Gamma Knife surgery is used at the University of Pittsburgh for the treatment of intractable tremor in elderly patients, those who have concomitant medical problems, or those who do not wish other open approaches. The effects of radiosurgery are usually not immediate. The gamma knife is used to create a focal brain lesion to stop the abnormal function of brain cells in a specific brain location. Radiation effects take time and most patients will note improvement over 1-4 months. However, we have seen patients who have had tremor improvement within several days. The effects will build for up to close to six months.

We generally use a standard amount of very focused radiation (130-140 Gy) and target a 4mm region in the brain. The targeting is completely based upon information from an MRI scan. Since we do not place an electrode into the brain, we cannot electrically map out the area prior to lesioning it. On the other hand, our mapping based upon imaging is similar to that used in patients who undergo stimulation as well as radiosurgery. The overall success rate is approximately 80%, (the percentage of patients who have a major improvement in their tremor). The goal of the procedure is not complete elimination of the tremor, but rather, a reduction in tremor to allow improved movement and function. One of the advantages to gamma knife surgery is that no hardware is placed into your body and that nothing needs to be turned on or off to achieve an effect as with a stimulator. On the other hand, unlike a stimulator, the lesioning effect is permanent. This procedure can be performed in patients on blood thinners.

The main complications of radiosurgery include radiation-induced effects to surrounding structures that could disrupt your function. These include a 5% risk for numbness of the hand, mouth or leg, weakness of the limb, slurred speech, or trouble with vision (looking off to one side). Generally, these problems would occur 4-12 months after the procedure and in most patients would be temporary. In some patients where radiation-induced brain swelling is identified, you may be treated with a short course of steroid medicine to treat the edema. We recommend that an MRI scan be performed 4 and 12 months after the procedure to check the appearance of the brain.