As soon as 16 days after inserting the right hand into the cast, the areas of the brain responsible for controlling the movements of the right and left hand are reorganized, according to a Swiss study reported by the journal “Neurology”.
These observations could lead to new methods of rehabilitation of people after stroke, the authors of the study say.
Researchers at the University Hospital in Zurich reached such conclusions on the basis of a study among 10 people with a fracture of the right arm that required at least 14 days of immobilization in a cast or a sling. All subjects were right-handed, but during this time they used their left hand for daily activities such as eating, brushing their teeth, and writing.
Participants’ brains were examined twice using magnetic resonance imaging. The first examination was performed 48 hours after the right arm was injured, and the second one 16 days after its immobilization.
Scientists measured the thickness of the cerebral cortex (ie, the gray matter) in the sensorimotor regions of the brain, and the degree of damage and degradation to the white matter that forms the cortico-spinal tract that innervates most of the body’s muscles. They also assessed the ability of the healthy left hand to perform precise movements.
“Over a short period of time, immobilization of the right hand caused changes in the areas of the brain responsible for sensory and motor skills,” explains co-author Nicki Langer. In the left hemisphere, which controls the movements of the right hand, the thickness of the cerebral cortex in the sensorimotor regions has decreased. Likewise, white matter making up the left cortico-spinal tract was more degraded.
At the same time, the improvement in the mobility of the left hand was accompanied by anatomical changes in the corresponding areas of the right hemisphere, controlling the functions of this hand. There was a thickening of the cerebral cortex in the sensorimotor areas; White matter has also developed forming the right cortico-spinal tract.
As commented by the authors of the study, this means that the immobilization of the limb stimulates a rapid reorganization of the sensorimotor system in the brain.
“Our research shows that this type of therapy has both positive and negative effects,” says Langer. In his opinion, they confirm the validity of the current guidelines in the field of trauma surgery, according to which an injured arm or leg should be immobilized as shortly as possible, but for as long as necessary.
According to the researchers, these results are also interesting for stroke patients who may suffer from paralysis in certain areas due to the death of the nerve tissue. As part of therapy, a properly functioning hand can be immobilized to strengthen the dexterity of the hand with paresis and stimulate the development of relevant areas of the brain, they explain.