Neurosurgical robot may boost brain operations in near future

Calgary 29 February 2004A prototype surgical robot has the potential to make brain surgery more accurate and precise than ever while re-creating the "sound, sight, and feel" of conventional neurosurgery, according to an article in the March issue of Neurosurgery. In the article, Dr. Deon F. Louw from the University of Calgary and colleagues describe the design and initial "breadboard" testing of the neurosurgical robot, dubbed neuroArm. The neuroArm, the first robot created for the specific purpose of performing micro-neurosurgery, was developed by the Canadian company MD Robotics, on commission from the University of Calgary.

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MD Robotics, working in collaboration with the Seaman Family MR Research Centre, at the University of Calgary's Foothills Hospital in Calgary, designed the neuroArm, a robotic tool for neurosurgery that represents the most advanced medical robotic device available in the world. The neuroArm system consists of two robot arms, each with eight degrees-of-freedom movement, which are manipulated by the surgeon, and a third arm equipped with two cameras providing 3D stereoscopic views. The independently operated robot arms can be fitted with special surgical tools, such as forceps or dissectors, and so forth.

The system functions under the direct control of a surgeon at the robotic workstation for all intra-cranial functions. The surgeon uses sophisticated hand controllers to translate his or her hand movements into motions of the robot arms. In initial tests, the controller accurately positioned surgical tools to within 30 micrometers, even better than the 100 micrometer resolution called for in the system design.

The hand controllers include force sensors to provide the surgeon with tactile feedback, lending a realistic "feel" to the operation. The neuroArm system uses filtering to eliminate the natural tremour of the hand. It also scales down the surgeon's hand motions to achieve greater precision than possible with the unaided human hand for example, moving the controller ten centimeters will move the "effector" holding the tool by only five millimeters. Safety switches are incorporated to prevent accidental movements from being transmitted to the robot arm.

The surgeon operates the neuroArm from the workstation with displays showing the live three-dimensional magnetic resonance imaging (MRI) scan of the patient's brain, including the position of the tool currently being used. Another display shows a colour video view of the brain through a surgical microscope, while a third provides system data and control settings. The system allows for updated MR images to be obtained during all phases of an operation without moving the patient. 3D stereoscopic and MRI generated views provide real-time data to the surgeon.

The robot arms and all associated systems are designed to be fully compatible with the MRI scanner in which the neuroArm operates. Under MRI guidance, the surgeon can navigate safely and accurately within the brain, with the tools' positioning confirmed by registration with the patient's MRI scan. Using the neuroArm's image guidance system, the surgeon can plan and even practise virtual operations before the actual surgical procedure.

Working with a specialized set of tools, neuroArm is designed to perform soft tissue manipulation, needle insertion, blunt dissection, suturing, grasping of tissue, cauterizing, cutting, manipulation of a retractor, tool cleaning, suction and irrigation. The neuroArm will have two basic modes of motion: coarse and fine. Coarse motion will be used for the extra-cranial motions such as moving to the work site, tool change and tool cleaning. Fine motion is used for intra-cranial operations where motions are slower, but very precise.

The project will serve as a base platform that can be extended to other types of surgery. In particular, operations that require image guidance and precise motion. Future applications include spinal surgery, where intra-operative images can be used to guide tools to precise targets while avoiding critical structures, and eye surgery. The neuroArm is also likely to find uses in surgical training and distance surgery or telesurgery.

Final construction on the neuroArm system will be completed this spring. Preliminary studies of its capabilities will then begin, eventually working up to live human studies. The neuroArm promises to enhance the neurosurgeon's fine motor control, while reducing fatigue during lengthy brain operations. Dr. Louw and colleagues concluded: "Embracing medical manipulators will allow neurosurgery to transcend these restraints and enter a new era in which robots supplement, not supplant, surgeons and together perform tasks better than either can do individually."


Leslie Versweyveld

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