Computer Assisted Surgery (CAS)
Computer-assisted surgery (also called image-guided surgery) is a broad term used to indicate an operation in which imaging scans and computer technology are used to make a three-dimensional (3-D) model of an organ. In the case of neurosurgery, the 3-D model is of the brain. The neurosurgeons use the model as a guide to safely and precisely navigate to and treat a tumor, vascular malformation, or other lesion in the brain.
Before computer-assisted surgery, neurosurgeons had to make a large incision in the scalp and an equally large opening in the skull to get a full view of the brain and other structures and locate the lesion. With computer-assisted surgery, our neurosurgeons can:
- Make much smaller incisions and openings
- Perform minimally invasive procedures
- Locate the lesion efficiently, resulting in a shorter length of operation
- Know where critical structures are and avoid them
- Plan, and even simulate, the best route to take
For brain tumors, computer-assisted surgery has allowed some tumors that were historically inoperable because of their location to become operable, meaning more patients are able to be successfully treated with surgery. Also, since they can visualize the tumor in 3-D with this technology, our neurosurgeons can resect tumors more completely while minimizing risk to healthy surrounding tissue, nerves, and blood vessels.
At Columbia University Irving Medical Center/NewYork-Presbyterian Hospital, our neurosurgeons use the most sophisticated computer-assisted navigation systems to perform computer-assisted surgery.
One system in use at Columbia uses robotic technology; it is called Robotized Surgical Assistant (ROSA). ROSA is both a computer system that can create 3-D maps and models of the brain and also a surgical tool that can assist our neurosurgeons during certain surgical procedures where pinpoint precision and accuracy are key. The ROSA system is frequently used during epilepsy surgery, stereotactic biopsy, brain tumor surgery, AVM surgery, and pediatric neurosurgery.
Stereotactic neurosurgery is a form of computer-assisted surgery. Specifically, stereotactic neurosurgery is a technique that uses computer technology, brain imaging, and a coordinate system to produce a 3-D model of the brain in order to locate a lesion.
The coordinate system can be either a rigid mechanical frame surrounding a patient’s head, referred to as frame-based stereotactic neurosurgery, or created by using reference points on the patient’s skull, referred to as frameless stereotactic neurosurgery. Which technique is used depends on the condition treated.
When is Computer Assisted Surgery (CAS) performed?
At Columbia University Irving Medical Center/NewYork-Presbyterian Hospital, our neurosurgeons use computer-assisted surgery for nearly all neurosurgical procedures in order to achieve the highest precision possible. Some of the more common surgical treatments in which computer-assisted surgery is used include:
- Minimally invasive surgery
- Endoscopic neurosurgery
- Endovascular neurosurgery
- Stereo EEG placement
- Deep brain stimulation
- AVM surgery
Computer-assisted surgery can be combined with other neurosurgical techniques, such as functional brain mapping. It can also be used as a part of diagnosis, as in the stereotactic biopsy of a brain tumor.
How should I prepare for Computer Assisted Surgery (CAS)?
First, either the head frame is attached to the head (for the frame-based technique), or tiny markers called fiducials are attached to the face and scalp (for the frameless technique).
Next, the brain is imaged, most often by magnetic resonance imaging (MRI).
Brain scans are then transferred to the computer system, and a 3-D model of your brain is created on the screen.
Next, the position and dimensions of the patient’s head are matched to the brain images taken earlier. This procedure, called registration, is done by touching a wand-like tool to the fiducials on the scalp and gently tracing the tool across the surface of the face and scalp. If a frame is used, the computer system automatically detects the fixed frame.
With a 3-D model of the brain and the registration complete, the neurosurgeon can begin planning the optimal route to reaching the target destination. Using a surgical pointer, the neurosurgeon can gently touch an area on the scalp or inside the brain and see on a monitor exactly what structures are located there. This technology provides the neurosurgeon with a crystal clear path that avoids critical structures.
The neurosurgeon then performs the treatment procedure.
Throughout the treatment procedure, the neurosurgeon uses the computer assisted navigation system to navigate safely and precisely around healthy brain tissue and critical structures, such as nerves and large blood vessels.
Also, the technology can be used toward the end of the procedure, particularly for brain tumor surgery. If a brain tumor is being removed, the neurosurgeon can use a pointer to gently touch the tissue from where the tumor was removed to determine whether the tumor has been completely removed.