Purpose of review: Radiation administered to treat CNS neoplasms or systemic cancers adjacent to the CNS can result in a variety of acute, subacute, and delayed clinical syndromes of the brain and spinal cord. Less commonly, the brachial or lumbosacral plexus or the cranial nerves are damaged by radiation therapy (RT). Cranial blood vessels can also be affected by brain RT, especially when it is administered during childhood and results in delayed vessel structural changes. These disorders are important because their presentation can mimic tumor recurrence. Knowledge of the classic clinical signs, imaging features, and time interval from RT will assist the practitioner in establishing the diagnosis and recommending treatment when appropriate.
Recent findings: The acute and subacute syndromes are temporary. An important subacute syndrome following focal external beam RT in combination with chemotherapy to treat newly diagnosed glioblastoma, termed pseudoprogression, has recently been characterized. In addition, recent clinical experience indicates that the delayed RT-induced CNS syndromes, once considered irreversible, can be treated effectively in some patients.
Summary: Recent and ongoing research is lending new insights into the mechanisms of RT-related CNS injury and will hopefully lead to more effective methods for the prevention and treatment of this undesired, but typically unavoidable, complication of RT.