the use of a high-powered microscope or other means of visual magnification during surgery, along with tiny surgical tools that enable the neurosurgeon to perform exceptionally delicate operations. Microsurgery is used where the structures in the brain are very small and precise movement is crucial. This technique may be helpful in removing tumor wrapped around blood vessels or nerves, or along the bony ridges of the skull base. NEURO-ENDOSCOPY A neuro-endoscope, or endoscope, is a long, narrow tube that has a camera lens and a light source at the end. Endoscopes are used to visualize hollow pathways in the brain, such as the ventricles. The endoscope is inserted through a small hole in the skull, then threaded into a ventricle. The endoscope provides a lighted picture of the area as it appears at that moment, in “real-time.” A surgical laser can also be attached, giving the neurosurgeon the ability to perform a biopsy within the ventricle, to remove blockage from a shunt, to remove tumors found in the ventricle and to remove cysts. Since this tool is long and very narrow, an endoscope is generally not used to remove larger tumors or tumors which are accessible with traditional surgical tools. PHOTODYNAMIC THERAPY (PDT) Photodynamic therapy is a procedure that involves the use of both a laser and a sensitizing drug. Just prior to surgery, the drug is injected into a vein or artery where it travels through the bloodstream and is absorbed by the tumor. The drug contains a special compound that causes tumor cells to appear a fluorescent “glowing green.” During surgery, the neurosurgeon aims the laser at the tumor, which activates the drug and kills the tumor cells. This type of therapy does have limitations: www.abta.org 19 SURGERY • Only tumors that are considered operable can be treated with this method. • Only tumor cells that are visible to the neurosurgeon can be identified and treated using the sensitizing drug. Portions of a tumor may be hidden and not susceptible to light. • Some tumors will not respond to the sensitizing drug. • Tumors near the brain stem cannot be treated with this method due to the risk of swelling that might occur. POLYMER WAFER IMPLANTS Because the cells of a malignant tumor may spread into the area surrounding the tumor, additional therapies may be suggested. Polymer wafers, also called Gliadel wafers or wafer implants, are one of these forms of additional treatment. Soaked with chemotherapy drug, the wafers can be placed in the tumor site at the time of surgery. Traditional forms of chemotherapy are given by mouth or injected into your bloodstream through a vein. One of the more common drugs given in chemotherapy is called carmustine, or BCNU. While BCNU has been shown to be effective in some patients, it can cause damage to the bone marrow when given into a vein. The bone marrow is where new blood cells are made. To avoid this side effect, researchers developed thin, dime-sized wafers soaked with BCNU that can be directly placed into the brain cavity where the tumor used to be. They can be inserted during the tumor removal surgery and require only a few additional minutes. As the neurosurgeon removes the tumor, up to eight wafers can be implanted into the brain cavity. The neurosurgeon then surgically closes the area, allowing the wafers to do their work. These wafers gradually dissolve over a two to three week period and bathe the surrounding cells with BCNU. It is usually not necessary to remove the wafers since they are bio-degradable. 20 AMERICAN BRAIN TUMOR ASSOCIATION This method of delivering BCNU: • Allows a controlled and predictable delivery of the chemotherapy drug to the tumor • Eliminates the overall effects of traditional chemotherapy drugs on the body as they pass through the body on their way to the tumor • Targets chemotherapy in the specific area that needs treatment • May increase the risk of wound healing problems • May make a patient ineligible for some clinical trials STEREOTACTIC SURGERY The use of highly advanced computers to locate and create a three-dimensional image of a tumor is called stereotaxy. When used during surgery, this technique is called stereotactic surgery. Conventional X-rays can only measure two dimensions: height and width. Stereotaxy adds the third dimension of depth, which enhances the neurosurgeon’s ability to precisely map the location of the tumor and find the best and safest pathway for removing it. Wafer Placement in the Cavity Created by a Tumor Removal SURGERY www.abta.org 21 Stereotactic techniques may be used to prepare for a surgery, during biopsy or tumor removal, while implanting radiation pellets, or to provide a navigation system during surgery. These techniques are especially useful in locating and removing tumors deep within the brain, such as brain stem and thalamic tumors. Stereotactic systems are used in operating rooms, enabling surgeons to view images of the brain as surgery is being performed. Some stereotactic techniques use a head frame and others do not. Frame-Based Stereotactic Surgery With frame-based stereotactic surgery, a lightweight frame is attached to the skull at four points. Local anesthesia is used to numb the places where the pins contact the skull. Once the frame is attached, a CT, MRI or dye scan (angiography) is done. Since