大脑中动脉梗死患者运动功能的恢复与脉络丛前动脉供血脑区有关？

no chinese abstract     

Motor outcome prediction using diffusion tensor tractography in pontine infarct

We investigated whether the integrity of the corticospinal tract classified by diffusion tensor tractography (DTT) can predict the motor outcome in 25 patients with pontine infarct. DTTs were obtained in the early stage of stroke (5-30 days) and were classified into two groups (type A: the integrity of corticospinal tract was preserved around the infarct; type B: corticospinal tract was interrupted). DTT type A patients showed better motor function than the type B patients at 6 months after onset. DTT obtained at the early stage of pontine infarct appears to have predictive value for motor outcome in patients with pontine infarct.     

Can stroke patients walk after complete lateral corticospinal tract injury of the affected hemisphere?

The lateral corticospinal tract is the major motor pathway in humans. The role of this tract on walking, however, is uncertain. The development of diffusion tensor tractography enables corticospinal tract status to be visualized at the subcortical level. In the present study, we undertook to demonstrate that some stroke patients can walk despite complete lateral corticospinal tract injury. Ten stroke patients who were able to walk with evidence of complete unilateral lateral corticospinal tract injury, as determined by clinical course, brain magnetic resonance imaging, and diffusion tensor tractography, were recruited. We conclude that some stroke patients can walk despite complete lateral corticospinal tract injury of the affected hemisphere.     

内囊后肢梗死患者皮质脊髓束的重组

Several diffusion tensor-imaging studies have demonstrated motor recovery mechanisms in stroke patients with subcortical infarct,including the corona radiata,pons,and medulla.However,studies of motor recovery mechanisms have not been reported in patients with posterior limb infarcts of the internal capsule.The present study reports on a 77-year-old man with complete paralysis of the left extremities at stroke onset.At 6 months after onset,motor function of the left extremities recovered to a nearly normal state.The 3-week diffusion tensor tractography of the affected(right) hemisphere showed that corticospinal tract discontinued below the posterior limb.In contrast,6-month diffusion tensor tractography revealed that the right corticospinal tract originated from the precentral gyrus and descended along the anterior area of the infarcted posterior limb.Motor function of the affected extremities was reorganized into the anterior area of the posterior limb infarct.     

延髓锥体梗死患者运动功能恢复与皮质脊髓束穿行于梗死延髓锥体的小块空余区

The present study reported a 58-year-old male patient who exhibited complete paralysis of the right extremities at stroke onset.Brain MR images showed an infarct in the left medullary pyramid and a small spared area on the medial side of the infarct.He gained the ability to extend the affected fingers against gravity and to dorsiflex the affected ankle without gravity at 3 months after stroke onset.Diffusion tensor imaging results showed that at 6 months after stroke onset,the corticospinal tract of the affected(left) hemisphere descended through the small spared area of the infarcted medullary pyramid.No motor-evoked potential was elicited from the affected(left) hemisphere at 2 weeks after stroke onset;however,motor-evoked potential was elicited at 6 months as shown by transcranial magnetic stimulation results.The motor function of the affected side of this patient appears to have been recovered via the corticospinal tract that passed through the small spared area within the infarcted medullary pyramid.     

Spared integrity of corticospinal tract within a pontine infarct A diffusion tensor tractography study

Integrity of the corticospinal tract is mandatory for good recovery of impaired motor function in patients who have suffered a stroke. A 67-year-old left hemiparetic female showed an infarct in the right pons. Three months after onset, motor function of the affected extremities recovered rapidly to a nearly complete state. Diffusion tensor tractography of both hemispheres showed that the corticospinal tract originated from the primary sensori-motor cortex and descended through the known corticospinal tract ...     

弥散张量成像在缺血性卒中患者运动功能预后评估中的研究进展

运动功能障碍是缺血性卒中最常见的后遗症之一，运用影像学技术评估卒中患者运动功能预后已成为新兴的研究方向。本文从弥散张量成像的角度出发，围绕该技术在评估皮质脊髓束及替代运动通路的受损程度、正常脑白质微观结构完整性等方面来预测缺血性卒中患者的运动功能预后进行文献综述，旨在为临床工作者提供理论支持。     

Microstructural status of ipsilesional and contralesional corticospinal tract correlates with motor skill in chronic stroke patients

Greater loss in structural integrity of the ipsilesional corticospinal tract (CST) is associated with poorer motor outcome in patients with hemiparetic stroke. Animal models of stroke have demonstrated that structural remodeling of white matter in the ipsilesional and contralesional hemispheres is associated with improved motor recovery. Accordingly, motor recovery in patients with stroke may relate to the relative strength of CST degeneration and remodeling. This study examined the relationship between microstructural status of brain white matter tracts, indexed by the fractional anisotropy (FA) metric derived from diffusion tensor imaging (DTI) data, and motor skill of the stroke‐affected hand in patients with chronic stroke. Voxelwise analysis revealed that motor skill significantly and positively correlated with FA of the ipsilesional and contralesional CST in the patients. Additional voxelwise analyses showed that patients with poorer motor skill had reduced FA of bilateral CST compared to normal control subjects, whereas patients with better motor skill had elevated FA of bilateral CST compared to controls. These findings were confirmed using a DTI‐tractography method applied to the CST in both hemispheres. The results of this study suggest that the level of motor skill recovery achieved in patients with hemiparetic stroke relates to microstructural status of the CST in both the ipsilesional and contralesional hemispheres, which may reflect the net effect of degeneration and remodeling of bilateral CST. Hum Brain Mapp, 2009. © 2009 Wiley‐Liss, Inc.     

Evaluating ischemic stroke with diffusion tensor imaging

Abstract

Introduction: In recent years, diffusion tensor imaging (DTI) has emerged as a promising tool to study ischemic stroke. The aim of this study is to evaluate the anisotropic changes of cerebral white matter tracks in patients with ischemic stroke using DTI, and investigate the correlation between corticospinal tract damage and muscle strength in such patients during acute ischemia.

Methods: Nine patients with acute ischemic stroke and nine healthy subjects were examined with T1 weighted magnetic resonance imaging (MRI), T2 weighted MRI and DTI. Fractional anisotropy (FA) was measured and the three-dimensional fibrous band images of bilateral corticospinal tracts were reconstructed. The muscle strength of the affected hand was assessed by Brunnstorm standard.

Results: In the control group, there was no significant difference in FA between the bilateral corticospinal tracts, but FA in different white matter structures of the same side was significantly different (t=3.12, p<0.05); while in the patient group, FA of the infarcted sites was significantly lower than the contralateral ones (t=5.570, p<0.01). The ipsilateral corticospinal tract demonstrated continuous interruption and the loss of consistent anatomic structure. The involved severity of corticospinal tract had significant correlation with that of muscle strength of the ipsilateral hand (r=1.30, p<0.01).

Conclusion: This study shows that DTI can be used to investigate ischemic stroke and assess ischemic stroke-induced damage. The damaged severity of corticospinal tracts is correlated with that of muscle strength.     

Changes in callosal motor fiber integrity after subcortical stroke of the pyramidal tract

In the healthy brain, there are close correlations between task-related activation of the primary motor cortex (M1), the magnitude of interhemispheric inhibition, and microstructural properties of transcallosal fiber tracts. After subcortical stroke affecting the pyramidal tract (PT), an abnormal pattern of bilateral activity develops in M1. With this prospective longitudinal study, we aimed to determine whether a morphological correlate of poststroke disinhibition could be measured within 20 days and 6 months of PT stroke. Using diffusion tensor imaging with tractography, we delineated transcallosal motor fibers (CMF) in nine PT stroke patients, six patients with subcortical infarct not affecting the PT (NonPT) and six transient ischemic attack patients. We compared changes in CMF fractional anisotropy ratios (rFA) with rFA in a distinct bundle of callosal occipital fibers (COF). At the initial time point, there were no significant differences in rFA between groups and fiber bundles. At follow-up, PT-group rFA(CMF) was significantly lower than PT-group rFA(COF) and NonPT-group rFA(CMF). PT-group rFA(CMF) decreased over time and correlated with rFA of the PT (rFA(PT)) retrograde to the infarct at 6 months. Our data suggest a progressive degenerative transsynaptic effect of PT stroke on CMF, which could be a morphological correlate of transcallosal disinhibition.     

硬脑膜下血肿清除前后皮质脊髓束的状态：弥散张量成像证据

Abstract Subdural hematoma can cause compression or damage to the neural tracts in the brain; however, very little is known about this injury. We report on a patient with subdural hematoma who was evaluated by diffusion tensor imaging prior to and after trephination and drainage of subdural hematoma. A 58-year-old male patient and ten age-matched normal control subjects were evaluated. The patient showed mild hemiparesis for 3 weeks prior to surgery. His hemiparesis recovered to a nearly normal state at 5 weeks post-surgery when the follow up diffusion tensor image was acquired. Two diffusion tensor image parameters, fractional anisotropy and apparent diffusion coefficient, were measured along the corticospinal tract. Pre-operative diffusion tensor image showed that the corticospinal tract of the affected hemisphere seemed to be injured or compressed. However, the follow up diffusion tensor image showed recovery of this corticospinal tract to a normal state. It would appear that diffusion tensor images are a useful tool for evaluation of the effects of subdural hematomas on neural tracts. Key Words: subdural hematoma; diffusion tensor imaging; hemiparesis; corticospinal tract     

Ipsilateral motor pathway without contralateral motor pathway in a stroke patient

The ipsilateral motor pathway from the unaffected motor cortex to the affected extremity is one of the mechanisms of motor recovery following stroke. We report on a stroke patient who showed the ipsilateral motor pathway without the contralateral motor pathway on functional MRI and diffusion tensor tractography. A 53-year-old left hemiparetic patient with an infarct in the right middle cerebral artery territory was evaluated. During a period of three months after onset, motor function of the affected (left) hand had recovered slowly, to the extent that the patient was able to overcome gravity. FMRI showed that only the unaffected (left) primary sensorimotor cortex was activated by movements of the unaffected (right) hand or of the affected (left) hand. On diffusion tensor tractography, the corticospinal tract of the left hemisphere originated from the primary sensori-motor cortex and descended through the known corticospinal tract pathway. By contrast, the right corticospinal tract showed a disruption with Wallerian degeneration to the upper medulla. We conclude that the motor function of the affected (left) hand appeared to be controlled only by the ipsilateral motor pathway from the left motor cortex to the left hand. Motor function of the affected hand appeared to have been reorganized to the ipsilateral motor pathway from the unaffected motor cortex to the affected hand.     

Diffusion tensor imaging of the corticospinal tract following cerebral hemispherectomy

Following cerebral hemispherectomy, the corticospinal tract is believed to undergo reorganizational changes, which can induce enhanced function of the contralateral motor pathway and mediate partial recovery of motor function. The aim of this study was to use diffusion tensor imaging to investigate the effects of hemispherectomy on the corticospinal tract, with particular attention to the corticospinal tract contralateral to the resection. Diffusion tensor imaging would presumably detect microstructural abnormalities through quantitative measurements of the fiber tract integrity and orientation. Four patients with anatomic hemispherectomy and three patients with subtotal hemispherectomy were examined and compared with age-matched normal controls. Apparent diffusion coefficient and fractional anisotropy values were measured in regions along the corticospinal tract: internal capsule, cerebral peduncle, rostral pons, midpons, and caudal pons. None of the patients with anatomic hemispherectomy or subtotal hemispherectomy showed significant changes in either apparent diffusion coefficient or fractional anisotropy values in the corticospinal tract contralateral to the resected hemisphere, whereas increased apparent diffusion coefficient and decreased fractional anisotropy were observed in the ipsilateral rostral pons, midpons, and caudal pons of all patients with anatomic hemispherectomy, as well as in the ipsilateral cerebral peduncle of one patient with subtotal hemispherectomy. Increased apparent diffusion coefficient values were also noted in the ipsilateral internal capsule of the same patient. This study revealed no evidence of significant reinforcement of the contralateral corticospinal tract in patients with hemispherectomy, at least from diffusion tensor imaging measurements, but suggests that wallerian degeneration most likely occurs in the ipsilateral motor pathway.     

Diffusion tensor MR imaging of the pyramidal tract can predict the need for orthosis in hemiplegic patients with hemorrhagic stroke

Diffusion tensor magnetic resonance (MR) imaging was used to evaluate motor functions in stroke patients. The aim of this study was to clarify whether imaging can be used to predict orthotic needs in patients with hemiplegia. We studied 25 patients (age range, 16–78 years) with intracerebral hemorrhages (putamen 15, thalamus 7, frontal subcortex 3). Diffusion tensor MR imaging was undertaken on admission at rehabilitation hospital for stroke patients. The fractional anisotropy (FA) value of the pyramidal tract was calculated. We compared the FA value in the ROI of the cerebral peduncle with the necessity for orthosis at discharge from the rehabilitation hospital. As a result, the FA values of the affected side in patients who needed orthosis at discharge were lower than those in patients who did not need orthosis. There was no significant difference in the FA values of the unaffected side. We concluded that the need for orthosis in patients with hemiplegia after stroke rehabilitation could be predicted using the diffusion tensor MR images of corticospinal tractography.     

Injury of the corticobulbar tract in patients with dysarthria following cerebral infarct: diffusion tensor tractography study

Objectives: Little is known about injury of the corticobulbar tract (CBT) in stroke patients. We attempted to investigate injury of the CBT in patients with dysarthria following cerebral infarct, using diffusion tensor tractography (DTT). Methods: Eight patients with dysarthria following a corona radiata infarct and 12 control subjects were recruited for this study. Diffusion tensor imaging was performed at 14.3 days after onset and reconstruction of the CBT was performed using the probabilistic tractography method. Fractional anisotropy, mean diffusivity, and tract volume of the CBT were measured. Results: Reconstructed CBTs in the affected hemisphere of the patient group were thinner than those of the unaffected hemisphere of the patient group and the control group. Regarding the DTT parameters of the CBTs, fractional anisotropy and tract volume were significantly lower in the affected hemisphere of the patient group than in the unaffected hemisphere of the patient group and the control group (p < 0.05). However, we did not observe any difference in the mean diffusivity value (p > 0.05). Conclusions: We demonstrated injury of the CBT in patients with dysarthria following cerebral infarct in the corona radiata using DTT. This result indicates the importance of CBT evaluation for dysarthria in patients with cerebral infarct. Therefore, we suggest that evaluations of the CBT using DTT would be useful for patients with dysarthria following cerebral infarct.     

Motor recovery via aberrant pyramidal tract in a patient with a cerebral peduncle infarct*●

The presence of the aberrant pyramidal tract has been demonstrated by several studies;however,little is known about its role in motor recovery in stroke patients.In the present study,we reported a 69-year-old right-handed female patient with an infarct in the mid to lateral portion of the left cerebral peduncle,who showed an aberrant pyramidal tract by diffusion tensor tractography.The patient presented with severe weakness of the right extremities at stroke onset.The patient showed progressive motor recovery as much as being able to extend the affected extremities against some resistance at 6 months after onset.At 20 months after stroke onset,motor function of the left extremities had recovered to a nearly normal state.Diffusion tensor tractography results showed that the PT was disrupted at the lower midbrain of the affected(left) hemisphere at 3 weeks after stroke onset and this disruption was not changed at 20 months.An aberrant pyramidal tract in the left hemisphere was also observed,which originated from the primary motor cortex and descended through the corona radiata,posterior limb of the internal capsule,thalamus,the medial lemniscus pathway from the midbrain to the pons,and then entered into the pyramidal tract area at the pontomedullary junction.Transcranial magnetic stimulation did not elicit motor evoked potential from the affected hand muscle at 3 weeks,but it elicited motor evoked potential with mildly delayed latency and low amplitude in the affected hand muscle at 20 months.The main motor functions of the affected extremities in this patient appeared to be recovered via this aberrant pyramidal tract.     

Microstructural properties of premotor pathways predict visuomotor performance in chronic stroke

Microstructural properties of the corticospinal tract (CST) descending from the motor cortex predict strength and motor skill in the chronic phase after stroke. Much less is known about the relation between brain microstructure and visuomotor processing after stroke. In this study, individual's poststroke and age‐matched controls performed a unimanual force task separately with each hand at three levels of visual gain. We collected diffusion MRI data and used probabilistic tractography algorithms to identify the primary and premotor CSTs. Fractional anisotropy (FA) within each tract was used to predict changes in force variability across different levels of visual gain. Our observations revealed that individuals poststroke reduced force variability with an increase in visual gain, performed the force task with greater variability as compared with controls across all gain levels, and had lower FA in the primary motor and premotor CSTs. Our results also demonstrated that the CST descending from the premotor cortex, rather than the primary motor cortex, best predicted force variability. Together, these findings demonstrate that the microstructural properties of the premotor CST predict visual gain‐related changes in force variability in individuals poststroke. Hum Brain Mapp 37:2039–2054, 2016. © 2016 Wiley Periodicals, Inc .     

弥散张量纤维素成像三维重建皮质脊髓束定位脑初级运动功能区

Functional MRI (fMRI) is widely used as a non-invasive method for the evaluation of pre-operation motor function.However,patients with cortical function impairment,such as those with hemiparesis,can rarely achieve hand clenching,a typical fMRI task for central sulcus identification,and the method is also of limited use in uncooperative children.Thus,it is important to develop a new method for identifying primary motor areas (PMA) in such individuals.This study used corticospinal tractography to identify the PMA in 20 patients with deep-seated brain tumor.Two regions of interest were set within the brainstem for corticospinal tract (CST) fiber tracking:one at the level of the pons and the other at the level of the cerebral peduncle.The CST fiber tracking results and fMRI activation signals were merged with three-dimensional anatomic MRI findings.The consistency of identifying the PMA by CST and fMRI was analyzed.fMRI activation signals were distributed mainly in the contralateral central sulcus around the omega-shaped hand knob.The CST consistently propagated from the pons and cerebral peduncle to the suspected PMA location.There was a good correlation between CST fiber tracking results and fMRI activation signals in terms of their abilities to identify the PMA.The differences between fMRI and CST fiber tracking findings may result from our functional task,which consisted only of hand movements.Our results indicate that diffusion tensor imaging is a useful brain mapping technique for identifying the PMA in paralyzed patients and uncooperative children.     

核磁共振弥散张量纤维素成像对脑血管病患者预后的判定

目的观察急性脑血管病患者皮质脊髓束的损伤状况,分析运动功能变化并对临床预后进行判定。方法对18例脑卒中患者(其中脑梗死患者16例,脑出血患者2例)进行磁共振弥散张量纤维素成像(DTI)检查纤维束的连续性及破坏情况。于患者入院时、发病后2周、1月及2月分别进行肌力判定和神经功能评分。结果皮质脊髓束受累情况分为2级,1级:皮质脊髓束完整,共5例;2级:皮质脊髓束中断,共13例。16例脑梗死患者不同时期肌力及NIHSS评分与皮质脊髓束级别明显相关(P<0.05),发病后2月NIHSS评分转归情况与皮质脊髓束级别有显著性差异(P=0.0202)。2例脑出血患者入院时肌力均为0级但DTI显示皮质脊髓束完整的其预后也较好。18例受试者均进入结果分析,不同时期NIHSS评分与皮质脊髓束级别明显相关(P<0.05),发病后2月NIHSS评分转归情况与皮质脊髓束级别有显著性差异(P=0.0269)。结论三维纤维束示踪成像图可以更立体直观的显示皮质脊髓束状况,并在脑血管病初期即可对其损伤情况进行判定,同时可以提示脑血管病患者的预后。     

Motor outcome of deep intracerebral haemorrhage in diffusion tensor imaging: comparison of data from different locations along the corticospinal tract

Abstract

Objectives:

Although diffusion tensor imaging (DTI) is widely studied to assess the motor outcome after ischaemic stroke, there is paucity of data regarding outcomes of intracerebral haemorrhage (ICH). The aim of this study was to determine the DTI data from different locations along the corticospinal tract (CST) and association to motor outcome.

Methods:

We prospectively recruited patients with deep ICH admitted to our hospital from November 2010 to July 2012.Diffusion tensor imaging was performed within 14?days after the onset of ICH. Fractional anisotropy (FA) was measured along the CST at corona radiata, perihaematomal oedema, cerebral peduncle and pons. Corticospinal tract integrity was classified into three types by diffusion tensor tractography (DTT): type A with preserved CST, type B with partially interrupted CST and type C with completely interrupted CST. Motor outcome was assessed by Motricity index (MI) at admission, after 1 and 3?months.

Results:

Forty-eight patients were enrolled with a mean age of 62?years. The median time interval from onset of ICH to DTI study was 7?days. The patients in type C had significantly worse MI at admission (P?<?0.001), after 1?month (P?<?0.001) and after 3?months (P?<?0.001) as compared to those with type A and type B. Lower rFA at the corona radiata was significantly correlated with poorer motor outcome at admission, after 1?month and after 3?months.

Discussion:

Clinical motor outcome of ICH within 2?weeks can be identified with a statistically significant decrease in rFA at the corona radiata.