Research findings could help thousands of stroke patients

07 March 2012

Research findings could help thousands of stroke patients

A drawing by a stroke patient suffering from left visual neglect

A researcher at Glasgow Caledonian University has uncovered startling new evidence that may have important implications for the understanding of stroke patients who suffer from left visual neglect, a severe brain condition that causes people to completely ‘forget’ one side of their body and surroundings.

Around 150,000 people in the UK suffer stroke every year and thousands of survivors (up to 80%) are left with visual neglect, a disabling condition that has puzzled and divided researchers for more than 100 years.

Caused by damage to the right side of the brain, patients behave as if the left side of their world does not exist, even though their sight has not been affected and they are not blind to that side.

For example, a man may shave only the right side of his beard and a woman may apply make-up to only the right side of her face.

This condition is also associated with numerous severe difficulties when carrying out daily life tasks such as getting dressed, eating (only one half of a meal is consumed), washing and moving around.

Now Dr Stephanie Rossit, lecturer in the Vision Neurosciences and Neuro-rehabilitation research groups at GCU’s Institute of Applied Health Research, has discovered that the brain’s autopilot can override left visual neglect when patients were asked to point to objects that moved suddenly from the centre to the right and left sides of space.

In the study, stroke patients with left visual neglect were asked to correct their on-going hand movements to targets that unpredictably jumped to the right or left sides of space. Dr Rossit found that despite their severe perceptual difficulties, most patients could still catch targets that changed position during the movement.

Dr Rossit said: “Astonishingly, even when the target jumped to the left, where there was no visual awareness, most patients with left visual neglect instinctively corrected their hand movements in-flight and successfully caught the target on their neglected side.”

In addition, the study showed that these patients even corrected their on-going hand actions when asked to stop their movements in response to the target jump, in a very similar way to that of stroke patients without neglect or even those who had never suffered a stroke.

Dr Rossit describes this phenomenon as ‘the zombie within’ which can automatically adjust our hand actions even without our awareness that it is doing so.

She said: “These new results provide insight into how our brains control our actions automatically and unconsciously. They indicate that the brain systems responsible for controlling our hand movements can even operate without awareness. For example, when we catch objects we are not consciously aware of all the complex steps involved to do so, as if we had a zombie within.”

The results of the study, which was funded by the Portuguese Foundation for Science and Technology (FCT) and carried-out in collaboration with researchers at the Universities of Glasgow (Dr. Monika Harvey, Dr. Keith Muir), Edinburgh (Dr. Robert McIntosh), Strathclyde (Dr. Stephen Butler) and the Imperial College of London (Dr. Paresh Malhotra), have been published in the journal Neuropsychologia.

Dr. Rossit believes that the study provides novel evidence on what brain systems are relatively preserved in stroke patients with left visual neglect. She said: “This study suggests that despite the severe lack of awareness to the left side of space, some patients with visual neglect are still able to perform hand actions towards objects in their neglected side and thus we may be able to tap into this spared function to rehabilitate the condition.

“Even though there is much research in the field of neglect rehabilitation, to date there is no accepted effective treatment for this severe condition.”

Dr. Rossit and her collaborators are currently investigating the effects of a simple rehabilitation treatment for visual neglect using repetitive hand action exercises.


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