Bevacizumab as a treatment option for radiation-induced cerebral necrosis.

Radiation necrosis of normal CNS tissue represents one of the main risk factors of brain irradiation, occurring more frequently and earlier at higher total doses and higher doses per fraction. At present, it is believed that the necrosis results due to increasing capillary permeability caused by cytokine release leading to extracellular edema. This process is sustained by endothelial dysfunction, tissue hypoxia, and subsequent necrosis. Consequently, blocking the vascular endothelial growth factor (VEGF) at an early stage could be an option to reduce the development of radiation necrosis by decreasing the vascular permeability. This might help to reverse the pathological mechanisms, improve the symptoms and prevent further progression. A patient with radiationinduced necrosis was treated with an anti-VEGF antibody (bevacizumab), in whom neurologic signs and symptoms improved in accordance with a decrease in T1-weighted fluid-attenuated inversion recovery signals. Our case report together with the current literature suggests bevacizumab as a treatment option for patients with symptoms and radiological signs of cerebral necrosis induced by radiotherapy.

Dose-related efficacy of a continuous intracisternal nimodipine treatment on cerebral vasospasm in the rat double subarachnoid hemorrhage model.

OBJECTIVE: Intracisternal continuous therapy is a concept in the treatment of cerebral vasospasm after subarachnoid hemorrhage. The purpose of the current study was to investigate the effect of intracisternal nimodipine after induced vasospasm. METHODS: Sixty-five male Wistar rats were randomized into 4 groups: the control sham-operated group, the control subarachnoid hemorrhage-only group, and the treatment groups receiving 5 or 10 microL/hour of intracisternal nimodipine continuously for 5 days via subcutaneously implanted Alzet osmotic pumps (Durect Corp., Cupertino, CA). Vasospasm was analyzed 5 days later by means of digital subtraction angiography. Morphological examination of the brain parenchyma was performed using Nissl-staining, c-Fos immunohistochemistry, and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling. RESULTS: Detailed analysis of the digital subtraction angiography was possible for 31 animals. Significant angiographic vasospasm was induced in the double hemorrhage-only group compared with the sham-operated group (P = 0.002). Among the 4 groups, there were statistically significant differences of the arterial vessel caliber as measured by digital subtraction angiography (P = 0.001, Kruskal-Wallis test). The treatment group receiving 5 microL/hour of nimodipine and the control sham-operated group demonstrated the largest intracranial artery diameters with a significant difference between control subarachnoid hemorrhage-only group and the treatment group receiving 10 microL/hour of nimodipine (P = 0.0328, Wilcoxon rank-sum test). Variation in vessel calibers, however, did not result in different brain tissue alterations, even when using sensitive markers for the induction of the stress response or apoptosis. CONCLUSION: Intracisternal nimodipine lavage with 5 microL/hour, but not with 10 microL/hour leads to significant arterial relaxation. Further research is needed to elucidate the underlying cause of the decreasing nimodipine effect at higher dosage.