Interview by Kal Kaur
In this Thought Leader interview, Professor J. Marc Simard, professor of neurosurgery at the University of Maryland's School of Medicine, talks to Kal Kaur from AZoRobotics about his work on a prototype robot for intracranial brain surgery.
KK: The neurosurgical intracranial robot prototype is a great example of how technology is starting to shape the world of surgical practice. Can you explain how this robot works and the functional components to this robot that allow it to perform?
JMS: There are several critical aspects of this robot that are different from anything currently available: (i) The robot is designed to work outside of the line of sight; that way, it can be placed into a tumor deep inside the brain with minimal harm, and once inside the tumor it can freely deploy to all regions of the tumor to destroy and remove it. (ii) The robot is designed to be under direct control of the operating neurosurgeon at all times, to assure maximum safety. (iii) The robot is MRI compatible; therefore, surgery will take place within the MRI scanner, with the neurosurgeon guiding the robot based on “frequently updated” MR imaging.
KK: How does the neurosurgeon work with this robot to conduct surgical procedures?
JMS: As noted above, the neurosurgeon watches the actions of the robot using “frequently updated” MRI, and guides the robot as it works from inside the tumor to resect the tumor.
KK: The UMB and UMCP research project have developed a “minimally invasive neurosurgical intracranial robot prototype”. Can you explain how your research team have been able to demonstrate its feasibility?
JMS: We have several models that have been used for development and to test feasibility. Most of the early work, as well as ongoing work, has been carried out using models of brain tumor, wherein a piece of animal tissue such as fat (because fat is easily seen on MRI) is placed inside of a model brain constructed of ballistic gel. This simple model has been extremely useful, since it reproduces many of the critical requirements of surgery without risking life. Subsequent demonstrations of feasibility have utilized a model of metastatic brain tumor in swine. We are still working with this model also.
KK: Can you discuss some of the next level challenges that are the basis of this project?
JMS: The current development work is focused on implementing robot manufacture using materials and actuators that are virtually transparent to the magnetic field of the MRI, thereby assuring minimal distortion of MR imaging. This aspect is something that we learned is of great importance in the last development cycle.
KK: The MINIR-II prototype is designed to obtain target information from a real-time MRI via sensors embedded within this system. Can you describe these sensors and how they work to make this robot more intuitive?
JMS: The sensors provide real time information on the precise location of the robot within the predefined target volume. These sensors report their location based on sensing the magnetic field of the MRI.
KK: With this technology having the potential to manage patients with difficult-to-reach intracranial tumours, it carries the advantage of being able to operate in smaller increments than a surgeon’s hand. Can you explain how precise this robot is in conducting such intricate procedures and the advantages of this to the patient and physician?
JMS: You are correct that the robot is designed to operate with high precision, but I would point out that surgeons currently working with magnified vision also are able to achieve remarkably precise maneuvers, e.g. sewing together 2 blood vessels that are 1 mm in diameter using multiple sutures much smaller than the finest human hair, spaced ~0.1 mm apart. The real limitation faced by all current surgery is that it has to be performed with line-of-site target visualization and target manipulations. The breakthrough promised by the robot is the capability to operate outside of the line-of-sight. This alone will revolutionize brain surgery.
KK: How is the recovery time for the patient affected by the application of this robot in conducting surgery on difficult-to-reach brain tumours?
JMS: Any time that manipulation of the brain is minimized, the patient fares better. At present, a simple procedure such as a brain biopsy can often be performed quickly, with no harm to the patient, who typically is discharged from the hospital the next day. In the future, the surgery to remove a deep tumor will resemble that of today’s simple biopsy in terms of patient involvement, and should allow the patient to be discharged the next day from the hospital.
KK: This robotic prototype system has been developed over a number of years. During this development phase, what has been the biggest challenge in terms of its design, development, and functional principle? Are there still elements to this robotic system that could be changed to optimise it from a structural and functional perspective?
JMS: One aspect that will continue to evolve is miniaturization, again, to push the boundaries of minimal harm to the brain.
KK: What are the future challenges for this project and how do you plan on addressing these challenges?
JMS: One of the greatest challenges that can be anticipated is how to deal with a highly vascularized tumors. We believe that the average tumor with average vascularization should be readily managed by the robot, but some tumors are highly vascularized, making the resection more difficult, and more dangerous. However, I am confident that we will develop the technology to deal with this, perhaps using local delivery of a ‘cocktail’ of vasoconstrictors and thrombogenic drugs, coupled with local tissue cooling to reduce blood flow.
KK: How do you see application of this robotic system diversifying within then field of surgical practice?
JMS: Solutions to the surgical challenges faced by neurosurgeons operating on the brain can be used to help general surgeons operating on tumors in other organs, for example, metastases in the liver and elsewhere. The concepts are similar, if somewhat less critical – safe, complete tumor resection with minimal harm to the organ.
About Prof. J Marc Simard MD Phd
Professor of Neurosurgery, Pathology and Physiology at the University of Maryland School of Medicine, Dr. Simard received his M.D., Ph.D. from Creighton University in 1980 and completed his residency training in neurosurgery at the University of Florida.
In 1983, he worked with Professor Hans Meves as a post-doctoral fellow at the Physiologisches Institut at the Universitat des Saarlandes in Germany. A board-certified neurosurgeon, Dr. Simard specializes in the treatment of brain tumors, stroke, and related diorders with special emphasis on carotid endarterectomy, aneurysm, and arteriovenous malformations treated by advanced microsurgical techniques and by Gamma Knife. He serves as Chief of Neurological Surgery at the Baltimore Veterans' Affairs Medical Center.
As Director of the Department's Cerebrovascular Research Laboratory, Dr. Simard studies cellular mechanisms regulating cerebral blood flow. A primary focus of this research involves patch clamp study of ion channel function in cerebral smooth muscle. The patch clamp, an exquisitely sensitive method for testing and recording cellular electrical currents, has been employed in the lab's recent investigations of calcium and potassium channels in smooth muscle cells from the basilar artery and in PC12 cells.
Dr. Simard has also recently published findings on early signaling events by endotoxin in neuronal cells and is currently studying ion channel function and regulation in astrocytes activated by injury to the central nervous system. The laboratory's work is funded by grants from the National Institutes of Health, the American Heart Association, and the University of Maryland School of Medicine. Dr. Simard has been an NIH-funded researcher for eight years and serves on the Neurology Advisory Panel of the National Institutes of Health. He has directed the work of several doctoral students.