Deep Brain Stimulation Safer for Patients with New MRI Compatible Electrode
Carbon electrodes will last longer than metal when embedded in the brain of patients with Parkinsons and tremors, and wont be affected by MRI.
Imagine having an electrode embedded in your brain in a surgical procedure that involves drilling holes in your skull to implant it. Now imagine going through an MRI scan for medical evaluation, when the metal electrode may react to the magnetic fields and vibrate, generate heat or even possibly damage the brain.
This is a reality that patients who need deep brain stimulation could face.
Now, Nov. 18 in Nature Microsystems & Nanoengineering describes a promising improvement to the procedure developed by 色情视频 engineers, in collaboration with researchers at Karlsruhe Institute of Technology (KIT) in Germany. The 色情视频 research team created a glassy carbon electrode as an alternative to the metal version, and new findings show it does not react to MRI scans, making it safer.
First developed in 2017 in researcher Sam Kassegne鈥檚&苍产蝉辫;, the carbon version is designed to last longer in the brain without getting corroded or deteriorated, and to emit and receive stronger signals. In 2018, that while the metal electrode degrades after 100 million cycles of electrical impulses applied to it, the glassy carbon material survived 3.5 billion cycles.
Deep brain stimulation 鈥� where electrodes implanted in the brain produce electrical impulses that control abnormal movement 鈥� is increasingly being used for those with movement disorders that don鈥檛 respond to medication, such as patients with Parkinson鈥檚 disease, tremors, and uncontrolled muscle contractions known as dystonia.
It鈥檚 also being considered for traumatic brain injury, addiction, dementia, depression and other conditions, so the potential applications are vast.
Until now, the electrodes have been made out of thin-film platinum or iridium oxide. But such metal-based electrodes can produce heat, interfere with the MRI images by creating bright spots that block views of the actual area in the brain being studied, and can become magnetized and move or vibrate when patients undergo scans, causing discomfort.
Carbon proves safer
鈥淥ur lab testing shows that unlike the metal electrode, the glassy carbon electrode does not get magnetized by the MRI, so it won't irritate the patient's brain,鈥� said Surabhi Nimbalkar, first author and doctoral candidate.
In addition, it can read both chemical and electrical signals from the brain, while the metal-based electrodes can only read electrical signals, so the carbon material is multi-modal as well as MRI compatible.
鈥淚t鈥檚 supposed to be embedded for a lifetime, but the issue is that metal electrodes degrade, so we鈥檝e been looking at how to make it last a lifetime,鈥� said Kassegne, senior author and professor of mechanical engineering at 色情视频. 鈥淚nherently, the carbon thin-film material is homogenous 鈥� or one continuous material 鈥� so it has very few defective surfaces. Platinum has grains of metal which become the weak spots vulnerable to corrosion.鈥�
Collaborators at developed a which enables precise measurements of vibrations during MRI. Working with the 色情视频 team, they were able to test the novel carbon electrodes directly in the MRI scanner, and confirm it was a safer, better alternative. This collaboration enabled extensive electrode testing for different interactions for the first time.
Cross-disciplinary collaborations
, who holds a patent for the process of electrode fabrication, has been working on thin-film carbon in his lab for more than 10 years, but became involved in customizing it for neurological applications when collaborators at the University of Washington and the Massachusetts Institute of Technology reached out to him for his expertise in micro- and nano-fabrication technologies.
Together, the three institutions are part of the National Science Foundation-funded , looking at engineering new ways to help the brain and spinal cord heal and recover from injury.
The micro-MRI group at KIT, led by Jan Korvink, works on MRI technologies for the brain, specifically MRI microscopy, an important prerequisite to analyze the behavior of these small electrodes with high-resolution details. Kassegne and Korvink met at a conference and decided to work together on the project.
"Inventing ways to make the MRI machine see more details of the brain is our key mission鈥�, said Korvink, joint senior author of the paper.
Nimbalkar, a doctoral student in Kassegne鈥檚 lab who has two pending patents, focuses on designing and fabrication of electrodes that would be compatible with the MRI process. She worked with Marty Sereno, director of , to test the carbon material.
鈥淲e scanned the electrodes using different imaging sequence techniques and found glassy carbon causes much less distortion of the image,鈥� Sereno said. 鈥淢etal disturbs the magnetic field which causes distortion, but carbon fiber has less induced currents in the magnetic field, so it won鈥檛 exert any force on the electrode itself, which is an advantage because it鈥檚 embedded in the soft tissue of the brain.鈥�
With lab testing completed, Kassegne鈥檚 collaborators on the clinical side will now test the carbon electrode in patients, while Nimbalkar and Kassegne work on testing different forms of carbon to be used in future electrodes.
