| Objectives It is confirmed that structural and functional reorganization will happen after cerebral infarction, namely neural plasticity. At present, different functional imaging techniques can help display the activation of the brain associated with the task status, and indirectly reflect functional areas. The vast majority of patients after cerebral infarction with the contralateral dyskinesia will recover in different degrees through a period of time after the recovery of motor function. In this study, blood oxygen level dependent functional magnetic resonance imaging(BOLD-f MRI) was used to observe the structural and functional reorganization in patients with brain infarction under the condition of bilateral clenching movements dynamically and explore its relation with motor function recovery at the same level of limb.Methods Thirty-four patients with ischemic infarction paralysis were invovled in this study. Infarction areas were all ischemia-induced and ascertained by CT or MRI, including paraventricular regions, basal ganglia, pons. The volume of infarction areas were 0.68-2.78 cm3 with an average volume of 1.46 ± 0.57cm3. There were twenty-three males and eleven females with an average age of 61.3 ± 10.3 years old. The total courses of infarction were all within one week(acute-stage) and patients were re-scanned five to seven weeks after infarction. Eleven patients have received second time scanning. Sixteen volunteers were performed as control, among which there were ten males and six females with age range from 38 to 79 years old. The average age was 63.7±8.6 years. f MRI was performed to test motor function of upper limbs with block design. Activated areas were presented in SPM8. SPSS 17.0 was used to analyzeprocessed data.Results The brain activation for healthy controls during bilateral clenching confirm the classic theory of cross innervation. In group of patients, primary and secondary motor cortex activation were found, namely partially activation of bilateral M1 zone, SMA zone and PMC zone during clenching of affected side at acute stage. In addition, bilateral cerebellar hemisphere were activated as well in different degree. These suggested that more brain regions participate in the compensation of motor function at acute stage of cerebral infarction and both affected side and unaffected side motor cortex play a certain role in rehabilitation of motor function. After five to seven weeks of rehabilitation, the activation of affected primary and secondary motor cortex(M1, SMA, PMC) also exist, while the area of unaffected hemisphere activation decreases significantly, which indicates that the compensation center for motor function transfer to the affected primary and secondary cortex. The activation areas in patients with acute infarction mainly localize in the primary motor cortex of unaffected side at acute and rehabilitation stage during the clenching of unaffected side, which is consistent with the activation model in normal control during bilateral clenching.The number of activating voxels in M1 zone at acute and rehabilitation stage was compared with independent sample t-test. It is shown that there is lateralization trend about the activation of bilateral M1 zone, that is to say, the activation volume of unaffected M1 zone decreased significantly(p<0.05), while the activation volume of affected side increased(p<0.05). The above results support the transfer of activation model to affected side in patients with cerebral infarction.The LI values and FMA scores during the clenching of the affected side were calculated and compared between early and rehabilitation stage. Acute stage: LI=0.33±0.12, FMA =31.89±10.72; Rehabilitation stage: LI=0.41±0.15, FMA=49.41±12.60. The LI values and FMA scores at the stage of rehabilitation were significantly higher than that at acutestage(LI:Z =-2.00,P=0.04;FMA: Z =-2.12,P=0.03). It indicates that the increase of LI values represent the improvement of motor function of patients to some extent.Conclusion(1) There is reorganization of motor cortex to compensate for in cerebral infarction patients with movement disorders at acute stage. With the recovery of affected limb movement, activation of unaffected motor cortex declines, while activation in affected increases. More activation in bilateral hemispheres, such as primarily bilateral SM1, SMA, PMC, cingulate cortex, occipital lobe were involved in patients with infarction.(2) The function reorganization presents obvious lateralization with the recovery of movement in cerebral infarction patients with hemiplegia. Both LI values and FMA scores will improve over a period of rehabilitation, and the increase of LI values suggests the affected hemisphere function recover its dominance, and the increase of FMA scores indicates the improvement of limb motor functions. |
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