Cortex Motor Function Reorganization in Stroke Patients

Overview

In China, 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. The previous fMRI studies shown that the cerebral motor cortex possess 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 ipsilateral activation and major contralateral activation in subacute stage to contralateral activation in chronic stage. We plan to recruit first-episode acute cerebral infarction patients with single lesion on middle cerebral artery supply area and age and sex matched healthy volunteers. All the patients are going to assess in three different sessions (V1, 3 days after the onset of complaint, V2,30 days after onset of complaint; V3, 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 is scanned by using bilateral arm motor tasks. Motor cortex activation regions, activation of voxel between healthy controls and patients in different checkpoint are collected. The purpose of this study is to investigate the dynamic process of motor cortical functional reorganization after cerebral stoke using functional magnetic resonance imaging combined with the behavior assessment. 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.

The cases derive from patients with acute ischemic stroke hospitalized in Neurology Department General Hospital of Guangzhou Military Command of PLA. The diagnosis of ischemic stroke is diagnosed using the diagnostic criteria of the International Association of Neurological Diseases and Stroke Association in 1982. The classification criteria for ischemic stroke are based on the current international TOAST etiological classification method. The study passed the approval of the ethics committee of General Hospital of Guangzhou Military Command of PLA, and all patients or their guardian sign informed consent. According to the location and diagnostic criteria, the patients are divided into three groups: left hemisphere infarction patients group, right hemisphere infarction patients group and normal healthy control group. The subjects performed index finger tapping test, the maximum hand grip strength test of both hands, National Institute of Health stroke scale(NIHSS), Barthel Index(BI), Hamilton Anxiety Scale(HAMA), Hamilton Anxiety Scale(HAMA) and functional magnetic resonance (fMRI) tests at 3 days (V1), 30 days (V2) and 90 days (V3 phase) after the onset of cerebral infarction. In the healthy control group, the above examination is performed only 1 times. All subjects are assessed for clinical behavior by an independent third party. Task-state function magnetic resonance design: Using the block design. There are two sequences. One sequence is in the way of rest and left hand movement, then repeat 5 times, ending at rest. The other is in the way of rest and right hand movement, then repeat 5 times, ending at rest. Each sequence lasted 220s, and the total duration of all tests was 440s. At the hand movement stage, each participant is at 1HZ Rhythm for the clenched fist movement with maximum strength, keep their whole body relaxed at the resting phase, with wrist and fingers not moving. participants use visual information to strictly control time and frequency of movement. Visual information is written by DMDX software, and accept the work instruction then sent to a transparent screen via a computer projector. Participants observed the information through a reflector mounted on a head coil. Magnetic resonance data acquisition: 1.5 Tesla superconducting magnetic resonance scanner of Siemens Sonata company is applied. The standard phased array head coil is the radio frequency coil. Gradient field is 40m T/m, and switching rate is 200m T/m/ms. The scanning sequence and parameters are as follows:(1) T1 WI scan, obtaining whole brain structure image data: repeat time is 683ms, echo time is 11ms, layer thickness is 4mm, layer spacing is 1mm, matrix is 192x144, field of vision is 230mmx230mm, a total of 28 layers, range including whole brain. (2) The blood oxygen level dependent signal of the motor task state and resting state functional magnetic resonance imaging: using gradient echo combined with single excitation echo plane Imaging technology, the parameters are as follows: repeat time is 2000ms, echo time is 49ms, layer thickness is 4mm, layer spacing is 1mm, matrix is 64x64, field of vision is 210mmx210mm, a total of 28 layers.