Shift of language function to right hemisphere impedes post-stroke aphasia recovery

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 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 . 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 . 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.

More information: "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.

add to favorites email to friend print save as pdf

Related Stories

The changing roles of 2 hemispheres in stroke recovery

Jan 31, 2011

Most people who survive a stroke recover some degree of their motor, sensory and cognitive functions over the following months and years. This recovery is commonly believed to reflect a reorganisation of the central nervous ...

Teaching the brain to speak again

Feb 16, 2013

Cynthia Thompson, a world-renowned researcher on stroke and brain damage, will discuss her groundbreaking research on aphasia and the neurolinguistic systems it affects Feb. 16 at the annual meeting of the American Association ...

New metric predicts language recovery following stroke

Jun 24, 2010

A team of researchers led by NewYork-Presbyterian Hospital/Columbia University Medical Center has developed a method to predict post-stroke recovery of language by measuring the initial severity of impairment. Being able ...

Unlocking the brain after stroke

Sep 23, 2008

University of Queensland research is set to unlock the regions of the brain central to successful language treatment following a stroke.

Recommended for you

Study links enzyme to autistic behaviors

21 hours ago

Fragile X syndrome (FXS) is a genetic disorder that causes obsessive-compulsive and repetitive behaviors, and other behaviors on the autistic spectrum, as well as cognitive deficits. It is the most common ...

A new cause of mental disease?

Jul 23, 2014

Astrocytes, the cells that make the background of the brain and support neurons, might be behind mental disorders such as depression and schizophrenia, according to new research by a Portuguese team from ...

Molecular basis of age-related memory loss explained

Jul 22, 2014

From telephone numbers to foreign vocabulary, our brains hold a seemingly endless supply of information. However, as we are getting older, our ability to learn and remember new things declines. A team of ...

The neurochemistry of addiction

Jul 22, 2014

We've all heard the term "addictive personality," and many of us know individuals who are consistently more likely to take the extra drink or pill that puts them over the edge. But the specific balance of ...

User comments