One of the most important clinical research aspects of electrical stimulation is the positioning of the DBS device during surgery. One millimeter difference in any direction can significantly affect the outcome.
"We're trying to provide visual feedback to the clinicians to improve their ability to understand how the stimulation is actually interfacing with the nervous system", stated Cameron C. McIntyre, Ph.D., assistant professor, Department of Biomedical Engineering, Lerner Research Institute, The Cleveland Clinic. "These devices need to be implanted within the brain in a very specific location. If you want to start making predictions on the kind of micro scale that we are interested in, you need to have detailed models that accurately represent the properties of the brain tissue and the electric field generated by the stimulation. To do that takes intense computer modelling techniques and, as a result, some very intense computation."
That is where the Silicon Graphics Prism visualization system comes into play. The large shared-memory and scalable computing capability of Silicon Graphics Prism will, for the first time, allow Cleveland Clinic researchers to view and work with stimulation anywhere in the brain interactively.
Dr. McIntyre and research associate Chris Butson, Ph.D., recently purchased a Silicon Graphics Prism visualization system running the Linux operating environment, with eight Intel Itanium 2 processors, 16GB RAM, and four ATI graphics pipes. The main modelling software used is SCIrun - SCI stands for Scientific Computing and Imaging, originally developed at the SCI Institute at the University of Utah. The Silicon Graphics Prism provides a shared-memory and multiprocessor environment with integrated visualization capability, all of which are important from a human interface standpoint.
"The neurologists who are doing these kinds of implants and programming these patients have limited visibility as to what's happening inside the brain", Dr. Butson stated. "It's really a trial-and-error process. With Silicon Graphics Prism, we anticipate being able to do whole-brain simulations and run these whole-brain models to create a near real-time visual feedback system for the neurosurgeons and clinicians. The integration of visualization, shared-memory and multiprocessing capability are integral to this process and we can't get that with any other architecture."
One of the Clinic's main goals with the Silicon Graphics Prism system is to implement a "near real-time visual feedback system" as both a pre-operative and a post-operative component of DBS. Drs. McIntyre and Butson want to provide the neurosurgeon with feedback before the doctor implants the electrode and, once it's implanted, help the neurologist customize the stimulation to the individual patient.
"These devices have thousands and thousands of combinations of stimulation parameters that can be adjusted, Dr. McIntyre explained. "For example, the technology can be customized based on a patient's particular symptoms and behavioural responses to the stimulation."
However, it is often difficult for a clinician to know what stimulation parameters are optimal for a given patient, and physicians currently only have trial-and-error clinical analysis to guide the parameter selection process. Therefore, clinicians are using anatomical and electrical models of DBS to provide patient-specific customization of the treatment by using the Silicon Graphics Prism for unparalleled visualization and computation capabilities for the clinician.
"Once the device is implanted, we can then provide the theoretical optimum of how the stimulator should be tuned or adjusted to target the stimulation to a specific part of the brain", Dr. McIntyre stated.
Ongoing clinical trials using neurostimulation devices are occurring for a wide range of diseases in many venues. Though not yet approved by the FDA, promising trials of DBS technology include symptom relief of obsessive-compulsive disorder, major depression, and epilepsy.
"The alleviation of suffering made possible by surgical implantation of electronic neurostimulators is improving the quality of life for countless people", stated Shawn Underwood, director, Visual Systems Group, SGI. "The immediate surgical benefits of full-brain visualization provided by the Silicon Graphics Prism system at the Cleveland Clinic will benefit hundreds if not thousands of future recipients of deep brain stimulation technology. The future possibilities in research and development of disease-specific devices sound like something out of science fiction and yet, here it is - soon to be a reality - made possible by SGI visualization technology which continues to power the best and brightest science and research the world over."
The Lerner Research Institute is home to all laboratory-based research at the Cleveland Clinic. Its mission is to understand the causes of human diseases and to develop new treatments and cures.