Posts tagged stroke
Articles and news from the latest research reports.
Robots that can read and respond to brain waves will eventually help stroke patients regain movement, using new neural interfaces that can re-train damaged motor pathways. Neuroscientists have made great strides in brain-machine interfaces that can respond to a person’s thoughts — a new generation will drive a non-invasive robotic orthotic, retraining the patient’s own body.
Patients who have suffered a stroke or other injury can lose the active use of their limbs, rendering them unable to simply think about moving an arm or hand and then do it. Sometimes it’s possible to re-establish the lost connection, with time and repetitive physical therapy. Researchers at Rice University are using a robotic exoskeleton and a neural interface to improve matters.
SOLITAIRE, which was approved by the U.S. Food and Drug Administration in March, is among an entirely new generation of devices designed to remove blood clots from blocked brain arteries in patients experiencing an ischemic stroke. It has a self-expanding, stent-like design, and once inserted into a blocked artery using a thin catheter tube, it compresses and traps the clot. The clot is then removed by withdrawing the device, reopening the blocked blood vessel.
Stroke disrupts how brain controls muscle synergies
The simple act of picking up a pencil requires the coordination of dozens of muscles: The eyes and head must turn toward the object as the hand reaches forward and the fingers grasp it. To make this job more manageable, the brain’s motor cortex has implemented a system of shortcuts. Instead of controlling each muscle independently, the cortex is believed to activate muscles in groups, known as “muscle synergies.” These synergies can be combined in different ways to achieve a wide range of movements.
This graphic shows the brain, with the motor cortex highlighted in yellow.
Graphic: Christine Daniloff
A new study from MIT, Harvard Medical School and the San Camillo Hospital in Venice finds that after a stroke, these muscle synergies are activated in altered ways. Furthermore, those disruptions follow specific patterns depending on the severity of the stroke and the amount of time that has passed since the stroke.
The findings, published this week in the Proceedings of the National Academy of Sciences, could lead to improved rehabilitation for stroke patients, as well as a better understanding of how the motor cortex coordinates movements, says Emilio Bizzi, an Institute Professor at MIT and senior author of the paper.
“The cortex is responsible for motor learning and for controlling movement, so we want to understand what’s going on there,” says Bizzi, who is a member of the McGovern Institute for Brain Research at MIT. “How does the cortex translate an idea to move into a series of commands to accomplish a task?”
A new study from The University of Queensland shows monitoring the brain of stroke patients using Quantitative EEG (QEEG) studies could inform treatments and therefore, minimising brain damage of stroke victims.
“The main goals of this research were to evaluate key findings, identify common trends and determine what the future priorities should be, both for research and for translating this to best inform clinical management of stroke patients,” Dr Finnigan from UQ’s Centre for Clinical Research said.
The review of outcomes from hundreds of patients has highlighted that QEEG indicators are particularly informative in two ways.
“Firstly they can help predict long-term deficits caused by stroke, … In addition, they could provide immediate information on how patients are responding to treatments and guide decisions about follow-on treatments, even before stroke symptoms change,” Dr Finnigan said.
The patient, known only as TN, was left blind after damage to the visual (striate) cortex in both hemispheres of the brain following consecutive strokes. His eyes are normal but his brain cannot process the information they send in, rendering him totally blind.
Researchers say TN’s successful performance was an example of the phenomenon “blindsight,” and say it suggests that some small amount of information is being transmitted from his undamaged eyes to a more primitive part of his brain, which operates beneath the level of consciousness.
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(Credit: audiodude)
Predicting recovery after stroke
August 1, 2012
(Medical Xpress) — In work that may revolutionise rehabilitation for stroke patients, researchers from The University of Auckland and the Auckland District Health Board have shown it is possible to predict an individual’s potential for recovery of hand and arm function after a stroke.
The new approach can be used to personalise rehabilitation so that patients and therapists set realistic goals for recovery. It may also improve outcomes of trials that evaluate new therapies, by identifying patients who are most likely to respond to specific treatments.
“One in six people worldwide will have a stroke in their lifetime,” says principal investigator Professor Winston Byblow. “After stroke, impairment of the arm and hand is very common and has a major impact on independence and quality of life.
“Until now it has only been possible to group patients together according to their broad similarity to others who have already gone through upper limb rehabilitation, but this information cannot inform an individual patient’s rehabilitation plan. We have developed the first clinical algorithm to actually predict the individual patient’s potential for recovery based on information gathered before rehabilitation begins.”
The lead author of the study, Dr Cathy Stinear explains: “The algorithm begins with a bedside test within three days of stroke. The test takes only a few minutes and requires no special equipment. This is sufficient to provide a prediction for many patients, but for others an additional test is required to measure the integrity of neural pathways from the brain to the arm. If this test gives no definitive result, an MRI assessment can be performed to better determine whether the pathways in the stroke-damaged side of the brain remain viable.”
The research team have trialled the process in patients and followed their recovery. “When the tests are combined in our stepwise algorithm they accurately predict each patient’s recovery at 12 weeks, which is around the time that therapy normally ends,” says Dr Stinear.
Neurologist Professor Alan Barber, a member of the research team and Head of the Auckland Hospital Stroke Service, says that the findings are very significant. “This is the first study to predict an individual’s potential for motor recovery using measures obtained from that patient in the initial days after stroke. This information can be used to tailor rehabilitation before it begins.”
The team is now involved in a three-year trial of the algorithm within the hospital. The results will show whether the algorithm leads to improved outcomes for patients and increases the efficiency of rehabilitation services.
Provided by University of Auckland
Source: medicalxpress.com
Molecule found that inhibits recovery from stroke
July 26, 2012 By Mark Wheeler
UCLA researchers say blocking this molecule may improve and speed recovery
FINDINGS:
Researchers at UCLA have identified a novel molecule in the brain that, after stroke, blocks the formation of new connections between neurons. As a result, it limits the brain’s recovery. In a mouse model, the researchers showed that blocking this molecule—called ephrin-A5—induces axonal sprouting, that is, the growth of new connections between the brain’s neurons, or cells, and as a result promotes functional recovery.
IMPACT:
If duplicated in humans, the identification of this molecule could pave the way for a more rapid recovery from stroke and may allow a synergy with existing treatments, such as physical therapy.
UCLA AUTHOR:
Dr. S. Thomas Carmichael, professor of neurology, and colleagues
JOURNAL:
The research appears online this week in the journal PNAS.
MORE:
Stroke is the leading cause of adult disability because of the brain’s limited capacity for repair. An important process in recovery after stroke may be in the formation of new connections, termed axonal sprouting. The adult brain inhibits axonal sprouting and the formation of these connections. In previous work the researchers found, paradoxically, that the brain sends mixed signals after a stroke—activating molecules that both stimulate and inhibit axonal sprouting. In this present work, the researchers have identified the effect of one molecule that inhibits axonal sprouting and determined the new connections in the brain that are necessary to form for recovery.
The researchers also developed a new tissue bioengineering approach for delivering drugs to the brain after stroke. This approach uses a biopolymer hydrogel, or a gel of naturally occurring brain proteins, to release neural repair molecules directly to the target region for recovery in stroke—the tissue adjacent to the center of the stroke.
Last, the paper also shows that the more behavioral activity after stroke, such as the amount an impaired limb is used, the more new connections are directly stimulated to form in the injured brain. This direct link between movement patterns, like those that occur in neurorehabilitation, and the formation of new brain connections, provides a biological mechanism for the effects of some forms of physical therapy after stroke.
Source: UCLA
New vision therapy for stroke victims
The innovative vision therapy tool will be used to evaluate and train people with a vision deficit caused by a brain injury or dysfunction.
Each year about 220,000 Australians suffer from an acquired brain injury caused by strokes, car accidents and trauma. Of those, about 30 to 35 per cent acquire neurological vision impairments as a result of damage to the brain, not the eyes, causing many patients to only see half an image.
The software, developed by MDPP Research Associate Dr Fabian Lim, will be trialled by NVT Systems as a new therapeutic product for their clients.
The touch screen tool features five visual tasks with varying degrees of difficulty, including a line-tracing exercise and a shopping catalogue task where the object is to match images in the catalogue with a shopping list.
Dr. Lim said the software would give health care providers a “quantitative measure” for assessing vision deficit, tracking improvements and targeting specific impediments, offering a more effective alternative to traditional pen and paper assessments.
“By repeatedly practicing these exercises patients learn how to scan their surroundings and look for things that might not be in their field of view, and ultimately improve their visual sense,” Dr. Lim said.
NVT Systems is now trialling the simulator software with patients from organisations such as Guide Dogs SA.NT.
NVT Systems Manager Training and Research, Mrs Allison Hayes, said the fantastic work by the Medical Device Partnering Program had enabled the company to expand its product range for local and international markets.
“One of the great things about this new tool is that we will be able to measure important parameters that could be used by carers to map improvements in performance and target specific deficits,” Mrs. Hayes said.
“The visual skills taught using the touch screen device can be transferred to functional activities of daily living, helping our clients to carry out important everyday activities in the home and community.”
Video games can be good for your health
Dr. Penelope McNulty, a neurophysiologist at Neuroscience Research Australia, will present new data that shows the Wii is an effective rehabilitation tool at an international conference of the Society of Electrophysiology and Kinesiology in Brisbane on 20 July.
Dr. McNulty’s data shows that an intensive, two-week training program based on the Wii can result in significant improvements in the way stroke patients are able to use their limbs, even for people that had a stroke many years ago.
“It was previously thought that the movement and function stroke patients had at the time they left hospital was the only recovery they would make,” says Dr. McNulty.
“But we have worked with people who have had strokes one month to 21 years ago, and excitingly, they all improve,” she added.
There are over 60,000 strokes in Australia each year and there is a crucial need to improve rehabilitation methods because this is the only method known to restore movement in stroke-affected limbs.
“The Wii is inexpensive, easy to use and, very importantly, fun. This type of rehabilitation motivates participants to actually complete their therapy, which is essential for maximum recovery,” Dr. McNulty says.
“Everyone notices improvements not just using the Wii, but in activities they do every day, such as opening a door or using a fork,” Dr. McNulty concluded.
Research shows nerve stimulation can reorganize brain
July 19, 2012 By Emily Martinez
(Medical Xpress) — UT Dallas researchers recently demonstrated how nerve stimulation paired with specific experiences, such as movements or sounds, can reorganize the brain. This technology could lead to new treatments for stroke, tinnitus, autism and other disorders.
Dr. Michael Kilgard helped lead a team that paired vagus nerve stimulation with physical movement to improve brain function.
In a related paper, UT Dallas neuroscientists showed that they could alter the speed at which the brain works in laboratory animals by pairing stimulation of the vagus nerve with fast or slow sounds.
A team led by Dr. Robert Rennaker and Dr. Michael Kilgard looked at whether repeatedly pairing vagus nerve stimulation with a specific movement would change neural activity within the laboratory rats’ primary motor cortex. To test the hypothesis, they paired the vagus nerve stimulation with movements of the forelimb in two groups of rats. The results were published in a recent issue of Cerebral Cortex.
After five days of stimulation and movement pairing, the researchers examined the brain activity in response to the stimulation. The rats who received the training along with the stimulation displayed large changes in the organization of the brain’s movement control system. The animals receiving identical motor training without stimulation pairing did not exhibit any brain changes, or plasticity.
People who suffer strokes or brain trauma often undergo rehabilitation that includes repeated movement of the affected limb in an effort to regain motor skills. It is believed that repeated use of the affected limb causes reorganization of the brain essential to recovery. The recent study suggests that pairing vagus nerve stimulation with standard therapy may result in more rapid and extensive reorganization of the brain, offering the potential for speeding and improving recovery following stroke, said Rennaker, associate professor in The University of Texas at Dallas’ School of Behavioral and Brain Sciences.
“Our goal is to use the brain’s natural neuromodulatory systems to enhance the effectiveness of standard therapies,” Rennaker said. “Our studies in sensory and motor cortex suggest that the technique has the potential to enhance treatments for neurological conditions ranging from chronic pain to motor disorders. Future studies will investigate its effectiveness in treating cognitive impairments.”