PURPOSE: We used functionnal magnetic resonance imaging(fMRI) to evaluate cortical activation in the sensory-motor areas of the contralateral and ipsilateral cerebral hemisphere during motor tasks and imagined movement with a biceps neurotised by a cross C7 graft.

METHODS:Seven patients with total brachial plexus avulsion underwent a transfer from a part of the contralateral C7 root onto the musculo cutaneous nerve or the lateral cord in order to restore the elbow flexion.They were studied with echo-planar MRI (1,5 T) while performing flexion tasks with both elbows and imagined flexion sequences on both sides. During the tasks, the areas of activated pixels were studied and compared on the ipsi and the contralateral cortex.

RESULTS:There was a bilateral coactivation between the two sensory motor cortex (primary motor area) when the patients were using the neurotized elbow. During the imagined tasks, the activated area of the contralateral cortex was significantly larger than the ipsilateral cortex activated area. This contralateral area looked similar to the contralateral area activated during motor tasks.

CONCLUSION: After cross C7 nerve graft, the contralateral cortex is already involved in the elaboration of the recovered movments in association with other motors areas.