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THE NEUROMATE® NEUROSURGICAL STEREOTACTIC ROBOT
The CEDIT was consulted by Professor Yves Keravel, Head of Neurosurgery and by Ms. Laurence OUADI, Head of Purchasing at the Henri-Mondor Hospital, for an evaluation of the NeuroMate® neurosurgical robot in view of a possible purchase of the new computerized control system.
TECHNICAL ASPECTS
The NeuroMate® system from the company ISS is a robot arm designed for the stereotactic positioning of an instrument-holder for surgical tools typically used in stereotactic Neurosurgery. It has the functions of the "AESOP" voice-command robot arm (cf. CEDIT file N°00.01), but is navigated by a computerized system using pre-operative 3D images (MRI, CT). It enables, in two possible function modes (with or without stereotactic frames):
- accurate and automatic positioning of the instrument-holder;
- visualization of instrument position in real time on a workstation. The NeuroMate® then acts as a single-axis neuronavigation system, that axis being the depth of penetration in the brain1.
This robot arm with 5 axes of movement consists of:
- mechanical systems to match the patient with the robot arm. Accessories to maintain patient position differ according to the function mode selected;
- an imaging workstation (VOXIM) with software for planning, for matching pre-operative images with the patient, for positioning the robot arm (ActMate) and for visualization of the instrument during the operation. Advance simulation of the operation can also help configure the arm (positioning its movements) for optimal ergonomics given the chosen trajectory and the case to be treated;
-an instrument-holder on which is fixed a tool guide. A linear potentiometer measures tool advancement;
- specific localizers to be used in the frameless version, with an ultrasound transmitter-receiver.
Regulatory Issues: the NeuroMate® received FDA clearance in May 1997 and an extension in May 1999 of its clearance for frameless stereotactic neurosurgical procedures. The full system, including the robot arm and VOXIM software control unit, has received CE markings.
Installed sites: in France, the Teaching Hospitals of Grenoble, Lille, Nantes, and the Fondation Rothschild in Paris are equipped with the machinery. According to the manufacturer, three other systems have been sold in the world.
Technological changes: first designed for stereotactic neurosurgery, the NeuroMate® might develop further in two directions:
- multipurpose use with the development of new applications such as spine surgery;
- the development of neuroendoscopy with isocentric displacement of the endoscope for very small zones.
Today's limitations on the use of robotic systems such as the Neuromate® are not related to their basic accuracy but to disadvantages inherent in MRI technology (magnetic sensitivity, non-linear gradients).
MEDICAL ASPECTS
The literature in the field is mainly descriptive (feasibility studies). The neurosurgical team in Grenoble, the first to have developed the Neuromate®, is the only one to have provided information on the benefit of robotics in stereotactic neurosurgery, such as reaching targets that are difficult to access, pre-operative simulation for teaching purposes, etc.
The bulk of data on the indications and benefit of the NeuroMate®, however, comes from the experience of users.
Since the goal is to reach lesions or cerebral functions without touching functional or vascular structures, this robot is used mainly in stereotactic biopsies, functional neurosurgery and neuroendoscopic surgery. It allows guidance of the cranial approach in stereotactic biopsies which are difficult to conduct and particularly risky. The accuracy of positioning and repositioning the NeuroMate® is shown to be crucial in small-size lesions occurring in deep and highly functional areas. This accuracy, equal to or less than 0.5 mm, is not provided by current techniques of neuronavigation. In addition, use of the robot is part of the current development of functional neurosurgery; whether in pain surgery, deep cerebral stimulation as in Parkinson's Disease2 or presurgical exploration of pharmaco-resistant epilepsy. Other possible applications are cell therapy and interstitial brachytherapy.
ECONOMIC AND FINANCIAL ASPECTS
The catalog price of the NeuroMate system (inclusive of all taxes) is 1,840 KF for the stereotactic frame-based version (including the robot arm NeuroMate® and its base, a central control unit for the arm, the Voxim workstation for visualization, software for planning and position simulation, and accessories). The catalog price of a stereotactic frame and its accessories is 450 KF (inclusive of all taxes).
An additional 1,200 KF (inclusive of all taxes) is required for the frameless stereotactic version (head frame and its base, specific localizors and ultrasound system). The maintenance contract (preventive and corrective) is offered at 314 KF (inclusive of all taxes) per year.
In its frameless version, use of the NeuroMate system in a department of the AP-HP would mean an annual supplementary cost of 380 KF (annual cost of the machinery and maintenance including financial costs at the current interest rate of the AP-HP). A single-use sterile operative cover is required for each intervention. The additional cost of consumables is 1,142 F (inclusive of all taxes) per intervention.
The various economic advantages expected from use of the robotic system in operative planning and operative assistance (shorter operation times, less complications and repeat interventions) have yet to be demonstrated.
Stereotactic neurosurgical procedures, conducted with or without the robotic system, are included in overall hospital budgets.
Robotic systems seem rather to improve accuracy and operative safety than enable overall advances in productivity. The high investment of this machinery, therefore, requires sustained levels of stereotactic neurosurgery and efficient co-ordination with neuroradiology departments.
RECOMMENDATION
This robot is seen to meet the requirements of accuracy, innocuity and "minimal invasion" characterizing neurosurgical practice. No other technique of neuronavigation currently provides this degree of accuracy.
The CEDIT recommends the NeuroMate® stereotactic robot for centres handling a large number of patients with stereotactic neurosurgery indications, but also recommends a harnessing of expertise (neurology, neuroradiology, neurosurgery, neurophysiology) with recognized experience in the field. The neurosurgery department of the Henri-Mondor hospital corresponds to these requirements.
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