Ask the Experts: What are the effects of radiation therapy on the brain and spine?

Neurology Now
October/November 2011
Volume 7(5)
p 68
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RADIATION

QWhat are the effects of radiation therapy on the brain and spine?

DRS. ORLY AVITZUR AND LYNNE TAYLOR RESPOND:

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A Often used in the treatment of tumors, radiation therapy (RT) can injure the healthy brain and spinal cord tissue nearby. It's believed that such injury is caused by damage to the blood vessels that supply these areas of the body and damage to the glia, which are the supportive cells of the central nervous system.

The neurologic complications caused by RT may occur immediately or weeks, months, or years after treatment. Five percent of patients experience early or acute injury, which occurs during the first two weeks after treatment. Symptoms include headache, nausea and vomiting, sleepiness, and fever.

Fifty percent of patients, especially children, experience early-delayed injury, which occurs from weeks to several months following RT. Symptoms include drowsiness, fatigue, and cognitive problems such as difficulty with thinking and memory. These changes are reversible and typically respond to treatment with steroids.

Late-delayed injury can follow many months or longer after treatment and is associated with permanent white matter changes in the brain, loss of brain tissue, and—if severe—dementia and death. These effects will vary based on other treatments or underlying diagnoses but can be present in up to 50 percent of people treated with whole brain radiotherapy and chemotherapy for central nervous system lymphoma.

When RT-induced injury occurs in the spinal cord, patients may feel a loss of sensation and weakness in the legs and experience bowel and bladder difficulties. Early-delayed damage to the spinal cord is often reversible, whereas late-delayed is often permanent. The risk of developing late-delayed injury increases with radiation dose, age, conditions such as diabetes and high blood pressure, and when RT is combined with chemotherapy.

To avoid long-term consequences of RT, patients should see a neuro-oncologist or a radiation therapist with expertise in neuro-oncology.

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