New Alternative for Catheter Manipulation Within the Brain

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Contact: Heather Monroe ([email protected]) 847/378-0517

Neurosurgeons Find New Alternative for Catheter Manipulation Within the Brain

ROLLING MEADOWS (August 28, 2000) -Neurosurgeons use stereotactic techniques to perform a variety of intracranial procedures. These techniques traditionally rely on preoperative imaging, an external reference point and a straight line to the target in the brain. Now neurosurgeons led by M. Sean Grady MD, Professor and Chairman of Neurosurgery at the University of Pennsylvania, have developed techniques that allows the procedure to be performed along a curved path and to be tracked by intraoperative imaging. In a study, "Experimental Study of the Magnetic Stereotaxis System for Catheter Manipulation within the Brain," published in the August issue of the Journal of Neurosurgery, neurosurgeons, tested the safety and performance accuracy of a new method called the Magnetic Stereotaxis System (MSS) in directing catheters through a nonlinear path to obtain biopsy specimens in pig brains. Authors of the study included M. Sean Grady, MD, Matthew A. Howard III, MD, Ralph G. Dacey Jr., MD, Walter Blume, Michael Lawson, Peter Werp and Rogers C. Ritter, PhD.

Stereotactic techniques are used in many neurosurgical procedures, including brain biopsy, placement of precise lesions or insertion of stimulators to treat diseases such as Parkinson's disease, intraoperative guidance during brain tumor resection, and as a targeting method for radiosurgery. These techniques are designed to improve the accuracy and safety of the procedure provided a linear path can be used. However, not all procedures can be safely performed using a linear path. In this study, the investigators attempted to find an easier method for accurately directing a surgical tool along a curved pathway in the brain and to follow and correct its course using intraoperative imaging. They describe the use of the MSS to perform brain biopsy procedures in pigs with a magnetically-guided catheter

Eleven pigs first underwent magnetic resonance (MR) imaging of the head to define a biopsy target and to plan a nonlinear path. Guided by the MSS, which used nearly real-time fluoroscopic imaging combined with the preoperative MR image (MRI), the authors non-invasively advanced a flexible catheter along a non-linear path to the biopsy target using magnetic navigation. Samples of brain tissue were obtained and submitted for examination. The animals were then observed for several days. The use of MSS was also compared to standard stereotactic procedures in 5 pigs. The authors found that the MSS allowed navigation of a flexible catheter and was safe and very accurate.

The MSS system described in this research report represents two significant advances in stereotactic techniques: 1) magnetic fields can be used to advance non-invasively a probe in a planned, nonlinear approach, and 2) nearly real time imaging offers the surgeon immediate feedback about the path along which the probe is traveling to allow timely corrections.

"A system that permits placements of flexible catheters with high accuracy and nearly real time navigation and localization would allow the neurosurgeon to improve the safety and efficiency of stereotactic operative procedures," says Ralph G. Dacey Jr., MD. "As the catheter moves, the system plots the actual path, comparing it with the designated path, and adjusts magnetic guidance accordingly."

As a stereotactic system, the MSS provided substantial accuracy both during its movement and its final position. The authors believe that the MSS has great potential for achieving precise control over catheter tips to assist neurosurgeons in performing minimally invasive surgical procedures.

The Journal of Neurosurgery is the scientific publication of the American Association of Neurological Surgeons. Founded in 1931 as the Harvey Cushing Society, the American Association of Neurological Surgeons is a scientific and educational association with nearly 5,800 members worldwide. The AANS is dedicated to advancing the specialty of neurological surgery in order to provide the highest quality of neurosurgical care to the public. All active members of the AANS are Board-certified by the American Board of Neurological Surgery. Neurological surgery is the medical specialty concerned with the prevention, diagnosis, treatment and rehabilitation of disorders that affect the spinal column, spinal cord, brain, nervous system and peripheral nerves.

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