Anticoagulation for radiation-induced neurotoxicity revisited

Garcinia kola improves cognitive and motor function of a rat model of acute radiation syndrome in the elevated plus maze

We reported recently that the elevated plus maze is a good tool for evaluating cognitive and motor functional changes in gamma-irradiated rats as a model for new drug evaluation and monitoring. The capacity of Garcinia kola to mitigate radiation-induced brain injury is currently unknown. We therefore assessed the effects of the neuroprotective medicinal plant Garcinia kola, on the cognitive and motor changes in this murine model of acute radiation syndrome. Wistar rats exposed once to an ionizing dose of Tc99m-generated Gamma radiation were treated with an ethyl acetate fraction of methanolic extract of Garcinia kola seeds (content of 100 mg/kg of extract) for 9 weeks. Cognitive and motor function indicators were assessed in the elevated plus maze in these animals and compared with irradiated control groups (vitamin C- and vehicle-treated groups) and the non-irradiated control rats. The irradiated control group displayed cachexia, shaggy and dirty fur, porphyrin deposits around eyes, decreased exploratory activity, reduced social interactions and a loss of thigmotaxis revealed by a marked decrease in rearing episodes and stretch attend posture episodes close to the walls of elevated plus maze closed arm, an increased central platform time, and decreases in open arm time and entries. This group further displayed a decrease in head dips and grooming episodes. Treatment with Garcinia kola, and in a lesser extent vitamin C, significantly prevented the body weight loss (P < 0.001) and mitigated the development of elevated plus maze signs of cognitive and motor affections observed in the irradiated control group (P < 0.05). Altogether, our data suggest for the first time that Garcinia kola seeds have protective properties against the development of cognitive and motor decline in the acute radiation syndrome-like context. Future studies are warranted to characterize the molecular mechanisms and neuronal networks of this action.

Temporal Lobe Necrosis Following Radiotherapy in Nasopharyngeal Carcinoma: New Insight Into the Management

Cerebral radiation necrosis (CRN) is one of the most prominent sequelae following radiation therapy for nasopharyngeal carcinoma (NPC), which might have devastating effects on patients' quality of life (QOL). Advances in histopathology and neuro-radiology have shed light on the management of CRN more comprehensively, yet effective therapeutic interventions are still lacking. CRN was once regarded as progressive and irreversible, however, in the past 20 years, with the application of intensity-modulated radiation therapy (IMRT), both the incidence and severity of CRN have declined. In addition, newly developed medical agents including bevacizumab-a humanized monoclonal antibody against vascular endothelial growth factor (VEGF), nerve growth factor (NGF), monosialotetrahexosylganglioside (GM1), etc., have shown great potency in successfully reversing radiation-induced CRN. As temporal lobes are most frequently compromised in NPC patients, this review will summarize the state-of-the-art progress regarding the incidence, pathophysiology, prevention, treatment, and prognosis of temporal lobe necrosis (TLN) after IMRT in NPC.

Characterization of the Cognitive and Motor Changes Revealed by the Elevated Plus Maze in an Experimental Rat Model of Radiation-Induced Brain Injury

Background:

Experimental models are needed to better understand the pathophysiology of neurodegenerative diseases to develop novel therapeutics. The neuropathology and clinical signs of acute radiation syndrome resemble those of neurodegenerative conditions. We characterized elevated plus maze (EPM) indicators of cognitive and motor impairment in rats exposed to brain-damaging doses of gamma radiation to develop a model for neurological component of the acute radiation syndrome.

Materials and Methods:

Technetium 99 m was administered once through tail vein to male Wistar rats to reach an absorbed dose of Gamma radiation of 667 mGy (66.7Rad). Animal performance in the EPM was assessed every 14 days. Rats were observed for 9 weeks for the occurrence of systemic and neurological signs. Comparisons were done between irradiated and nonirradiated rats, and in each group with baseline performance.

Results:

EPM indicators of cognitive and motor impairment, anxiety, and depression were observed concomitantly and increased with the severity of acute radiation syndrome-like systemic and neurological signs. Alterations in EPM indicators appeared 3 weeks postirradiation and their severity increased with time. Notably, arm transitions and the distance covered in the maze were decreased (−56.71% and −73.62%, P < 0.001), as well as open arm entries and time spent in open arms (−77.78% and −76.19%, P < 0.05) and the indicator of thigmotaxis rearing (−92.45, P < 0.001).

Conclusions:

Our results suggest that irradiated rat performance in the EPM paradigm reflects disease severity and could be used to perform both acute and subchronic pharmacological studies in acute radiation syndrome-like diseases in rats.

Brain Metastasis Recurrence Versus Radiation Necrosis: Evaluation and Treatment

Radiation necrosis (RN) occurs in 5% to 25% of patients with brain metastases treated with stereotactic radiosurgery. RN must be distinguished from recurrent tumor to determine appropriate treatment. Stereotactic biopsy remains the gold standard for identifying RN. Initial treatment of RN often involves management of edema using corticosteroids, antiangiogenic therapies, and hyperbaric oxygen therapy. For refractory symptoms, surgical resection can be considered. Minimally invasive stereotactic laser ablation has the benefit of providing tissue diagnosis and treating RN or recurrent tumor with similar efficacy. Laser ablation should be considered for lesions in need of intervention where the diagnosis requires tissue confirmation.

Radiation Necrosis in Intracranial Lesions

Radiation necrosis (RN) is a challenging potential complication of cranial radiation therapy. Believed to result from a complex interplay of vascular, glial, and immunologic factors, the exact mechanism of RN remains unclear. Patients who develop RN typically have a history of treatment with stereotactic radiation surgery or some other form of radiation-based therapy. The time frame for its development is variable, but it most often occurs one to three years following radiation therapy. Reported treatment doses capable of inducing radiation necrosis are variable, with higher doses per fraction more likely to induce RN. Furthermore, RN remains a challenging diagnosis for clinicians to make, as its presentation is often nonspecific and imaging studies might not clearly differentiate RN from tumor recurrence or pseudoprogression. RN is initially managed with corticosteroids, followed by bevacizumab, surgical resection, or laser interstitial thermal therapy if symptoms persist. In this review, we examine the literature regarding pathophysiology, incidence, imaging characteristics, and management strategies for radiation necrosis.

[Management of cerebral radionecrosis: experience in the Department of Neurology at the Mohammed V Military Teaching Hospital]

La radionécrose cérébrale est une complication rare mais redoutable de la radiothérapie externe pour les cancers ORL en particulier du nasopharynx et pour les tumeurs cérébrales. Peu de travaux se sont intéressés à cette complication aussi bien dans la population maghrébine qu'africaine. L'objectif de notre étude est donc de décrire les aspects démographiques, cliniques, paracliniques, thérapeutiques et évolutifs de la radionécrose cérébrale au sein du Service de Neurologie de l'Hôpital Militaire d'Instruction Mohammed V de Rabat (HMIMV) sur une durée de 18 ans (2000-2017). Il s'agissait de 04 femmes et 13 hommes âgés en moyenne de 50 ans. Le délai moyen entre la fin de la radiothérapie et le début des signes neurologiques était de 28 mois. La réalisation systématique d'une IRM cérébrale parfois complété d'une spectro-IRM avait permis de faire le diagnostic chez 100% des cas. Sur le plan étiologique, cette complication survenait après radiothérapie pour cancer du cavum et du larynx chez tous les cas. 15 patients ont été traités par l'association: corticothérapie en bolus, antiagrégants plaquettaires, associée à l'oxygénation hyperbare (OHB) avec une bonne évolution, et 2 patients, chez qui l'oxygénothérapie était contre-indiquée pour problème pulmonaire, et ORL, ont reçu l'association corticothérapie en bolus et antiagrégants plaquettaires avec une évolution stationnaire. À la lumière de ces résultats, nous insistons sur l'intérêt du diagnostic précoce en raison de la gravité potentielle de certains tableaux surtout neuropsychiatriques ainsi que sur le traitement par association bolus de corticoïdes + OHB car il est le meilleure garant d'une évolution favorable de ces atteintes, sans omettre le rôle crucial des mesures de prévention.

A prospective, multicentre, single-arm clinical trial of bevacizumab for patients with surgically untreatable, symptomatic brain radiation necrosis†

Background

Brain radiation necrosis (BRN) can be a complication of radiotherapy for primary and secondary brain tumors, as well as head and neck tumors. Since vascular endothelial growth factor (VEGF) is also a vascular permeability factor in the brain, bevacizumab, a humanized antibody that inhibits VEGF, would be expected to reduce perilesional edema that often accompanies BRN.

Methods

Patients with surgically untreatable, symptomatic BRN refractory to conventional medical treatments (eg, corticosteroid, anticoagulants, or hyperbaric oxygen therapy) were enrolled. We judged that a major cause of perilesional edema with a lesion-to-normal brain ratio ≤1.8 on ¹¹C-methionine or ≤2.5 on ¹⁸F-boronophenylalanine PET was BRN, not tumor recurrence, and 6 cycles of biweekly bevacizumab (5 mg/kg) were administered. The primary endpoint was a ≥30% reduction from the patients' registration for perilesional edema continuing for ≥1 month.

Results

Of the 41 patients enrolled, 38 were fully eligible for the response assessment. The primary endpoint was achieved in 30 of the 38 (78.9%) patients at 3.0 months (median) after enrollment. Sixteen patients (42.1%) experienced improvement of their Karnofsy Performance Score. Corticosteroid use could be reduced in 29 patients (76.3%). Adverse events at grade ≥3 occurred in 10 patients (24.4%).

Conclusions

Bevacizumab treatment offers certain clinical benefits for patients with surgically untreatable, symptomatic BRN. The determination of BRN using amino-acid PET, not biopsy, is adequate and less invasive for determining eligibility to receive bevacizumab.

In search of a treatment for radiation-induced optic neuropathy

OPINION STATEMENT

Radiation-induced optic neuropathy (RON) is an iatrogenic complication that causes severe, irreversible vision loss in one or both eyes within the months to years following radiation therapy. Posterior RON is a rare but devastating toxicity of radiation applied to the visual pathways to treat paranasal sinus and skull base tumors. Anterior RON is an unavoidable consequence of proton beam irradiation or ophthalmic plaque treatment of orbital, choroidal, or retinal tumors. Various treatments aimed at stabilizing and ideally reversing vision loss have been investigated but only in small cases series. Systemic corticosteroids and anticoagulants, which are moderately effective when used for cerebral radiation necrosis, have shown no signs of benefit for RON. Hyperbaric oxygen therapy may promote short-term, partial recovery of vision in select patients, especially at partial pressures of at least 2.4 atm and when administered early after symptom onset. Reversal of visual deficits through treatment with systemic bevacizumab has been reported, but until controlled studies are performed, the side effect profile of stroke and myocardial infarction should limit its use in a population with predisposing cardiovascular risk factors. Intravitreal bevacizumab has shown promising results in patients with anterior RON, but repeated, long-term injections are required for sustained effect. As no intervention has been clearly shown to halt or reverse vision loss, larger prospective studies are needed to validate observed benefits for any of the treatments that have been described.

Delayed cerebral radiation necrosis after neutron beam radiation of a parotid adenocarcinoma: a case report and review of the literature

Cerebral radiation necrosis (CRN) is a well described possible complication of radiation for treatment of intracranial pathology. However, CRN as sequelae of radiation to extracranial sites is rare. Neutron beam radiation is a highly potent form of radiotherapy that may be used to treat malignant tumors of the salivary glands. This report describes a patient who underwent neutron beam radiation for a parotid adenocarcinoma and who developed biopsy-confirmed temporal lobe radiation necrosis thirty months later. This represents the longest time interval described to date, from initial neutron radiation for extracranial pathology to development of CRN. Two other detailed case studies exist in the literature and are described in this report. These reports as well as our patient's case are reviewed, and additional recommendations are made to minimize the development of CRN after extracranial neutron beam radiation. Physicians should include the possible diagnosis of CRN in any patient with new neurologic signs or symptoms and a history of head and neck radiation that included planned fields extending to the base of the skull. Counseling of patients prior to neutron beam radiation should include potential neurologic complications associated with CRN and risks of treatment for CRN including neurosurgical intervention.

Bevacizumab as a treatment for radiation necrosis of brain metastases post stereotactic radiosurgery

BACKGROUND

Cerebral radiation necrosis (RN) is a difficult to treat complication of stereotactic radiosurgery (SRS) that can result in progressive neurologic decline. Currently, steroids are the standard of care treatment for brain RN despite their adverse effect profile and limited efficacy. The purpose of this study was to evaluate the treatment efficacy of cerebral RN to bevacizumab in patients with brain metastases previously treated with SRS.

METHODS

We retrospectively reviewed 14 lesions in 11 patients treated with bevacizumab for brain RN secondary to SRS for their brain metastases. Steroid dosing, RN-associated symptoms, and magnetic resonance imaging (MRI) scans were examined before, during, and after bevacizumab administration.

RESULTS

Of the 11 patients included, 6 had metastatic non-small cell lung cancer, and 5 had metastatic breast cancer. The mean percentage decrease in RN volume seen on T1 post-Gadolinium and fluid-attenuated inversion recovery (FLAIR) MRI at first follow-up, at a mean of 26 days (range, 15-43 days), was 64.4% and 64.3%, respectively. MRI changes were sustained on follow-up MRI scans, obtained at a mean of 33 days (range, 7-58 days) after bevacizumab discontinuation. After bevacizumab treatment, all patients initially receiving steroids had a reduction in steroid requirement, and all but one had an improvement in or stability of RN-associated symptoms. No patients experienced intratumoral bleeds or other adverse effects related to their bevacizumab treatment.

CONCLUSIONS

Bevacizumab is effective and safe for the treatment of RN after SRS for brain metastasis. In this context, bevacizumab offers symptomatic relief, a reduction in steroid requirement, and a dramatic radiographic response.

Cerebral radiation necrosis: a review of the pathobiology, diagnosis and management considerations

Radiation therapy forms one of the building blocks of the multi-disciplinary management of patients with brain tumors. Improved survival following radiation therapy may come with a cost, including the potential complication of radiation necrosis. Radiation necrosis impacts the quality of life in cancer survivors, and it is essential to detect and effectively treat this entity as early as possible. Significant progress in neuro-radiology and molecular pathology facilitate more straightforward diagnosis and characterization of cerebral radiation necrosis. Several therapeutic interventions, both medical and surgical, may halt the progression of radiation necrosis and diminish or abrogate its clinical manifestations, but there are still no definitive guidelines to follow explicitly that guide treatment of radiation necrosis. We discuss the pathobiology, clinical features, diagnosis, available treatment modalities, and outcomes in the management of patients with intracranial radiation necrosis that follows radiation used to treat brain tumors.

[Neurological complications of neurooncological therapy]

Neurological complications of therapeutic procedures for brain tumors are increasingly being recognized. These encompass the classic types of central and peripheral neurotoxicity, such as radiotherapy-induced leukoencephalopathy and platinum-induced neuropathy. However, the advent of novel protocols and targeted therapeutics has expanded the spectrum of neurological complications. A problem of considerable importance is pseudoprogression after radiochemotherapy with temozolomide. Among the new targeted drugs complications of therapy with bevacizumab are the subject of intense discussion. In this review article the neurotoxic potential of intrathecal chemotherapy, kinase inhibitors, immunological strategies and local therapies are summarized. Knowledge about neurological complications of brain tumor therapy procedures is important for risk assessment and patient information.

Diagnostic and therapeutic strategy for confounding radiation myelitis

We report a case of confounding radiation myelitis to demonstrate the usefulness of surgical biopsy in ensuring the correct diagnosis and to avoid unnecessary treatment. The patient was a 40-year-old man with a history of epiglottis carcinoma and sarcoidosis. Six months after radiation therapy and chemotherapy for epiglottis carcinoma, he noticed paresthesia and dysesthesia in the left arm and leg. Two months after that, he complained of severe neck pain and rapidly progressing weakness in all extremities. MRI showed an enhanced intramedullary lesion with extensive edema in the cervical spinal cord. Radiation myelitis, intramedullary spinal tumor, and neurosarcoidosis were considered as differential diagnoses. Spinal cord biopsy with laminectomy was performed and radiation myelitis was diagnosed. After the surgery, the lesion was significantly decreased in size even though corticosteroid therapy was rapidly tapered. We emphasize that a spinal cord biopsy is indicated to obtain a pathological diagnosis and to make a clear treatment strategy for patients with associated diseases causing lesions of the spinal cord.