Pathophysiology, Diagnosis, and Treatment of Radiation Necrosis in the Brain

Abstract

New radiation modalities have made it possible to prolong the survival of individuals with malignant brain tumors, but symptomatic radiation necrosis becomes a serious problem that can negatively affect a patient's quality of life through severe and lifelong effects. Here we review the relevant literature and introduce our original concept of the pathophysiology of brain radiation necrosis following the treatment of brain, head, and neck tumors. Regarding the pathophysiology of radiation necrosis, we introduce two major hypotheses: glial cell damage or vascular damage. For the differential diagnosis of radiation necrosis and tumor recurrence, we focus on the role of positron emission tomography. Finally, in accord with our hypothesis regarding the pathophysiology, we describe the promising effects of the anti-vascular endothelial growth factor antibody bevacizumab on symptomatic radiation necrosis in the brain.

Brain Radionecrosis: Case Report

“…Late cerebral radiation necrosis can be a consequence of total brain radiation therapy that appears with doses up to 50 Gy, but with higher incidences depending on doses, fraction and addiction of chemotherapy [2,3]. In a general way, its incidence varies from 0.5% to 25%, with the peak within the third year from radiation therapy [4].…”

“…Saying that, on brain, the vascular endothelium and the oligodendrocytes can be more affected by radiation [4]. Vascular damage due to changes on endothelium induced by radiation leads to microvasculopathy, resulting in vascular insufficiency and infarction, followed by brain necrosis [2,3]. Late cerebral necrosis (months to years Methods of brain imaging like head CT, MRI and PET-CT, although useful for cerebral radionecrosis, are not specific [1].…”

“…When associated with history of radiation therapy, interpretation becomes more reliable [8]. Some patterns like "Swiss cheese" and "soap bubble" are characteristics of cerebral radionecrosis on enhanced T1WI MRI [1,2]. Besides these well-known patterns, it can be doubtful when the site irradiated had previously a tumor [8].…”

“…Besides these well-known patterns, it can be doubtful when the site irradiated had previously a tumor [8]. The gold standard for that is histopathologic analysis [1,2,4].…”

“…Most patients develop this degeneration after being treated with radiation therapy for brain or head and neck tumors [2].…”