Akinetic mutism and gait disturbance in a patient with delayed post-hypoxic leukoencephalopathy.

We report on a patient with delayed post-hypoxic leukoencephalopathy (DPHL) who showed akinetic mutism and gait disturbance, neural injuries that were demonstrated on diffusion tensor tractography (DTT). A patient was exposed to carbon monoxide (CO) and rapidly recovered; however, two weeks after onset, he began to show cognitive impairment and gait disturbance. At six weeks after CO exposure, he showed akinetic mutism and gait inability. DTT at 6-weeks post-exposure showed discontinuations in neural connectivities of the caudate nucleus to the medial prefrontal and orbitofrontal cortex in both hemispheres. In addition, the corticoreticulospinal tract revealed severe thinning in both hemispheres.

Correlation between Thalamocortical Tract and Default Mode Network with Consciousness Levels in Hypoxic-Ischemic Brain Injury Patients: A Comparative Study Using the Coma Recovery Scale-Revised.

BACKGROUND The thalamocortical tract (TCT) links nerve fibers between the thalamus and cerebral cortex, relaying motor/sensory information. The default mode network (DMN) comprises bilateral, symmetrical, isolated cortical regions of the lateral and medial parietal and temporal brain cortex. The Coma Recovery Scale-Revised (CRS-R) is a standardized neurobehavioral assessment of disorders of consciousness (DOC). In the present study, 31 patients with hypoxic-ischemic brain injury (HI-BI) were compared for changes in the TCT and DMN with consciousness levels assessed using the CRS-R. MATERIAL AND METHODS In this retrospective study, 31 consecutive patients with HI-BI (17 DOC,14 non-DOC) and 17 age- and sex-matched normal control subjects were recruited. Magnetic resonance imaging was used to diagnose HI-BI, and the CRS-R was used to evaluate consciousness levels at the time of diffusion tensor imaging (DTI). The fractional anisotropy (FA) values and tract volumes (TV) of the TCT and DMN were compared. RESULTS In patients with DOC, the FA values and TV of both the TCT and DMN were significantly lower compared to those of patients without DOC and the control subjects (p<0.05). When comparing the non-DOC and control groups, the TV of the TCT and DMN were significantly lower in the non-DOC group (p<0.05). Moreover, the CRS-R score had strong positive correlations with the TV of the TCT (r=0.501, p<0.05), FA of the DMN (r=0.532, p<0.05), and TV of the DMN (r=0.501, p<0.05) in the DOC group. CONCLUSIONS This study suggests that both the TCT and DMN exhibit strong correlations with consciousness levels in DOC patients with HI-BI.

Hypothalamic Injury and Clinical Outcomes in Patients with Post-Traumatic Hyponatremia: A Diffusion Tensor Imaging Case-Control Study.

BACKGROUND Diffusion tensor imaging (DTI) is an advanced magnetic resonance imaging (MRI) method used to identify changes in microstructures in the brain's white matter. Severe brain injuries after trauma are associated with disorders of consciousness (DOC) and may result in hyponatremia due to damage to the hypothalamus. This case-control study aimed to use DTI to evaluate the hypothalamus in 36 patients with hyponatremia and DOC due to severe brain injuries. MATERIAL AND METHODS Thirty-six patients with DOC after traumatic brain injury (TBI) and 36 healthy control subjects were enrolled in this study. The diagnosis of DOC was based on the coma recovery scale-revised (CRS-R). The 36 patients were divided into 2 groups: Group A (18 with hyponatremia, serum sodium level <135 mmol/L) and group B (18 without hyponatremia). The DTI scans were conducted using a 6-channel head coil on a 1.5T Philips Gyroscan Intera scanner. Among the DTI data, fractional anisotropy (FA) and the apparent diffusion coefficient (ADC) of the hypothalamus were analyzed. RESULTS Patient group A had a lower FA value (P=0.044) and higher ADC value (P=0.004) of the hypothalamus and showed a longer length of hospital stay (P=0.03), lower CRS-R score at discharge (P=0.01), and less change in CRS-R score (P=0.004) compared to patient group B. The improvements in the CRS-R score revealed a moderate negative correlation (r=-0.467) with the severity of the hyponatremia (P=0.004). CONCLUSIONS Post-traumatic hyponatremia was associated with hypothalamic injury and the presence and severity of hyponatremia were associated with poor clinical outcomes in DOC patients.

Cerebellar Peduncle Injuries in Patients with Mild Traumatic Brain Injury.

BACKGROUND: The cerebellum is connected to the brain stem by three pairs of cerebellar peduncles (CPs)-superior (SCP), middle (MCP), and inferior (ICP)-which carry proprioceptive information to regulate movement and maintain balance and posture. Injury or damage to the CPs caused by tumors, infarcts, or traumatic brain injuries (TBI) results in poor coordination and balance problems. Current data on CP-related injuries and their effect on balance control are sparse and restricted to a few case studies. There have been no studies to date that have investigated CP injuries in a large sample of patients with balance problems following a mild TBI. Hence, we investigated CP-related injuries in patients with balance problems following mild TBI using diffusion tensor tractography (DTT). METHODS: Twenty-one patients with TBI and 21 normal subjects were recruited for this study. Balance was evaluated using the Balance Error Scoring System (BESS). Three DTT-related parameters-fractional anisotropy (FA), apparent diffusion coefficient (ADC), and fiber number (FN) of the CPs-were measured. RESULTS: The FN values of the SCP and ICP in the patient group were significantly lower than those in the control group (p < 0.05). No significant differences in the FA, ADC, and FN values of the MCP were observed between the patient and control groups (p > 0.05). CONCLUSIONS: Using DTT, we demonstrated injuries to the SCP and ICP in mild TBI patients with balance problems. Our results suggest that DTT could be a useful tool for detecting injuries to the CPs that may not be identified on conventional brain magnetic resonance imaging in mild TBI patients.

Injury of the Spinothalamic Tract Following Whiplash Injury: A Diffusion Tensor Tractography Study.

OBJECTIVES: Using diffusion tensor tractography (DTT), we demonstrated the spinothalamic tract (STT) injury in patients with central pain following whiplash injury. Our primary hypothesis is that fractional anisotropy (FA) and tract volume (TV) of the STT in injured people differ from non-injured people. Our secondary hypothesis is that the direction of the collision results in a different type of injury. METHODS: Nineteen central pain patients following whiplash injury and 19 normal control subjects were recruited. The STT was reconstructed by the DTT, the FA and TV of the STT were measured. In addition, different characteristics of the STT injury according to the collision direction were investigated. RESULTS: The FA value did not differ significantly between the patient and control groups (p > 0.05). However, the significantly lower value of the TV was observed in patient group than the control group (p < 0.05). The onset of central pain was significantly delayed (13.5 days) in patients who were involved in a frontal collision, compared to patients with rear-end collision (0.6 days) (p < 0.05). In contrast, the Visual Analogue Scale was higher in the patients with rear-end collision (p < 0.05). CONCLUSIONS: We found the STT injury mild traumatic brain injury (TBI) who suffered central pain after whiplash injury, using DTT. In addition, we demonstrated different characteristics of the STT injury according to the collision direction. We believe that injury of the STT would be usefully detected by DTT following whiplash injury.

Relationship between the Consciousness State and the Default Mode Network in Traumatic Brain Injury.

INTRODUCTION: This study investigated the relationship between Coma Recovery Scale-Revised (CRS-R) and the neural networks between the medial prefrontal cortex (mPFC) and precuneus (PCun)/posterior cingulate cortex (PCC) in disorders of consciousness (DOC) patients with a traumatic brain injury (TBI) using diffusion tensor tractography (DTT). MEASURES: Twenty-five consecutive patients with TBI admitted to the rehabilitation department of a university hospital were enrolled in this study. The Coma Recovery Scale-Revised (CRS-R) was used to evaluate the consciousness state. The pathway of the neural networks between the mPFC and the PCun (mPFC-PCun DMN)/PCC (mPFC-PCC DMN) were reconstructed using DTT. Fractional anisotropy (FA) and the tract volume (TV) were obtained to assess the diffusion tensor imaging parameters. RESULTS: The CRS-R score had strong positive correlations with the FA value and TV of the mPFC-PCun DMN (p < 0.05), while it showed a moderate positive correlation with the TV of the mPFC-PCC DMN (p < 0.05). In addition, the FA value of the mPFC-Pcun DMN showed that it could explain the variability in the CRS-R score. CONCLUSIONS: The close correlation was noted between the consciousness state and the mPFC-PCun DMN and mPFC-PCC DMN in DOC patients with TBI. On the other hand, the mPFC-PCun DMN appeared to be more closely correlated with the consciousness state than the mPFC-PCC DMN.

Relation Between the Corticospinal Tract State and Activities of Daily Living in Patients With Intracerebral Hemorrhage.

BACKGROUND AND PURPOSE: We investigated the relation between the ipsilesional corticospinal tract (CST) state and activity of daily living independence in patients with chronic intracerebral hemorrhage. METHODS: Fifty-six consecutive patients with unilateral intracerebral hemorrhage and 38 healthy control subjects were recruited for this study. The Motricity index and the modified Barthel index were used to evaluate motor function of the affected extremities and activity of daily living independence, respectively. The diffusion tensor imaging parameter values for fractional anisotropy (FA) and voxel number (VN) of the CST were determined. Ratios of the ipsilesional to the contralesional CST measures were calculated and are presented as the CST-ratio (FA value and VN). RESULTS: The FA value and VN of the ipsilesional CST and the CST-ratio in the patient group were lower than those of the control group (P<0.05). There was a strong positive correlation between the Motricity index score of the affected extremities and the modified Barthel index score (P<0.05), while the FA value and VN of the ipsilesional CST and the CST-ratio showed moderate and strong positive correlations with the Motricity index and modified Barthel index scores, respectively (P<0.05). In addition, the VN of the ipsilesional CST showed excellent utility as a classifier, whereas the FA value of the ipsilesional CST and the FA value and VN of the CST-ratio showed good classifier utility (P<0.05). CONCLUSIONS: We demonstrated that impairment of activity of daily living independency was closely related to the injury severity of the ipsilesional CST in patients with chronic intracerebral hemorrhage. In addition, the injury severity of the ipsilesional CST can be used to classify the degree of activity of daily living independency. Registration: URL: http://www.e-irb.com/index.jsp; Unique identifier: 2021-03-014.

Comparative study of vestibular projection pathway connectivity in cerebellar injury patients and healthy adults.

OBJECTIVE: Cerebellar injury can not only cause gait and postural instability, nystagmus, and vertigo but also affect the vestibular system. However, changes in connectivity regarding the vestibular projection pathway after cerebellar injury have not yet been reported. Therefore, in the current study, we investigated differences in the connectivity of the vestibular projection pathway after cerebellar injury using diffusion tensor imaging (DTI) tractography. METHODS: We recruited four stroke patients with cerebellar injury. Neural connectivity in the vestibular nucleus (VN) of the pons and medulla oblongata in patients with cerebellar injury was measured using DTI. Connectivity was defined as the incidence of connection between the VN on the pons and medulla oblongata and target brain regions such as the cerebellum, thalamus, parieto-insular vestibular cortex (PIVC), and parietal lobe. RESULTS: At thresholds of 10 and 30, there was lower connectivity in the ipsilateral hemisphere between the VN at the medullar level and thalamus in the patients than in healthy adults. At a threshold of 1 and 10, the patient group showed lower VN connectivity with the PIVC than healthy adults. At a threshold of 1, VN connectivity with the parietal lobe in the contralateral hemisphere was lower in the patients than in healthy adults. Additionally, at a threshold of 30, VN connectivity at the pons level with the cerebellum was lower in healthy adults than in the patients. CONCLUSION: Cerebellar injury seems to be associated with decreased vestibular projection pathway connectivity, especially in the ipsilateral thalamus, PIVC, and contralateral parietal lobe.

Role of Diffusion Tensor Tractography in Diagnosis of Limb-Kinetic Apraxia in Stroke Patients: A Mini-Narrative Review.

Limb-kinetic apraxia (LKA) is an execution disorder of movements caused by an injury to the secondary motor area (the supplementary motor area and premotor cortex) with preservation of an intact corticospinal tract (CST). A precise diagnosis of LKA is often limited because it is made based on the clinical observation of movement characteristics with confirmation of the CST state, and no specific clinical assessment tools for LKA have been developed. Diffusion tensor tractography (DTT) enables a three-dimensional estimation of the neural tracts related to LKA, such as the CST and corticofugal tract from the secondary motor area. This article reviewed 5 DTT-based studies on LKA-related neural tracts in stroke patients. These studies suggest that DTT could be a useful diagnostic tool for LKA along with previous diagnostic tools, such as brain magnetic resonance imaging and transcranial magnetic stimulation. In particular, DTT for the affected corticofugal tract can provide useful evidence for diagnosing LKA when clinicians cannot observe the movement characteristics because of severe weakness after a severe injury to the affected CST. Furthermore, a reviewed study suggested that LKA might be related to the unaffected neural tracts for motor function when the affected neural tracts were severely injured. This review summarizes the role of DTT in the diagnosis of LKA in stroke patients.

Evaluation of Structural Neural Connectivity Between the Primary Auditory Cortex and Cognition-Related Brain Areas Using Diffusion Tensor Tractography in 43 Normal Adults.

BACKGROUND Little is known about the structural neural connectivity between the primary auditory cortex and cognition-related brain areas in the human brain. This study aimed to evaluate the structural neural connectivity between the primary auditory cortex and cognition-related brain areas in normal subjects, using diffusion tensor tractography (DTT). MATERIAL AND METHODS Forty-three healthy subjects with no prior history of audiological, neurological, physical, or psychiatric illnesses were recruited for this study. Diffusion tensor imaging data analysis was performed using the Oxford Centre for Functional Magnetic Resonance Imaging of Brain (FMRIB) Software Library. In each subject, a region of interest was set on the primary auditory cortex, including the subcortical white matter. We assessed the neural connectivity between the primary auditory cortex and cognition-related brain areas (the dorsolateral prefrontal cortex [DLPFC]; ventrolateral prefrontal cortex [VLPFC]; orbitofrontal cortex [OFC]; hippocampus; parahippocampal cortex; amygdala, anterior and posterior cingulate gyrus; and fornix). RESULTS According to the results of DTT, the primary auditory cortex showed neural connectivity (over 50%) with the following areas: the threshold of 1 streamline - the VLPFC (94.2%), OFC (84.9%), fornix (80.2%), hippocampus (76.7%), parahippocampal cortex(74.4%) and DLPFC (58.1%); the threshold of 5 streamlines - the VLPFC (88.4%), OFC (81.4%), fornix (66.3%), hippocampus (55.8%), and parahippocampal cortex (53.5%); and the threshold of 15 streamlines - the VLPFC (82.6%), OFC (74.4%), and fornix (53.5%). CONCLUSIONS In normal human subjects, DTT showed that the primary auditory cortex had a high degree of neural connectivity with the prefrontal cortex, fornix, hippocampus, and parahippocampal cortex, which are brain areas associated with cognition and memory.

A Review of Studies on the Role of Diffusion Tensor Magnetic Resonance Imaging Tractography in the Evaluation of the Fronto-Subcortical Circuit in Patients with Akinetic Mutism.

Akinetic mutism (AM) is characterized by the complete absence of spontaneous behavior (akinesia) and speech (mutism) with the preservation of executive functions for movements and speaking. Elucidation of the pathophysiological mechanisms or neural correlates for AM is clinically important because patients can recover from AM after medication and neuromodulation. The fronto-subcortical circuit is a critically important neural structure in the pathophysiology of AM. Using diffusion tensor tractography, a few neural tracts in the fronto-subcortical circuit can be reconstructed. This mini-review article evaluated 6 DTT-based studies on the fronto-subcortical circuit injury in patients with AM. According to these results, the neural tracts among the fronto-subcortical circuit, which are related to AM, were as follows (in decreasing order of importance): 1) the prefronto-caudate tract, 2) the prefronto-thalamic tract, and 3) the cingulum. In particular, the medial prefrontal cortex is an important brain area related to recovery from AM. However, only 6 studies on this topic have been published, and most were case reports. In addition, these studies analyzed only a few neural tracts in the fronto-subcortical circuit. Because AM is a rare disorder, studies involving a large number of subjects might be impossible. Nevertheless, an analysis of various neural tracts in the fronto-subcortical circuit is necessary. For this, reconstruction of the other neural tracts in the fronto-subcortical circuit should be performed first. This review aims to present the findings from recent studies on the role of DTT in evaluation of fronto-subcortical circuit injury in patients with AK.

Use of a Brain Navigator to Identify the Precentral Knob of the Precentral Gyrus in Normal Subjects.

BACKGROUND [color=black]The precentral knob of the precentral gyrus is the original site for hand somatotopy in the corticospinal tract, and it is considered an important target for neuromodulation. However, little is known about the anatomical location of the precentral knob for easy clinical use. This study aimed to describe the use of an optical tracking brain navigator to identify the anatomical location of the precentral knob in the precentral gyrus in normal subjects. [/color] MATERIAL AND METHODS [color=black]Twenty healthy right-handed subjects were enrolled for this study. The locations of target and surface points in each subject were determined using a brain navigator. The target and surface points were defined as the precentral knob and the area of the scalp in the vertical direction from the target point, respectively. Then, by placing a marked 1-cm grid on each subject's head, the horizontal and vertical distances from the midline central (Cz) were measured using the point marker.[/color] RESULTS [color=black]The average distance from Cz to the location of the precentral knob in the horizontal direction was 30.75 mm in the right hemisphere, 31.25 mm in the left hemisphere, and 31.00 mm in both hemispheres. The average distance from Cz to the location of the precentral knob in the vertical direction was -12.75 mm in the right hemisphere, -14.50 mm in the left hemisphere, and -13.62 mm in both hemispheres. [/color] CONCLUSIONS [color=black]This study showed that the anatomical location of the precentral knob in normal subjects could be identified using a brain navigator and this method may be used clinically for patients requiring neuromodulation.[/color].

Changes in subcortical white matter in the unaffected hemisphere following unilateral spontaneous intracerebral hemorrhage: a tract-based spatial statistics study.

We investigated changes in the subcortical white matter in the unaffected hemisphere in patients with unilateral intracerebral hemorrhage (ICH) by applying tract-based spatial statistics (TBSS) analysis. Twenty-four patients with ICH and 17 healthy control subjects were recruited for this study. Diffusion tensor imaging (DTI) data were obtained at least four weeks after ICH onset. TBSS analysis was performed using fractional anisotropy (FA) DTI data. We calculated mean FA values across the tract skeleton and within 27 regions of interest (ROIs) based on the observed intersections between the FA skeleton and the probabilistic Johns Hopkins University white matter atlases. The FA values of 27 ROIs in the unaffected hemisphere in the patient group were significantly lower than those of the control group (p < 0.05). In terms of a causal relationship between possible confounding factors (sex, age, lateralization [right], lesion volume), a negative correlation coefficient was observed in five ROIs (the tapetum, sagittal stratum, column and body of the fornix, posterior corona radiate, inferior cerebellar peduncle, superior cerebellar peduncle) in the regression analysis (p < 0.05). In the patient group, moderate negative correlations were detected between ICH volume and the FA values of two ROIs: the sagittal stratum, r = -0.479, p < 0.05; the tapetum, r = -0.414, p < 0.05. We detected extensive neural injury of the subcortical white matter in the unaffected hemisphere in patients with unilateral ICH. In addition, injury severities of neural structures located around the mid-sagittal line or periventricular areas were correlated with ICH volume.

Relationship between short-term memory impairment and the dorsolateral prefrontal cortex injury in patients with mild traumatic brain injury.

BACKGROUND: The prefrontal cortex (PFC) has been reported to be related to memory function. Especially, the dorsolateral PFC (DLPFC) is a substantial neural structure in short-term memory. In this study, using diffusion tensor tractography (DTT), we investigated the relationship between short-term memory impairment and the DLPFC injury in patients with mild traumatic brain injury (TBI). METHODS: We recruited 46 consecutive chronic patients with mild TBI and 42 normal control subjects. Fractional anisotropy (FA) and fiber number (FN) of the prefronto-thalamic tracts were determined for both hemispheres. RESULTS: Significant differences were detected in the FA value of the DLPFC and FN value of the prefronto-thalamic tracts in the patient and control groups (p < 0.05). However, no significant differences were detected in the ventrolateral PFC (VLPFC) and orbitofrontal cortex (OFC) between the patient and control groups (p > 0.05). In addition, the FN value of the DLPFC showed moderate positive correlation with short-term memory (r = 0.510, p < 0.05). However, no significant correlations were detected between the short-term memory and the FA value of the DLPFC, and the FA and FN values of the VLPFC and OFC in the patient group (p > 0.05). CONCLUSIONS: We found that the short-term memory impairment was closely associated with the DLPFC injury in patients with mild TBI. Our results suggest that the estimation of the DLPFC using DTT would be useful for patients with severity of short-term memory impairment following mild TBI.

Prefronto-thalamic tract injury and cognitive outcome according to external ventricular drainage location in stroke patients.

OBJECTIVES: We investigated the characteristics of prefronto-thalamic tract (PF-TT) injuries in stroke patients using diffusion tensor tractography (DTT) and assessing cognitive outcome according to location of the external ventricular drainage (EVD). METHODS: Forty-five consecutive stroke patients who underwent EVD and 24 control subjects were recruited. The patients were classified into three groups: group A (EVD on the lesion or one side, 17 patients), group B (EVD on the hemisphere opposite to the lesion, 12 patients), and group C (EVD on both sides, 16 patients). Mini-Mental State Examination (MMSE) results were performed at the beginning (average 2.27 months from onset) and end (average 4.19 months from onset) of rehabilitation. Three parts of the PF-TT (dorsolateral PF-TT[DLPF-TT], ventrolateral PF-TT[VLPF-TT], orbitofronto-thalamic tract[OF-TT]) were reconstructed and the fractional anisotropy (FA) and tract volume (TV) measurements were obtained. RESULTS: With the EVD on the stroke-affected side, the values of FA and TV of all three parts of the PF-TTs in three patient groups were lower than those of the control group (p < 0.05). With the EVD on the unaffected side, the FA values of the DLPF-TT in groups B and C and the OF-TT in group C were lower than those of the control group (p < 0.05). There was no difference in initial MMSE score among three patient groups; however, group A had a higher mean follow-up MMSE score than that of groups B and C (p < 0.05). CONCLUSIONS: Patients who underwent EVD of the affected hemisphere showed better results in terms of the PF-TT injury and cognitive outcome than patients who underwent EVD through the unaffected hemisphere or through both hemispheres.

Entropy Could Quantify Brain Activation Induced by Mechanical Impedance-Restrained Active Arm Motion: A Functional NIRS Study.

Brain activation has been used to understand brain-level events associated with cognitive tasks or physical tasks. As a quantitative measure for brain activation, we propose entropy in place of signal amplitude and beta value, which are widely used, but sometimes criticized for their limitations and shortcomings as such measures. To investigate the relevance of our proposition, we provided 22 subjects with physical stimuli through elbow extension-flexion motions by using our exoskeleton robot, measured brain activation in terms of entropy, signal amplitude, and beta value; and compared entropy with the other two. The results show that entropy is superior, in that its change appeared in limited, well established, motor areas, while signal amplitude and beta value changes appeared in a widespread fashion, contradicting the modularity theory. Entropy can predict increase in brain activation with task duration, while the other two cannot. When stimuli shifted from the rest state to the task state, entropy exhibited a similar increase as the other two did. Although entropy showed only a part of the phenomenon induced by task strength, it showed superiority by showing a decrease in brain activation that the other two did not show. Moreover, entropy was capable of identifying the physiologically important location.

Delayed development of aphasia related to degeneration of the arcuate fasciculus in the dominant hemisphere nine years after the onset in a patient with intracerebral hemorrhage: a case report.

BACKGROUND: We report on a patient with an intracerebral hemorrhage (ICH), who showed delayed development of aphasia, which was demonstrated via follow up diffusion tensor tractography (DTT) to be related to neural degeneration of the arcuate fasciculus (AF). CASE PRESENTATION: A 51-year-old, right-handed male presented with right hemiparesis, which occurred at the onset of a spontaneous ICH in the left corona radiata and basal ganglia. Brain magnetic resonance images showed a hematoma in the left subcortical area at one month after onset and hemosiderin deposits in the left subcortical area at nine years after onset. At four weeks after onset, he exhibited severe aphasia, and Western Aphasia Battery (WAB) testing revealed an aphasia quotient in the 39.6 percentile (%ile). However, his aphasia improved to nearly a normal state, and at three months after onset, his aphasia quotient was in the 90.5 %ile. At approximately eight years after onset, he began to show aphasia, and his aphasia increased slowly with time resulting in a WAB aphasia quotient in the 12.5 %ile at nine years after onset. The integrity of the left AF over the hematoma was preserved on 1-month post-onset DTT. However, the middle portion of the left AF in the middle of the hemosiderin deposits showed discontinuation on 9-year post-onset DTT. The fractional anisotropy value of the left AF was higher on the 9-year post-onset DTT (0.48) than that on the 1-month post-onset DTT (0.35), whereas the mean diffusivity value was lower on the 9-year post-onset DTT (0.10) than that on the 1-month post-onset DTT (0.32). The fiber number of the left AF was decreased to 175 on the 9-year post-onset DTT from 239 on the 1-month post-onset DTT. CONCLUSIONS: We report on a patient with ICH who showed delayed development of aphasia, which appeared to be related to degeneration of the AF in the dominant hemisphere. Our results suggest that DTT would be useful in ruling out neural degeneration of the AF.

White Matter Abnormalities in Traumatic Subarachnoid Hemorrhage: A Tract-Based Spatial Statistics Study.

BACKGROUND The pathophysiology of traumatic subarachnoid hemorrhage and brain injury has not been fully elucidated. In this study, we examined abnormalities of white matter in isolated traumatic subarachnoid hemorrhage patients by applying tract-based spatial statistics. MATERIAL AND METHODS For this study, 10 isolated traumatic subarachnoid hemorrhage patients and 10 age- and sex-matched healthy control subjects were recruited. Fractional anisotropy data voxel-wise statistical analyses were conducted through the tract-based spatial statistics as implemented in the FMRIB Software Library. Depending on the intersection between the fractional anisotropy skeleton and the probabilistic white matter atlases of Johns Hopkins University, we calculated mean fractional anisotropy values within the entire tract skeleton and 48 regions of interest. RESULTS The fractional anisotropy values for 19 of 48 regions of interest showed significant divergences (P<0.05) between the patient group and control group. The regions showing significant differences included the corpus callosum and its adjacent neural structures, the brainstem and its adjacent neural structures, and the subcortical white matter that passes the long neural tract. CONCLUSIONS The results demonstrated abnormalities of white matter in traumatic subarachnoid hemorrhage patients, and the abnormality locations are compatible with areas that are vulnerable to diffuse axonal injury. Based on these results, traumatic subarachnoid hemorrhage patients also exhibit diffuse axonal injuries; thus, traumatic subarachnoid hemorrhage could be an indicator of the presence of severe brain injuries associated with acute or excessive mechanical forces.

Relationships among language ability, the arcuate fasciculus and lesion volume in patients with putaminal hemorrhage: a diffusion tensor imaging study.

Relationships among language ability, arcuate fasciculus and lesion volume were investigated by use of diffusion tensor tractography in patients with putaminal hemorrhage. Thirty-three right-handed patients within six weeks of hemorrhage onset were recruited. Correlation of the aphasia quotient with subset (fluency, comprehension, repetition, naming) scores, diffusion tensor tractography parameters and lesion volume of patients, aphasia quotient (r = 0.446) with subset (naming: r = 0.489) score had moderate positive correlations with fractional anisotropy of the left arcuate fasciculus. The aphasia quotient subset (repetition) score had a strong positive correlation with fractional anisotropy of the left arcuate fasciculus (r = 0.520), whereas, aphasia quotient subset (fluency and comprehension) scores had no significant correlations with fractional anisotropy of the left arcuate fasciculus after Benjamini-Hochberg correction. Aphasia quotient (r = 0.668) with subset (fluency: r = 0.736, comprehension: r = 0.739, repetition: r = 0.649, naming: r = 0.766) scores had strong positive correlations with the tract volume of the left arcuate fasciculus and strong negative correlations with lesion volume (r = -0.521, fluency: r = -0.520, comprehension: r = -0.513, repetition: r = -0.518, naming: r = -0.562). Fractional anisotropy of the left arcuate fasciculus had a moderate negative correlation with lesion volume (r = -0.462), whereas the tract volume of the left arcuate fasciculus had a strong negative correlation with lesion volume (r = -0.700). According to the result of mediation analysis, tract volume of the left arcuate fasciculus fully mediated the effect of lesion volume on the aphasia quotient. Regarding the receiver operating characteristic curve, the lesion volume cut-off value was 29.17 cm3 and the area under the curve (0.74), sensitivity (0.77) and specificity (0.80) were higher than those of fractional anisotropy, tract volume and aphasia quotient cut-off values. It was found that level of language disability was related to lesion volume as well as to injury severity of arcuate fasciculus in the dominant hemisphere of patients with putaminal hemorrhage. In particular, the tract volume of the arcuate fasciculus in the dominant hemisphere fully mediated the effect of lesion volume on language ability. Additionally, a lesion volume of approximately 30 cm3 was helpful in discriminating arcuate fasciculus discontinuation in the dominant hemisphere.

Dysphagia prognosis prediction via corticobulbar tract assessment in lateral medullary infarction: a diffusion tensor tractography study.

We investigated the capacity for dysphagia prognosis prediction using diffusion tensor tractography (DTT) to assess the state of the corticobulbar tract (CBT) during the initial period following lateral medullary infarction (LMI). Twenty patients with LMI and 20 control subjects were recruited for this study. The patients were classified into two subgroups: subgroup A (16 patients with nasogastric tube required for six months or less after LMI onset) and subgroup B (4 patients with nasogastric tube required for more than six months after onset). DTT was used to reconstruct the CBTs of each patient and control subject, and the fractional anisotropy (FA) and tract volume (TV) measurements were obtained. In the affected hemisphere, the FA value of the CBT was significantly lower in subgroup B than in subgroup A and the control group (p < 0.05), with no significant difference between subgroup A and the control group. In the affected and unaffected hemispheres, the TV values of CBT in subgroups A and B were lower than those of the control group (p < 0.05), with no significant difference between subgroups A and B. In addition, among the four patients of subgroup B, reconstruction of the CBT was not possible in three patients, and the remaining patients exhibited on old lesion in the corona radiate involving descending pathway of the CBT in the affected hemisphere. We found that the injury severity of the CBT in the affected hemisphere appeared to be related to a poor dysphagia prognosis following LMI. Our results suggest that evaluation of the CBT state during the early post-LMI could be useful for dysphagia prognosis prediction.