Understanding recovery process could have implications for many different injuries of the central nervous system
An interdisciplinary team of neuroscientists and neurosurgeons from the University of Rochester has used a new imaging technique to show how the human brain heals itself in just a few weeks following surgical removal of a brain tumor.
This is a human visual pathway, including the optic chiasm, tracts and radiations, revealed by MRI. This subject has a large pituitary tumor, in red, causing compression. These tumors caused by demyelination of the vision pathways and vision loss, but surgery to remove the tumor leads to remarkably rapid remyelination and vision recovery.
Credit: David A. Paul/University of Rochester School of Medicine
In a study featured on the cover of the current issue of the journal Science Translational Medicine, the team found that recovery of vision in patients with pituitary tumors is predicted by the integrity of myelin--the insulation that wraps around connections between neurons--in the optic nerves.
"Before the study, we weren't able to tell patients how much, if at all, they would recover their vision after surgery," explained David Paul, an M.D. candidate in the Department of Neurobiology and Anatomy, and first author of the study.
When pituitary tumors grow large, they can compress the optic chiasm, the intersection of the nerves that connect visual input from the eyes to the brain. Nerve compression can lead to vision loss, which usually improves after these tumors are surgically removed through the nose.
Paul and his colleagues used a technique called diffusion tensor imaging (DTI) to show how changes in a particular bundle of nerve fibers relate to vision changes in these patients.
"DTI measures how water spreads in tissue," explained Bradford Mahon, assistant professor in the Department Brain and Cognitive Sciences and the Department of Neurosurgery, and senior author of the study. "The myelin insulation normally prevents water from spreading within the nerves, which would cause the nerves to malfunction."
Paul describes myelin damage by analogy to an insulated copper cable. In the human brain, DTI can measure the "leakiness of the insulation," or how well myelin constrains the flow of water in brain tissue.
One DTI-based measurement, called radial diffusivity, can be used as an indicator of myelin insulation; an increase in this measure means there is less insulation to restrict the movement of water within a nerve. In their study, the researchers found that inadequate insulation resulted in poorer visual ability in patients.
Paul said this particular patient population is unique because unlike other diseases such as stroke, trauma or multiple sclerosis, these patients have a problem that can be treated by surgery and the effect of the tumor on the brain is the same every time. Every pituitary tumor that grows large enough will compress the optic chiasm in more or less the same place, and removal of the tumor is often followed by a recovery of visual abilities.
"These patients grant us a unique opportunity to understand human brain repair because the surgery is minimally invasive and patients recover very quickly after surgery," said Edward Vates, director of the Pituitary Program in the Department of Neurosurgery at the University of Rochester Medical Center, and co-author of the study.
The measurements established in the study provide a new way to measure the structural integrity of nerve fibers, and may ultimately be applicable across the full range of brain diseases and injuries.
"There's a lot of variability in how people recover from brain injuries," said Mahon. "Anything we can learn about patients who go on to make a good recovery may help us to promote recovery from brain injury of any cause." he adds that the visual system is the best understood circuitry in the human brain, and his lab has developed very precise ways of studying vision before and after surgery.
"If we can develop our prognostic methods in the context of the early visual pathway, then we can apply the same types of models to more complex systems in the brain, like language recovery after a stroke," said Mahon.
"This kind of research will create novel treatments to fix broken nervous systems," said Bradford Berk, director of the new Rochester Neurorestorative Institute. "Harnessing new technologies to help us understand how the brain repairs itself and restores function, and how we can accelerate that process will be one of the keys to restoring neurological function in a wide range of conditions, such as multiple sclerosis, stroke, and traumatic brain injury."
Additional researchers on the study include Elon Gaffin-Cahn, Eric B. Hintz, Giscard J. Adeclat, and Zoë R. Williams from the University of Rochester/University of Rochester School of Medicine, and Tong Zhu from the University of Michigan Medical Center.
The National Institute of Neurological Disorders and Stroke and the National Eye Institute supported the research.
About the University of Rochester
The University of Rochester is one of the nation's leading private universities. Located in Rochester, N.Y., the University gives students exceptional opportunities for interdisciplinary study and close collaboration with faculty through its unique cluster-based curriculum. Its College, School of Arts and Sciences, and Hajim School of Engineering and Applied Sciences are complemented by its Eastman School of Music, Simon Business School, Warner School of Education, Laboratory for Laser Energetics, School of Medicine and Dentistry, School of Nursing, Eastman Institute for Oral Health, and the Memorial Art Gallery.
Monique Patenaude | EurekAlert!
Lego-like wall produces acoustic holograms
17.10.2016 | Duke University
New evidence on terrestrial and oceanic responses to climate change over last millennium
11.10.2016 | University of Granada
Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.
"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...
In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.
A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...
By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.
"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...
COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.
In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...
'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.
Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...
14.10.2016 | Event News
14.10.2016 | Event News
12.10.2016 | Event News
24.10.2016 | Life Sciences
21.10.2016 | Health and Medicine
21.10.2016 | Information Technology