Radiation Toxicity in the Central Nervous System: Mechanisms and Strategies for Injury Reduction

Abstract

The potential for radiation-induced toxicities in the brain produces significant anxiety, both among patients receiving radiation therapy and those radiation oncologists providing treatment. These concerns often play a significant role in the medical decision-making process for most patients with diseases in which radiotherapy may be a treatment consideration. Although the precise mechanisms of neurotoxicity and neurodegeneration after ionizing radiation exposure continue to be poorly understood from a biological perspective, there is an increasing body of scientific and clinical literature that is producing a better understanding of how radiation causes brain injury; factors that determine whether toxicities occur; and potential preventative, treatment, and mitigation strategies for patients at high risk or with symptoms of injury. This review will focus primarily on injuries and biological processes described in mature brain.

Figure 1

(A) Axial T2 weighted axial MRI image of leukoencephalopathy (arrow) occurring in a 53 year old female patient 5 years after receiving chemoradiation (60 Gy) treatment for a high grade glioma. (B) Axial FLAIR MRI image of radionecrosis as a hypoenhancing center (arrow) surrounded by a rim of enhancement indicating active inflammation in a 48 year old male patient following chemoradiation (60 Gy) treatment for high grade glioma.

Figure 2

Combined strategic interventions for combating radiation-induced toxicity in the CNS.