Medial reorganization of motor function demonstrated by functional MRI and diffusion tensor tractography

Purpose: Peri-lesional reorganization is a motor recovery mechanism after brain injury. The object of this study was to demonstrate the peri-lesional reorganization, using functional MRI (fMRI) and diffusion tensor tractography (DTT). Methods: Six control subjects and a 53 year-old woman with left primary sensori-motor cortex (SM1) and underlying (Jeep white matter injury were evaluated. The patient presented with complete paralysis of the right hand after the resection of a meningioma on the left SM1. The motor function of the affected hand had recovered slowly the extent of her being able to overcome some resistance for 6 months. At 2 years after the operation, fMRI was performed at 1.5 T in parallel with timed finger flexion-extension movements in all subjects and DTT was performed only in the patient. Results: The contralateral SM1 centered on the precentral knob was activated during hand movements of unaffected (left) side or control subjects. However, the medial area of the injured SM1 was activated during affected (right) hand movements. DTT of the affected (left) hemisphere originated from the medial area of the injured SM1 and descended along the medial side of injured deep white matter. Conclusions: It seems that the motor function of the affected hand was reorganized into the medial area of the injured SM1 and deep white matter in this patient.