Evaluating The Relevance Of Corticospinal Tract Injury And Motor Function Recovery In Cerebral Infarction By Using Diffusion Imaging

【Objective】Acute cerebral infarction is the most common clinical disorder of the nervous system,it has high fatality and disability rate.The restoration of Limb motor function after cerebral infarction directly related to the neurons of the central nervous system and plasticity of the structure of conduction system,magnetic resonance diffusion imaging technology provides a reliable visualized basis to study the rehabilitation mechanism of the motor function after cerebral infarction.Research of this topic is the value in diffusion weighted imaging and diffusion tensor imaging of cerebral infarction at different times,but also investigate the relations in the extent of CST damage with the changes and the restoration of the motor function,observing the shape and the integrity of CST according to the three-dimensional reconstruction of corticospinal tract by diffusion tensor tractography.【Materials and Methods】60 cases of cerebral infarction in varying degrees on the side of limb muscle strength weakened,according to the disease time divided into five groups,including ultra-acute stage(less than 6 hours) in 12 cases, the acute phase(6 to 24 hours) of 18cases,acute late(1 to 3 days) in 13 cases,early subacute(4 to 7 days) in 10 cases,late subacute(1 to 8 weeks) in 7 cases.All cases were performed conventional MRI and DTI examination,conventional MRI including T₁WI,T₂WI,FLAIR and DWI.All the patients were accepted the inspection of the affected limb muscle strength in the incidence and 3 months after the disease accepted the treatment of conventional neurology in hospital.Processing the raw datas by the workstation,establishing ADC maps,FA maps,two-dimensional color-coded vector maps,and three-dimensional reconstruct CST to observe the relationships between CST and the lesion.Measuring FA and ADC in cerebral white matter of lesion side and the contralateral side.And calculating the relative FA (rFA = FA in affected side / FA in contralateral side).Comparing the differences between bilateral values(FA and ADC) using paired t-test;group analysis, comparing the differences between affected and contralateral ADC and FA values, using ANOVA.The correlations of Cerebral white matter FA values with the incidence of time,rFA with affected limb's muscle strength and the extent of CST injury with the changes and the restoration of the motor function use Spearman rank correlation,the measurement results indicated with(?)±s,P＜0.05 that the difference was statistically significant.【Results】1.ADC changes in the Cerebral white matterAll the cases except the fifth group,the affected white matter ADC values than those in the corresponding contralateral normal white matter reduction.The first to fifth group,the affected and contralateral ADC values were 3.230±1.013,7.824±0.556;3.476±1.145,7.761±0.548;4.241±1.923,7.699±0.487;5.242±1.876,7.819±0.602;7.841±2.785,7.757±0.614.Inâ… -â…£groups(super-acute phase, acute phase,acute late phase and early subacute phase),the differences between ADC in affected and the contralateral normal side,by the paired samples t-test,were found significant statistical difference,P＜0.001,the fifth group(the late subacute) affected ADC values than the contralateral normal white matter was no significant difference,P＞0.05.ADC values of lesion side follow the time were gradually increased.The different values between the affected side and the normal side of ADC in each group were -4.592±1.713,-4.284±1.625,-3.458±1.109, -2.577±1.007,0.086±0.031,by ANOVA,comparing ADC changes in super-acute phase and late subacute phase,there was a significant difference in statistical,P＜0.005;the rest of the group difference were not statistically significant.2.FA changes in the Cerebral white matter In the hyperacute phase(the first group) there were 10 cases that FA in affected side were higher than it in the normal white matter,the disease times were all less than 3 hours;FA in affected side in the remaining 50 cases were lower than in the normal side.The first to fifth group,the affected and contralateral FA values were 0.513±0.103,0.448±0.046;0.296±0.075,0.440±0.081;0.288±0.064,O.446±0.062;0.244±0.045,0.468±0.077;0.117±0.021,0.432±0.054.In theâ… -â…£groups, the differences between FA in affected and the contralateral normal side,by the paired samples t-test,were found significant statistical difference,P＜0.001.The different values between the affected side and the normal side of FA in each group were 0.067±0.034,-0.144±0.016,-0.158±0.037,-0.223±0.019,-0.316±0.023, by ANOVA,comparing FA changes in super-acute phase and the other phases,there were significant differences in statistical significance,P＜0.005;the rests of the group differences were not statistically significant.3.Using the Spearman rank correlation analysis revealed,there was a significant negative correlation(r_s=-0.856,P＜0.001) between FA of affected side and the disease time.4.There was no correlation between the relative FA values and the affected limb muscle strength in disease time by the Spearman rank correlation analysis(r_s= 0.384,P＞0.05).And there was a positive correlation between the relative FA values and the affected limb muscle strength in 3 months after the disease by the Spearman rank correlation analysis(r_s=0.791,P＜0.001).5.In the 60 cases,the CSTs in 10 cases were complete and the affected limb's muscle strength for the 5 or 5 - level;31 cases were compressed,the affected limb's muscle strength for the 3 level in 9 cases,4 level in 18 cases,5 level in 4 cases;the CST in the remaining 19 cases were interrupted,each affected limb muscle strength was lower than 4 level,0 level in 8 cases of these cases.3 months after onset of cerebral infarction,through conventional treatment,CST without interruption,and no symptoms of muscle strength decline;CST only was compressed,without interruption,after treatment,26 cases of muscle strength returned to normal,5 cases of muscle strength for the 4 or 5^- evel;CST with interruption,13 cases of muscle strength were not obvious recovered,but there were 6 cases' muscle strength return to more than 4 level.There was a negative correlation between the score of the CST and the affected limb muscle strength in disease time by the Spearman rank correlation analysis(r_s=-0.765,P＜0.001).And there was also a negative correlation between the score of the CST and the affected limb muscle strength in 3 months after the disease by the Spearman rank correlation analysis(r_s=-0.921,P＜0.001).【Conclusion】1.ADC in the white matter of hyperacute,acute,acute late and early subacute phases cerebral infarction were significant lower than it in the contralateral normal white matter.ADC in the white matter of late subacute phase cerebral infarction were no significant changes than it in the contralateral normal white matter,ADC maps of this phase were isointensity.ADC values of lesion side follow the time were gradually increased.2.FA in affected white matter of less than 3 hours of super-acute cerebral were higher than it in the contralateral normal white matter;FA in affected white matter of much than 3 hours of super-acute cerebral were lower than it in the contralateral normal white matter.There was a significant negative correlation between FA in affected white matter and the disease time,the disease time was much longer and the FA in affected white matter was much lower.3.A positive correlation between the relative FA values and the affected limb muscle strength in 3 months after the disease,rFA lower indicate poor recovery of motor function,it can be used to predict motor function recovery after cerebral infarction.4.DTT can clearly and accurately show the relationship between the CST and cerebral lesion,the degree of CST damage was closely related with the change and the recovery in motor function.The more serious damage in CST,the much lower score of limb muscle strength,and poorer recovery in limb motor function.In accordance with the relations of the CST damage degree and muscle strength can provide valuable prognostic information for cerebral infarction treatment and rehabilitation.