Ji Heon Hong

Dentatorubrothalamic tract in human brain: diffusion tensor tractography study

IntroductionThe dentatorubrothalamic tract (DRTT) originates from the dentate nucleus in the cerebellum and terminates in the contralateral ventrolateral nucleus (VL) of the thalamus after decussating to the contralateral red nucleus. Identification of the DRTT is difficult due to the fact that it is a long, multisynaptic, neural tract crossing to the opposite hemisphere. In the current study, we attempted to identify the DRTT in the human brain using a probabilistic tractography technique of diffusion tensor imaging.MethodsDiffusion tensor imaging was performed at 1.5-T using a synergy-L sensitivity encoding head coil. DRTTs were obtained by selection of fibers passing through three regions of interest (the dentate nucleus, the superior cerebellar peduncle, and the contralateral red nucleus) from 41 healthy volunteers. Probabilistic mapping was obtained from the highest probabilistic location at 2.3xa0mm above the anterior commissure–posterior commissure level.ResultsDRTTs of all subjects, which originated from the dentate nucleus, ascended through the junction of the superior cerebellar peduncle and the contralateral red nucleus and then terminated at the VL nucleus of the thalamus. The highest probabilistic location for the DRTT at the thalamus was compatible with the location of the VL nucleus.ConclusionsWe identified the DRTT in the human brain using probabilistic tractography. Our results could be useful in research on movement control.

Injury of the Spino-Thalamo-Cortical Pathway Is Necessary for Central Post-Stroke Pain

Objectives: We investigated the relationship between injury of the spino-thalamo-cortical pathway (STP) and central post-stroke pain (CPSP) in patients with intracerebral hemorrhage, using diffusion tensor tractography (DTT). Methods: 30 consecutive chronic patients, in whom integrity of the STP and the medial lemnisco-thalamo-cortical pathway (MLP) were spared in both hemispheres, were recruited. We classified the patients into two groups according to the presence of the CPSP. DTTs were obtained using the FMRIB Software Library. Fractional anisotropy (FA), mean diffusivity (MD), and tract volume were measured. A laterality index (LI) was used to determine asymmetry of DTT parameters between the hemispheres. Results: The LI for tract volume of the STP in the CPSP group was lower than that of the non-CPSP group (p = 0.000). However, there were no differences between the CPSP group and non-CPSP group for the LIs of FA or MD of the STP or for the LIs of FA, MD, or tract volume of the MLP (p > 0.05). Conclusions: Decrease of tract volume without changes in the STP FA or MD values in the CPSP group indicates partial injury of STP. Therefore, injury of the STP seems to be a requirement for the development of CPSP in patients with intracerebral hemorrhage.

Location of the corticospinal tract at the corona radiata in human brain.

Little is known about the location of the corticospinal tract (CST) at the corona radiata (CR). In the current study we attempted to elucidate the location of the CST for the hand at the CR using diffusion tensor tractography analysis based on functional MRI activation results. Functional MRI was performed at 1.5-T with timed hand grasp-release movements, and diffusion tensor tractography was performed using a Synergy-L Sensitivity Encoding (SENSE) head coil. Probabilistic mapping was obtained for 16 normal subjects using areas of functional MRI activation as the first region of interest (ROI 1) and the CST area in the lower pons as the second region of interest (ROI 2). The authors measured the antero-posterior and medio-lateral locations of pixels in the CST in two areas of the CR (CR 1 - the first axial image to show the septum pellucidum and the body of the fornix from the vertex, and CR 2 - the axial image showing the insular gyrus). The most probable locations in the medio-lateral direction (from the most medial point of the lateral ventricle wall to the most lateral point of the cerebral cortex) were 24.2% in both CR 1 and 2, and the most probable locations in the antero-posterior direction (from the most anterior point of the lateral ventricle to the most posterior point of the lateral ventricle) were 66.7 and 63.6% in CR 1 and 2, respectively. It was found that the CST for the hand descended through about one quarter (medio-lateral direction) and two-thirds (antero-posterior direction) at the CR.

Neural pathway from nucleus basalis of Meynert passing through the cingulum in the human brain

With the exception of post-mortem brain study, there has been no specific evaluation method for the nucleus basalis of Meynert (NBM) and its cholinergic pathway. In the current study, we attempted to identify the neural pathway from the NBM passing through the cingulum in the human brain, using diffusion tensor tractography (DTT). We recruited 22 healthy volunteers for this study. Diffusion tensor images (DTIs) were scanned using 1.5-T; images of the neural pathway from the NBM passing through the cingulum were obtained using the FMRIB Software Library (FSL). Values for fractional anisotropy (FA), mean diffusivity (MD), and tract volume were measured for the neural pathway. The neural pathway, which originated from the NBM, entered the cingulum, running to the anterior portion of the genu of the corpus callosum in the anterior, superior, and lateral directions. The rest of the pathway was through the cingulum to the splenium, or posteriorly to the retrosplenial area. In terms of fractional anisotropy, mean diffusivity, or tract volume, there were no significant differences between hemispheres (P>0.05). Using a probabilistic tractography technique, we identified the neural pathway from the NBM passing through the cingulum in the human brain. Methodology and data from this study of the neural pathway from the NBM passing through the cingulum will be helpful in elucidation of the pathology of diseases involving the basal forebrain or frontal lobe.

The rubrospinal tract in the human brain: diffusion tensor imaging study.

The rubrospinal tract (RST) is an extrapyramidal motor pathway in the human brain. In this study, using diffusion tensor tractography (DTT), we attempted to identify the RST in the normal human brain. Twenty-one healthy volunteers were recruited for this study. A 1.5-T scanner was used for scanning of diffusion tensor images, and the RSTs were isolated by DTT using FMRIB software. Values of fractional anisotropy (FA), mean diffusivity (MD), and tract volume of the RSTs were measured. Among 42 hemispheres of 21 subjects, RSTs were isolated in 27 hemispheres (64.28%) of 15 subjects. All identified tracts originated from the red nucleus and crossed the midline via ventral tegmental decussation. Then, they passed through the area between the inferior olivary nucleus and the inferior cerebellar peduncle in the contralateral medulla. The tracts finally descended through the lateral funiculus of the upper spinal cord. Mean values of FA, MD, and tract volume did not differ significantly between the left and right hemispheres (P>0.05). We believe that the methodologies used and the results of this study would be helpful to researchers interested in the function of the human RST and its clinical implications.

Limb apraxia in a patient with cerebral infarct: Diffusion tensor tractography study

We report on a patient with ideomotor apraxia (IMA) and limb-kinetic apraxia (LKA) following cerebral infarct, which demonstrated neural tract injuries by diffusion tensor tractography (DTT). A 67-year-old male was diagnosed as cerebral infarct in the left frontal cortex (anterior portion of the precentral gyrus and prefrontal cortex) and centrum semiovale. The patient presented with severe paralysis of the right upper extremity and mild weakness of the right lower extremity at onset. At the time of DTT scanning (5 months after onset), the patient was able to move all joint muscles of the right upper extremity against gravity, except for the finger extensors, which he could extend partially against gravity. The patient showed intact ideational plan for motor performance; however, his movements were slow, clumsy, and mutilated when executing grasp-release movements of his affected hand. The patients score on the ideomotor apraxia test was 20 (cut-off score < 32). DTTs for premotor cortex fibers, supplementary motor area fibers, and superior longitudinal fasciculus of the left hemisphere showed partial injuries, compared with those of the right side, and these injuries appeared to be responsible for IMA and LKA in this patient.

The Prevalence of Central Poststroke Pain according to the Integrity of the Spino-Thalamo-Cortical Pathway

Objectives: Little is known about the prevalence of central poststroke pain (CPSP) according to the integrity of the spino-thalamo-cortical pathway (STP). Using diffusion tensor tractography, we investigated the prevalence of CPSP according to the integrity of the STP in patients with intracerebral hemorrhage. Methods: We recruited 52 consecutive chronic patients and 10 normal control subjects. Patients were classified into two groups according to preservation of the integrity of the STP. Each group was divided into two subgroups according to the presence of CPSP. Results: The preserved group included 34 patients [CPSP subgroup, 16 (47%) patients; non-CPSP subgroup, 18 (53%) patients], and 18 patients were enrolled into the disrupted group [CPSP subgroup, 3 (17%) patients; non-CPSP subgroup, 15 (83%) patients]. The fractional anisotropy and mean diffusivity values of the CPSP and non-CPSP subgroups of the preserved group were decreased and increased when compared with those of the control group, respectively (p < 0.05). Conclusions: We found that the prevalence of CPSP in patients with partial injury of the STP was higher than that of patients with complete injury of the STP. Partial injury of the STP appears to be more vulnerable to development of CPSP than complete injury of the STP in patients with intracerebral hemorrhage.

The anatomical characteristics of superior longitudinal fasciculus I in human brain: Diffusion tensor tractography study

The superior longitudinal fasciculus (SLF) I is known to be involved in regulation of higher aspects of motor function. Using diffusion tensor imaging (DTI), we attempted to identify the SLF I and to investigate the anatomical characteristics of the SLF I in the human brain. We recruited 30 healthy subjects for this study. The SLF I was obtained using the FMRIB Software Library. The seed region of interest (ROI) was given at the superior parietal lobule (SPL) and the target ROI was the supplementary motor area (SMA) along with the dorsal part of the premotor area (PMA). Values of fractional anisotropy (FA), mean diffusivity (MD), and tract volume were measured. The SLF I originated from the SPL and medial parietal cortex, passed through the white matter of the SPL and superior frontal gyrus, and then terminated in the SMA and dorsal PMA. There were no significant differences between hemispheres in terms of the FA, MD, and tract volume. We present with the anatomical characteristics of the SLF I in the human brain using DTI. We think that the methodology and results of this study would be helpful to researchers in this field.

The effect of a stretching device on hand spasticity in chronic hemiparetic stroke patients

We attempted to evaluate the effect of a stretching device for treatment of hand spasticity in chronic stroke patients. We recruited 21 chronic hemiplegic stroke patients with severe finger flexor spasticity and randomly assigned them to the intervention group (10 patients) and control group (11 patients). The stretching device consisted of a resting hand splint, finger stretcher, and frame. The stretching state was maintained for 30 seconds and relaxed for the next 30 seconds. This stretching and relaxation were repeated for 20 minutes (one session). The stretching program was practiced 2 sessions/day and 6 days/week for 3 weeks for the patients of the intervention group. The effect of this stretching device was assessed using the modified Ashworth scale (MAS) score of finger flexor muscles. Patients in both groups were assessed six times within an interval of one week and patients in the intervention group were assessed two times before starting the stretching program. The two-way repeated measures analysis of variance (ANOVA) test for evaluation of the effect of intervention across all time-points between the two groups showed a significant interaction between time and effect of intervention (P < 0.001). Within the intervention group, the average of mean MAS score at Pre-1 and Pre-2 were 2.83 and 2.93, respectively (the difference between Pre-1 and Pre-2 was not significant (P> 0.05)), and this improved significantly to 1.97 at Inter-1, 1.55 at Inter-2, 1.20 at Inter-3, and 1.97 at Post-1 (P < 0.001) using the one-way repeated measures ANOVA test for evaluation of the effect of intervention across all time-points. We found that our stretching device was effective in relieving hand spasticity in chronic stroke patients.

Neuronal loss in the medial cholinergic pathway from the nucleus basalis of Meynert in patients with traumatic axonal injury: a preliminary diffusion tensor imaging study.

Objective:The recent development of diffusion tensor imaging (DTI) allows visualization and estimation of the medial cholinergic pathway (MCP), which originates from the nucleus basalis of Meynert and provides cortical cholinergic innervation to the cerebral cortex. We investigated the injury to the MCP in patients with traumatic axonal injury (TAI), using DTI. Design:Retrospective survey. Participants:Fourteen patients with chronic TAI and 14 age- and sex-matched normal control subjects. Main Outcome Measures:Using the Functional Magnetic Resonance Imaging of the Brain (FMRIB) Software Library (FMRIB analysis group, Oxford University, United Kingdom), diffusion tensor images were acquired by using a sensitivity-encoding head coil at 1.5 T DTIs. Fractional anisotropy (FA), mean diffusivity (MD), and tract volume of the MCP were measured. Results:The FA value and tract volume were significantly decreased in the group with TAI compared with those of the control group (P < .05); in contrast, there was no difference in the MD value between the 2 groups (P > .05). Conclusions:Changes in DTI parameters of the TAI group appear to be due to neuronal loss of the MCP. We believe that DTI would be useful for the evaluation of the MCP in patients with TAI.