In February, neurology hit the headlines as national newspapers claimed that an epilepsy sufferer had been “cured” using a robot that helped identify the epicentre of his attacks, which was then removed. However, this is not the only engineering advance being made in the field.
The robot in question, called Neuromate, was developed by metrology specialist Renishaw. The procedure, a robotic stereotactic electroencephalogram (sEEG), enables EEGs to be carried out at different depths and sections of the brain.
During the procedure 1.5-2mm diameter holes are drilled into the skull, and 10-20 accurately targeted electrodes are passed into the brain. The electrodes record the brain’s activity from the surface and deep within it and help identify where the epilepsy is originating from.
Less invasive surgery
Stuart Campbell, clinical sales development manager of Renishaw’s neurological products division, says: “It’s a less invasive way of trying to identify where the seizures are taking place.Traditionally following a craniotomy, open brain surgery, strips and grids with electrical contacts are placed on the surface of the brain to monitor the electrical activity.”
The neurosurgeon plans the sEEG procedure using software that sends the trajectory coordinates to the robot. The robot positions itself and the neurosurgeon delivers the instrumentation and electrodes with the robot to the target. Once the electrodes have been implanted, they connect the patient up to a machine which monitors the brain activity.
“The robot itself plays a small, but very important part, in terms of positioning the arm so the electrodes can be precisely delivered,” says Campbell. “It’s a very accurate and stable platform which reduces the time the patient needs to be in surgery. You can pre-plan all these trajectories in advance so the robot moves from one trajectory to another just by hitting a key on the computer keyboard”.
Four of these systems – which can also be used for treating Parkinson’s disease using deep brain simulation and stereotactic biopsies – are being used in the UK.
The company is also developing a system for delivering drugs directly into the brain, again using the robot for the implantable part. Whilst work continues on looking at non-invasive ways of monitoring epilepsy, this technology is a significant step forward in improving epilepsy diagnosis. “Ultimately it would be nice not to perform invasive diagnostic tests in the future, but this is some way off and the neuromate system provides the opportunity to improve the current process,” says Campbell.
“We’re looking at how we can help deliver novel technologies accurately and repeatedly to very small and difficult to reach targets within the brain. It’s a very difficult part of the body to measure and control, but as a metrology company we are applying our engineering know how to this challenging field.“
It’s about reducing the time the patient is in theatre, which reduces the cost to the health service, and hopefully contributing to better patient outcomes. We are talking to lots of neurosurgeons around the world about the technology. We have to see if we can help with these life changing conditions.”
Seeing the brain in 3D
Engineers and clinicians at University College London (UCL) are developing similar technology alongside the National Hospital for Neurology and Neurosurgery. They have developed a 3D neuro-navigation system, called EpiNav, that displays critical areas of the brain to assist in planning and guiding surgical interventions for epilepsy.
Professor Sebastien Ourselin, deputy director of the Centre for Medical Image Computing at the college, says: “It was challenging for surgeons to identify where to insert these electrodes and coping with multiple insertions – there could be up to 16 electrodes and they can’t touch each other or it will damage the signal. You don’t want them to be too close to, or hit, blood vessels.
“Our system enables the clinician to look at the brain in three dimensions: MRIs provide a set of 2D slices of the brain, and we have algorithms to extract 3D images of the surface and components of the brain.
“We provide a way to see all of this information in a more intuitive manner. They can click on where they want an electrode to be placed or they can ask the software to suggest placements if they want to probe specific areas of the brain. All the constraints have been programmed into the software.”
Ourselin says the system has reduced the time taken to plan operations. When surgeons do it manually it takes a minimum of three or four hours, while using the Epilepsy Navigator it takes 10-15 minutes.
The UCL team has recently secured another grant from the Wellcome Trust, which will provide funding for four years, to refine the software and begin clinical trials. The researchers will also develop a mechanical-assisted system to improve implantation in the operating theatre.
Ourselin says: “We want to avoid using the word robot – it won’t automatically do the implantation. We need a way of ensuring that our plan is fully implemented – once an implantation has been carried out we scan the patient and we know that sometimes there is a difference between the plan and the final result.”
John Duncan, professor of clinical neurology at UCL, says: “Renishaw’s technology is very similar to ours, but they use a robotic guidance system to align the electrode trajectory precisely, and the robot being used is a big thing. This month we are going to take delivery of a much smaller robot from Micro Guided Systems.
Precise and safe
“Implementing this to get precise electrode delivery will make the process quicker, more precise and safer, enabling a greater number of patients to be treated.”
UCL will continue to work with the National Hospital for Neurology and Neurosurgery to develop the system, but is also creating an international network of centres to trial its technology.
Ourselin says it is essential for engineers and clinicians to work closely together to solve these types of problems. “The only way to make a difference in healthcare engineering is close collaboration from the beginning to the end of the project between clinicians and engineers,” he says. “We have very frequent meetings with the whole team, from the software engineers to the mechanical engineers, neurologists, and neurosurgeons.
“Sometimes it’s overlooked by engineers who like to solve the problem in the lab and once they have a solution they try to find a way of applying it, rather than capturing the requirement from the beginning with a clinician and delivering something that really makes a difference to patient care.”
Another option for those where medication has failed to control seizures, but the patients are not suitable for surgery, is the Responsive NeuroSimulator system from NeuroPace. The system is made up of a titanium implant, including a battery and programmable computer chip, which rests in a contoured tray screwed to the patient’s skull. Two five-inch-long electrodes are inserted into predetermined areas of the brain which are attached to the stimulator by five-inch leads – their job is to send current to the electrodes.
The system monitors the brain’s signals, interprets them, provides stimulation when needed, and then assess the brain’s response. Previous neurostimulation therapies stimulated the brain without determining the need for treatment or monitoring the brain’s response.
NeuroPace’s system can provide doctors with meaningful data about seizure and brain activity, as each patient has a monitor at home to wirelessly collect and upload data from their neurostimulator. Frank Fischer, chief executive of NeuroPace, says: “We’re learning so much about the brain and its response to stimulation that I’m as excited about the potential for future developments as I am about the current product.” So far, 130 of these devices have been installed in US patients since the Food and Drug Administration gave its approval in 2013.
Also in the US, engineers at Tennessee-based Vanderbilt University have developed a working prototype of a robot designed to treat epilepsy by entering the brain through the cheek, which avoids having to drill through the skull and is much closer to the target area, dramatically reducing the patient’s recovery time.
The device consists of a 1.14mm nickel-titanium needle that operates like a mechanical pencil, with concentric tubes, some of which are curved, that allow the tip to follow a curved path into the brain.
A robotic platform, which has been designed to operate in the intense magnetic field of a MRI scanner, advances the needle segments a millimetre at a time using compressed air. The needle is inserted in tiny steps so the surgeon can track its position by taking successive MRI scans. The engineers have designed the system so that much of it can be made using 3D printing, keeping costs down.
Joseph Neimat, associate professor of neurological surgery at Vanderbilt Medical Center in Nashville, says: “The systems we have now that let us introduce probes into the brain deal with straight lines and are only manually guided. To have a system with a curved needle and unlimited access would make surgery minimally invasive. We could do a dramatic surgery with nothing more than a needle stick to the cheek.”
The robot could be in operating theatres within the next decade.
Reaching more patients
US company Monteris Medical’s NeuroBlate system is also being used to treat epilepsy in the US. Under realtime MRI guidance, the system employs diode laser energy delivered via a CO2-cooled fibre-optic probe to remove the area of the brain where the epilepsy originates. Thermography measures when it has reached the proper temperature.
Neimat says: “It’s exciting to have these new technologies. If you talk to people who are leading epilepsy programmes, they feel the field has changed dramatically in the past five years. It’s estimated that something like 5% of the patients eligible for surgery actually get operated on.
“We’re hopeful that these new technologies will make it more feasible to reach and help more epilepsy patients.”