In a study designed to differentiate why some stroke patients recover from aphasia and others do not, investigators have found that a compensatory reorganization of language function to right hemispheric brain regions bodes poorly for language recovery. Patients who recovered from aphasia showed a return to normal left-hemispheric language activation patterns. These results, which may open up new rehabilitation strategies, are available in the current issue of Restorative Neurology and Neuroscience.
“Overall, approximately 30% of patients with stroke suffer from various types of aphasia, with this deficit most common in stroke with left middle cerebral artery territory damage. Some of the affected patients recover to a certain degree in the months and years following the stroke. The recovery process is modulated by several known factors, but the degree of the contribution of brain areas unaffected by stroke to the recovery process is less clear,” says lead investigator Jerzy P. Szaflarski, MD, PhD, of the Departments of Neurology at the University of Alabama and University of Cincinnati Academic Health Center.
For the study, 27 right-handed adults who suffered from a left middle cerebral artery infarction at least one year prior to study enrollment were recruited. After language testing, 9 subjects were considered to have normal language ability while 18 were considered aphasic. Patients underwent a battery of language tests as well as a semantic decision/tone decision cognitive task during functional MRI (fMRI) in order to map language function. MRI scans were used to determine stroke volume.
The authors found that linguistic performance was better in those who had stronger left-hemispheric fMRI signals while performance was worse in those who had stronger signal-shifts to the right hemisphere. As expected, they also found a negative association between the size of the stroke and performance on some linguistic tests. Right cerebellar activation was also linked to better post-stroke language ability.
The authors say that while a shift to the non-dominant right hemisphere can restore language function in children who have experienced left-hemispheric injury or stroke, for adults such a shift may impede recovery. For adults, it is the left hemisphere that is necessary for language function preservation and/or recovery.
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NOTES FOR EDITORS
“Recovered vs. not-recovered from post-stroke aphasia: The contributions from the dominant and non-dominant hemispheres,” by Jerzy P. Szaflarski, Jane B. Allendorfer, Christi Banks, Jennifer Vannest and Scott K. Holland. Restorative Neurology and Neuroscience, 31:4 (July 2013), DOI 10.3233/RNN-120267. Published by IOS Press online ahead of issue.
Full text of the article is available to credentialed journalists upon request. Contact Daphne Watrin, IOS Press, +31 20 688 3355, firstname.lastname@example.org. Journalists wishing to interview the authors should contact Dr. Jerzy P. Szaflarski at email@example.com.
This study was supported by the National Institutes of Health grants R01 HD068488 and R01 NS048281.
ABOUT RESTORATIVE NEUROLOGY AND NEUROSCIENCE (RNN)
An interdisciplinary journal under the editorial leadership of Bernhard Sabel, PhD, Restorative Neurology and Neuroscience publishes papers relating the plasticity and response of the nervous system to accidental or experimental injuries and their interventions, transplantation, neurodegenerative disorders and experimental strategies to improve regeneration or functional recovery and rehabilitation. Experimental and clinical research papers adopting fresh conceptual approaches are encouraged. The overriding criteria for publication are novelty, significant experimental or clinical relevance and interest to a multidisciplinary audience. www.iospress.com/journal/restorative-neurology-and-neuroscience
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Prof. Dr. Bernhard Sabel
Institut für Medizinische Psychologie
Otto-v.-Guericke Universität Magdeburg
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