Clinical And Diffusion Tensor Imaging Study On Wallenerian Degeneration Of Corticospinal Tract After Cerebral Infarction

Part I:Diffusion tensor imaging in detection of early Wallerian degeneration of corticospinal tract after cerebral infarctionObjective:To investigate the feasibility in the corticospinal tract with early Wallerian degeneration after cerebral infarction using diffusion tensor imaging(DTI). Methods:Total 23 patients with middle cerebral artery infarction were recruited. All cases were assessed with DTI within 14 days from infarction attack. Quantitative FA and MD were obtained in region of interest (ROI) at the part of infarction, the posterior limb of the internal capsule(PLIC) and cerebral peduncle(CP) along the ipsilateral corticospinal tract(CST). The indices of FA and MD of ipsilateral regions were compared with that of matched contralateral regions. Results:FA of the ipsilateral CST began to decrease at the third day from attack and FA showed decrease in all cases at the 7 days after the lesion. FA of the affected side were lower than that of the unaffected side(p<0.05) and MD showed no significant differences between both sides(p>0.05). Conclusions:DTI could detect Wallerian degeneration of CST as early as at the 3 days after infarction attack. It would be said that the Wallerian degeneration of CST began earlier than expected.Part II:Diffusion tensor imaging in detection of plasticity of CST and clinical outcomes after cerebral infarctionObjective:To test plasticity of contralesional corticospinal tract(CST) after early cerebral infarction, to obtain the diffusion tensor imaging(DTI) indices of Wallerian degeneration in the CST at the 1,2 weeks after infarction attack and to predict the clinical outcomes with the DTI indices at the 3 months after cerebral infarction. Methods:Total 16 patients with middle cerebral artery infarction were recruited within 16 days after infarction attack. And all cases were assessed with DTI. Quantitative FA and MD, obtained by regions of interest (ROI) at the ipsilateral cerebral peduncle(CP), upper and lower slices of the pons, were compared with matched contralateral regions. The neurological examinations, together with NIHSS, MI and mRS were performed in all cases at the 1,2 weeks and 3 months after cerebral infarction. Results:There were no significant differences in the FA and MD of the contralesional CSTs at the 1,2 weeks after cerebral infarction, and compared with the DTI indices of matched regions in controls. There was no significant difference in the DTI indices between the affected and unaffected sides at the 1 week after cerebral infarction. And there was significant difference in the FA but not in the MD at the 2 weeks after cerebral infarction. There were no significant correlations between the rFA of the CSTs and the NIHSS,MI at the second week after cerebral infarction. There were significant negative correlations between the rFA of the CSTs and the NIHSS, mRS and there were significant positive correlation between the rFA of the CSTs and the MI at the 3 months after cerebral infarction. Conclusions:There was no detectable plasticity in the contralesional CSTs in the patients with cerebral infarction at the 2 weeks after infarction attack. The long-term clinical outcomes would be predicted by the changes of FA at the second week after infarction attack.Partâ…¢:Time course of Wallerian degeneration of corticospinal tract after cerebral infarction detected by diffusion tensor imagingObjective:To study the changes of diffusion tensor imaging(DTI) indices in the degenerated ipsilateral corticospinal tract(CST) dynamically at the early, subacute and chronic stage after infarction attack. Methods:Total 34 patients with motor pathway lesions were recruited and followed-up successfully from 5 hours to 2 years after cerebral infarction attack. All cases were assessed with DTI on admission. Of the all patients,5 cases were performed repeatedly with DTI at the time of 1 week,2 weeks, 1 month,3 months,6 months and 1 year after infarction attack. Quantitative FA and MD were obtained in region of interest(ROI) at the bilateral cerebral peduncle(CP). The ratios of the fractional anisotropy(rFA) and mean diffusivity(rMD) were analysed statistically between the affected and unaffected side of the CSTs.Results: The rFA was decreased obviously within the first month, decreased slowly from 1 month to 3 months after infarction attack, and remained stability relatively after 3 months. The rMD was not changed significantly within the first 2 weeks, and increased from 2 weeks to 3 months after infarction attack, then reached stability relatively after 3 months. Conclusions:The FA value of the degenerated CST decreased gradually from early stage, subacute to chronic period after cerebral infarction. DTI would be an effective method to detect the state and time course of Wallerian degeneration in corticospinal tract after cerebral infarction.