The fate of injured corticospinal tracts in patients with intracerebral hemorrhage: diffusion tensor imaging study

Prognosis of the Ipsilesional Corticospinal Tracts with Preserved Integrities at the Early Stage of Cerebral Infarction: Follow Up Diffusion Tensor Tractography Study

This study examined the prognosis of the ipsilesional corticospinal tracts (CSTs) with preserved integrities at the early stage of cerebral infarction using follow-up diffusion tensor tractography (DTT). Thirty-one patients with a supratentorial infarction were recruited. DTT, Motricity Index (MI), modified Brunnstrom classification (MBC), and functional ambulation category (FAC) were performed twice at the early and chronic stages. The patients were classified into two groups based on the integrity of the ipsilesional CST on the second DTT: Group A (24 patients; 77.4%)—preserved integrity and Group B (7 patients; 22.6%)—disrupted integrity. No significant differences in MI, MBC, and FAC were observed between groups A and B at the first and second evaluations, except for FAC at the first evaluation (p > 0.05). MI, MBC, and FAC at the second evaluation were significantly higher than at the first evaluation in both groups A and B (p < 0.05). On the second DTT, one patient (4.2%) in group A showed a false-positive result, whereas five patients (71.4%) in group B had false-negative results. Approximately 20% of patients showed disruption of the ipsilesional CST at the chronic stage. However, the clinical outcomes in hand and gait functions were generally good. Careful interpretation considering the somatotopy of the ipsilesional CST is needed because of the high false-negative results on DTT at the chronic stage.

An overview of fractional anisotropy as a reliable quantitative measurement for the corticospinal tract (CST) integrity in correlation with a Fugl-Meyer assessment in stroke rehabilitation

[Purpose] Understanding the essential mechanisms in post-stroke recovery not only provides important basic insights into brain function and plasticity but can also guide the development of new therapeutic approaches for stroke patients. This review aims to give an overview of how various variables of Magnetic Resonance-Diffusion Tensor Imaging (MR-DTI) metrics of fractional anisotropy (FA) can be used as a reliable quantitative measurement and indicator of corticospinal tract (CST) changes, particularly in relation to functional motor outcome correlation with a Fugl-Meyer assessment in stroke rehabilitation. [Methods] PubMed electronic database was searched for the relevant literature, using key words of diffusion tensor imaging (dti), corticospinal tract, and stroke. [Results] We reviewed the role of FA in monitoring CST remodeling and its role of predicting motor recovery after stroke. We also discussed the mechanism of CST remodeling and its modulation from the value of FA and FMA-UE. [Conclusion] Heterogeneity of post-stroke brain disorganization and motor impairment is a recognized challenge in the development of accurate indicators of CST integrity. DTI-based FA measurements offer a reliable and evidence-based indicator for CST integrity that would aid in predicting motor recovery within the context of stroke rehabilitation.

Significant Injury of the Mammillothalamic Tract without Injury of the Corticospinal Tract After Aneurysmal Subarachnoid Hemorrhage: A Retrospective Diffusion Tensor Imaging Study

OBJECTIVE

Little is known about the pathophysiologic mechanisms of white matter injury after aneurysmal subarachnoid hemorrhage (aSAH). The purpose of this study is to investigate whether the mammillothalamic tract (MTT) or corticospinal tract (CST) is more affected by aSAH in the same patients with good outcome (Grade 5 on Glasgow Outcome Scale at 3 months) using diffusion tensor imaging (DTI).

METHODS

Between June 2013 and September 2016, 21 patients with aSAH with good outcome and 21 sex- and age-matched normal healthy control participants were recruited. DTI was obtained at 8.92 ± 2.4 weeks after onset. Moreover, reconstruction of the CST and the MTT was completed with DTI-studio software. Apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values were measured. In addition, the motricity index and Mini-Mental State Examination scores were obtained.

RESULTS

There was no statistically significant difference detected in the ADC and FA values of the CST between the patient and control groups (P > 0.05). On the contrary, there was a statistically significant difference in ADC and FA values of the MTT between the patient and control groups (P < 0.05). In addition, in the patient group, no correlation (P > 0.05) was observed between motricity index scores and DTI parameters (ADC and FA), whereas the Mini-Mental State Examination showed a positive correlation with FA (r = 0.591, P = 0.029) without correlation to ADC (r = 0.142, P = 0.628).

CONCLUSIONS

Patients with good outcomes (Grade 5 on Glasgow Outcome Scale at 3 months) after aSAH appeared to suffer an injury of the MTT without an associated injury of the CST compared with the control group. This injury showed a correlation with cognitive dysfunction.

Minimally Invasive Surgery for Evacuating the Intracerebral Hematoma in Early Stages Decreased Secondary Damages to the Internal Capsule in Dog Model of ICH Observed by Diffusion Tensor Imaging

BACKGROUND

Diffusion tensor imaging was used to observe the effects of performing early minimally invasive surgery (MIS) on internal capsule in dog model of intracerebral hemorrhage (ICH).

METHODS

Twenty-five male dogs were selected to prepare an ICH model, and then they were randomly distributed into a model control (MC) group (5 dogs) or an MIS group (20 dogs). In the MIS group, the intracerebral hematoma was evacuated by stereotactic minimally invasive procedures over 6 hours (5 dogs), 12 hours (5 dogs), 18 hours (5 dogs), or 24 hours (5 dogs) after successful induction of ICH. The same procedure was performed in the MC group but without evacuating the hematoma. All the animals were sacrificed within 2 weeks after the hematoma was surgically evacuated. The neurologic deficit score and diffusion tensor imaging (DTI) were observed before and after the MIS. The perihematomal blood-brain barrier (BBB) permeability and the brain water content (BWC) were measured 2 weeks after the hematoma was surgically evacuated.

RESULTS

The DTI demonstrated that integrity of the internal capsule restored largely after surgery and the fractional anisotropy (FA) values of the internal capsule on the hematoma side increased significantly as compared with those in the MC group or those before surgery in the same group. The postoperative ratios of FA values of each MIS subgroup increased compared with the MC group and those before surgery in the same subgroup before operation. The neurologic deficit score, the perihematomal BBB permeability, and the BWC of each MIS subgroup decreased significantly compared with those of the MC group. The 6-12-hour group displayed a more favorable result.

CONCLUSIONS

Performing the MIS in the early stage (6-12 hours) after ICH could decrease the secondary damages to the internal capsule so as to promote the recovery of motor function. The optimal time window for MIS should be within 6-12 hours after onset of ICH.

Change of the Corticospinal Tract in the Unaffected Hemisphere by Change of the Dominant Hand Following Stroke: A Cohort Study

We investigated the change of the corticospinal tract (CST) in the unaffected hemisphere by the change of the dominant hand in stroke patients, using diffusion tensor tractography (DTT).Forty-eight stroke patients with right-hand dominance were recruited. The patients were assigned to 3 groups: group A (12 patients)-right-hand dominance was maintained after the right-hand weakness, group B (17 patients)-right-hand dominance changed to the left-hand dominance after the right-hand weakness, and group C (19 patients)-right-hand dominance was maintained after the left-hand weakness had developed. The function of the unaffected upper extremity was evaluated using the grip strength (GS), Manual Function Test (MFT), Purdue Pegboard Test (PPT), and modified Barthel Index (MBI). DTT was performed twice (1st DTT, 2nd DTT), and the fractional anisotropy (FA), apparent diffusion coefficient (ADC), and voxel number (VN) of the CST in the unaffected hemisphere were measured.In group B, the VN on 2nd DTT was significantly increased compared with the 1st DTT, and all other clinical data (GS, MFT, PPT, and MBI) showed a significant increase between 1st and 2nd DTT (P < 0.05). The change of the VN showed moderate correlation with the change of the GS (r = 0.499, P < 0.05), PPT (r = 0.531, P < 0.05), and MBI (r = 0.551, P < 0.05).We found that the fiber number of the CST in the unaffected hemisphere was increased by the change of the dominant hand in stroke patients. We believe that our results have important implications in terms of neurorehabilitation.

A comparative study of fractional anisotropy measures and ICH score in predicting functional outcomes after intracerebral hemorrhage

BACKGROUND

Improved prognostication during the acute phase of intracerebral hemorrhage (ICH) could influence goals of care. We investigated the utility of diffusion tensor imaging (DTI)-derived data obtained during the acute phase of ICH in predicting outcome, compared with the ICH score.

METHODS

We measured fractional anisotropy (FA) values in 5 slices below the level of the lesion on the affected and unaffected corticospinal tracts (CST) and in the cerebral peduncles (CPs) in 32 patients with supratentorial ICH who had DTI MRI within 4 days after ictus. We calculated the FA ratio (rFA = FAaffected side/FAunaffected side), and examined the value of the ICH score and rFA in predicting functional outcome assessed by modified Ranking Scale (mRS) at follow-up, using ROC analyses.

RESULTS

The rFA values at the CPs level, but not the 5 slices below the lesion, were significantly lower in the group with poor functional outcome (defined as mRS > 2) than in those with good functional outcome (0.96 ± 0.14 vs. 0.99 ± 0.08, p = 0.025). The ICH score had greater areas under ROC curve in predicting functional outcome compared to the mean rFA (AUC 0.74 vs. 0.44; p = 0.01 for mRS > 2; and 0.84 vs. 0.40; p < 0.001 for mRS > 3).

CONCLUSIONS

The prognostic value of the ICH score surpassed that of DTI-derived data during the acute phase of ICH in this cohort of patients. Prospective and larger studies are needed to validate our findings and to assess the prognostic role of various DTI-derived measures at different times following ICH.

Longitudinal quantification and visualization of intracerebral haemorrhage using multimodal magnetic resonance and diffusion tensor imaging

OBJECTIVE

To demonstrate a set of approaches using diffusion tensor imaging (DTI) tractography whereby pathology-affected white matter (WM) fibres in patients with intracerebral haemorrhage (ICH) can be selectively visualized.

METHODS

Using structural neuroimaging and DTI volumes acquired longitudinally from three representative patients with ICH, the spatial configuration of ICH-related trauma is delineated and the WM fibre bundles intersecting each ICH lesion are identified and visualized. Both the extent of ICH lesions as well as the proportion of WM fibres intersecting the ICH pathology are quantified and compared across subjects.

RESULTS

This method successfully demonstrates longitudinal volumetric differences in ICH lesion load and differences across time in the percentage of fibres which intersect the primary injury.

CONCLUSIONS

Because neurological conditions such as intracerebral haemorrhage (ICH) frequently exhibit pathology-related effects which lead to the exertion of mechanical pressure upon surrounding tissues and, thereby, to the deformation and/or displacement of WM fibres, DTI fibre tractography is highly suitable for assessing longitudinal changes in WM fibre integrity and mechanical displacement.

Anatomical location of the frontopontine fibers in the internal capsule in the human brain: a diffusion tensor tractography study

The frontopontine fibers (FPFs) originate from the frontal lobe and end in the pontine nuclei. Many neuroanatomy textbooks have described the FPFs as descending through the anterior limb of the internal capsule. However, several studies have reported controversial results. In this study, using diffusion tensor tractography, we investigated the anatomical location of the FPFs in the internal capsule in the human brain. We recruited 53 healthy volunteers for this study. For reconstruction of the FPFs, the seed region of interest was given in the medial cerebral peduncle of the reconstructed corticospinal tract. The target regions of interest were placed in the three cerebral cortices, respectively: Brodmann's area (BA) BA 6, BA 8, and BA 9. The anatomical locations of the FPFs were evaluated using the highest probabilistic location in the internal capsule. We measured the relative distance of the FPFs from the middle point at the genu of the internal capsule to the most posterior point of the lenticular nucleus. The relative mean distances of the highest probabilistic location for the FPFs from BA 9, 8, and 6 were 18.18, 32.08, and 43.83% from the middle point of the genu of the internal capsule, respectively. By contrast, the highest probabilistic location for the corticospinal tract was 74.18%. According to our findings, the FPFs were located at the anterior half of the posterior limb in the internal capsule, in the following order, from the anterior direction: the FPFs from BA 9, BA 8, and BA 6.

Characteristics of injury of the corticospinal tract and corticoreticular pathway in hemiparetic patients with putaminal hemorrhage

Background

No study on the characteristics of injury of the corticospinal tract (CST) or corticoreticular pathway (CRP) in patients with putaminal hemorrhage has been reported. In this study, using diffusion tensor tractography, we attempted to investigate the characteristics of injury of the CST and CRP in hemiparetic patients with putaminal hemorrhage.

Method

Fifty seven consecutive patients with putaminal hemorrhage and 57 healthy control subjects were recruited for this study. Diffusion tensor imaging was performed during the early period (8 ~ 30 days) after onset. We defined injury of the CST or CRP in terms of the configuration (discontinuation of a neural tract) or abnormal DTT parameters (the fractional anisotrophy value or fiber number was more than two standard deviations lower than that of normal control subjects). The Motricity Index, the modified Brunnstrom Classification, and the Functional Ambulation Categories were used for evaluation of motor function.

Results

Among 57 patients, injury of the CST was found in 41 patients (71.9%) and injury of the CRP was found in 50 patients (87.8%), respectively, and 37 patients (64.9%) had injury of both the CST and CRP. All three motor functions of patients with injury of both the CST and CRP were significantly lower than those of patients with injury of either the CST or CRP (p < 0.05).

Conclusion

Our results indicate that the putaminal hemorrhage frequently accompanies injury of both the CST and CRP, and the CRP appears to be more vulnerable to putaminal hemorrhage than the CST. These findings suggest the necessity for evaluation of both the CRP and the CST in patients with putaminal hemorrhage.

CST recovery in pediatric hemiplegic patients: Diffusion tensor tractography study

Many diffusion tensor imaging (DTI) studies have reported an association between corticospinal tract (CST) injury and motor dysfunction. In this study, we investigated CST recovery in 29 pediatric patients with clinical hemiplegia using DTI. We measured the fractional anisotropy (FA), apparent diffusion coefficient (ADC), and asymmetric anisotropy (AA) of both CSTs. The patients were classified into three groups according to severity of CST disruption of the more affected hemisphere. DTI was followed up for 9.34 ± 2.07 months after initial evaluation. The FA value of the more affected CST showed a significant decrease compared to the opposite side at initial and follow up evaluation, respectively (p<0.05). The FA value of both CSTs showed a significant increase at follow up compared to the initial evaluation, while more changes were observed on the more affected side, compared with the less affected side (p<0.05). AA showed a significant decrease at follow up, and showed significant correlation with interval change of FA value of the more affected side, not with that of the less affected side (r=0.543, p<0.05). 19 patients showed change of CST integrity. In the current study, the results of DTI showed recovery of the CST and provided radiologic evidence for a scientific basis of brain plasticity in pediatric patients.