Immobilized Limb Leads to Changes in the Brain

Breaking and immobilizing an arm can lead to a significant change in the brain, including skill transfer from the dominant to the nondominant hand, a recently concluded longitudinal study suggests.

Professor Lutz Jäncke and colleagues at the University of Zurich in Switzerland conducted the study involving 10 right-handed patients who injured their right arm and required it to be immobilized for at least 14 days.

During the study, the researchers performed two MRIs on the participants, the first of which was conducted within 48 hours of the injury and the second after an average of 16 days of immobilization.

They then measured the “cortical thickness of sensorimotor regions and [fractional anisotropy] of the corticospinal tracts”, which allowed them to assess the dexterity of their left hands, according to a study abstract.

They found that, after the arm had been immobilized for at least 14 days, there was a significant decrease in cortical thickness in the left primary motor and somatosensory area of the brain, the side which controls the right arm; they also noted a decrease in fractional anisotropy.

They noted that the left hand’s dexterity increased over this time as well due to the patients’ reliance on it while their dominant hand was unusable. This they related to the increased fractional anisotropy and cortical thickness in the right motor cortex.

Jäncke suspects that the cortical thickness associated with the dominant arm will be regained once the arm is no longer immobilized. He said that he would like to have the patients return for another examination now that their arms are healed.

This finding could have major implications for the way physical therapists approach rehabilitation therapy.

“Given that limb immobilization is a standard intervention technique in constraint-induced therapy, therapists should be aware of both the positive and negative effects of this intervention,” said Jäncke in the abstract.

This study is published in the journal Neurology.