In-vivo Banner, Vol 3 No12, Nov/Dec 2004 co branded with the Columbia University Medical Center logo


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Stroke
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STROKE

"Neuroplasticity" Helps Brain Recover After Injury

A new technique helps restore vision after stroke by coaxing uninjured cells to take over

Randolph Marshall with patient Rosemary Connor
Randolph Marshall with patient Rosemary Connor, who is using a new device that can help patients reduce visual deficits caused by stroke.

A few weeks after Rosemary Connor, 39, gave birth to her second child, she suffered a series of strokes that left her with both legs and one arm paralyzed, with her memory erased, and blind.

Eventually, most of these deficits reversed themselves, but several months later she still has vision loss, with dark sections in parts of her visual field. "My vision is like a jigsaw puzzle with some pieces missing," she says. Her vision problems impede her ability to perform daily functions such as driving, reading or caring for her baby.

But Ms. Connor hopes that her vision will improve because of a new FDA-approved therapy now being offered at Columbia University Medical Center by Randolph S. Marshall, M.D., associate professor of clinical neurology. The therapy is a computer-based targeted stimulation program for the brain called Vision Restoration Therapy (VRT) from NovaVision Inc. of Boca Raton, Fla. CUMC is one of only four sites in the United States that offer the device.

The therapy is based on neuroplasticity – the ability of the nervous system to modify its structure and function to recover from injury or respond to changes in the environment. When a stroke occurs, brain tissue that is cut off from the blood supply dies. Brain function can often recover to some degree, however, because neurons near the damaged area appear to take on some of the duties of the neurons that have died. "The concept of neuroplasticity is not new," Dr. Marshall says. "But we're only starting to understand the brain mechanisms involved because of advances in imaging technologies, such as fMRI, and behavioral techniques such as visual stimulation therapy."

Anesthesia Provides Window into Stroke Recovery Mechanisms

People who have had a stroke with attendant deficits in speech, vision or movement – but who have recovered – sometimes exhibit those deficits again temporarily when they are anesthetized during surgery. In an NIH-funded study of 200 patients, Ronald M. Lazar, M.D., professor of clinical neuropsychology in neurology and neurological surgery, is investigating whether this finding can be used to learn more about how the brain recovers after stroke.

"It appears that anesthesia enables us to peel away a layer of recovered function, so to speak, giving us a special view into how the brain reorganizes to redistribute functional responsibilities," Dr. Lazar says.

In his study, Dr. Lazar and his colleagues give participants mild sedatives to see which deficits briefly return under anesthesia and to define how the brain changes. They use fMRI to determine whether a change in activation of brain regions follows injury from stroke or transient ischemic attack.

Dr. Lazar believes a neurochemical mechanism is important to stroke recovery. "If such a mechanism can be determined, that could lead to better treatments targeted at achieving the best recovery," Dr. Lazar says.

—Matthew Dougherty

In Ms. Connor's case, VRT is training her to focus on flashing dots in the border areas where her vision goes from good to hazy. Eventually, this targeted stimulation can make the missing "jigsaw pieces" smaller by filling in the holes in her visual field. Research has indicated that about 65 percent of patients who used VRT for six months showed measurable improvements in their vision.

Dr. Marshall and his colleague, Ronald M. Lazar, Ph.D., professor of clinical neuropsychology in neurology and neurological surgery, are experts in neuroplasticity and co-direct the Levine Cerebral Localization Laboratory, where they investigate behavioral manifestations of stroke and related vascular diseases.

They are tracking the Columbia patients who use VRT to see how effective the product is and what can be learned from the therapy about visual recovery. They plan to conduct an fMRI study to see how brains function before and after VRT. "We haven't studied vision specifically in the past but our studies of neuroplasticity involving visual perception problems – such as when stroke patients unknowingly neglect one side of their body – do fit together nicely with this new effort," says Dr. Marshall.

Drs. Marshall and Lazar, along with their colleagues John W. Krakauer, M.D., assistant professor of neurology, and Eric D. Zarahn, Ph.D., assistant professor of clinical psychiatry, are also collaborating on a project that is funded by the recently awarded NIH grant called SPOTRIAS (Specialized Programs of Translational Research in Acute Stroke.) CUMC researchers were awarded this highly competitive $12 million grant for a number of stroke-related studies. Dr. Marshall's project involves an fMRI study to see whether altered patterns of brain activity shortly after the onset of stroke can predict recovery. Dr. Marshall's preliminary studies have demonstrated emergence of activity in the opposite brain hemisphere from where a stroke occurs. If these alterations in the brain have functional significance, the researchers will investigate whether treatment can mitigate the neurological deficits.

"It's an exciting time in neurology right now because of many new ideas," Dr. Marshall says. "The visual system, for example, was thought to be immutable and hard wired. But neuroplasticity is proving that idea is wrong and patients are benefiting directly from it."

—Matthew Dougherty


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