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| Archive : Fall 2005 |
Reasons for Hope:
Vampire bats, cell-suicide preventers, free-radical scavengers, neuron revivers, improved logistics for better care faster.
Why Strokes Still Kill [page 3]
 By Cathryn M. Delude
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Other efforts at neuron revival involve gases. Oxygen, says Aneesh Singhal, a clinician-scientist in the Massachusetts General Hospital Neurology Department and Neuroprotection Research Lab, has long been controversial. Giving a stroke patient oxygen may relieve oxygen-starved neurons—or increase harmful free radicals. Singhal recently led a small pilot study among patients who arrived too late for TPA. The results, published in Stroke, show improvement in the disability caused by stroke and reduction in the size of MRI lesions (which are usually not reversible) during high-flow oxygen therapy. "We think early oxygen therapy could support stroke-endangered tissue longer and thereby extend the time window for TPA," says Singhal, who has applied for NIH funding for a larger clinical trial.
Increasing nitric oxide (NO) levels in blood vessel walls might also help. Michael Moskowitz, professor of neurology at Harvard Medical School and a stroke researcher at the Massachusetts General Hospital, explains that NO increases blood flow in the endangered region during a stroke. Moreover, NO promotes the growth of both new blood vessels and neurons, enhancing recovery in the remaining neural tissue, according to Michael Chopp, scientific director of the Neuroscience Institute at the Henry Ford Health Sciences Center. And there are two well-known and widely used drugs that rev up NO and activate other neurorestorative pathways: Viagra and the cholesterol-lowering drugs known as statins. "Both have a similar effect in increasing the production of new blood vessels and new brain cells, which are common denominators for inducing restored brain function," Chopp explains.
As encouraging as much of this seems, true breakthroughs are likely to come slowly, warns Gregory del Zoppo, associate professor in the department of molecular and experimental medicine at Scripps Research Institute in California. "The brain is still pretty much a black box," he says. "Every positive outcome has a neural and a vascular component, and at this point, we usually don't know which is which."
There's also a bigger problem. Whatever the advances in stroke treatment, many victims won't benefit if they don't find their way to facilities equipped with the best technology and staffed with physicians willing and able to provide the latest therapies. Rather than being taken to the nearest hospital, patients need to be transported to designated stroke centers, where they can be treated effectively. In other words, the emergency network for stroke needs to emulate the system for emergency cardiac units, which in turn followed the one devised for trauma victims.
Hemingway probably owes her nearly complete recovery to such a stroke network in Massachusetts, for which Schwamm was a prime mover. As in several other states, patients are transported to specialized stroke centers that are staffed 24/7 with a neurologist, trained technicians and magnetic resonance imaging or CAT scans in the ER. Helicopters can quickly deliver patients from anywhere in New England. And Schwamm has developed a "telestroke" program, in which a neurologist at a stroke center can consult while viewing the ER scene and brain images on a monitor as doctors treat a stroke patient in a distant hospital. Such logistical initiatives may save more patients than will a pharmacy full of new therapies.
But something else is needed—early recognition. As with most strokes, Hemingway's came without warning. "One minute I was fine and the next I was numb on my right side," she recalls. Many might have missed the urgency of the situation, particularly because Hemingway, a young woman, wasn't a typical stroke patient. And as long as the vast majority of the public—83% at last report—remains oblivious to a stroke's warning signs, most victims will continue to lose their race against time.
 Dossier
1. "Mechanisms, Challenges, and Opportunities in Stroke," by Eng H. Lo, Turgay Dalkara and Michael A. Moskowitz, Nature Reviews: Neuroscience, May 2003. A well-illustrated historical overview of the understanding of stroke biology, brain imaging, treatments and new research directions.
2. "Exciting, Radical, Suicidal: How Brain Cells Die After Stroke," by Eng H. Lo, Michael A. Moskowitz and Thomas P. Jacobs, Stroke, Feb. 2005. A helpful summary of recent research about cell death and the neurovascular unit.
3. "Recommendations for the Establishment of Stroke Systems of Care," by Lee H. Schwamm et al, Stroke, March 2005. Influential recommendations from the American Stroke Association's task force for establishing a network of stroke centers, as well as education for prevention, emergency response, treatment and rehabilitation.
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From top: Photo, Creatas; Photo courtesy the Massachusetts General Hospital
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