What are the risk factors or side effects of the gamma knife surgery?

Variable: Overall side effect profile is better than conventional radiation. Common side effects include- local pain, scalp swelling, headaches, discomfort from stablizing pin insertion. Other less common side effects include nausea, vomitting, skin rash, some hair loss, brain swelling or necrosis in the treated area. Seizure risk and hearing or visual changes are rare.

Minimal: Gamma knife surgery doesn't involve any incisions. This means that all the side affects are due to the radiation itself. The first side effect is a fatigue that occurs during the first few weeks. There can be swelling in the brain or near the treatment site, which can cause headaches or nausea. Finally there may be problems with an irritated scalp or hair lone.