Stereotactic radiosurgery is the most accurate way to use radiation to destroy tumors or abnormally functioning tissue in and around the brain. A Swedish neurosurgeon, Dr. Lars Leksell, conceived of the technique more than 50 years ago. His idea for a safer way to perform neurosurgery has evolved over the past half century to become an extremely important technique used for the management of cancer and other conditions affecting the brain. Yale physicians have treated nearly 3,000 patients with stereotactic radiosurgery since 1991, when this treatment was initially offered to patients on a modified linear accelerator. In 1998, the device developed by Dr. Leksell for performing radiosurgery, the Gamma Knife®, was brought to Yale-New Haven Hospital to provide patients with the most precise and conformal tool available for stereotactic radiosurgery. Remaining at the forefront of Gamma Knife centers, the Gamma Knife was recently upgraded in August 2017 to the Gamma Knife Icon - the latest and most advanced technology available to treat brain tumors in the world. We currently treat between 3 and 8 patients each week with radiosurgery.
A multidisciplinary approach is followed for patients that may be candidates for treatment with Gamma Knife® stereotactic radiosurgery. Before scheduling a patient for Gamma Knife® stereotactic radiosurgery, the patient is evaluated independently by both a radiation oncologist and a neurosurgeon to make sure that all of the appropriate treatment options have been discussed. These two consultations provide an opportunity to make sure that there is no potentially better option for treatment than Gamma Knife® stereotactic radiosurgery and for the risks and benefits of all the therapeutic options to be considered. At these consultations, the relevant medical records and imaging will be reviewed, a medical history will be taken, and a physical examination will be performed to determine whether or not stereotactic radiosurgery is a recommended therapy.
Stereotactic radiosurgery is sometimes not recommended for a patient if microsurgical resection or another neurosurgical approach may provide a better outcome, and similarly, if a different technique to deliver radiation therapy is felt to be more likely to provide a better result, this may be recommended rather than stereotactic radiosurgery. Stereotactic radiosurgery is best suited for small lesions that are clearly seen on MRI, CT, or angiography. Larger lesions or multiple lesions may require different management strategies to achieve the best outcome. Occasionally radiation therapy or surgery is recommended before radiosurgery to achieve the best results.
Stereotactic radiosurgery is very rarely associated with complications, and each patient’s case is different, so that all discussions of possible complications should occur with the neurosurgeon and radiation oncologist at the time of the initial consultation.
The physicians that use the Gamma Knife® are interested in developing better ways of assessing who is a good candidate for treatment with this device, and there are several research studies that patients getting radiosurgery may be eligible for. These include studies sponsored by the National Institutes of Health and the National Cancer Institute as well as studies developed by investigators at Yale. Patients are encouraged to ask about research that they may participate in.
A number of tumors are treated with stereotactic radiosurgery with excellent results. Commonly treated tumors include metastatic cancerous tumors that have spread to the brain from elsewhere in the body as well as tumors arising in and around the brain such as meningiomas, acoustic neuromas, and pituitary adenomas. Occasionally, other types of brain tumors or tumors arising from tissues around the brain and skull are treated with stereotactic radiosurgery as well. Other conditions that are commonly treated with stereotactic radiosurgery at Yale include trigeminal neuralgia, in which stereotactic radiosurgery is used to treat an abnormally functioning nerve that is causing severe facial pain and arteriovenous malformations (AVMs), in which abnormal blood vessels exist in the brain and predispose patients to strokes.
The team that provides stereotactic radiosurgery includes not only a radiation oncologist and a neurosurgeon, but also a physicist and a nurse. Important logistical support in obtaining insurance preauthorization and scheduling on the day of the radiosurgical treatment is provided by a dedicated administrative assistant.
Typically, on the day of treatment, before treatment can occur, a dedicated set of images to guide treatment is obtained after the placement of a stereotactic headframe on the patient’s head by the neurosurgeon. These images may include MRI, CT, and angiography. These images are sent to a dedicated computer where the treatment plan is developed by the physicist, radiation oncologist, and neurosurgeon. The plan is evaluated in virtual reality and optimized before any treatment is delivered. Only after the treatment plan has been approved by the radiation oncologist, physicist, and neurosurgeon can treatment start.
The same headframe that was placed at the beginning of the day before the imaging is then used to position the patient’s head with submillimeter accuracy for treatment. A number of successive adjustments of the position of the patients’ head may be required to give the total treatment, but the entire treatment will be completed in a single visit to the Gamma Knife® Center. Following removal of the headframe, the patient is either discharged home or may be admitted for overnight observation.
Alternately, Yale physicians now have the capability of performing frameless Gamma Knife radiosurgery using the Gamma Knife Icon system. This system allows for precise treatment of brain tumors without the need for stereotactic headframe placement. In most cases, however, the additional precision found with the stereotactic headframe makes the headframe still the preferred method of treatment. However, the Icon system gives physicians the flexibility to treat tumors over several days, which sometimes is necessary when tumors are too large or too close to critical structures to allow for safe one-day treatments.
With any form of gamma knife radiosurgery (with frame or frameless), there is no prolonged recovery time; most patients resume their normal activities within 1-2 days. Followup is shared with the referring physicians and the physicians who delivered the treatment and usually includes periodic additional imaging of the brain as well as clinical assessments of benefits and side-effects.