Stroke survivors often suffer from long-term problems in their arms, and the condition of both arms may deteriorate together.
When one arm is severely affected, using the other arm also becomes difficult, making even simple tasks exhausting and discouraging.
Compared to the dominant hand of a healthy person, stroke survivors may take up to three times longer to complete daily tasks using their less affected arm. Many are forced to rely almost entirely on this arm for eating, dressing, and performing household chores.
A stroke occurs when the flow of oxygen-rich blood to a part of the brain is interrupted due to a blockage or bleeding in a blood vessel, leading to the death of brain cells.
Because each side of the brain controls the opposite side of the body, a stroke often causes weakness in the arm opposite the affected side. Therefore, traditional rehabilitation programs have focused on restoring movement in the more severely affected arm.
However, recent research has shown that both hemispheres of the brain contribute to controlling the movements of both arms, and that damage to one side of the brain can affect both arms. Thus, the "less affected" arm also becomes abnormal, exhibiting weakness, slowness of movement, and poor coordination.
In a clinical trial involving over 50 people with chronic stroke and severe impairment in one arm, participants were randomly assigned to two groups: one group trained their more severely affected arm, and the other trained their less severely affected arm. Both groups received five weeks of therapy that included challenging hand movements, realistic tasks, and virtual reality simulations to improve coordination and timing.
The results showed that participants who trained their less damaged arm became faster and more efficient at performing everyday tasks, such as picking up small objects or lifting a cup, and this improvement lasted for six months after training.
This lasting improvement is most likely due to a feedback loop: the better the arm's function, the more it is used in daily life, which reinforces training and helps to consolidate gains.
Rehabilitation has traditionally focused on the more severely affected arm, but many do not fully regain its function and are forced to rely on the less affected arm. However, this arm is not entirely "healthy," and any problems with it can affect a person's independence and quality of life.
Improving the performance of this arm makes everyday tasks faster, easier, and less tiring, even years after a stroke.
Future research will focus on integrating training for the less affected arm with standard treatment programs for the more affected arm, and how to apply these methods in everyday life at home.
For many recovering people, recovery may not mean getting back what was lost, but rather strengthening what remains.
The report was prepared by Candice Maenza, Research Project Manager and Assistant Director of the Center for Translational Neuroscience in Rehabilitation, Pennsylvania State University; and Robert Seinberg, Professor of Kinesiology and Neuroscience, Pennsylvania State University.
