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!
36 big data research projects
21.02.2017 | Schweizerischer Nationalfonds SNF
Coastal wetlands excel at storing carbon
01.02.2017 | University of Maryland
Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...
The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.
The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...
Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...
Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".
Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...
13.02.2017 | Event News
10.02.2017 | Event News
09.02.2017 | Event News
24.02.2017 | Life Sciences
24.02.2017 | Life Sciences
24.02.2017 | Trade Fair News