Gamma knife is targeted radiation

Dear Dr. Roach: I don’t read many questions about brain tumors. I am 53 years old, diagnosed almost four years ago with multiple meningiomas. I had an atypical meningioma removed, followed up with gamma knife. My question is whether I will be at a greater risk for Alzheimer’s or Parkinson’s disease because of these brain tumors. — J.Z.

A meningioma is a type of tumor of the lining of the brain. It is considered a brain tumor, but is most commonly benign. You had an atypical meningioma, which, though still benign, is closer to a rare (1 to 3 percent) malignant (cancerous) meningioma. Meningiomas, even those that are malignant, rarely spread, but they are harder to completely eradicate.

Treatment for benign meningiomas is usually preferred if the tumor is in a location where surgery is possible, or with radiation if surgery is difficult or impossible. Gamma knife is a precision type of radiation treatment. Atypical meningiomas often are treated with both surgery and followup radiation to reduce the risk of recurrence.

Because the tumors are on the outside of the brain, not brain tissue itself, surgery should not increase your risk of Alzheimer’s or Parkinson’s disease. However, a review of studies showed that many people with meningiomas do have some decrease in some areas of brain function before treatment. This may be due to pressure of the tumor on the brain.

Brain tissue is relatively resistant to radiation. Although high doses of radiation to the whole brain can cause memory issues, the smaller amount of radiation from gamma knife and the limited area of the brain affected make development of dementia or Parkinson’s unlikely.

In the same large study on meningioma patients, treatment actually improved brain function. Write to Dr. Roach at ToYourGoodHealth @med.cornell.edu or mail to 628 Virginia Dr., Orlando, FL 32803.