, for early and late time points).

CONCLUSIONS

CMBs predominantly form in regions receiving at least 30 Gy, but form in lower dose regions with longer follow-up. We do not observe a clear dose-response relationship at doses above 30 Gy. These findings provide important information to assess the risk of late microvascular sequelae from cranial irradiation.

Cerebral microhemorrhages: mechanisms, consequences, and prevention

The increasing prevalence of multifocal cerebral microhemorrhages (CMHs, also known as "cerebral microbleeds") is a significant, newly recognized problem in the aging population of the Western world. CMHs are associated with rupture of small intracerebral vessels and are thought to progressively impair neuronal function, potentially contributing to cognitive decline, geriatric psychiatric syndromes, and gait disorders. Clinical studies show that aging and hypertension significantly increase prevalence of CMHs. CMHs are also now recognized by the National Institutes of Health as a major factor in Alzheimer's disease pathology. Moreover, the presence of CMHs is an independent risk factor for subsequent larger intracerebral hemorrhages. In this article, we review the epidemiology, detection, risk factors, clinical significance, and pathogenesis of CMHs. The potential age-related cellular mechanisms underlying the development of CMHs are discussed, with a focus on the structural determinants of microvascular fragility, age-related alterations in cerebrovascular adaptation to hypertension, the role of oxidative stress and matrix metalloproteinase activation, and the deleterious effects of arterial stiffening, increased pulse pressure, and impaired myogenic autoregulatory protection on the brain microvasculature. Finally, we examine potential treatments for the prevention of CMHs based on the proposed model of aging- and hypertension-dependent activation of the reactive oxygen species-matrix metalloproteinases axis, and we discuss critical questions to be addressed by future studies.

Radiation-induced abnormal cortical thickness in patients with nasopharyngeal carcinoma after radiotherapy

Conventional MRI studies showed that radiation-induced brain necrosis in patients with nasopharyngeal carcinoma (NPC) in years after radiotherapy (RT) could involve brain gray matter (GM) and impair brain function. However, it is still unclear the radiation-induced brain morphological changes in NPC patients with normal-appearing GM in the early period after RT. In this study, we acquired high-resolution brain structural MRI data from three groups of patients, 22 before radiotherapy (pre-RT) NPC patients with newly diagnosed but not yet medically treated, 22 NPC patients in the early-delayed stage after radiotherapy (post-RT-ED), and 20 NPC patients in the late-delayed stage after radiotherapy (post-RT-LD), and then analyzed the radiation-induced cortical thickness alteration in NPC patients after RT. Using a vertex-wise surface-based morphometry (SBM) approach, we detected significantly decreased cortical thickness in the precentral gyrus (PreCG) in the post-RT-ED group compared to the pre-RT group. And the post-RT-LD group showed significantly increased cortical thickness in widespread brain regions, including the bilateral inferior parietal, left isthmus of the cingulate, left bank of the superior temporal sulcus and left lateral occipital regions, compared to the pre-RT group, and in the bilateral PreCG compared to the post-RT-ED group. Similar analysis with ROI-wise SBM method also found the consistent results. These results indicated that radiation-induced brain injury mainly occurred in the post-RT-LD group and the cortical thickness alterations after RT were dynamic in different periods. Our findings may reflect the pathogenesis of radiation-induced brain injury in NPC patients with normal-appearing GM and an early intervention is necessary for protecting GM during RT.

Evolution of cerebral microbleeds after cranial irradiation in medulloblastoma patients

OBJECTIVE

To characterize the temporal and spatial pattern of cerebral microbleeds (CMBs) after cranial irradiation in patients with medulloblastoma.

METHODS

We retrospectively identified patients with medulloblastoma treated with craniospinal irradiation at the Massachusetts General Hospital between 1999 and 2015. Longitudinal MRI including T2*-weighted gradient-recalled echo (GRE) sequences were reviewed, and the prevalence, spatial pattern, and risk factors associated with CMBs were characterized.

RESULTS

We identified a total of 27 patients; 5 patients were children (median age 6.3 years) and 22 patients were adults (median age 28.8 years). CMBs were found in 67% (18/27) of patients, who were followed for a median of 4.1 years. Patients with CMBs had longer GRE follow-up time compared to those without CMBs (4.9 vs 1.7 years, p = 0.035). The median latency of the appearance of CMBs was 2.79 years (interquartile range 1.76-4.26). The prevalence of CMBs increased with each year from time of radiation therapy, and the cumulative prevalence was highest in patients age <20 years (100% cumulative prevalence, vs 59% in adult patients treated at age ≥20 years). CMBs were mostly found in lobar distribution and predominately in bilateral occipital lobes. Patients using antithrombotic medications developed CMBs at a significantly higher rate (p = 0.041).

CONCLUSIONS

Our data demonstrate a high prevalence of CMBs following cranial irradiation, progressively increasing with each year from time of radiation therapy.

Reducing radiation-related morbidity in the treatment of nasopharyngeal carcinoma

While radiation therapy is the mainstay of treatment for nasopharyngeal carcinoma, the anatomic location of the nasopharynx in close proximity to radiation-sensitive organs such as the salivary glands, optic nerves and chiasm, cochlea, brainstem and temporal lobes presents a special challenge. Technological approaches to reducing the morbidity of nasopharyngeal cancer irradiation have been historically successful with the evolution from 2D techniques to increasingly conformal forms of radiation therapy. This report reviews normal tissue dose constraints and major considerations in target delineation for patients with nasopharyngeal cancer in the intensity-modulated radiation therapy era. Furthermore, this report discusses more contemporary approaches to toxicity reduction such as the judicious reduction or omission of radiation to low-risk regions and the potential role of particle beam therapy.