Frameless Stereotactic Surgery

The frameless stereotactic apparatus allows the surgeon to navigate through the spine and cranium with image guidance. CT or MR images of the surgical field  are imported into the computer software. A digitizing camera senses the position of the surgeon's instruments in space and indicates the position of the instrument on the image displayed on the computer monitor in real time, as the operation proceeds.
The advantages include:    

We use the Danek-Stealth system. This has proven to be very useful in biopsy, tumor removal and spinal instrumentation. An example of intracranial tumor removal is the case of a young woman who developed a seizure disorder. An MRI scan disclosed a small, enhancing area in the right temporal lobe. Within several weeks the tumor had grown several centimeters in diameter and surgery was recommended.

Prior to surgery several fiducial markers were fixed to the head and she underwent MRI scanning once again. These images were imported into the Danek-Stealth work station and the surgeons developed a surgical plan with the software. After anesthesia was begun, the computerized images were merged with the patients cranial anatomy by touching each fiducial marker on the skull with a probe containing light-emitting diodes. A digitizing camera linked to the computer senses the LEDs, allowing the computer to "see" the probes position in space.   Special surgical instruments, containing LEDs   can also be followed in space by the computer. The position of the instruments is indicated on MRI scans in  the work station monitor. This allow precision in the surgical exposure, and optimizes tumor removal.

Image guided surgery is useful in the placement of instrumentation to stabilize the lumbar spine. In this example, a young lady developed spinal instability   leading to severe low back pain following a previous lumbar laminectomy and discectomy. Because of the failure of conservative measures and her disability, a fusion of adjacent lumbar vertebrae was recommended. Internal fixation with pedicle screws and rods enhances the prospects for a successful fusion. The Stealth image guidance system allows preoperative planning for accurate placement of the pedicle screws. In this case CT scans were obtained a week prior to surgery and imported into the work station. The surgeon developed a surgical plan for the placement of each of four pedicle screws. At surgery, a drill guide containing LEDs was oriented into the precise trajectory for each screw using image guidance. The width and screw length were calculated and the screws were accurately placed, avoiding injury to adjacent nerves.