The concept of stereotactic brain surgery is simple. This technique uses images of the brain to guide the surgeon to a target within the brain. A colorful term for this surgery is neuro-navigation! This technique may utilize an external frame attached to the head (frame-based) or imaging markers attached to the scalp (frameless or image-guided surgery) to orient the surgeon in his approach. The term "stereotactic" was coined from Greek and Latin roots meaning "touch in space."
With frame-based stereotactic surgery, a light-weight frame is attached to the head using local anesthesia. The head is imaged by CT, MR or angiography to identify the target in relationship to the external frame. Since both the frame and the target are "seen" in the images, the distance of the target from reference points on the frame can be measure in three dimensions. Surgical apparatus attached to the head frame can be adjusted to the three-dimensional coordinates of the target, and the target can be accurately approached by the surgeon. A common example is stereotactic brain biopsy. Deep tumors within the brain may be difficult and dangerous to approach by an open operation. Using a stereotactic biopsy apparatus fixed to the head frame and adjusted to the target coordinates, a biopsy probe is passed through a small hole in the skull to sample tissue for diagnosis.This technique is also used to place electrodes in the deep brain to treat movement disorders such as Parkinson's disease.
Frameless stereotactic surgery relies on fiducial markers which are taped to the scalp before the brain is imaged. In the operating room, the orientation of these markers is used to register the computer containing the brain images. Once registration is completed, the computer can show the relationship of our surgical instruments to the imaged brain. Frameless or image guided surgery is very helpful for the accurate approach and removal of large brain tumors.
Click here for more information on image guided neurosurgery.