Stroke damage in a brain region known as the putamen is strongly linked to motor neglect, a condition that makes patients slow to move toward the left side, according to researchers at Washington University School of Medicine in St. Louis.
"Earlier attempts to treat stroke patients with neglect with dopamine-like compounds have produced mixed results," says Ayelet Sapir, Ph.D., postdoctoral researcher in neurology. "It's possible, though, that those unfavorable outcomes resulted from an inability to identify the patients most likely to benefit from the intervention. Our data indicate that patients with damage to the putamen may respond differently to this treatment than patients who have neglect from stroke damage to other parts of brain."
Dr. Sapir describes the research, which appears in The Journal of Neuroscience, as part of a broader effort to precisely determine how strokes in different parts of the brain's right hemisphere affect patients. Some patients with stroke in the right brain develop slightly different forms of neglect. How to separate slowness to notice a stimulus (spatial neglect) from slowness to act on a stimulus (motor neglect) has been a persistent problem for neuroscientists. Dr. Sapir was able to overcome this problem and of 29 patients tested, six were able to respond promptly to left-side stimuli, suggesting they had motor neglect.
When Sapir compared high-resolution MRI brain scans from the two groups, she found a that all the patients identified as having motor neglect had damage to the putamen, while those who still responded slowly to left-side stimuli did not.
Although the putamen isn't damaged in Parkinson's disease, scientists have identified it as a brain region that processes dopamine, which drops to low levels in Parkinson's patients. This could suggest that stroke victims with motor neglect would be more likely to respond to Parkinson’s disease medication than those with spatial neglect.