| In developed countries, stroke is among the highest morbidity and mortality, especially in senile population. Most of those patients had survived with various degrees of cerebral dysfunction; among them about 50% were motor deficit. Previous in vitro studies indicated that recovery of motor function after stroke were related not only to axonal regeneration or synapse reformation, but also functional reorganization of adjacent areas and other functional associated areas. In recent years, neuro-imaging techniques such as positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) are widely applied in clinic studies. They enabled us to observe the cerebral motor functional recovery periodically following stroke.The previous fMRI studies shown that the cerebral motor cortex posses the natural ability of self compensation and self reorganization in the situation of brain damage. It was characterized by equally bilateral activation in acute stage to partial ipsi-lateral activation and major contralateral activation in subacute stage to contralateral activation in chronic stage. However, we also found many problems existent in those studies. First of all,they enrolled too few patients, secondly, they did not strictly controlled the enrolled condition, some of the stroke patients were in acute stage and others were in the subacute or chronic stage. Thirdly, the task design in some of studies were inconsistent. And finally all those studies did not focus on the differences of reorganization between dominant hemisphere and non-dominant hemisphere after cerebral stroke. Therefore, in our study we expected to strictly control the enrolling criteria, more patients be recruited and the same task be used through all procedure. And most importantly, we would compare the different characters of dominant hemisphere and non-dominant hemisphere's motor cortex compensation after stroke.Purpose:Functional magnetic resonance imaging combined with the behavior assessment were used in our study to investigate the dynamic process of motor cortical functional reorganization after cerebral stoke. Meanwhile,we also studied the differences of motor function recovery and motor cortex compensation between dominant hemisphere and non-dominant hemisphere after stroke. Therefore, we could provide a theoretical basis and build up a useful evaluation system for rehabilitation after stroke and other arious cerebral injury.?Method:Acute stroke patients with single lesion on middle cerebral artery supply area and age and sex matched healthy volunteers were recruited. All the patients were assessed in three different sessions (T1, 3 days after the onset of complaint, T2,30 days after onset of complaint; T3, 90 days after onset of the complaint ) with both clinical check as well as fMRI scan. The clinical assessment including dynamometer and finger tapping test to evaluate the strength and the flexibility of each upper legs and it also included the corresponding scales to exclude poststroke dementia and moderate and serious poststroke depression. The fMRI was scanned by using bilateral arm motor tasks. Motor cortex activation regions, activation of voxel between healthy controls and patients in different checkpoint were collected.Results:1. 16 acute stroke patients and 10 healthy volunteers were enrolled. There were no differences in age/sex/lesion volume /period from onset of disease to enrollment in both left hemisphere stroke group and right hemisphere stroke group.2.The results of index finger tapping test :Left hemisphere stroke patients group: The average execution of right hand at T1session, 20.61±3.28 times/10 seconds; at T2 session, 26.49±2.04 times/10 seconds; at T3 session 32.28±2.34 times/10 seconds. Session T2 was quicker than session T1, p <0.05; Session T3 was quicker than session T2, p <0.05. Left hand index finger tapping test at session T1, T2 and T3, no any improvement, p> 0.05.Right hemisphere stroke patients group: The average execution of left hand at T1session, 26.52±2.81 times/10 seconds; at T2 session, 32.71±2.11 times/10 seconds, at T3 session ,37.72±3.01 times/10 seconds. Session T2 was quicker than session T1, p <0.05; sessionT3 was quicker than session T2, p <0.05. Right index finger tapping test at T1, T2 and T3, no any improvement, p> 0.05.Compare the paretic hand of left hemisphere stroke group with right hemisphere stroke patient group ,right hemisphere stroke group show more quicker than left hemisphere stroke group , p <0.05.(2). The maximum hand grip strength test results:Left hemisphere stroke patients group: The average execution of right hand at T1 session, 9.37±2.34 Kg;at T2 session, 15.39±3.21Kg;at T3 session ,20.92±2.91Kg. Session T2 were bigger than session T1, p <0.05; session T3 were bigger than session T2,p <0.05. Left-hand grip at session T1, T2 and T3, no any improvement, p> 0.05.Right hemisphere stroke patients group: The average execution of left hand at T1session, 14.21±2.93 Kg; at T2 session, 20.65±2.57 Kg; at T3 session, 26.01±2.87 Kg. Session T2 were bigger than session T1, p <0.05; session T3 were bigger than session T2,p <0.05. Left-hand grip at session T1, T2 and T3, no any improvement, p> 0.05. Compare the paretic hand of left hemisphere stroke group with right hemisphere stroke patient group ,right hemisphere stroke group show more bigger than left hemisphere stroke group , p <0.05.3. fMRI results(1). Left hemisphere stroke group, motor cortex activation during hand movement : Left hemisphere stroke group: right hand movement activated bilateral S1M1 area, ipsilateral PMC area at session T1; activated bilateral S1M1 area, ipsilateral SMA and contralateral PMC at session T2; only activated contralateral S1M1 at session T3. Left hand movement activated bilateral S1M1, the contralateral SMA at T1 session; at sessionT2 and T3, only activated contralateral S1M1.(2). Right hemisphere stroke group, motor cortex activation during hand movement : Right hemisphere stroke group: left hand movement activated bilateral S1M1, contralateral SMA at T1 session; activated bilateral S1M1 ipsilateral SMA and contralateral PMC at T2 session; only activated contralateral S1M1 at session T3. Right hand movement activated bilateral S1M1, ipsilateral SMA and contralateral PMC at T1 session; at sessionT2 and T3, only activated contralateral S1M1.(3) . Differences of motor cortex activation between left and right stroke group(3.1). Motor cortex activation when moving the paretic hand: Left hemisphere stroke group Vs right hemisphere stroke group: The voxels of left motor cortex ,when moving right hand in left hemisphere stroke group , were bigger than the voxel of right motor cortex, when moving left hand in right hemisphere stroke group, at sessionT1 and T2,p<0.05;There were no differences at T3 session. The voxels of right motor cortex ,when moving right hand in left hemisphere stroke group , were bigger than the voxel of left motor cortex, when moving left hand in right hemisphere stroke group, at sessionT1 and T2,p<0.05;There were no differences at T3 session.(3.2) . Motor cortex activation when moving the healthy hand:Left hemisphere stroke group Vs right hemisphere stroke group:The voxels of left motor cortex ,when moving left hand in left hemisphere stroke group , were bigger than the voxel of right motor cortex, when moving right hand in right hemisphere stroke group, at sessionT1 p<0.05;There were no differences at session T2 and T3. The voxels of right motor cortex ,when moving right hand in left hemisphere stroke group , didn't show differences with the voxel of left motor cortex, when moving left hand in right hemisphere stroke group, at sessionT1,T2 and T3. (4). We found that improvement of index finger tapping test of the paretic hand positive and significantly correlated with the the activation of ipsilesion motor cortex decreased and negative correlated with the activation of contralesion motor cortex decreased.Conclusion:1. The implementation capacity of paralytic hands of stroke patients was significantly decreased than healthy control since acute stage. Furthermore, it was slightly recovered in sub-acute but still inferior to healthy control in chronic stage.2.Our results also proved that motor cortical activation induced by moving paretic hand changes with time. The dynamic process were equally bilateral activation at acute stage, partial activation in ipsilateral cortex with major activation in contralateral cortex in subacute stage, contralateral activation in chronic stage.3. It was also showed in our study that the dynamic process of motor cortical activation induced by moving healthy hand were bilateral activation in acute stage, contralateral activation in both subacute stage and chronic stage.4. The improvements of index finger tap test from acute stage to subacute stage as well as from subacute stage to chronic stage have positive correlation to the contralateral S1M1 activation enhancement, while a negative correlation to the ipsilateral S1M1. 5. There were differences of motor functional recovery and motor cortex compensation between dominant hemisphere and non-dominant hemisphere after stroke. The paretic limb implementation capacity in patients with dominant hemisphere stroke was inferior to those with non-dominant hemisphere stroke. The contralateral and ipsilateral motor cortex activation of dominant hemisphere stoke were more extensive than those in non-dominant hemisphere stroke both in acute stage and subacute stage. |
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