Posts tagged brain surgery
Articles and news from the latest research reports.
Brain surgery through the cheek
For those most severely affected, treating epilepsy means drilling through the skull deep into the brain to destroy the small area where the seizures originate – invasive, dangerous and with a long recovery period.
Five years ago, a team of Vanderbilt engineers wondered: Is it possible to address epileptic seizures in a less invasive way? They decided it would be possible. Because the area of the brain involved is the hippocampus, which is located at the bottom of the brain, they could develop a robotic device that pokes through the cheek and enters the brain from underneath which avoids having to drill through the skull and is much closer to the target area.
To do so, however, meant developing a shape-memory alloy needle that can be precisely steered along a curving path and a robotic platform that can operate inside the powerful magnetic field created by an MRI scanner.
The engineers have developed a working prototype, which was unveiled in a live demonstration this week at the Fluid Power Innovation and Research Conference in Nashville by David Comber, the graduate student in mechanical engineering who did much of the design work.
The business end of the device is a 1.14 mm 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. (Unlike many common metals, nickel-titanium is compatible with MRIs). Using compressed air, a robotic platform controllably steers and advances the needle segments a millimeter at a time.
According to Comber, they have measured the accuracy of the system in the lab and found that it is better than 1.18 mm, which is considered sufficient for such an operation. In addition, the needle is inserted in tiny, millimeter steps so the surgeon can track its position by taking successive MRI scans.
According to Associate Professor of Mechanical Engineering Eric Barth, who headed the project, the next stage in the surgical robot’s development is testing it with cadavers. He estimates it could be in operating rooms within the next decade.
To come up with the design, the team began with capabilities that they already had.
“I’ve done a lot of work in my career on the control of pneumatic systems,” Barth said. “We knew we had this ability to have a robot in the MRI scanner, doing something in a way that other robots could not. Then we thought, ‘What can we do that would have the highest impact?’”
At the same time, Associate Professor of Mechanical Engineering Robert Webster had developed a system of steerable surgical needles. “The idea for this came about when Eric and I were talking in the hallway one day and we figured that his expertise in pneumatics was perfect for the MRI environment and could be combined with the steerable needles I’d been working on,” said Webster.
The engineers identified epilepsy surgery as an ideal, high-impact application through discussions with Associate Professor of Neurological Surgery Joseph Neimat. They learned that currently neuroscientists use the through-the-cheek approach to implant electrodes in the brain to track brain activity and identify the location where the epileptic fits originate. But the straight needles they use can’t reach the source region, so they must drill through the skull and insert the needle used to destroy the misbehaving neurons through the top of the head.
Comber and Barth shadowed Neimat through brain surgeries to understand how their device would work in practice.
“The systems we have now that let us introduce probes into the brain – they deal with straight lines and are only manually guided,” Neimat said. “To have a system with a curved needle and unlimited access would make surgeries minimally invasive. We could do a dramatic surgery with nothing more than a needle stick to the cheek.”
The engineers have designed the system so that much of it can be made using 3-D printing in order to keep the price low. This was achieved by collaborating with Jonathon Slightam and Vito Gervasi at the Milwaukee School of Engineering who specialize in novel applications for additive manufacturing.
Tool helps guide brain cancer surgery
A tool to help brain surgeons test and more precisely remove cancerous tissue was successfully used during surgery, according to a Purdue University and Brigham and Women’s Hospital study.
The Purdue-designed tool sprays a microscopic stream of charged solvent onto the tissue surface to gather information about its molecular makeup and produces a color-coded image that reveals the location, nature and concentration of tumor cells.
”In a matter of seconds this technique offers molecular information that can detect residual tumor that otherwise may have been left behind in the patient,” said R. Graham Cooks, the Purdue professor who co-led the research team. “The instrumentation is relatively small and inexpensive and could easily be installed in operating rooms to aid neurosurgeons. This study shows the tremendous potential it has to enhance patient care.”
Current surgical methods rely on the surgeon’s trained eye with the help of an operating microscope and imaging from scans performed before surgery, Cooks said.
"Brain tumor tissue looks very similar to healthy brain tissue, and it is very difficult to determine where the tumor ends and the normal tissue begins," he said. "In the brain, millimeters of tissue can mean the difference between normal and impaired function. Molecular information beyond what a surgeon can see can help them precisely and comprehensively remove the cancer."
The mass spectrometry-based tool had previously been shown to accurately identify the cancer type, grade and tumor margins of specimens removed during surgery based on an evaluation of the distribution and amounts of fatty substances called lipids within the tissue. This study took the analysis a step further by additionally evaluating a molecule associated with cell growth and differentiation that is considered a biomarker for certain types of brain cancer, he said.
"We were able to identify a single metabolite biomarker that provides information about tumor classification, genotype and the prognosis for the patient," said Cooks, the Henry Bohn Hass Distinguished Professor of Chemistry. "Through mass spectrometry all of this information can be obtained from a biopsy in a matter of minutes and without significantly interrupting the surgical procedure."
For this study, which included validation on samples and use during two patients’ surgical procedures, the tool was tuned to identify the lipid metabolite 2-hydroxyglutarate or 2-HG. This biomarker is associated with more than 70 percent of gliomas and can be used to classify the tumors, he said.
A paper detailing the results of the National Institutes of Health-funded study will be published in an upcoming issue of the Proceedings of the National Academy of Sciences and is published online.
In mass spectrometry molecules are electrically charged and turned into ions so that they can be identified by their mass. The new tool relies an ambient mass spectrometry analysis technique developed by Cooks and his colleagues called desorption electrospray ionization, or DESI, which eliminated the need for chemical manipulations of samples and containment in a vacuum chamber for ionization. DESI allows ionization to occur directly on surfaces outside of the mass spectrometers, making the process much simpler, faster and more applicable to surgical settings.
The tool couples a DESI mass spectrometer with a software program designed by the research team that uses the results to characterize the brain tumors and detect boundaries between healthy and cancerous tissue. The program is based on earlier studies of lipid patterns that correspond to different types and grades of cancer and currently covers the two most common types of brain tumors, gliomas and meningiomas. These two types of tumors combined account for about 65 percent of all brain tumors and 80 percent of all malignant brain tumors, according to the American Brain Tumor Association.
Additional classification methodologies and metabolite biomarkers could be added to tailor the tool to different types of cancer, Cooks said.
The brain surgery was performed in the Advanced Multi-Modality Image Guided Operating suite, or AMIGO at Brigham and Women’s Hospital.
Dr. Nathalie Agar, director of the Surgical Molecular Imaging Laboratory within the neurosurgery department at Brigham and Women’s Hospital, led the study.
Non-Invasive Mapping Helps to Localize Language Centers Before Brain Surgery
A new functional magnetic resonance imaging (fMRI) technique may provide neurosurgeons with a non-invasive tool to help in mapping critical areas of the brain before surgery, reports a study in the April issue of Neurosurgery, official journal of the Congress of Neurological Surgeons. The journal is published by Lippincott Williams & Wilkins, a part of Wolters Kluwer Health.
Evaluating brain fMRI responses to a “single, short auditory language task” can reliably localize critical language areas of the brain—in healthy people as well as patients requiring brain surgery for epilepsy or tumors, according to the new research by Melanie Genetti, PhD, and colleagues of Geneva University Hospitals, Switzerland.
Brief fMRI Task for Functional Brain Mapping
The researchers designed and evaluated a quick and simple fMRI task for use in functional brain mapping. Functional MRI can show brain activity in response to stimuli (in contrast to conventional brain MRI, which shows anatomy only). Before neurosurgery for severe epilepsy or brain tumors, functional brain mapping provides essential information on the location of critical brain areas governing speech and other functions.
The standard approach to brain mapping is direct electrocortical stimulation (ECS)—recording brain activity from electrodes placed on the brain surface. However, this requires several hours of testing and may not be applicable in all patients. Previous studies have compared fMRI techniques with ECS, but mainly for determining the side of language function (lateralization) rather than the precise location (localization).
The new fMRI task was developed and evaluated in 28 healthy volunteers and in 35 patients undergoing surgery for brain tumors or epilepsy. The test used a brief (eight minutes) auditory language stimulus in which the patients heard a series of sense and nonsense sentences.
Functional MRI scans were obtained to localize the brain areas activated by the language task—activated areas would “light up,” reflecting increased oxygenation. A subgroup of patients also underwent ECS, the results of which were compared to fMRI.
Non-invasive Test Accurately Localizes Critical Brain Areas
Based on responses to the language stimulus, fMRI showed activation of the anterior and posterior (front and rear) language areas of the brain in about 90 percent of subjects—neurosurgery patients as well as healthy volunteers. Functional MRI activation was weaker and the language centers more spread-out in the patient group. These differences may have reflected brain adaptations to slow-growing tumors or longstanding epilepsy.
Five of the epilepsy patients also underwent ECS using brain electrodes, the results of which agreed well with the fMRI findings. Two patients had temporary problems with language function after surgery. In both cases, the deficits were related to surgery or complications (bleeding) in the language area identified by fMRI.
Functional brain mapping is important for planning for complex neurosurgery procedures. It provides a guide for the neurosurgeon to navigate safely to the tumor or other diseased area, while avoiding damage to critical areas of the brain. An accurate, non-invasive approach to brain mapping would provide a valuable alternative to the time-consuming ECS procedure.
"The proposed fast fMRI language protocol reliably localized the most relevant language areas in individual subjects," Dr. Genetti and colleagues conclude. In its current state, the new test probably isn’t suitable as the only approach to planning surgery—too many areas "light up" with fMRI, which may limit the surgeon’s ability to perform more extensive surgery with necessary confidence. The researchers add, "Rather than a substitute, our current fMRI protocol can be considered as a valuable complementary tool that can reliably guide ECS in the surgical planning of epileptogenic foci and of brain tumors."
Cat brain surgery: the story of an operation – in pictures
Harry, a 12-year-old maine coon, has a tumour on his pituitary gland, causing uncontrolled diabetes. In an attempt to save his life, his owners have opted for cutting-edge brain surgery at the Royal Veterinary College’s Queen Mother hospital for animals.