Study On FMRI And Resting State FcMRI Of Motor Cortex After Contralateral Cervical 7 Nerve Transposition

PART IMotor imagery of the patients with brachial plexus injury:an fMRI study[AAbstract] Objective To detect the changes of neural activation patterns before and after nerve transfer while performing motor imagery task.Methods and Materials14patients with5roots of unilateral brachial plexus avulsion injury and7healthy volunteers were recruited in this study. All patients had brachial plexus avulsion injury on the right side,7of whom underwent fMRI before nerve transfer was performed while another7patients underwent fMRI after contralateral C7nerve transferred to the median nerve. The subjects performed imaginary unilateral hand grasping movement without overt movement of the hand during fMRI scanning. Activation maps of the whole brain for different groups were processed using SPM8. Results Bilateral SMA and PMA, left inferior parietal lobe and basal ganglia were activated while the healthy controls performed imaginary unilateral hand grasping movement. Activated areas were similar when the pre-operation and post operation patients performed imaginary grasping movement of the healthy hand and the areas were:bilateral SMA, right PMA and superior parietal lobe. A few motor areas were activated during pre-operation patients performing imaginary grasping movement of the affected hand, but the areas differed from every patient in single subject analysis, hence the group analysis showed no activations. Bilateral SMA, left PMA and superior parietal lobe were activated when post operation patients performed imaginary grasping movement of the affected hand. Contrast between pre-operation and post operation patients with right brachial plexus injury:right superior parietal lobe was obtained after subtracted pre-operation group from post operation group.Conclusion Motor imagery and motor execution share the same brain functional areas. Brachial plexus injury disrupts the afferent and efferent pathway, which is on the basis of reorganization of brain areas represented for motor imagery. Combining motor imagery and physical therapy would be helpful to promote functional recovery of the affected limb and thus improve the quality of the patient’s life. Long-range cerebral plasticity of the human brain after contralateral cervical nerve transfer:an fMRI study[Abstract] Objective To assess the characteristics of long-range cerebral plasticity of the human brain cortex after the seventh contralateral cervical nerve transfer by using functional MRI (fMRI). Materials and Methods Nine healthy male volunteers and8male patients with total brachial plexus traction injury who had received the contralateral seventh cervical nerve root transfer of the unaffected side were studied by using fMRI. Five of8patients suffered right brachial plexus root avulsion injury and the rest suffered left brachial plexus root avulsion injury. The delay between surgery and fMRI scan was more than2years (average71±39.8months) for every patient. Functional brain images were acquired under the condition of hand grasping of unilateral hand. Control tasks were performed for the block-design and SPM8was used to analyze the data and obtain the activated brain regions. Numbers of activated voxels were used to calculate lateralization index (L) and group analyses were performed for the control group and the right brachial plexus root avulsion injury group respectively. Results All healthy volunteers’unilateral hand movement generated strong signal change in the contralateral sensorimotor cortex while a few of them generated signal change in the ipsilateral sensorimotor cortex and the laterality index of every healthy control was positive. Group analysis of the control group showed the same result as single subject analysis. Movement of the affected hand of patient was associated with a bilateral network activity but the laterality index was positive, which implied that the main activated areas were located in the contralateral cortex. Group analysis of the5right brachial plexus injury patients and single subject analysis of the3left brachial plexus injury patients revealed the same results.Conclusion The brain may try to restore the control of an injured limb to its original cortex. Changes of inter-hemispheric functional connectivity between motor cortices after brachial plexuses injury and nerve transfer:A resting-state fcMRI study[Abstract] Objective The aim of this study is to explore the changes of inter-hemispheric functional connectivity in patients with unilateral brachial plexus injury before the contralateral C7nerve transfer and during the follow-up at different times after nerve transfer. Methods25patients with5roots of unilateral brachial plexus avulsion injury and9healthy controls were recruited in this study. The subjects were divided into4groups:group A was constituted by9healthy controls, group B was constituted by9patients underwent MRI before contralateral nerve transfer, group C8patients underwent MRI during follow-up at a short term (less than2years) after contralateral C7nerve transfer, and group D8patients underwent MRI during follow-up at a long term (more than3years). Resting-state functional connectivity magnetic resonance image was used to study the differences of inter-hemispheric functional connectivity between patients and healthy controls. Four areas were defined as regions of interest (ROI):the two primary motor areas (Ml areas) and two supplementary motor areas in the two hemispheres activated when the healthy volunteers performed unilateral hand grasping movement of the’ two hands respectively. Functional connectivity maps were generated by correlating the regional time course of each ROI with that of every voxel in the whole brain. Then, functional connectivity was calculated by correlating the functional magnetic resonance image signal time courses of every two ROIs. Results The correlation coefficients of the two M1s was significantly different in the four groups (Kruskal-wallis test with unequal variances, P=0.0028).The correlation coefficients of the two M1s were significantly different between groups A and B (P=0.0031), and groups A and C (P=0.0071). The correlation coefficients of the two M1s were significantly different between groups D and B (P=0.016), and groups D and C (F=0.027). The correlation coefficients of the supplementary motor areas showed no difference in the four groups.Conclusions Our results indicate that brachial plexus injury decreases resting-state inter-hemispheric functional connectivity of the two primary motor areas, however, after the recanalization of the neural pathway and rehabilitative exercise, the functional connectivity of the two M1areas would increase to a normal level. These results provide new insight into functional reorganization of the cerebral cortex after brachial plexus injury.