Category: Stroke

 From drinking coffee to having sex to blowing your nose, you could temporarily raise your risk of rupturing a brain aneurysm — and suffering a stroke, according to a study published in Stroke: Journal of the American Heart Association.

Dutch researchers identified eight main triggers that appear to increase the risk of intracranial aneurysm (IA), a weakness in the wall of a brain blood vessel that often causes it to balloon. If it ruptures, it can result in a subarachnoid hemorrhage which is a stroke caused by bleeding at the base of the brain. An estimated 2 percent of the general population have IAs, but few rupture.

Calculating population attributable risk — the fraction of subarachnoid hemorrhages that can be attributed to a particular trigger factor — the researchers identified the eight factors and their contribution to the risk as:

• Coffee consumption (10.6 percent)
• Vigorous physical exercise (7.9 percent)
• Nose blowing (5.4 percent)
• Sexual intercourse (4.3 percent)
• Straining to defecate (3.6 percent)
• Cola consumption (3.5 percent)
• Being startled (2.7 percent)
• Being angry (1.3 percent)

"All of the triggers induce a sudden and short increase in blood pressure, which seems a possible common cause for aneurysmal rupture," said Monique H.M. Vlak, M.D., lead author of the study and a neurologist at the University Medical Center in Utrecht, the Netherlands.

Risk was higher shortly after drinking alcohol, but decreased quickly, researchers said.

"Subarachnoid hemorrhage caused by the rupture of an intracranial aneurysm is a devastating event that often affects young adults," Vlak said. "These trigger factors we found are superimposed on known risk factors, including female gender, age and hypertension."

Few people with IAs have symptoms before such a rupture, such as vomiting, vision problems, loss of consciousness, and especially severe headaches. Many have none. With the increasing use of neuroimaging techniques, more incidental aneurysms are being detected, researchers said.

The researchers sought to identify potential triggers and their level of risk. They asked 250 patients with aneurysmal subarachnoid hemorrhage to complete a questionnaire about exposure to 30 potential trigger factors in the period shortly before their event and their usual frequency and intensity of exposure to these triggers. They then assessed relative risk using a case-crossover design that determines if a specific event was triggered by something that happened just before it.

Although physical activity had triggering potential, researchers don't advise refraining from it because it's also an important factor in lowering risk of other cardiovascular diseases.

"Reducing caffeine consumption or treating constipated patients with unruptured IAs with laxatives may lower the risk of subarachnoid hemorrhage," Vlak said. "Whether prescribing antihypertensive drugs to patients with unruptured IAs is beneficial in terms of preventing aneurysmal rupture still needs to be further investigated."

The findings were limited by the retrospective design of the study and the average three weeks between subarachnoid hemorrhage and completion of the questionnaire, researchers said. Moreover, specifically asking for exposure in a particular time frame may have been limited by recall bias and including patients in a relatively good clinical condition could have led to survival bias.

Co-authors are Ale Algra, M.D., Ph.D.; Gabriel J.E. Rinkel, M.D., Ph.D.; Paut Greebe, R.N., Ph.D.; and Johanna van der Bom, M.D., Ph.D. Author disclosures are on the manuscript.

The Julius Center for General Health and Primary Care and the Department of Neurology of the University Medical Center in Utrecht, the Netherlands funded the study.

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Journal Reference:

1. Monique H.M. Vlak, Gabriel J.E. Rinkel, Paut Greebe, Johanna G. van der Bom, and Ale Algra. Trigger Factors and Their Attributable Risk for Rupture of Intracranial Aneurysms: A Case-Crossover Study. Stroke, 2011; DOI: 10.1161/STROKEAHA.110.606558

A new study shows that susceptibility-weighted imaging (SWI) is a powerful tool for characterizing infarctions (stroke) in patients earlier and directing more prompt treatment.

In the United States, stroke is the third leading cause of death and overall affects almost one million people each year, said Dr. Mark D. Mamlouk, lead author of the study at the University of California, Irvine. He states, "There are different causes of stroke of which the thromboembolic (clot) subtype is one of the most common." Traditionally, SWI, which is a specific MRI sequence, has been used as a secondary tool to evaluate intracerebral (brain) hemorrhages and detect clots with middle cerebral artery (MCA) infarctions. Now, Dr. Mamlouk said, "Any patient that has a suspicion of stroke, we can add the SWI sequence as part of their MRI brain protocols to better characterize the [origin of the] stroke."

For the study, researchers assessed that of the 35 patients with thromboembolic infarctions, SWI detected thromboemboli in 30 patients. Additionally, 14 of these thromboemboli were located in arteries other than the anterior division of the MCA. Dr. Mamlouk said, "At our institution, we are amazed at how often SWI detects thromboemboli in all major cerebral arteries, not just the MCA. Given SWI's high sensitivity (86%) of thromboemboli detection, we found that there is an adjunctive role of SWI in classifying cerebral infarctions in patients."

While MRIs have been the gold standard for evaluating infarctions, adding SWI to the routine MRI sequences for evaluating patients with a clinical suspicion of stroke will hasten their time to treatment and improve overall recovery, said Dr. Anton Hasso, senior author of the study. Dr. Mamlouk states, "The utility of SWI extends beyond the evaluation of hemorrhage. Using SWI in patients with cerebral infarctions will decrease further imaging and its associated costs and radiation exposure, but more importantly this imaging technique will guide direct management in a timelier manner."

Dr. Mamlouk is delivering a presentation on this study May 4, 2011 at the 2011 ARRS Annual Meeting at the Hyatt Regency Chicago.

The results are part of a survey of 1,248 Americans ages 18-44 on their attitudes about health, including influences of and beliefs about health behaviors and their risks for stroke. Stroke is a leading cause of death and disability in America.

Eight in 10 people between ages 25-44 years old believe they're living healthy lifestyles and are more likely to engage in healthy behaviors than 18-24 year olds participating in the survey.

"This survey shows the dangerous disconnect that many young Americans have about how their behaviors affect their risks for stroke and other cardiovascular diseases," said Ralph Sacco, M.D., neurologist and president of the American Heart Association/American Stroke Association. "Starting healthy behaviors at a young age is critical to entering middle age in good shape. The investment you make in your health now will have a large payoff as you age. We want everyone — especially young people — to strive to avoid stroke, which can affect anyone at any age."

People who make healthy lifestyle choices lower their risk of having a first stroke by as much as 80 percent compared with those who don't make healthy choices, according to American Heart Association/American Stroke Association guidelines released in December. The healthy behaviors include eating a low-fat diet high in fruits and vegetables, drinking alcohol and sugar-sweetened beverages in moderation, exercising regularly, maintaining a healthy body weight and not smoking.

Most 18-24 year olds said they want to live long and maintain quality health throughout their life. On average, they want to live to age 98. Yet, one-third of those surveyed don't believe engaging in healthy behaviors now could affect their risk of stroke in the future and 18 percent could not identify at least one stroke risk factor.

"Young adults need to make a connection between healthy behaviors and a healthy brain and healthy heart," Sacco said. "If we are not able to help young adults understand the relevance of their actions now and their risk of stroke tomorrow, then we could be looking at an increase in stroke diagnoses and deaths within the next 10 to 20 years."

"Everyone should recognize the severity of stroke, which threatens quality of life and can be prevented. People need to think in terms of striving for ideal health as well as surviving and thriving if a stroke occurs. An easier way to remember this is: Strive, Survive and Thrive," Sacco added.

Results from the survey also revealed that as people age, they become more aware of their overall health and risk factors for heart disease and stroke:

• Among 35-44 year olds, only 22 percent said they were not concerned about cardiovascular diseases and conditions, including heart disease/heart attack; high blood pressure; obesity; high cholesterol; diabetes; and stroke. Yet, about half (48 percent) of them are more likely to have health concerns they struggle with today.
• Thirty-six percent of 25-34 year olds said they were not concerned about cardiovascular diseases and conditions.
• Forty-three percent of 18-24 year olds were least concerned about cardiovascular disease.
• All groups said that they're least worried about stroke as a personal health threat

Long life with quality health is also a goal of many 25-44 year olds. The average age this group wishes to reach is 91. If they continue to live healthfully, they will have a better chance of reaching that goal than those under 25.

Stroke occurs when a blood vessel in or leading to the brain bursts or is blocked by a blood clot. When this happens, part of the brain can't get the blood or oxygen it needs, so it starts to die. Depending on the severity of the stroke, immobility or paralysis may occur. In the United States, someone suffers a stroke every 40 seconds.

On the cover of a recent edition of Neurosurgery, readers saw an artist's intricate depiction of the high-flow brain bypass technique developed by SLU professor of neurosurgery, Saleem Abdulrauf, M.D.

Also in the March issue (Volume 63.3) of the journal, Abdulauf shared details of a surgery he performed to treat a patient's brain aneurysm, a weak area in the wall of an artery that supplies blood to the brain.

Abdulrauf's high-flow procedure means improved outcomes for patients. His technique is less invasive and keeps more blood flowing in the brain than previous surgeries.

Abulrauf likens brain bypass to bypass surgery for the heart. When a patient has an aneurysm involving a brain blood vessel or a tumor at the base of the skull wrapping around a blood vessel, surgeons eliminate the problem vessel by replacing it with an artery from another part of the body.

Brain bypass surgery was first developed in the 1960's in Switzerland by M. Gazi Yasargil, M.D, who is considered the father of modern neurosurgery. Used for complex aneurysms and tumors deep in the base of the skull, Abdulrauf built upon the procedure developed by his mentor, Yasargil.

Instead of replacing a problem artery with a healthy one from the scalp, as the original procedure did, Abdulrauf used an artery from the arm to allow a larger vessel to be replaced.

"With this new technique, we can treat patients in a way that minimizes recovery time and offers the best chance at keeping their brains healthy," Abdulrauf said.

The odds of surviving stroke appear to be much better for seniors living in neighborhoods where they interact more often with their neighbors and count on them for help, according to research published in Stroke: Journal of the American Heart Association.

"Social isolation is unhealthy on many levels, and there is a lot of literature showing that increased social support improves not just stroke, but many other health outcomes in seniors," said Cari Jo Clark, Sc.D., lead author of the study and assistant professor of medicine at the University of Minnesota in Minneapolis. "What is unique about our research is that we have taken this to the neighborhood level instead of just looking at the individual."

Clark and colleagues at the University of Minnesota and Rush University in Chicago studied 5,789 seniors (60 percent women, 62 percent black, average age 75) living in three adjacent neighborhoods in Chicago. Researchers interviewed the participants about their neighborhood and their interactions with neighbors. Using the National Death Index and Medicare claim files, they identified 186 stroke deaths and 701 first strokes over 11 years of follow-up. In their analysis, they factored out potential contributing variables such as socioeconomic status and cardiovascular risk factors like high blood pressure, smoking, physical inactivity, diabetes and obesity.

The researchers used questions measuring "cohesiveness." They asked how often (often, sometimes, rarely or never) the following occurred in each neighborhood:

• Do you see neighbors and friends talking outside in the yard or on the street?
• Do you see neighbors taking care of each other, such as doing yard work or watching children?
• Do you see neighbors watching out for each other, such as calling if they see a problem?

They were also asked how many neighbors:

• Do you know by name?
• Do you have a friendly talk with at least once a week?
• Could you call on for assistance in doing something around your home or yard or "borrow a cup of sugar" or ask some other small favor?

For each single point increase in the neighborhood "cohesion" scoring system, survival increased 53 percent.

While stroke incidence didn't differ among neighborhoods, stroke survival was far better for seniors living in "cohesive" neighborhoods, regardless of their gender. However, the benefit was only observed among whites.

"I think this indicates that a positive neighborhood social environment is as important to senior health as stress or even crime, but it is a really complex issue," Clark said. "Nonetheless, it underscores the positive aspects of close neighbors and neighborhoods, and should help bolster efforts to improve such cohesiveness."

One possible reason for improved survival is that seniors living in closer neighborhoods have others looking out for them who can get help sooner if they start experiencing stroke symptoms. They're also less mobile, and neighborhood conditions may be especially relevant. Recent longitudinal research has also found a significant protective relationship between social support and stroke mortality, but not stroke incidence.

Why seniors in African-American neighborhoods didn't fare as well is unclear and further research is needed, Clark said. "Obviously, a complex set of factors influences health in older adults and we need to be careful drawing conclusions from these data. Other research also has shown that the health protective effects of cohesive neighborhoods may be stronger in whites. We plan to conduct future studies to try to understand these findings."

Co-authors are Susan A. Everson-Rose, Ph.D.; Hongfei Guo, Ph.D.; Scott Lunos, M.S.; Neelum T. Aggarwal, M.D.; Todd Beck, M.S.; Denis A. Evans, M.D.; and Carlos Mendes de Leon, Ph.D. The study was funded by the National Institutes of Health and the University of Minnesota.

— Increased levels of a protein that helps regulate the body's blood pressure may also predict a major cardiovascular event in high-risk patients, according to a study led by St. Michael's Hospital's cardiovascular surgeon Subodh Verma. Measuring the amount of the protein, known as plasma renin activity (PRA), in the blood stream may give doctors another tool to assess a patient's risk and help prevent a heart attack or stroke.

"Conventional factors like genetics and environment do not always provide a complete patient story and an understanding of cardiovascular risk," says Dr. Subodh Verma, senior author, researcher and cardiovascular surgeon at St. Michael's Hospital. "The plasma renin activity blood marker allows us to identify people at a higher risk and that gives us the opportunity to introduce therapies that would work to lower a patient's PRA levels."

Published in March in the European Heart Journal, the paper was based on 2,913 Canadian HOPE (Heart Outcomes Prevention Evaluation) study patients. Patients in the study had stable chronic vascular disease and/or diabetes and one cardiovascular risk factor.

"This study makes a strong case for further study of PRA and its association with cardiovascular death," explains Dr. Verma. "The next step will be to move into larger trials with PRA therapies and study whether or not this impacts the cardiovascular death rate. This could be a big step forward in our battle against heart disease."

The Heart & Stroke Foundation estimates that heart disease and stroke costs the Canadian economy more than $22.2 billion every year in physician services, hospital costs, lost wages and decreased productivity.

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Journal Reference:

1. S. Verma, M. Gupta, D. T. Holmes, L. Xu, H. Teoh, S. Gupta, S. Yusuf, E. M. Lonn. Plasma renin activity predicts cardiovascular mortality in the Heart Outcomes Prevention Evaluation (HOPE) study. European Heart Journal, 2011; DOI: 10.1093/eurheartj/ehr066

A University of Iowa study finds that patients treated with a short course of antidepressants after a stroke have significantly greater improvement in physical recovery than patients treated with a placebo. Moreover, the study is the first to demonstrate that this physical recovery continues to improve for at least nine months after the antidepressant medication is stopped.

"The idea that antidepressants might benefit early recovery from stroke has been around for a couple of years," said Robert Robinson, M.D., UI professor and head of psychiatry and senior study author. "But one major question left unanswered by previous studies was 'does the effect last after the medication stops?'

"What our study demonstrates is that not only does the beneficial effect last, but the improvement in physical recovery continues to increase even after the patients stop taking the medication."

The study, which was published online in the American Journal of Geriatric Psychiatry Feb. 24, found that both depressed and non-depressed stroke patients who received antidepressant medication had greater physical recovery after stroke than patients who received placebo. In addition, the effect compared to placebo was observed even after controlling for patients' age, total hours of rehabilitation therapy and initial severity of stroke.

Stroke is the leading cause of adult disability in the United States, and an estimated 795,000 strokes occur annually, according to the National Stroke Association.

Current treatment of patients with acute ischemic stroke generally focuses on therapies to restore blood supply to the brain within the first few hours of onset of stroke. Unfortunately, most patients with stroke do not arrive within the short time window for effective treatment. Other patients may not have a favorable outcome even with treatment. Post-stroke treatment focuses on prevention of recurrent stroke or other complications of the brain illness and on maximizing recovery with rehabilitation.

"The findings of this study are important because they imply that early administration of an adjunctive medication, an antidepressant, might have an effect on improving outcomes independent of the medication's actions on mood," said Harold Adams, M.D., UI professor of neurology and a study co-author. "If future studies confirm our observation regarding the use of antidepressant medications as an ancillary therapy given to people with stroke, including those without depression, the public health impact could be huge."

The study suggests that the antidepressant medication is doing something, independent of treating depression, that improves physical recovery from stroke. Robinson notes that although the mechanisms underlying the effect are not yet known there is evidence that antidepressants can inhibit a type of inflammatory protein that is released in the brain during stroke, and can promote growth of new cells in specific parts of the brain.

"Our hypothesis is that the antidepressant medication is blocking the inflammatory proteins that inhibit cellular growth and that's why you get the cellular growth in certain parts of the brain," said Robinson, who also holds the Paul W. Penningroth Chair. "These new neurons may also explain why the improvement continues, because for a period of months and perhaps more than a year these cells continue to develop new connections, synapses and continue to grow and augment the recovery from the stroke that disrupted those motor neurons."

In the UI study, 83 patients who had recently had a stroke were randomly assigned to receive antidepressants (54 patients) or placebo (29 patients) for three months. The patients' physical, cognitive and psychiatric symptoms were assessed every three months for one year. Thirty-six of the patients who received antidepressants and 25 of the patients on placebo completed the one-year study.

Using a global measure of overall physical and motor disability called the Rankin Scale, the UI researchers showed that antidepressants significantly reduced physical disability over the one-year period compared to placebo. The Rankin Scale categorizes disability on a six-point scale, with zero being no disability.

Patients who got placebo did have initial recovery for several months, but then the recovery leveled off compared to patients who received the antidepressants and continued to improve steadily over the year of the study.

"Based on our study we saw an improvement of 1 to 1.5 categories on the Rankin Scale. Patients were moving from having such severe physical disability that they required help in daily activities to a situation where they still had some symptoms but, on average, could take care of their own daily activities," Robinson said.

Robinson acknowledged that the study's relatively small size and similarities among the patient population represented limitations. The team aims to validate the importance of their findings by testing the effect of antidepressants on physical recovery from stroke in a much larger and more diverse group of patients.

In addition to Robinson and Adams, the UI research team included Katsunaka Mikami, M.D., Ph.D.; Ricardo Jorge, M.D.; Patricia Davis, M.D.; Enrique Leira, M.D.; and Mijin Jang.

The study was funded in part by grants from the National Institutes of Health.

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Journal Reference:

1. Katsunaka Mikami, Ricardo E. Jorge, Harold P. Adams, Patricia H. Davis, Enrique C. Leira, Mijin Jang, Robert G. Robinson. Effect of Antidepressants on the Course of Disability Following Stroke. American Journal of Geriatric Psychiatry, 2011; : 1 DOI: 10.1097/JGP.0b013e31821181b0

Virtual reality and other video games can significantly improve motor function in stroke patients, according to research from St. Michael's Hospital. Patients who played video games, such as Wii and Playstation, were up to five times more likely to show improvements in arm motor function compared to those who had standard therapy.

"Virtual reality gaming is a promising and potentially useful alternative to enhance motor improvement after stroke," said Dr. Gustavo Saposnik, the lead author of the study and the director of the Stroke Outcomes Research Unit at the hospital. "It provides an affordable, enjoyable and effective alternative to intensify treatment and promote motor recovery after a stroke."

The study, published in the April edition of Stroke: Journal of the American Heart Association, reviewed 12 existing studies that looked at the effects of electronic games on upper arm strength and mobility.

Between 55 and 75 per cent of stroke survivors experience motor problems in their arm. Yet conventional therapy — physiotherapy and occupational therapy — provide only "modest and sometimes delayed effects," said Saposnik, also a Heart and Stroke Foundation-funded researcher.

Current research suggests effective therapy needs to be challenging, repetitive, task-specific and novel. Video games apply these concepts, helping the brain to heal through a process called neuroplasticity — the brain's ability to remodel itself after injury by creating new nerve cell connections.

"Recovery of motor skill depends on neurological recovery, adaptation, and learning new strategies," Saposnik said. "Virtual reality systems drive neuroplasticity and lead to benefits in motor function improvement after stroke."

Most of the studies Saposnik looked at included patients who had mild to moderate strokes. He said further research is needed to determine the effects of video games on treatment for more severe cases.

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Journal Reference:

1. G. Saposnik, F. Barinagarrementeria, R. D. Brown, C. D. Bushnell, B. Cucchiara, M. Cushman, G. deVeber, J. M. Ferro, F. Y. Tsai. Diagnosis and Management of Cerebral Venous Thrombosis: A Statement for Healthcare Professionals From the American Heart Association/American Stroke Association. Stroke, 2011; 42 (4): 1158 DOI: 10.1161/STR.0b013e31820a8364

 Devices which could be used to rehabilitate the arms and hands of people who have experienced a stroke have been developed by researchers at the University of Southampton.

In a paper to be presented this week (6 April) at the Institution of Engineering and Technology (IET) Assisted Living Conference, Dr Geoff Merrett, a lecturer in electronic systems and devices, will describe the design and evaluation of three technologies which could help people who are affected by stroke to regain movement in their hand and arm.

Dr Merrett worked with Dr Sara Demain, a lecturer in physiotherapy and Dr Cheryl Metcalf, a researcher in electronic systems and devices, to develop three 'tactile' devices which generate a realistic 'sense of touch' and sensation — mimicking those involved in everyday activities.

Dr Demain says: "Most stroke rehabilitation systems ignore the role of sensation and they only allow people repetitive movement. Our aim is to develop technology which provides people with a sense of holding something or of feeling something, like, for example, holding a hot cup of tea, and we want to integrate this with improving motor function."

Three tactile devices were developed and tested on patients who had had a stroke and on healthy participants. The devices were: a 'vibration' tactile device, which users felt provided a good indication of touch but did not really feel as if they were holding anything; a 'motor-driven squeezer' device, which users said felt like they were holding something, a bit like catching a ball; and a 'shape memory alloy' device which has thermal properties and creates a sensation like picking up a cup of tea.

Dr Merrett adds: "We now have a number of technologies, which we can use to develop sensation. This technology can be used on its own as a stand-alone system to help with sensory rehabilitation or it could be used alongside existing health technologies such as rehabilitation robots or gaming technologies which help patient rehabilitation."

A medical device developed by retired U.S. Navy sonar experts, using submarine technology, is a new paradigm for the detection, diagnosis and monitoring of stroke, says a team of interventional radiologists at the Society of Interventional Radiology's 36th Annual Scientific Meeting in Chicago, Ill. Each type of stroke and brain trauma is detected, identified and located using a simple headset and portable laptop-based console. The device's portability and speed of initial diagnosis (under a couple of minutes) make it appropriate for many uses outside of the hospital setting, including by military doctors in theater who need to assess situations quickly and efficiently in order to provide critically injured troops with treatment.

"We have developed and validated this portable device for the detection of stroke that is based on decades of submarine warfare technology," said Kieran J. Murphy, M.D., FSIR, professor and vice chair, director of research and deputy chief of radiology at the University of Toronto and University Health Network, Toronto, Ontario, Canada. He said this technology could easily differentiate normal brain from life-threatening conditions, such as swelling (hematoma) and bleeding (hemorrhage). "For example, when a physician suspects stroke time is of the essence, doctors could use the system to determine treatment that needs to begin immediately," he added. The device's continuous monitoring capability — unique in neurodiagnostics — will allow immediate detection of changes in a patient's condition. In addition to its being ideal for field ER, ambulance or military use, the researchers' hope is for the technology to be adapted and used in other areas of acute care, such as open heart surgery (where stroke is an ever-present concern), in other vascular indications elsewhere in the body and in monitoring the progression of disease for drug efficacy.

"Stroke is the third leading cause of death in the United States and the leading cause of disability," explained Murphy. A stroke or "brain attack" occurs when a blood clot blocks an artery or a blood vessel breaks, interrupting blood flow to an area of the brain, he said. When either of these things happens, brain cells begin to die and brain damage occurs. And, stresses Murphy, "time to diagnosis is critical to improving patient outcomes; time is brain."

"The system is very simple in principle, yet it yields exceedingly rich data," said Murphy. He explained that the device's basis in submarine technology means it works to measure a patient's complex brain pulsations and to provide information on the type and location of an abnormality in many of the same ways as sonar works on submarines. Both use an array of sensors to measure movement and generate signals to be processed and analyzed, matching the signals to objects or conditions. "As sonar sorts out whales and other objects from vessels, the device sorts out cerebral abnormalities such as aneurysms, arteriovenous malformations (AVMs, an abnormal connection between veins and arteries), ischemic strokes and traumatic brain injury from normal variations in physiology," noted Murphy.

Traditionally in transcranial ultrasound, the thinner areas of the skull are used as "windows" through which ultrasound can "see" or "listen," said Murphy. This system does not rely on these "windows." It measures the movement of the skull (acceleration) to separate confounding acoustic signals from the motion created by the in-rushing blood flow in this way: blood flows into the brain during each pulse and a pressure wave emulates from the vessels outward in all directions. The wave encounters the skull and accelerates it. The device measures the acceleration and records this complex waveform with a time synchronized high-resolution digitizer, explained Murphy.

In a 40-patient proof-of-principle trial, the patients — 16 men and 24 women — with a wide variety of cerebrovascular conditions, including intracerebral hemorrhage, subarachnoid hemorrhage, intracranial aneurysms, AVMs, ischemic stroke and transient ischemic attack (an episode in which a person has stroke-like symptoms for up to 1-2 hours), were studied. The researchers employed gold standard imaging — using CT magnetic resonance imaging or catheter angiography — to verify the diagnosis of the patients, who were then measured. The analysis team was blinded as to a patient's clinical history. For normal controls the research team relied on data taken on some 30 normal subjects (apart from the study). The team's algorithms were able to separate normal from all other conditions, to separate all patients with a specific condition into their own category and to provide information about the location of the abnormality. Initial blood vessel models were used to identify data signatures that were subsequently verified on patients in the clinic. The interventional radiologists said that, as they continue to increase their signature library, their expectation is that the location capability, as well as the capacity to detect other neurologic conditions with a high degree of sensitivity and specificity, will also increase.