White matter lesions and encephalopathy in patients treated for primary central nervous system lymphoma

Cumulative incidence and risk factors for radiation induced leukoencephalopathy in high grade glioma long term survivors

The incidence and risk factors associated with radiation-induced leukoencephalopathy (RIL) in long-term survivors of high-grade glioma (HGG) are still poorly investigated. We performed a retrospective research in our institutional database for patients with supratentorial HGG treated with focal radiotherapy, having a progression-free overall survival > 30 months and available germline DNA. We reviewed MRI scans for signs of leukoencephalopathy on T2/FLAIR sequences, and medical records for information on cerebrovascular risk factors and neurological symptoms. We investigated a panel of candidate single nucleotide polymorphisms (SNPs) to assess genetic risk. Eighty-one HGG patients (18 grade IV and 63 grade III, 50M/31F) were included in the study. The median age at the time of radiotherapy was 48 years old (range 18-69). The median follow-up after the completion of radiotherapy was 79 months. A total of 44 patients (44/81, 54.3%) developed RIL during follow-up. Twenty-nine of the 44 patients developed consistent symptoms such as subcortical dementia (n = 28), gait disturbances (n = 12), and urinary incontinence (n = 9). The cumulative incidence of RIL was 21% at 12 months, 42% at 36 months, and 48% at 60 months. Age > 60 years, smoking, and the germline SNP rs2120825 (PPARg locus) were associated with an increased risk of RIL. Our study identified potential risk factors for the development of RIL (age, smoking, and the germline SNP rs2120825) and established the rationale for testing PPARg agonists in the prevention and management of late-delayed radiation-induced neurotoxicity.

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.

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.

Challenges and prospects in the diagnosis and treatment of primary central nervous system lymphoma

Introduction: Primary central nervous system lymphoma (PCNSL) retains peculiar biological and clinical characteristics and a worse prognosis with respect to other comparable lymphomas. The need for high doses of chemotherapy to achieve valid drug concentrations in cerebral tissues and/or radiotherapy results in severe treatment-related toxicities, mainly neurologic, which are frequently as disabling as the disease itself.Areas covered: Several emerging combined therapies are addressed that focus on treating PCNSL. The prognosis has improved in the last years but several questions remain unanswered and the research of more effective therapies goes on. Information and data were obtained from direct authors' experience and a PubMed search of recent peer-reviewed original articles, review articles, and clinical guidelines.Expert commentary: The substantial progress observed in PCNSL has to be ascribed to a carefully combination of standard chemotherapeutic drugs. High-dose methotrexate-based polychemotherapy followed by mainteinance therapy offers one of the best chances to control the disease. Major issues that deserve many efforts by researchers are the definition of optimal consolidation treatment and a shared management of specific conditions such as elderly population and intra-ocular localization.

The role of pre-treatment white matter abnormalities in developing white matter changes following whole brain radiation: a volumetric study

White matter injury is a known complication of whole brain radiation (WBRT). Little is known about the factors that predispose a patient to such injury. The current study used MR volumetrics to examine risk factors, in particular the influence of pre-treatment white matter health, in developing white matter change (WMC) following WBRT. Thirty-four patients with unilateral metastatic disease underwent FLAIR MRI pre-treatment and at several time points following treatment. The volume of abnormal FLAIR signal in the white matter was measured in the hemisphere contralateral to the diseased hemisphere at each time point. Analyses were restricted to the uninvolved hemisphere to allow for the measurement of WBRT effects without the potential confounding effects of the disease on imaging findings. The relationship between select pre-treatment clinical variables and the degree of WMC following treatment was examined using correlational and regression based analyses. Age when treated and volume of abnormal FLAIR prior to treatment were significantly associated with WMC following WBRT; however, pre-treatment FLAIR volume was the strongest predictor of post-treatment WMCs. Age did not add any predictive value once white matter status was considered. No significant relationships were found between biological equivalent dose and select cerebrovascular risk factors (total glucose, blood pressure, BMI) and development of WMCs. The findings from this study identify pre-treatment white matter health as an important risk factor in developing WMC following WBRT. This information can be used to make more informed decisions and counsel patients on their risk for treatment effects.

Complications of brain tumors and their treatment

The diverse medical and neurologic complications of central nervous system (CNS) neoplasms or their treatment cause significant morbidity and mortality. Thus, their recognition and appropriate management by all members of the interdisciplinary team engaged in the care of patients with brain tumors is essential in optimizing quality of life and extending survival. Recognition of the acute, early delayed, and late complications of brain irradiation is essential to optimize management and mitigate their clinical impact.

Leukoencephalopathy and disseminated necrotizing leukoencephalopathy following intrathecal methotrexate chemotherapy and radiation therapy for central nerve system lymphoma or leukemia

OBJECTIVE

Intrathecal methotrexate (MTX) therapy combined with whole brain radiotherapy (WBRT) is one of the major treatment modalities for leukemia and lymphoma involving the central nervous system (CNS). The purpose of this study was to retrospectively determine the incidences of leukoencephalopathy and disseminated necrotizing leukoencephalopathy (DNL) following intrathecal MTX therapy for CNS lymphoma or leukemia and to assess the potential risk factors.

METHODS

Between January 2000 and August 2009, 143 patients with CNS lymphoma or leukemia received intrathecal MTX therapy alone or in combination with WBRT at a single institution. Patients were followed up clinically and radiologically at regular two- or three-month intervals. Medical records were reviewed to obtain information regarding the patients' demographics, medical histories, radiologic characteristics, treatments, and clinical courses.

RESULTS

On follow-up MR images, leukoencephalopathy was found in 95 of 143 patients (66.4%). The median time to develop leukoencephalopathy was 6.6 months. Among those with leukoencephalopathy, four patients showed seven extensive white-matter changes with strongly enhancing lesions demonstrating DNL. Histological confirmation was done in six lesions of three patients and radiological diagnosis alone in one patient. Four lesions spontaneously disappeared on MR images without any treatment, with a mean duration of 14 months before disappearance of DNL.

CONCLUSION

Leukoencephalopathy is a common phenomenon that occurs following intrathecal MTX therapy; however, DNL occurs at a very low incidence. For newly developed enhancing lesions, consideration for the occurrence of DNL should be taken to avoid unnecessary invasive procedures or therapies.

Neurotoxicity of the CNS: diagnosis, treatment and prevention

Treatment-induced CNS toxicity remains a major cause of morbidity in patients with cancer. Real advances in the design of safer radiation procedures have been counterbalanced by a wider use of combined radiotherapy (RT)-chemotherapy regimens, the development of radiosurgery, and the increasing number of long-term survivors. While classic radionecrosis or chemonecrosis have become less common, more subtle changes such as progressive cognitive dysfunction are increasingly reported after RT (radiation-induced leukoencephalopathy) or chemotherapy (administered alone or in combination). The most important and controversial complications of RT, chemotherapy and combined treatments in the CNS are reviewed here, including new diagnostic tools, practical management and prevention that will influence the future management of cancer patients.

Imaging of brain tumors: functional magnetic resonance imaging and diffusion tensor imaging

The eloquent brain can be identified using functional MR (fMR) imaging for the gray matter and diffusion tensor (DT) imaging for the white matter. fMR imaging and DT imaging are especially important for patients with tumors near the important motor and language centers of the brain, where the normal anatomic references may be distorted by the tumor and associated edema. This article explains fMR imaging and DT imaging techniques and illustrates their clinical applications and limitations.

Primary central nervous system lymphoma in the elderly: a multicentre retrospective analysis

Elderly patients with primary central nervous ystem lymphoma (PCNSL) do not tolerate treatment with combined radio-chemotherapy well because of leuco-encephalopathy; they are usually treated initially with chemotherapy or radiotherapy alone. Little is known about the efficacy and toxicity of these treatments outside clinical studies. This study was a retrospective analysis of all patients aged 60 years or over who were admitted with PCNSL to one of five Dutch centers between 1998 and 2007. A total of 74 patients were identified. Twenty-nine were treated with radiotherapy only (Group A), in 36 the intended treatment was chemotherapy alone (Group B), and nine were planned to receive chemotherapy followed by radiotherapy (Group C). Median overall survival was 20 months; 4 months in patients with a Karnofsky performance status (KPS) <70, 25 months in patients with a KPS ≥ 70 (P < 0·001). Treatment modality was not an independent prognostic factor. Forty patients were treated with methotrexate 3 g/m(2) : there were two toxic deaths. Ten patients discontinued chemotherapy because of toxicity. Delayed encephalopathy was reported in 10 patients. In conclusion, community hospitals still frequently utilize whole brain radiotherapy in elderly PCNSL patients, though a majority tolerates chemotherapy well. Performance status was the most important variable determining prognosis. Short and long term toxicities must be weighed against possible clinical benefits of each treatment, making treatment decisions a highly individualized process.

CNS complications of radiotherapy and chemotherapy

Treatment-induced CNS toxicity remains a major cause of morbidity in patients with cancer. Advances in the design of safe radiation procedures have been counterbalanced by widespread use of combined radiotherapy and chemotherapy, development of radiosurgery, and the increasing number of long-term survivors. Although classic radionecrosis and chemonecrosis have become less common, subtle changes such as progressive cognitive dysfunction are increasingly reported after radiotherapy (radiation-induced leukoencephalopathy) or chemotherapy (given alone or in combination). We review the most important and controversial complications of radiotherapy, chemotherapy, and combined treatments in the CNS, and discuss new diagnostic tools, practical management, prevention, and pathophysiological data that will affect future management of patients with cancer.

Maintenance of white matter integrity in a rat model of radiation-induced cognitive impairment

Radiation therapy is used widely to treat primary and metastatic brain tumors, but also can lead to delayed neurological complications. Since maintenance of myelin integrity is important for cognitive function, the present study used a rat model that demonstrates spatial learning and memory impairment 12 months following fractionated whole-brain irradiation (WBI) at middle age to investigate WBI-induced myelin changes. In this model, 12-month Fischer 344 x Brown Norway rats received 9 fractions of 5 Gy delivered over 4.5 weeks (WBI rats); Sham-IR rats received anesthesia only. Twelve months later, the brains were collected and measures of white matter integrity were quantified. Qualitative observation did not reveal white matter necrosis one year post-WBI. In addition, the size of major forebrain commissures, the number of oligodendrocytes, the size and number of myelinated axons, and the thickness of myelin sheaths did not differ between the two groups. In summary, both the gross morphology and the structural integrity of myelin were preserved one year following fractionated WBI in a rodent model of radiation-induced cognitive impairment. Imaging studies with advanced techniques including diffusion tensor imaging may be required to elucidate the neurobiological changes associated with the cognitive impairment in this model.

Diffusion tensor imaging screening of radiation-induced changes in the white matter after prophylactic cranial irradiation of patients with small cell lung cancer: first results of a prospective study

BACKGROUND AND PURPOSE

Diffusion tensor imaging (DTI) will show abnormal fractional anisotropy (FA) in the normal-appearing brain after prophylactic cranial irradiation (PCI). These abnormalities will be more accentuated in patients with underlying vascular risk factors.

MATERIALS AND METHODS

A prospective study by use of DTI and conventional T2-weighted MR images was performed with a 1.5T unit with 16 patients with small cell lung cancer and undergoing PCI. All of the T2-weighted images were evaluated with respect to abnormalities in signal intensity of white matter as markers of radiation damage. Measurements of FA were performed before, at the end of, and 6 weeks after radiation therapy. On the FA maps, the bifrontal white matter, the corona radiata, the cerebellum, and the brain stem were evaluated. FA values were compared with respect to age, demographic, and vascular risk factors. Statistical analyses (Friedman test, Wilcoxon test, and Mann-Whitney U test) were performed.

RESULTS

Fractional anisotropy decreased significantly in supratentorial and infratentorial normal-appearing white matter from the beginning to the end of PCI (P < .01). A further decline in FA occurred 6 weeks after irradiation (P < .05). A stronger reduction in FA was observed in patients with more than 1 vascular risk factor. There was an age-related reduction of white matter FA. Patients 65 years and older showed a trend toward a stronger reduction in FA.

CONCLUSION

During the acute phase, after PCI, patients with many vascular risk factors showed stronger damage in the white matter compared with patients with only 1 risk factor.

The sequelae of cranial irradiation on human cognition

Cranial irradiation (CI) confers remediation of many CNS anomalies. CI, however, carries risks to cognitive performance. A wealth of data describes such deficits specifically in humans. Risk factors that promote increased susceptibility to cognitive decline have also been identified. This paper discusses and grades these risk factors, including age, gender, and the inclusion of chemotherapy, that increase the likelihood of pathologic cognitive development in the human population.

Lymphomatosis cerebri as a cause of white matter dementia

Primary central nervous system lymphoma most often presents as a solitary, isolated lesion in immunocompetent patients. Rarely, the disease presents as a diffuse, infiltrating condition without formation of a cohesive mass, a pattern called lymphomatosis cerebri. We present 3 immunocompetent individuals who developed rapidly progressive dementia. Magnetic resonance imaging features mimicked other disorders of white matter and prompted preoperative diagnoses of Binswanger's disease (subcortical ischemic vascular dementia), unknown leukoencephalopathy, viral infection, or infiltrating glioma. Neuropathologic examination at biopsy (Poon T, Matoso I, Tchertkoff V, Weitzner I Jr, Gade M. CT features of primary cerebral lymphoma in AIDS and non-AIDS patients. J Comput Assist Tomogr . 1989;13:6-9) and autopsy (Schwaighofer BW, Hesselink JR, Press GA, Wolf RL, Healy ME, Berthoty DP. Primary intracranial CNS lymphoma: MR manifestations. Am J Neuroradiol . 1993;10:725-9) demonstrated nonnecrotic, diffusely infiltrating, large-cell B-cell lymphoma of white matter, with relative sparing of gray matter, and without significant leptomeningeal involvement or bulky periventricular disease at autopsy. Microglial and astrocytic reactions, but only subtle myelin pallor, were evident as individual tumor cells permeated the entire brain and spinal cord, albeit with considerable variation in cell density. Individual tumor cells could be identified from the optic nerve to spinal cord, documenting the "whole-brain" nature of the disease. CD20 immunostaining was necessary to fully appreciate the extent of individual lymphoma cell percolation through the white matter. The neurobehavioral deficits manifested by these patients demonstrate that lymphomatosis cerebri is an additional neoplastic cause of white matter dementia and can be added to the growing list of disorders responsible for this syndrome.

A critical review of the clinical effects of therapeutic irradiation damage to the brain: the roots of controversy

We critically examined the damaging affects of therapeutic irradiation by comparing results from cross-disciplinary studies of early- and late-delayed radiotherapy effects. Focus is attained by concentrating on clinical treatment issues (volume of brain, dose, timing of effects, age, modality types, and stereotactic treatment techniques), rather than on methodological means or problems, which is necessary to understand the mechanisms and characteristics of radiotherapy-induced behavioral dysfunction including cognition. We make observations and hypotheses about the actual risks from radiotherapy that could be informative in the treatment decision process, and which may lessen the concerns of some patients and their families about the risks they take when receiving radiation. Conditions that predispose to radiation injury are reviewed: (1) higher doses even to part of the brain versus lower doses to the whole brain, (2) combined treatment modalities, (3) malignancy itself, (4) radiation early during postnatal brain development, and (5) late-delayed effects (more than 3 years posttreatment). Current neurocognitive frameworks for understanding cognitive change over time in children and adults are summarized, along with the literature on effects of brain tumors and treatment on depression. No studies have as yet identified candidate brain regions that are more sensitive to radiotherapy. Two studies have provided early, preliminary evidence for a specific vulnerability of visual attention/memory to the early stage of late radiation damage. Furthermore, radiation effects appear severe only in a minority of patients. Risk is related to direct and indirect effects of cancer type, concurrent clinical factors, and premorbid risk factors.

Cognitive deficits in adult patients with brain tumours

Cognitive function, with survival and response on brain imaging, is increasingly regarded as an important outcome measure in patients with brain tumours. This measure provides us with information on a patient's clinical situation and adverse treatment effects. Radiotherapy has been regarded as the main cause of cognitive decline in these patients, because children with brain tumours can develop intellectual deterioration caused by radiotherapy. In long-term surviving patients, radiotherapy may indeed lead to cognitive deficits, or even dementia. Recent studies, however, have made clear that focal radiotherapy in patients with glioma is not the main reason for cognitive deficits. The tumour itself and other medical treatments contribute largely to the cognitive deficits. Cognitive function is now also recognised as an independent prognostic factor in the survival of glioma patients. Additionally, cognitive deterioration can be the first indicator of progressive disease after treatment.

Transduction of neurons lining the cerebral external capsules in mice with feline immunodeficiency virus based vectors

Gene therapy in the brain has focused mainly on neurons (gray matter), with little comparable research on white matter. In this study, injections into mice cerebral white matter of mice were done to assess the distribution of gene transfer with recombinant feline immunodeficiency virus vectors expressing either beta-galactosidase or beta-glucuronidase. Our results show that vectors were preferentially distributed along the white matter of the external capsule, which was the site of vector injection as confirmed by horseradish peroxidase labeling. Moreover, we found gene transfer almost exclusively to NeuN(+) cells lining the external capsule, which then robustly secreted recombinant beta-glucuronidase throughout the white matter of the entire external capsule on the injected side. These results may have application to lysosomal storage diseases with widespread central nervous system deficits, and other disorders such as multiple sclerosis and human immunodeficiency virus dementia.