Brain surgery is one of medicine’s riskiest procedures. In 10 percent of all cases, the surgeon inadvertently damages areas of the brain; the rate of risk is usually higher in other, more complicated, neurological operations. So, imagine a technology that helps perform brain surgery with 10 times greater sensitivity than a surgeon’s hands.
That is precisely the goal of Robocast, a multinational project involving Israeli researchers that relies on robotic technology to assist medical specialists. In this “keyhole” (that is, minimally invasive) neurosurgery, a robotic sensor is inserted into a tiny hole in the skull, called a burr hole. Needles and catheters are inserted through the hole into the brain for purposes of both biopsy and therapy. These include, among others, the tasks of blood/fluid sampling, tissue biopsy, cryogenic and electrolytic ablation, brachytherapy, deep brain stimulation (DBS), diagnostic imaging, and other surgical procedures.
The technology can assist those with epilepsy, Parkinson’s disease and clinical depression, among other conditions.
The project has been undertaken by Israeli researchers from both the Hebrew University’s Laboratory for Computer Aided Surgery and Medical Image Processing and the robotics laboratory of the Technion – Israel Institute of Technology. They are part of a consortium, funded by the European Union, that also includes researchers from Britain, Italy and Germany.
In addition, with no connection to the consortium endeavor, Israeli researchers – led by Dr. Yigal Shoshan (director of the neurosurgery department at Hadassah University Hospital, and a participant in the Robocast project), and Prof. Leo Joskowicz, of the Hebrew University Laboratory for Computer Aided Surgery – have recently developed a computer program that enables neurosurgeons to plan in advance the safest possible course for a procedure. The program collates data taken from relevant, previous procedures performed on the patient, supplements it with the results of MRI and brain-mapping procedures. “We are not necessarily talking about the shortest surgical route available, but rather the safest one, in accordance with data compiled from image processing,” explains Dr. Shoshan.
“Today’s neurosurgery procedures make use of navigation systems that help the surgeon reach the target area in a precise fashion. Yet these systems do not factor in parameters such as blood vessels, or regions in the brain that influence movement and language and which are also connected to the senses,” notes Shoshan. “The new program relates to such parameters, and it therefore improves the efficiency of procedures.”
Shoshan adds that “there are certain tracks in the brain that cannot be detected by the unassisted eye; if they are cut accidentally, some of the patient’s functions are liable to be impaired.” These areas, called “white matter,” operate alongside ‘gray matter,’ the brain cells that initially assimilate data.
“Pyramidal tracts, for example, relay orders between the cerebral cortex and the spinal cord and muscles − these orders relate to the body’s movement. If such tracts are damaged, a patient can end up being paralyzed after the operation.”
Dr. Shoshan adds that “in neurosurgical procedures, damage to the brain’s visual tracts must also be avoided; these are tracts which relay information between the eyes and the cerebral cortex. Also to be avoided is damage to another tract linked to the brain’s language center.”
Brain surgery on the rise
In Israel, as in the world at large, the number of brain-related operations performed by neurosurgery specialists has risen significantly in recent years. Health Ministry data indicate that between 2005 and 2010 the number of neurosurgical procedures in Israel rose by 7 percent. During this period, 2,777 operations were performed, 455 of them on patients under the age of 18. Also, in 2010, 200 ventriculostomy procedures − in which a hole is made in a cerebral ventricle for drainage − were carried out. This represents a 13 percent increase in such procedures compared to 2005.
Additional new technologies have been deployed in recent years to heighten the precision level of surgeons and mitigate the risks of such procedures. These innovations are modifications of ultrasound or MRI technologies that have been utilized in neurosurgery for some time.
One such innovation is intraoperative neurophysiological monitoring, which Shoshan calls a “mini-revolution” in neurosurgery. This technology helps surgeons identify, in the course of a procedure, regions in the brain that are responsible for movement, sense functions and language ability.
“In an anatomical sense, everyone’s brain is built more or less the same way. But under certain circumstances, such as with the growth of a tumor, we identify structural change in the brain. Sophisticated intraoperative monitoring equipment helps the surgeon determine how close he is to sensitive areas in the brain, and assess the extent to which the removal of a tumor is liable to impair motor functions after the procedure,” explains Shoshan.
Another innovation is the use of a fluorescent material called 5-aminolevulinic acid (5-ALA), which helps neurosurgeons detect a tumor not fully visible under regular microscopic light imaging. The aminolevulinic acid material attaches itself to the tumor cells and alters their chemical basis, making them fluorescent.
“Fluorescent microscopic lighting facilitates identification of a tumor’s characteristics with a high level of reliability, and promotes more precise tumor removal, lessening the risk that the tumor will reappear later in life,” says Shoshan. This innovation has been introduced in a number of neurosurgery wards at several hospitals in Israel over the past few years.
Increasing the level of precision in neurosurgery is vital, says Shoshan. “In contrast to other parts of the body, you don’t have leeway with the brain. There is an ongoing need to strike the right balance between the medical necessity of removing a growth in as wide and total a fashion as possible, and the imperative of preserving a patient’s motor and neurological functions after the operation. The new technologies assist surgeons as they work to strike such a balance,” he says.
Though robotics technologies are advancing in neurosurgery, a scenario wherein a robot part replaces the human hand of a surgeon remains in the realm of science fiction. “I don’t believe that it will be possible to replace the human hand so quickly,” says Shoshan. “Today, the hand remains the safest and surest way of operating on something as sensitive in the human body as the brain.”
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