No abstract available.
Pyramidal Tracts*

Diffusion tensor tractorgraphy which is based on line propagation method with brute force approach is implemented and the vector correlation function is proposed in addition to the conventional fractional anisotrophy value as a criterion to select seed points. For the whole tractography, the proposed method used 41% less seed points than the conventional brute force approach for FA > or =0.3 and most of the fiber tracks in the outer region of white matter were removed. For the corticospinal tract passing through region of interest, the proposed method has produced similar results with 50% less seed points than conventional one.
Diffusion ; Pyramidal Tracts

According to the anatomical pathways of the corticobulbar tract, it is known that the responsible lesion site of central facial palsy is at the level of the midpons or the more rostral portion. In rare cases, central facial palsy is found in medullary lesions. We report two cases of medullary infarctions which presented as central facial palsy. These cases suggested that the hypothesis that part of the pathway of the facial corticobulbar fibers descend ipsilaterally to the lower medulla before decussating and ascending contralaterally to the facial nucleus.
Facial Paralysis* ; Infarction* ; Pyramidal Tracts

No abstract available.
Brain ; Muscle Spasticity ; Paraparesis, Spastic ; Pyramidal Tracts

PURPOSE: Diffusion tensor imaging (DTI) data must be analyzed by an analyzer after data processing. Hence, the analyzed data of DTI might depend on the analyzer, making it a major limitation. This paper reviewed previous DTI studies reporting the repeatability and reproducibility of data from the corticospinal tract (CST), one of the most actively researched neural tracts on this topic. MATERIALS AND METHODS: Relevant studies published between January 1990 and December 2018 were identified by searching PubMed, Google Scholar, and MEDLINE electronic databases using the following keywords: DTI, diffusion tensor tractography, reliability, repeatability, reproducibility, and CST. As a result, 15 studies were selected. RESULTS: Measurements of the CSTs using region of interest methods on 2-dimensional DTI images generally showed excellent repeatability and reproducibility of more than 0.8 but high variability (0.29 to 1.00) between studies. In contrast, measurements of the CST using the 3-dimensional DTT method not only revealed excellent repeatability and reproducibility of more than 0.9 but also low variability (repeatability, 0.88 to 1.00; reproducibility, 0.82 to 0.99) between studies. CONCLUSION: Both 2-dimensional DTI and 3-dimensional DTT methods appeared to be reliable for measuring the CST but the 3-dimensional DTT method appeared to be more reliable.
Diffusion Tensor Imaging ; Diffusion ; Methods ; Pyramidal Tracts

We report the clinical usefulness of elucidating the state of the corticospinal tract (CST) by the use of diffusion tensor image tractography (DTT) in hemiparetic stroke patients. DTT was performed using 1.5 T magnetic resonance imaging. DTT demonstrated that the CST of the affected hemisphere was preserved in the medial portion of the hematoma in patient 1, but was interrupted by a hematoma in patient 2. DTT seems to be useful for elucidating the status of the CST in hemiparetic stroke patients.
Diffusion ; Hematoma ; Humans ; Magnetic Resonance Imaging ; Pyramidal Tracts ; Stroke

No abstract available.
Diffusion ; Leukoencephalopathies ; Pyramidal Tracts ; Sepsis ; Sepsis-Associated Encephalopathy

Opalski syndrome is a rare lateral medullary infarction variant presenting with ipsilateral motor deficits known to be caused by involvement of the post-decussating pyramidal tract. Here, we report two rare cases of Opalski syndrome presenting as ipsilateral sensorimotor deficits in cerebral infarction.
Cerebral Infarction ; Infarction ; Lateral Medullary Syndrome ; Pyramidal Tracts

OBJECTIVE: Differentiation of demyelination in white matter from axonal damage can be determined using diffusion tensor imaging (DTI). In this study using meningioma patients an attempt was made to evaluate the relationship between preoperative weakness and the changes of diffusion parameters in the corticospinal tract (CST) using DTI. METHODS: Twenty-six patients with meningioma were enrolled in this study. Eleven of them suffered from objective motor weakness and were classified as Group 1. The remaining 15 patients did not present motor weakness and were classified as Group 2. Fiber tractography and CST diffusion parameters were obtained using DTIStudio. The ratios (lesion side mean value/contralateral side mean value) of CST diffusion parameters were compared with 1.0 as a test value using a one-sample t-test. RESULTS: In Group 1, fractional anisotropy (FA), tensor trace (TT), and radial diffusivity (RD, lambda2 and lambda3) of the CST were significantly different between two hemispheres, but axial diffusivity (AD, lambda1) of the CST was not significantly different between two hemispheres. In Group 2, FA and lambda3 of CST did not differ significantly between the hemispheres. In Group 2, TT, lambda1, and lambda2 of CST in the ipsilateral hemisphere were significantly higher than those of the unaffected hemisphere. However, the differences were small. CONCLUSION: Motor weakness was related to a low FA and high TT resulting from increased RD of the CST fibers. CST diffusion changes in patients with weakness are similar to those for demyelination.
Anisotropy ; Axons ; Demyelinating Diseases* ; Diffusion Tensor Imaging* ; Diffusion* ; Humans ; Meningioma* ; Pyramidal Tracts*

In the rat lumbar spinal cord, the pathways and distribution of corticospinal tract (CST) axons were investigated using retrograde transport of Fast Blue(FB) and Fluoro-Gold(FG). The purpose of this study was, therefore, to fond the extent of CST projections in the lateral funiculus in the rat. Total of twelve female rats were used in this study. The laminectomy was performed at the 78 cord level to expose the spinal cord. Using a radiofrequency lesioning device, the CST, including the dorsal columns, were lesioned bilaterally. Three to seven days after lesioning, two laminectomies were performed at C6-8 and L3-5 to expose the spinal cord for dye injections. Retrograde tracing of fast blue(FB) and fluoro-gold(FG) were used to quantitate the number of cerebral cortex neurons projecting to the lumbar cord through tracts other than the CST in the dorsal column. New findings of the this study are : (1) a small number of CST axons projected to lumbosacral spinal cord bilaterally in the dorsolateral funiculi. (2) some axons projecting to the lumbar cord through the dorsolateral funiculi are collateral of neuron that project to the cervical spinal cord. Our results suggest that there are a larger number of CSTs than previously thought projecting to the lumbar spinal cord through the lateral funiculi. These residual tracts may play a role in the functional recovery of the affected limbs.
Animals ; Axons ; Cerebral Cortex ; Extremities ; Female ; Humans ; Laminectomy ; Neurons ; Pyramidal Tracts* ; Rats* ; Spinal Cord*