|Immobilization of an arm has an effect of the brain. German and Swiss researchers saw in magnetic resonance imaging (MRI) scans a decrease of brain parts which are responsible for motor and sensory skills of the immobilized arm, whereas brain parts and skills of the free arm increase.
The Swiss team around Nicolas Langer and Lutz Jäncke from the University of Zurich report 2012 their findings in the journal Neurology. They examined ten patients with a broken arm. MRI scans of the brain were made before and at least 14 days after the immobilization of the entire arm by cast and sling. It was observed that the volume of those areas of the cerebral cortex which process the signals from the immobilized arm and control its muscles are reduced by 10%. However, the brain regions for the other arm were getting larger, because this arm had to take over activities such as brushing teeth, writing and eating.
Three years before, Silke Lissek and her colleagues from the Ruhr University Bochum, Germany reported similar findings in the journal Current Biology. They recruited 31 cast-wearing volunteers (with no arm injuries) and 36 controls without cast. After the volunteers wore the short arm cast for two weeks, a reduced activation in the somatosensory cortex was found in MRI scans. Furthermore the compensatory effects of the free hand even exceed the capabilities of the control group. Two to three weeks after cast removal, the changes of the former casted side returned to normal, whereas the improved capabilities on the non-casted side remained.
These findings of both research groups show a rapid adaptability of the brain, even in adulthood. Immobilization in connection with a transfer of skills to the healthy limb induces a reorganization of the sensorimotor system.
Langer N, Hänggi J, Müller NA, Simmen HP, Jäncke L.
Lissek S, Wilimzig C, Stude P, Pleger B, Kalisch T, Maier C, Peters S, Nicolas V, Tegenthoff M, Dinse H.
Effects of limb immobilization on brain plasticity.
Neurology. 2012; 78(3):182-188.
Immobilization impairs tactile perception and shrinks somatosensory cortical maps.
Current Biology. 2009; 19:837-842.