A commonly-available imaging technique can identify stroke patients most likely to benefit from a procedure to restore blood flow – a potential breakthrough in care that could save thousands of lives every year, according to a new study.
Large vessel occlusion strokes occur when a clot travels up from the heart or the neck and blocks blood flow in one of the large arteries providing blood to the brain. This form of stroke is responsible for most stroke-related deaths and long-term disability.
Endovascular thrombectomy, a treatment in which a tube is inserted into the blocked vessel to remove or destroy the clot, is highly effective for treating large vessel occlusions, but it has limitations.
“Thrombectomy is over 90 per cent effective if we get to the patient in time,” said study co-first author Dr R. Gilberto Gonzalez, from the Department of Radiology at Massachusetts General Hospital (MGH) in Boston.
“The problem is, we’re only treating less than 10 per cent of the people who might benefit.”
One reason for the shortfall is the difficulty in the challenge in determining which patients need the treatment immediately and which can wait—a function of how fast the brain injury, known as the ischemic core, is growing.
In a previous study, Dr Gonzalez and colleagues discovered that the ischemic core grows very slowly in a significant subset of patients, meaning they can still benefit from thrombectomy 24 hours or more after the blockage occurs.
To learn more about how to identify these patients, Dr Gonzalez and his team looked at results from 31 stroke patients who upon admission underwent computed tomography angiography (CTA), an imaging technique commonly available in hospitals. The patients also had MRIs at four time points over the next two days to track ischemic growth.
Results revealed a strong link between ischemic core growth and blood flow in the collateral blood vessels, smaller blood vessels recruited by the brain to make up for the loss of flow through the large vessels.
A symmetric collateral pattern was strongly associated with slow growing, highly treatable ischemic cores.
“Our data shows that in almost half of patients, the core grows very slowly,” Dr Gonzalez said.
“That’s a huge number of people who are potentially treatable.”
Because CTA is widely available, patterns derived from it offer a potential lifeline for the tens of thousands of stroke victims who live in areas with no access to advanced imaging like CT perfusion and MRI.
In theory, any person with a stroke who shows up at a hospital with limited facilities and gets CT and CTA could be quickly identified as having a good collateral circulation pattern, and then transferred to another hospital and treated.
“With CT angiography, we’ve found a way that’s widely available to identify these slow progressors,” Dr Gonzalez said. “Now, a large number of patients with the most severe type of strokes can be treated.”
The researchers are currently working on an artificial intelligence algorithm that can automatically detect the specific patterns of collateral circulation associated with slower stroke progression. The algorithm can be run in the cloud so that any hospital can send data to it and get an evaluation within minutes.
“This method is very amenable to automation,” Dr Gonzalez said. “This is how I see it having a major effect and benefitting tens of thousands of people every year.”
TRAIL study brings new remote rehab potential to stroke survivors
The telerehabilitation programme will assess the impact of exercise-based therapy that has been traditionally done in-person
Through the use of telerehabilitation, stroke survivors are being supported in new ways to progress rehab that would traditionally have been done in-person. NR Times speaks to the Canadian-based pioneers of the TRAIL program, Dr Ada Tang and Dr Brodie Sakakibara, to learn more about their work
What is the purpose and intention of the TRAIL study?
We developed the TeleRehablitation with Aims to Improve Lower extremity recovery post-stroke (TRAIL) program to address the need for continued lower extremity rehabilitation after stroke that were not being met through standard hospital-based rehab services.
The COVID-19 pandemic certainly contributed to further reductions in access to stroke rehabilitation, so we realised there were even greater gaps in care than ever before.
Our study is examining the effectiveness of the four-week TRAIL program through a randomised controlled trial. We will compare how participants with stroke do after TRAIL, compared to those who participate in an education program.
We will compare the groups in terms of various lower extremity functional measures of mobility (through the Timed Up and Go), strength, balance and motor impairment, as well as balance self-efficacy, health-related quality of life, and use of healthcare resources and healthcare
Why did you choose to investigate rehabilitation for lower extremity recovery after stroke – what is the existing provision in this area?
Research shows that 80 per cent of people living with stroke report residual motor impairment that affect many daily activities such as dressing, bathing and walking.
There is lots of strong evidence showing that lower extremity exercise programs, delivered in-person and face-to-face, improves independence, walking and balance after stroke. Exercise also improves psychosocial outcomes such as balance, self-confidence and quality of life.
The rapid growth in internet use and mobile devices has opened up many possibilities for people with stroke to access specialised rehabilitation remotely from their homes and their communities (i.e. telerehabilitation).
To date, most of the research around telerehabilitation focuses on check-in sessions, or education and counselling after stroke, whereas the use of technology to deliver remote exercise interventions for the lower extremity is much more limited. Instead, most exercise programs that focus on lower extremity recovery for walking and balance have been delivered in-person to manage safety issues and risk of falls.
How has your project developed since its launch in 2019?
When we first conceived TRAIL, we looked at the small body of research that has focused on telerehabilitaiton for lower extremity recovery after stroke and found that most studies provided very minimal therapist oversight, and none were conducted in the first year following stroke when the opportunity for neuroplastic change is greatest.
We designed the TRAIL program to provide opportunities for live videoconference interaction with a physiotherapist two times a week for four weeks for the exercise portion. We also designed the program to encourage independent exercise in at least one additional session per week, to add volume of exercise without using therapist resources, and to provide participants with strategies for exercise self-management.
In early 2020, we were getting ready to soon launch the study when the COVID-19 pandemic swept across the globe. We quickly realised that telerehabilitation was needed more than ever, but we needed to change a few things about our study.
Namely, we moved to virtual outcomes assessments in addition to virtual delivery of the exercise program. We consulted with many expert
therapists and researchers on how best to do this, who were incredibly generous with their advice and suggestions.
We conducted a pilot study of TRAIL in 2020-2021 that involved 32 participants. We also completed a qualitative study with our participants to help us understand how they perceived TRAIL, as well was with the physiotherapists for their perceptions of delivering TRAIL. We are in the process of analysing the data from the pilot study and the qualitative interviews right now.
In summer 2021, we were excited to learn that we received grants from the Canadian Institutes of Health Research and Canadian Medical Association to continue our work in TRAIL, which we are using now for the randomised controlled trial.
Why did you choose to work on a telehealth project? What was the response to this pre-pandemic and how has this changed?
TRAIL was a way to fill and unmet need by providing access to lower extremity rehabilitation opportunities once in-person services had ended.
We started planning the first TRAIL study in late 2019 – little did we know that a global pandemic was about to hit and the need for telerehabilitation programs became even greater.
How vital is the use of technology in joint working across the miles?
We wouldn’t be able to run TRAIL without technology! And are glad to be able to get lower extremity rehabilitation programs to more people.
Canada is a large country though with a large geographical area and many regions that are rural and remote. There will be some people who don’t have access to the technology needed to participate in TRAIL.
In our studies, we are looking at the feasibility of TRAIL (for example, who can access TRAIL, how far (distance) can it go) as much as we are looking at its effectiveness.
We are getting ready to launch the randomised controlled trial early this year. We have two of our five sites ready to go; the other three are not far behind. We aim to enrol 96 people into the study.
Once complete, it will be one of the largest RCT to date looking at telerehabilitation for lower extremity recovery after stroke.
- Dr Ada Tang is an associate professor in the School of Rehabilitation Science at McMaster University. Dr Brodie Sakakibara is an assistant professor with the Department of Occupational Science and Occupational Therapy at the University of British Columbia
Dr Tang and Dr Sakakibara will discuss TRAIL and its impact at the Virtually Successful conference, a first-of-its-kind five-day event next week organised by Remote Rehab in association with NR Times, to assess the impact and potential of digitalisation in therapy.
For more details or to sign up, visit here
New hope for sight recovery in stroke survivors
The use of MRI imaging to map visual brain activity could deliver a breakthrough
The use of MRI imaging to map visual brain activity in stroke survivors with sight loss is giving new hope for rehabilitation and recovery.
Scientists have revealed new insights by combining data from clinical sight tests with brain imaging to precisely map the areas of the brain affected by sight loss.
This allows identification of visual brain areas where function could potentially be improved with rehabilitation.
Every year around 150,000 people in the UK have a stroke with roughly 30 per cent experiencing some kind of sight loss as a result.
Visual field loss is a common and devastating complication of cerebral strokes. This type of sight loss, called hemianopia, affects one side of a person’s vision and is caused by damage to the visual pathway in the brain.
A visual field test called perimetry is the current gold standard for measuring residual visual field coverage. However, its coverage is often coarse, it requires good attentional engagement of participants, and provides only indirect information about where in the visual pathway the key processing deficit is located.
This limits the ability to identify potential strategies for visual rehabilitation, in terms of location in the visual field and the kinds of visual stimuli most likely to support recovery.
This new study – from the University of Nottingham, funded by charity Fight for Sight – combines detailed perimetry and multiple brain imaging datasets from four stroke survivors which shows that perimetry can be augmented with brain imaging data to provide a novel measure of residual visual field function.
This combined approach provides potential for a personalised approach to therapy, guided by functional activity patterns in the post-stroke brain.
The research has been led by PhD student Anthony Beh from the University of Nottingham’s School of Psychology, supervised by Dr Denis Schluppeck, Dr Ben Webb and Prof Paul McGraw.
“A common misconception with stroke-related sight loss is that it affects vision through a particular eye,” says Anthony.
“What is actually happening is that the eyes are seeing normally but the brain can’t process some of the information.
“This type of vision loss can be a particular problem for driving, reading or navigating a crowded space. It can also increase the risk of falls in older people.
“By exploring stroke-damaged brains with functional MRI and different kinds of visual stimulation, we found residual activity in the visual cortex, not detected by perimetry. This opens up possibilities for rehabilitation and offers new hope to stroke survivors.”
Dr Schluppeck adds: “By examining different types of brain scans we can actually see areas of ‘residual vision’ – places where the eyes and brain can still process images, even if this doesn’t reach awareness.
“Using MRI to pinpoint these areas of functional vision, clinicians could work with the stroke survivor and train them to recover some function in that particular spot.”
Ikram Dahman, CEO (Interim) at Fight for Sight, said: “This important research gives new and much-needed hope for people experiencing sight loss due to brain injury after a stroke.
“This work could truly be transformative in people’s recovery, helping to restore independence and improve overall quality of life. We look forward to the important outcomes of this study.”
Strokes and death rate drop since 1990, study reveals
But overall numbers of ischemic stroke remain high, especially in high- and middle-income countries
The worldwide incidence and mortality rates for stroke decreased slightly from 1990 to 2019, but the overall numbers are still high, especially in high- and middle-income countries, according to a new study.
“The decrease is likely due to better medical services available in high-income countries, which may offer earlier detection of stroke risk factors and better control of these risk factors,” said study author Dr Liyuan Han, of the University of Chinese Academy of Sciences in Ningbo, China.
“But even in these countries, the total number of people with strokes is increasing due to population growth and ageing. And worldwide stroke is the leading cause of death and a major cause of disability for adults.”
The study focused on ischemic stroke, which is caused by blood clots and makes up 85 per cent of stroke cases, and analysed data from the Global Health Data Exchange.
During the period of 1990 to 2019, the average age-adjusted incidence rate of stroke decreased by 0.43 per cent, from a rate of 105 strokes per 100,000 people to 95 strokes per 100,000 people. The rate was higher in middle- and high-middle-income countries than in other areas.
At a regional level, the highest rates were in East Asia with 144 per 100,000 and North Africa, the Middle East and Eastern Europe with rates of 135. The lowest region was Australasia at 44 strokes per 100,000 people.
At a country level, the highest rates were in the United Arab Emirates at 208, Macedonia at 187 and Jordan at 181. The lowest rates were in Ireland at 36, Nepal at 37 and Switzerland at 38 strokes per 100,000 people.
Egypt and China had the most pronounced increases in stroke rates, with an increase of 1.4 per cent in Egypt and 1.1 per cent in China.
Similar to the stroke occurrence rate, the rate of death from stroke decreased slightly over the three decades, or by 1.6 per cent, but the overall numbers were high. The death rate decreased from 66 deaths per 100,000 people to 44 deaths per 100,000 people.
The highest death rates were in Eastern Europe, with a rate of 100, Central Asia at 79 and Central Europe at 67.
The lowest rates were in high-income North America at 16, Australasia at 17 and high-income Asia Pacific at 18.
“Since ischemic stroke is highly preventable, it is essential that more resources be devoted to prevention, especially in low- and middle-income countries where economic development is leading to changes in diet and lifestyle that may increase people’s risk factors for stroke,” Dr Han said.
“It has been estimated that at least half of all strokes may be preventable if effective changes were made to common lifestyle factors such as high blood pressure, obesity, smoking and inactivity.”
A limitation of the study was that quality and accuracy of data from some underdeveloped countries cannot be guaranteed as many did not have reliable information on deaths and strokes, said the research team.
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