Late Cerebrovascular Complications After Radiotherapy for Childhood Primary Central Nervous System Tumors

Radiation-induced cavernoma in pediatric CNS tumors: a systematic review and treatment paradigm

PURPOSE

This retrospective systematic literature review aimed to summarize available data regarding epidemiology, etiology, presentation, investigations, differentials, treatment, prevention, monitoring, complications, and prognosis for radiation-induced cavernous malformations (RICMs) in pediatric patients.

METHODOLOGY

Review conducted per PRISMA guidelines. Google Scholar, PubMed, Trip Medical Database, and Cochrane Library searched utilizing a keyphrase, articles filtered per inclusion/exclusion criteria, duplicates excluded. Based on criteria, 25 articles identified, 7 further excluded from the systematic data but included in discussion (5 × insufficient data, 2 × other systematic reviews).

RESULTS

Many studies did not contain all explored data. 2487 patients reviewed, 325 later found to have RICM (143 male, 92 female). Mean age at irradiation 7.6 years (range 1.5-19). Mean total radiation dose 56 Gy (12-112). Most common indications for radiation-medulloblastoma 133x, astrocytoma 23x, ependymoma 21x, germinoma 19x. Mean age at RICM diagnosis 18 years (3.6-57). Mean latency to RICM 9.9 years (0.25-41). Most common anatomic locations-temporal 36, frontal 36, parietal 13, basal ganglia 16, infratentorial 20. Clinical presentation-incidental 270, seizures 19, headache 11, focal neurological deficit 7, other 13. 264 patients observed, 34 undergone surgery. RICM bled in 28 patients. Mean follow-up 11.7 years (0.5-50.3). Prognostic reporting highly variable.

CONCLUSIONS

From our data, pediatric RICMs appear to display slight male predominance, present about 10 years after initial irradiation in late teen years, and present incidentally in majority of cases. They are mostly operated on when they bleed, with incidental lesions mostly being observed over time. Further prospective detailed studies needed to draw stronger conclusions.

Clinical significance of cerebral microbleeds in patients with germinoma who underwent long-term follow-up

PURPOSE

This study identified the factors affecting cerebral microbleed (CMBs) development. Moreover, their effects on intelligence and memory and association with stroke in patients with germinoma who had long-term follow-up were evaluated.

METHODS

This study included 64 patients with germinoma who were histologically and clinically diagnosed with and treated for germinoma. These patients were evaluated cross-sectionally, with a focus on CMBs on susceptibility-weighted magnetic resonance imaging (SWI), brain atrophy assessed through volumetric analysis, and intelligence and memory.

RESULTS

The follow-up period was from 32 to 412 (median: 175.5) months. In total, 43 (67%) patients had 509 CMBs and 21 did not have CMBs. Moderate correlations were observed between the number of CMBs and time from initial treatments and recurrence was found to be a risk factor for CMB development. Increased temporal CMBs had a marginal effect on the processing speed and visual memory, whereas brain atrophy had a statistically significant effect on verbal, visual, and general memory and a marginal effect on processing speed. Before SWI acquisition and during the follow-up periods, eight strokes occurred in four patients. All of these patients had ≥ 15 CMBs on SWI before stroke onset. Meanwhile, 33 patients with < 14 CMBs or 21 patients without CMBs did not experience stroke.

CONCLUSION

Patients with a longer time from treatment initiation had a higher number of CMBs, and recurrence was a significant risk factor for CMB development. Furthermore, brain atrophy had a stronger effect on memory than CMBs. Increased CMBs predict the stroke onset.

Risk of Cerebrovascular Events Among Childhood and Adolescent Patients Receiving Cranial Radiation Therapy: A PENTEC Normal Tissue Outcomes Comprehensive Review

PURPOSE

Radiation-induced cerebrovascular toxicity is a well-documented sequelae that can be both life-altering and potentially fatal. We performed a meta-analysis of the relevant literature to create practical models for predicting the risk of cerebral vasculopathy after cranial irradiation.

METHODS AND MATERIALS

A literature search was performed for studies reporting pediatric radiation therapy (RT) associated cerebral vasculopathy. When available, we used individual patient RT doses delivered to the Circle of Willis (CW) or optic chiasm (as a surrogate), as reported or digitized from original publications, to formulate a dose-response. A logistic fit and a Normal Tissue Complication Probability (NTCP) model was developed to predict future risk of cerebrovascular toxicity and stroke, respectively. This NTCP risk was assessed as a function of prescribed dose.

RESULTS

The search identified 766 abstracts, 5 of which were used for modeling. We identified 101 of 3989 pediatric patients who experienced at least one cerebrovascular toxicity: transient ischemic attack, stroke, moyamoya, or arteriopathy. For a range of shorter follow-ups, as specified in the original publications (approximate attained ages of 17 years), our logistic fit model predicted the incidence of any cerebrovascular toxicity as a function of dose to the CW, or surrogate structure: 0.2% at 30 Gy, 1.3% at 45 Gy, and 4.4% at 54 Gy. At an attained age of 35 years, our NTCP model predicted a stroke incidence of 0.9% to 1.3%, 1.8% to 2.7%, and 2.8% to 4.1%, respectively at prescribed doses of 30 Gy, 45 Gy, and 54 Gy (compared with a baseline risk of 0.2%-0.3%). At an attained age of 45 years, the predicted incidence of stroke was 2.1% to 4.2%, 4.5% to 8.6%, and 6.7% to 13.0%, respectively at prescribed doses of 30 Gy, 45 Gy, and 54 Gy (compared with a baseline risk of 0.5%-1.0%).

CONCLUSIONS

Risk of cerebrovascular toxicity continues to increase with longer follow-up. NTCP stroke predictions are very sensitive to model variables (baseline stroke risk and proportional stroke hazard), both of which found in the literature may be systematically erring on minimization of true risk. We hope this information will assist practitioners in counseling, screening, surveilling, and facilitating risk reduction of RT-related cerebrovascular late effects in this highly sensitive population.

Radiation-Induced Cerebral Cavernous Malformations: A Single-Center Experience and Systematic Literature Review

OBJECTIVE

Radiation was first demonstrated to be associated with cavernomagenesis in 1992. Since then, a growing body of literature has shown the unique course and presentation of radiation-induced cavernous malformations (RICMs). This study summarizes the literature on RICMs and presents a single-center experience.

METHODS

A prospectively maintained single institution vascular malformation database was searched for all cases of intracranial cavernous malformation (January 1, 1997-December 31, 2021). For patients with a diagnosis of RICM, information on demographic characteristics, surgical treatments, radiation, and surgical outcomes was obtained and analyzed. A comprehensive literature search was conducted using PubMed, Embase, Cochrane, and Web of Science databases for all reported cases of RICM.

RESULTS

A retrospective review of 1662 patients treated at a single institution yielded 10 patients with prior radiation treatment in the neck or head region and a subsequent diagnosis of intracranial RICM. The median (interquartile range) latency between radiation and presentation was 144 (108-192) months. Nine of 10 patients underwent surgery; symptoms improved for 5 patients, worsened for 3, and were stable for 1. The systematic literature review yielded 64 publications describing 248 patients with RICMs. Of the 248 literature review cases, 71 (28.6%) involved surgical resection. Of 39 patients with reported surgical outcomes, 32 (82%) experienced improvement.

CONCLUSIONS

RICMs have a unique course and epidemiology. RICMs should be considered when patients with a history of radiation present with neurologic impairment. When RICMs are identified, symptomatic patients can be treated effectively with surgical excision and close follow-up.

Neurocognitive and radiological changes after cranial radiation therapy in humans and rodents: a systematic review

BACKGROUND

Radiation-induced brain injury is a common long-term side effect for brain cancer survivors, leading to a reduced quality of life. Although there is growing research pertaining to this topic, the relationship between cognitive and radiologically detected lesions of radiation-induced brain injury in humans remains unclear. Furthermore, clinically translatable similarities between rodent models and human findings are also undefined. The objective of this review is to then identify the current evidence of radiation-induced brain injury in humans and to compare these findings to current rodent models of radiation-induced brain injury.

METHODS

This review includes an examination of the current literature on cognitive and radiological characteristics of radiation-induced brain injury in humans and rodents. A thorough search was conducted on PubMed, Web of Science, and Scopus to identify studies that performed cognitive assessments and magnetic resonance imaging techniques on either humans or rodents after cranial radiation therapy. A qualitative synthesis of the data is herein reported.

RESULTS

A total of 153 studies pertaining to cognitively or radiologically detected radiation injury of the brain are included in this systematic review; 106 studies provided data on humans while 47 studies provided data on rodents. Cognitive deficits in humans manifest across multiple domains after brain irradiation. Radiological evidence in humans highlight various neuroimaging-detectable changes post-irradiation. It is unclear, however, whether these findings reflect ground truth or research interests. Additionally, rodent models do not comprehensively reproduce characteristics of cognitive and radiological injury currently identified in humans.

CONCLUSION

This systematic review demonstrates that associations between and within cognitive and radiological radiation-induced brain injuries often rely on the type of assessment. Well-designed studies that evaluate the spectrum of potential injury are required for a precise understanding of not only the clinical significance of radiation-induced brain injury in humans, but also how to replicate injury development in pre-clinical models.

Acute ischemic stroke secondary to ventriculoperitoneal shunt dysfunction in a child with Moyamoya syndrome

Background:

Patients with brain vascular disease and hydrocephalus may be predisposed to acute ischemic stroke in case of shunt dysfunction and subsequent increased intracranial pression. Patients with brain tumor may develop hydrocephalus as a consequence of obstruction of cerebrospinal fluid pathways and radiation-induced moyamoya syndrome secondary (RIMS) to radiotherapy (RT).

Case Description:

A 15-year-old male patient, affected by hydrocephalus and RIMS, presented acute cerebral ischemia after an episode of shunt malfunction. The shunt was promptly revised and the areas of ischemia visible at magnetic resonance imaging significantly decreased.

Conclusion:

Children who receive RT for brain tumor, particularly if the circle of Willis region is involved, require close surveillance for the development of vasculopathy and consequent stroke. This surveillance must be even tighter if the patient has been treated with ventricular shunt for the possible synergistic interaction between the two causes on reducing cerebral perfusion and increasing the risk of acute ischemic events.

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.

Review: Neurological Complications From Therapies for Pediatric Brain Tumors

Surgery, chemotherapy and radiation have been the mainstay of pediatric brain tumor treatment over the past decades. Recently, new treatment modalities have emerged for the management of pediatric brain tumors. These therapies range from novel radiotherapy techniques and targeted immunotherapies to checkpoint inhibitors and T cell transfer therapies. These treatments are currently investigated with the goal of improving survival and decreasing morbidity. However, compared to traditional therapies, these novel modalities are not as well elucidated and similarly has the potential to cause significant short and long-term sequelae, impacting quality of life. Treatment complications are commonly mediated through direct drug toxicity or vascular, infectious, or autoimmune mechanisms, ranging from immune effector cell associated neurotoxicity syndrome with CART-cells to neuropathy with checkpoint inhibitors. Addressing treatment-induced complications is the focus of new trials, specifically improving neurocognitive outcomes. The aim of this review is to explore the pathophysiology underlying treatment related neurologic side effects, highlight associated complications, and describe the future direction of brain tumor protocols. Increasing awareness of these neurologic complications from novel therapies underscores the need for quality-of-life metrics and considerations in clinical trials to decrease associated treatment-induced morbidity.

Natural history and treatment options of radiation-induced brain cavernomas: a systematic review

Radiation-induced cavernous malformations (RICMs) are delayed complications of brain irradiation during childhood. Its natural history is largely unknown and its incidence may be underestimated as RCIMS tend to develop several years following radiation. No clear consensus exists regarding the long-term follow-up or treatment. A systematic review of Embase, Cochrane Library, PubMed, Google Scholar, and Web of Science databases, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, was performed. Based on our inclusion/exclusion criteria, 12 articles were included, totaling 113 children with RICMs, 86 were treated conservatively, and 27 with microsurgery. We were unable to precisely define the incidence and natural history from this data. The mean age at radiation treatment was 7.3 years, with a slight male predominance (54%) and an average dose of 50.0 Gy. The mean time to detection of RICM was 9.2 years after radiation. RICM often developed at distance from the primary lesion, more specifically frontal (35%) and temporal lobe (34%). On average, 2.6 RICMs were discovered per child. Sixty-seven percent were asymptomatic. Twenty-one percent presented signs of hemorrhage. Clinical outcome was favorable in all children except in 2. Follow-up data were lacking in most of the studies. RICM is most often asymptomatic but probably an underestimated complication of cerebral irradiation in the pediatric population. Based on the radiological development of RICMs, many authors suggest a follow-up of at least 15 years. Studies suggest observation for asymptomatic lesions, while surgery is reserved for symptomatic growth, hemorrhage, or focal neurological deficits.

Evaluation of the Impact of Magnetic Resonance Imaging with Susceptibility-weighted Imaging for Screening and Surveillance of Radiation-induced Cavernomas in Long-term Survivors of Malignancy

AIMS

Radiation-induced cavernomas (RIC) are common late toxicities in long-term survivors of malignancy following cerebral irradiation. However, the natural history of RIC is poorly described. We report the first series of long-term surveillance of RIC using modern magnetic resonance imaging (MRI) including highly sensitive susceptibility-weighted imaging (SWI). The aims of this research were to better characterise the natural history of RIC and investigate the utility of MRI-SWI for screening and surveillance.

MATERIALS AND METHODS

Eligibility required long-term survivors of malignancy with previous exposure to cerebral irradiation and RIC identified on MRI-SWI surveillance. The number and size of RIC were reported on Baseline MRI-SWI and last Follow-up MRI-SWI.

RESULTS

In total, 113 long-term survivors with RIC underwent MRI-SWI surveillance; 109 (96%) were asymptomatic at the time of RIC diagnosis. The median age at cerebral irradiation was 9.3 years; the median radiotherapy dose was 50.4 Gy. The median time from cerebral irradiation to Baseline MRI-SWI was 17.9 years. On Baseline MRI-SWI, RIC multiplicity was present in 89% of patients; 34% had >10 RIC; 65% had RIC ≥4 mm. The median follow-up from Baseline MRI-SWI was 7.3 years. On Follow-up MRI-SWI, 96% of patients had multiple RIC; 62% had >10 RIC; 72% had RIC ≥4 mm. Of the 109 asymptomatic patients at RIC diagnosis, 96% remained free from RIC-related symptoms at 10 years. Only two required neurosurgical intervention for RIC; there was no RIC-related mortality.

CONCLUSIONS

RIC are commonly multiple, asymptomatic and typically increase in size and number over time. Our findings suggest that MRI-SWI for screening of RIC is unlikely to influence longer term intervention in asymptomatic cancer survivors. In the absence of neurological symptoms, assessment or monitoring of RIC are insufficient indications for MRI-SWI surveillance for long-term survivors of malignancy with past exposure to cerebral irradiation.

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.

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.

Systematic review of the incidence and risk factors for cerebral vasculopathy and stroke after cranial proton and photon radiation for childhood brain tumors

BACKGROUND

The aim of our study is to determine the incidence, timing, and risk factors for cerebral vasculopathy after cranial proton and photon radiation for pediatric brain tumors.

METHODS

We performed a single-institution retrospective review of a cohort of children treated with proton radiation for brain tumors. MRA and/or MRI were reviewed for evidence of cerebral vascular stenosis and infarcts. Twenty-one similar studies (17 photon, 4 proton) were identified by systematic literature review.

RESULTS

For 81 patients with median follow-up of 3 years, the rates of overall and severe vasculopathy were 9.9% and 6.2% respectively, occurring a median of 2 years post radiation. Dose to optic chiasm greater than 45 Gy and suprasellar location were significant risk factors. Results were consistent with 4 prior proton studies (752 patients) that reported incidence of 5% to 6.7%, 1.5 to 3 years post radiation. With significantly longer follow-up (3.7-19 years), 9 studies (1108 patients) with traditional photon radiation reported a higher rate (6.3%-20%) and longer time to vasculopathy (2-28 years). Significant risk factors were neurofibromatosis type 1 (NF-1; rate 7.6%-60%) and suprasellar tumors (9%-20%). In 10 studies with photon radiation (1708 patients), the stroke rate was 2% to 18.8% (2.3-24 years post radiation).

CONCLUSIONS

Childhood brain tumor survivors need screening for vasculopathy after cranial radiation, especially with higher dose to optic chiasm, NF-1, and suprasellar tumors. Prospective studies are needed to identify risk groups, and ideal modality and timing, for screening of this toxicity.

Neuroimaging Biomarkers and Neurocognitive Outcomes in Pediatric Medulloblastoma Patients: a Systematic Review

Medulloblastoma is a malign posterior fossa brain tumor, mostly occurring in childhood. The CNS-directed chemoradiotherapy treatment can be very harmful to the developing brain and functional outcomes of these patients. However, what the underlying neurotoxic mechanisms are remain inconclusive. Hence, this review summarizes the existing literature on the association between advanced neuroimaging and neurocognitive changes in patients that were treated for pediatric medulloblastoma. The PubMed/Medline database was extensively screened for studies investigating the link between cognitive outcomes and multimodal magnetic resonance (MR) imaging in childhood medulloblastoma survivors. A behavioral meta-analysis was performed on the available IQ scores. A total of 649 studies were screened, of which 22 studies were included. Based on this literature review, we conclude medulloblastoma patients to be at risk for white matter volume loss, more frequent white matter lesions, and changes in white matter microstructure. Such microstructural alterations were associated with lower IQ, which reached the clinical cut-off in survivors across studies. Using functional MR scans, changes in activity were observed in cerebellar areas, associated with working memory and processing speed. Finally, cerebral microbleeds were encountered more often, but these were not associated with cognitive outcomes. Regarding intervention studies, computerized cognitive training was associated with changes in prefrontal and cerebellar activation and physical training might result in microstructural and cortical alterations. Hence, to better define the neural targets for interventions in pediatric medulloblastoma patients, this review suggests working towards neuroimaging-based predictions of cognitive outcomes. To reach this goal, large multimodal prospective imaging studies are highly recommended.

Management and Surveillance of Short- and Long-Term Sequelae of Radiation Therapy for the Treatment of Pediatric Brain Tumors

Radiation therapy (RT) is a mainstay for the treatment of pediatric brain tumors. As improvements in and sophistication of this modality continue to increase the survival of patients, the long-term sequelae of RT pose significant challenges in the clinical management of this patient population as they transition into adulthood. In this special edition, we review the short- and long-term effects of RT for the treatment of pediatric brain tumors and the necessary surveillance required for follow-up.

Multiple Ischemic Strokes Associated with Childhood Progressive Radiation-Induced Occlusive Cerebral Vasculopathy

There is little knowledge on the pathophysiology of pediatric stroke associated with radiation-induced occlusive cerebral vasculopathy (RIOCV). Herein, we present an extremely rare case of a child with multiple ischemic strokes in association with progressive RIOCV. The possibility of hemodynamic compromise and artery-to-artery embolism as a cause of the ischemic events is discussed.

Cancer and Cerebrovascular Disease

PURPOSE OF REVIEW

To review the latest information about the interactions between cancer and cerebrovascular disease.

RECENT FINDINGS

Additional data support the finding that both ischemic and hemorrhagic stroke are important complications of cancer or its treatment. Reperfusion therapy is being given successfully to patients with stroke complicating cancer. Hemorrhagic stroke may occur with metastatic disease to the brain, coagulopathies from cancer, in particular leukemia, or as complications of chemotherapy. Ischemic stroke also may be a complication of metastatic disease with local invasion of vessels, a pro-thrombotic disorder such as non-bacterial thrombotic endocarditis (NBTE) or disseminated intravascular coagulation (DIC), or secondary to chemotherapy. Stroke also is a potential consequence of radiation therapy to the head and neck. Venous sinus thrombosis may develop with hematologic malignancies or chemotherapy. Although many patients will have a history of cancer at the time of stroke, a cerebrovascular event may be the initial manifestation of a malignancy.

Long-term follow-up of intensive chemotherapy followed by reduced-dose and reduced-field irradiation for intracranial germ cell tumor

OBJECTIVE The authors analyzed the efficacy of intensive chemotherapy followed by reduced-dose and reduced-field irradiation for intracranial germ cell tumors (GCTs) and evaluated the long-term late effects caused by chemoradiotherapy (CRT). METHODS The authors performed a retrospective study. The subjects were 24 patients who received CRT between April 1994 and April 2015. After surgery, intensive chemotherapy followed by reduced-dose and reduced-field irradiation was administered. For those with pure germinoma, who comprised the “good prognosis” group, five courses of conventional-dose chemotherapy (CDC) were administered, and radiotherapy (24 Gy) was applied to the whole ventricle. For all others, defined as the “intermediate and poor prognosis” group, two or three courses of CDC and high-dose chemotherapy were administered with peripheral blood stem cell transplantation and radiotherapy (24–30 Gy) applied to the whole ventricle or a larger field with or without local boost irradiation (20 Gy), which was applied as needed. RESULTS The median period of follow-up was 112.5 months (range 28–261 months), and the 5-/10-year overall and progression-free survival rates were 100%/83.5% and 91.3%/86.5%, respectively. The 5-/10-year overall survival rates determined based on the histological subtypes were 100%/100% for pure germinoma and 93.8%/78.7% for others, respectively. The late toxicities were as follows: endocrine disorder (33% in pure germinoma, 56% in others), involuntary movements (17% in pure germinoma, 39% in others), ear and labyrinth disorders (17% in pure germinoma, 33% in others), and psychiatric disorders (0% in pure germinoma, 33% in others). Nineteen of 24 patients underwent MRI (T2*- or susceptibility-weighted imaging) after radiotherapy, and 16 (84%) of those 19 patients had microbleeds detected, while 2 (10.5%) had radiation-induced cavernous vascular malformations detected. CONCLUSIONS Intensive chemotherapy followed by reduced-dose and reduced-field irradiation for intracranial GCTs had the same outcome as that reported in the literature, but late adverse effects after treatment were observed. Almost all of the complications were relatively mild but had the potential to lead to psychiatric disorders and intracranial hemorrhaging. ABBREVIATIONS AFP = alpha-fetoprotein; CDC = conventional-dose chemotherapy; CMB = cerebral microbleed; CRT = chemoradiotherapy; CSI = craniospinal irradiation; EP = etoposide and cisplatin; GCT = germ cell tumor; HCG = human chorionic gonadotropin; HDC = high-dose chemotherapy; ICE = ifosfamide, cisplatin, and etoposide; NGGCT = nongerminomatous GCT; OS = overall survival; PBSCT = peripheral blood stem cell transplantation; PFS = progression-free survival; RICM = radiation-induced cavernous malformation; STGC = syncytiotrophoblastic giant cell; SWI = susceptibility-weighted imaging.

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.

Susceptibility-weighted magnetic resonance imaging of cerebrovascular sequelae after radiotherapy for pediatric brain tumors

BACKGROUND AND PURPOSE

Due to sensitive neuroimaging techniques, cerebrovascular complications such as cerebral microbleeds (CMB) and cerebral cavernous malformations (CCM) are increasingly recognized as considerable late effects after treatment for pediatric brain tumor. The aim of this study was to analyze CMB in a cohort of patients after cranial irradiation therapy for medulloblastoma or other pediatric brain tumors using susceptibility-weighted magnetic resonance imaging (SWI).

MATERIALS AND METHODS

Forty former pediatric brain tumor patients were enrolled in this prospective cross-sectional study and examined by cranial MRI including SWI sequences. Cerebral microbleeds, clinical symptoms and disability were evaluated.

RESULTS

Thirty-six (90%) of the examined individuals (mean follow-up age 22.2 y; mean follow-up time 13.5 y) were affected by CMB. Longer follow-up time and higher craniospinal irradiation doses correlated with higher total lesion count (p < 0.01). Thirteen patients (32.5%) presented with clinical symptoms. Individuals with CMB were more severely disabled than patients without CMB (p < 0.05).

CONCLUSIONS

Cerebrovascular sequelae occur frequently after treatment for pediatric brain tumor. In this study, a remarkable part of pediatric brain tumor patients presents with CMB. As a sign of vascular damage, they can cause clinical symptoms and may correspond to neurocognitive decline. Further studies are needed to standardize MRI protocols and to improve quality of long-term follow-up.

Novel loss of function mutation in KRIT1/CCM1 is associated with distinctly progressive cerebral and spinal cavernous malformations after radiochemotherapy for intracranial malignant germ cell tumor

PURPOSE

Cerebrospinal cavernous malformations (CCMs) are vascular lesions characterized by dilated and leaky capillary caverns. CCMs can cause seizures, focal neurological deficits or acute intracranial hemorrhage; however, most patients are asymptomatic. CCMs occur either sporadically or as a familial autosomal-dominant disorder. We present a clinical and molecular study of a patient with distinctive cerebral and spinal cavernous malformations following radiochemotherapy for a malignant brain tumor.

METHODS

The patient had multiple magnet resonance imaging (MRI) examinations of his brain and spine following radiochemotherapy for a primary intracranial germ cell tumor (GCT), as part of his oncologic follow-up. The MRI sequences included susceptibility-weighted imaging (SWI). The coding exons and their flanking intronic regions of KRIT1/CCM1 gene were analyzed for mutations by polymerase chain reaction (PCR) and direct sequencing.

RESULTS

MRI revealed numerous cerebral and spinal microhemorrhages and pronounced cavernous malformations that progressed with subsequent follow-up imaging. Genetic analysis demonstrated a novel heterozygous KRIT1/CCM1 two base pair deletion (c.1535_1536delTG) in exon 14. This deletion leads to a frameshift with a premature stop codon at nucleotide position 1553 and a highly likely loss of function of the KRIT1 protein.

CONCLUSION

We describe a patient with a novel heterozygous germ line loss of function mutation in KRIT1, which is associated with rapid-onset and highly progressive CCMs after radiochemotherapy for a malignant brain tumor.

Microbleeds and cavernomas after radiotherapy for paediatric primary brain tumours

BACKGROUND

With the expected growth and aging of the population of primary central nervous system tumours (PCNST) survivors, attention to the radiation-induced late brain injury is fundamental. Late focal hemosiderin deposition (FHD) lesions, namely microbleeds and cavernomas, are among the presumable late cerebrovascular complications associated with radiotherapy for PCNST.

OBJECTIVE

To explore association between PCNST radiotherapy and the occurrence FHD lesions and to address the correlation between the topographic location of these microvascular lesions with the focal radiotherapy location.

METHODS

Retrospective cohort study of 190 paediatric patients being followed for PCNST in a single referral oncological centre. The frequency of FHD lesions was compared between paediatric PCNST treated (n=132) and not treated (n=58) with brain radiation. Microbleed Anatomical Rating Scale (MARS) was used for systematic identification of these cerebrovascular lesions and to address the consistency between the topographic location of each lesion and the location of the focal radiotherapy area. Univariate analysis to address the role of variables such as tumour histology, location, gender and age of children at the beginning of radiotherapy, duration of follow-up and chemotherapy was performed.

RESULTS

FHD lesions (microbleeds and cavernomas) occurred exclusively and in a high percentage (41.6%) in PCNST survivors treated with brain radiation. Younger age at the diagnosis (p=0.031), duration of follow-up (p=0.010) and embryonal histology (p=0.003) positively correlated with the occurrence FHD lesions. FHD lesions were topographically concordant with the brain focal irradiation area in 3/19 (15.8%) patients from the focal RT subgroup and in 22/111 (19.8%) patients from the WBRT plus focal RT subgroup.

CONCLUSION

Our study, which is one of the largest to date on the topic, shows that FHD lesions are a common complication after radiotherapy for childhood PCNST. The young brain is probably more susceptible to radiation-induced late cerebrovascular injury. Diffuse small vessel disease and ceiling effect may account for the low topographic concordance we found. The clinical implications of FHD lesions in this specific population are yet to be clarified.

Presence of cerebral microbleeds is associated with worse executive function in pediatric brain tumor survivors

BACKGROUND

A specific form of small-vessel vasculopathy-cerebral microbleeds (CMBs)-has been linked to various types of dementia in adults. We assessed the incidence of CMBs and their association with neurocognitive function in pediatric brain tumor survivors.

METHODS

In a multi-institutional cohort of 149 pediatric brain tumor patients who received cranial radiation therapy (CRT) between 1987 and 2014 at age <21 years and 16 patients who did not receive CRT, we determined the presence of CMBs on brain MRIs. Neurocognitive function was assessed using a computerized testing program (CogState). We used survival analysis to determine cumulative incidence of CMBs and Poisson regression to examine risk factors for CMBs. Linear regression models were used to assess effect of CMBs on neurocognitive function.

RESULTS

The cumulative incidence of CMBs was 48.8% (95% CI: 38.3-60.5) at 5 years. Children who had whole brain irradiation developed CMBs at a rate 4 times greater than those treated with focal irradiation (P < .001). In multivariable analysis, children with CMBs performed worse on the Groton Maze Learning test (GML) compared with those without CMBs (Z-score -1.9; 95% CI: -2.7, -1.1; P < .001), indicating worse executive function when CMBs are present. CMBs in the frontal lobe were associated with worse performance on the GML (Z-score -2.4; 95% CI: -2.9, -1.8; P < .001). Presence of CMBs in the temporal lobes affected verbal memory (Z-score -2.0; 95% CI: -3.3, -0.7; P = .005).

CONCLUSION

CMBs are common and associated with neurocognitive dysfunction in pediatric brain tumor survivors treated with radiation.

Association between the rs112735431 polymorphism of the RNF213 gene and moyamoya disease: A case-control study and meta-analysis

Ring finger protein 213 (RNF213) gene polymorphisms are thought to be significant in the etiology and pathogenesis of moyamoya disease (MMD). Due to the rarity of MMD patients, their ethnic diversity, and the use of varying methodologies, studies of the association between these polymorphisms and MMD have not been repeatable. This lack of reproducibility affects the strength of the conclusions drawn from their results. We conducted the present case-control study and meta-analysis to provide more precise estimates of the association between the rs112735431 (c.14576G>A) polymorphism and the risk of MMD. A total of 81 MMD patients and 100 healthy controls were enrolled in our case-control study. The RNF213 rs112735431 (c.14576G>A) polymorphism was genotyped using Sanger sequencing after amplification with polymerase chain reaction (PCR). The genetic algorithm (GA) genotype and A allele frequencies of RNF213 rs112735431 (c.14576G>A) (odds ratio, OR=7.10, 95% confidence interval, CI=1.51-33.43, p=0.006; OR=9.37, 95% CI=2.10-41.84, p<0.001, respectively) were significantly higher in the MMD group than those in the control group. In our meta-analysis, we assessed a total of eight case-control studies, including 985 patients and 2335 controls. Pooled ORs indicated a significant association between the presence of the rs112735431 (c.14576G>A) polymorphism and MMD risk (dominant model: OR=74.55, 95% CI=35.86-154.98, p<0.00001). Subgroup analysis based on country and sensitivity analysis verified these results. Our case-control study and meta-analysis both provide evidence of an association between the rs112735431(c.14576G>A) polymorphism in the RNF213 gene and MMD risk.