2/3/97

Regulus Navigator (RN) is a tool used by neurosurgeons to help them during brain surgery. The Regulus is able to take CT scan and MRI information and allow the surgeon to know precisely where he is within the brain at all times. This study will help surgeons find out how useful the instrument is, what degree of accuracy is possible and the situations in which it might be helpful. The Regulus consists of a sophisticated computer, which is capable of taking information from the CT and MRI scans. It then creates a display on a computer screen in the operating room which the surgeon can use during surgery. It is able to use a special pointer in the area where surgery is being performed, and that location will be displayed on the screen in reference to the abnormalities on the imaging studies.

Participation in this study will include a standard physical exam and diagnostic work-up, as well as imaging studies. Routine procedures pertaining to all other brain surgery performed in the hospital will be maintained. The only addition to the standard procedures will be the use of the Regulus Navigator. Before surgery, the participant in the study will be taken for a CAT and MRI scan, and will have 3 marks placed on the head. The information created by the scanner with the marks in place is fed into a stereotactic computer.

During the surgery, 3 points on the patient's head are selected and with the Regulus Navigator, the computer performs a process relating the markers on the images to the actual patient's anatomy. This is called a mathematical transformation. The location of the pointer from the Regulus Navigator is then displayed as a mark on the computer screen with the patient's diagnostic studies. That mark will help the surgeon orient himself precisely during the surgery in relation to the abnormality being operated upon.

The potential benefits during a frameless stereotactic procedure are:

• You will not have the stereotactic headframe applied for data acquisition (CT, MRI, Angiogram)
• Smaller incisions
• Smaller bone opening
• Less brain trauma
• Greater tumor removal
• Shorter time in the operating room
• Fewer neurological deficits
• Shorter hospital stay