Oh Lyong Kim

The relation between fornix injury and memory impairment in patients with diffuse axonal injury: A diffusion tensor imaging study

Little is known about the relation between fornix injury and memory impairment in diffuse axonal injury (DAI). In the current study, we attempted to investigate fornix injury in patients with memory impairment following DAI, using diffusion tensor imaging (DTI). Nine patients with DAI and nine age-and sex-matched control subjects were recruited. The DTIs were acquired using a sensitivity-encoding head coil on a 1.5 T. Five regions of interest (ROI) were drawn manually on a color fractional anisotropy (FA) map: two ROIs for each column, one ROI for the body, and two ROIs for each crus. The FA and apparent diffusion coefficient (ADC) were measured in each of the ROIs. Cognitive function was evaluated using the Memory Assessment Scale, Wechsler Intelligence Scale, and Mini-Mental State Exam. In the DAI group, the FA value in the fornix body was significantly decreased compared with that of the control group. In contrast, we did not find significant differences in the column and crus of the fornix. Among all of the cognitive function scales, only the Memory Assessment Scale scores were significantly correlated with the FA values of the fornix body in the DAI group. We found that memory impairment in patients with DAI is closely related to neuronal injury of the fornix body among the three fornix regions that we assessed. DTI could be useful in the evaluation of patients with memory impairment following DAI.

Cerebellar peduncle injury in patients with ataxia following diffuse axonal injury.

No diffusion tensor imaging (DTI) study has yet investigated ataxia in diffuse axonal injury (DAI). In the current study, we used DTI to investigate cerebellar peduncle lesions of patients who showed severe ataxia following DAI. Six patients with severe ataxia following DAI and six age-and sex-matched control subjects were recruited. DTIs were acquired using a sensitivity-encoding head coil on a 1.5T system. Using DTI-Studio software, three cerebellar peduncles (superior cerebellar peduncle, SCP; middle cerebellar peduncle, MCP; inferior cerebellar peduncle, ICP) were evaluated. In each cerebellar peduncle, fractional anisotropy was estimated using the regions of interest method. We defined a lesion as a fractional anisotropy value two standard deviations below that of normal controls. All six patients had an average of 6.3 lesions (range 3-12). Twenty of 36 total cerebellar peduncles revealed more than one lesion (SCP: 8, ICP: 7, MCP: 5). In each of the 20 cerebellar peduncles, all the lesions displaying the lowest FA values relative to that of normal controls (11 peduncles; 55%) were located in the junction between brain stem and cerebellum and post-junctional area (nine peduncles; 45%). The junction and peri-junctional areas between the brain stem and cerebellum appear to be the most vulnerable area by DAI, with the order of incidence SCP, ICP, and MCP. Evaluation of the cerebellar peduncles using DTI can be helpful in patients with ataxia following DAI.

Corticospinal tract injury in patients with diffuse axonal injury: A diffusion tensor imaging study

Diffusion tensor imaging (DTI) can be useful in detecting corticospinal tract (CST) injury at the subcortical white matter level. In the current study, we attempted to investigate the incidence and distribution of CST injury in patients with diffuse axonal injury (DAI), using DTI. Fourteen patients who showed motor weakness without any specific lesion along the CST pathway on conventional brain MRI, and twelve age-matched, normal healthy control subjects were recruited. DTI was performed using 1.5 T with a synergy-L Sensitivity Encoding (SENSE) head coil. Fractional anisotropy was measured using the region of interest method. A CST injury was defined as the FA value of a certain area being decreased two standard deviations below that of normal controls. All 14 patients had more than one lesion at the CST injury, and the mean number of CST injuries was 3.6 (range: 2-7). The CSTs were involved at the following locations: the pons (61%), the cerebral peduncle (39%), the corona radiata (21%), the medulla (14%), and the posterior limb (11%). The pons was the most prevalent area of CST injury in patients with weakness caused by DAI at the subcortical level. We found that DTI is a useful technique for detecting a DAI of the CST at the subcortical level.

Relation between cingulum injury and cognition in chronic patients with traumatic brain injury; diffusion tensor tractography study

OBJECTIVES Many diffusion tensor imaging (DTI) studies have reported an association between cingulum injury and cognition in patients with traumatic brain injury (TBI) using DTI parameters. In this study, we attempted to investigate the relation between cingulum injury and cognition in chronic patients with TBI, using the integrity of the cingulum as well as DTI parameters. METHOD Thirty five consecutive chronic patients with TBI were recruited. The intelligence quotient (IQ) of the Wechsler Intelligence Scale and Memory Assessment Scale (MAS) was used for assessment of cognition. The patients were classified into three groups, according to continuity to the lower portion of the genu of the corpus callosum: type A-both sides of the cingulum showed intact continuity, type B-either cingulum showed a discontinuation, and, type C-both cingulums showed discontinuation. We measured the fractional anisotropy (FA), apparent diffusion coefficient (ADC), and voxel number of both cingulums. RESULTS The IQ and MAS scores of type A and B were significantly higher than those of type C, respectively (p < 0.05), however, we did not observe a significant difference between type A and type B (p > 0.05). A positive correlation was observed between the FA value of the cingulum, and IQ and MAS, respectively (IQ r = 0.373, p < 0.05, MAS r = 0.357, p < 0.05), and between the voxel number and MAS (r = 0.500, p < 0.05). By contrast, we observed a negative correlation between the ADC value and IQ (r = -0.353, p < 0.05). CONCLUSION In terms of integrity to the basal forebrain and DTI parameters of the injured cingulum, DTI findings showed a close association with whole cognition and memory in chronic patients with TBI.

Fornix Injury in a Patient With Diffuse Axonal Injury

D I F F U S E A X O N A L injury (DAI) is characterized by widespread axonal d a m a g e d u e t o shearing forces by acceleration, deceleration, or rotation of the brain. Diffuse axonal injury is the most frequent cause of poor clinical outcomes in patients with traumatic brain injury. However, conventional brain magnetic resonance imaging is not sufficiently sensitive to diagnose DAI, as most DAI lesions are microscopic. Recent advancements in diffusion tensor tractography (DTT) have allowed the fornix to be visualized 3-dimensionally. Wang et al demonstrated that the fornix bodies of patients with DAI were injured using the data obtained from DTT. In the current study, we describe a patient with DAI who showed a fornix injury on DTT. A 40-year-old, right-handed man who was in a traffic crash underwent conservative management for DAI at the department of neurosurgery in a university hospital. The patient lost consciousness for 45 days after the injury. Brain magnetic resonance imaging, including diffusion tensor imaging, was performed 30 months after the injury and showed leukomalactic lesions at the isthmus of the corpus callosum and the cingulate gyrus (Figure). He showed severe memory impairments (total intelligence quotient on the Wechsler Adult Intelligence Scale, 114; total score on the Memory Assessment Scale, 56). The diffusion tensor images were acquired using a sensitivity-encoding head coil on a 1.5-T Philips Gyroscan Intera using single-shot echoplanar imaging. Sixty contiguous slices (matrix, 128 128; field of view, 221 mm; repetition time/ echo time = 10 726/76 milliseconds; b=1000 mm/s; thickness, 2.3 mm) were acquired for each of the 32 noncollinear diffusion-sensitizing gradients. Three-dimensional reconstructions of the fiber tracts were obtained using PRIDE, and the termination criteria were fractional anisotropy of less than 0.2 at an angle greater than 45°. Fiber tracts passing through both regions of interest (anterior and middle body of fornix) were designated as the final areas of interest. We recruited a 41year-old right-handed man without a neurological disease history as a control subject. The DTT results of the patient showed that the posterior body of the fornix was disrupted compared with that of the control subject.

Neural injury of uncinate fasciculus in patients with diffuse axonal injury

The recent development of diffusion tensor imaging (DTI) allows visualization and estimation of the uncinate fasciculus (UF). We investigated injuries of the UF in patients with diffuse axonal injury (DAI) who showed no specific lesions except for DAI lesions on conventional brain MRI. Twenty-one chronic patients with DAI, and 21 age- and sex-matched normal control subjects were recruited for this study. Diffusion tensor images were acquired using a sensitivity-encoding head coil at 1.5 T and the UF was reconstructed using DTI-Studio software. Fractional anisotropy (FA), apparent diffusion coefficient (ADC) value, and fiber number of the UF were measured. In the DAI group, the FA values and fiber numbers were significantly decreased compared to those of the control group (P< 0.05). The FA value and fiber number decreased 8.4% and 26.5% in the DAI group compared to those of the control group. By contrast, the ADC value did not show any difference between the DAI and control groups (P> 0.05). Changes in the DTI parameters of the DAI group appeared to indicate neural injury of the UF. We believe that DTI can be a useful evaluation tool for detecting hidden neural injuries of UF in patients with DAI.

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.

Optic radiation injury in a patient with traumatic brain injury

Primary objective: This study reports on a patient who showed an optic radiation (OR) injury on diffusion tensor imaging (DTI) following head trauma. The patient, who had suffered a traffic accident, underwent conservative management for diffuse axonal injury and contusions in the left midbrain, temporal lobe and anterior to mid-portion of left OR. He complained of right homonymous hemianopsia from the onset of TBI and right bilateral homonymous hemianopsia was detected at the 6-month Humphrey visual field test. Methods and procedures: A 20 year-old man with traumatic brain injury (TBI) and eight age-matched normal subjects were recruited for this study. Main outcomes and results: The left OR of the patient showed a discontinuation around the mid-portion. The FA (fractional anisotropy) values of the posterior portions of left OR decreased over two standard deviations of normal controls, but the ADC (apparent diffusion coefficient) values of these sites increased over two standard deviations of normal controls. Conclusions: Consequently, it was assumed that the main injury site of the left OR was located around the posterior portion of the left OR. This results suggest that DTI may be a useful technique for detection of an OR injury in patients with TBI.

Clinical application of diffusion tensor tractography for elucidation of the causes of motor weakness in patients with traumatic brain injury

Diffusion tensor tractography (DTT) is useful for elucidating the status of the corticospinal tract (CST). The purpose of this study was to investigate the usefulness of DTT for determining the causes of motor weakness in patients with traumatic brain injury (TBI). Five patients with TBI were recruited for this study. DTT was performed using 1.5-T with a Synergy-L Sensitivity Encoding (SENSE) head coil. DTT was obtained with termination criteria of FA < 0.2 and an angle change > 45 degrees . On the DTT of patient 1, who had diffuse axonal injury, the focal lesion was detected in the left pons, and was not detected on routine brain images. In patients with deep cerebral hemorrhage, the integrity of the CST of patient 3 was preserved, although the lesion was more extensive than that of patient 2, who showed severe degeneration with the disruption of the CST at the lesion site. In patient 4, the integrity of the left CST was disrupted by a left transtentorial herniation. Although the CST of the affected hemisphere was connected at the cortex level in patient 5, who had a cortical contusional hemorrhage, the motor function of the lower extremity was worse than that of the upper extremity according to the involvement of the somatotopic area of the primary motor cortex. DTT would be useful in elucidating the causes of motor weakness in patients with TBI at the subcortical level, including conditions such as diffuse axonal injury, deep intracerebral hemorrhage, and transtentorial herniation.

Long-term recovery of motor function in a quadriplegic patient with diffuse axonal injury and traumatic hemorrhage: A case report

There have been no studies on motor recovery in severe quadriplegic patients with traumatic brain injury (TBI) resulting from combined causes of weakness; this type of patient is often seen in rehabilitation clinics. We report on a quadriplegic patient who showed long-term motor recovery from severe weakness caused by a diffuse axonal injury (DAI) on the brainstem and a traumatic intracerebral hemorrhage (ICH) on left cerebral peduncle, as evaluated by diffuse tensor imaging (DTI) and functional MRI (fMRI). A 17-year-old male patient presented with quadriparesis at the onset of TBI. Over the 28-month period following the onset of the injury, the motor function of the four extremities slowly recovered to a range that was nearly normal. Two longitudinal DTIs (at 11 and 28 months from onset) and fMRI (at 28 months) were performed. Fractional anisotropy and an apparent diffusion coefficient were measured using the region of interest method, and diffusion tensor tractography was conducted using a DTI/fMRI combination. Fractional anisotrophy values in the brainstem, which were markedly decreased on the 11-month DTI, were increased on the 28-month DTI. On the fMRI performed at 28 months, the contralateral primary sensori-motor cortex was activated by the movement of either the right or left hand. Diffusion tensor tractography showed that fiber tracts originating from the motor-sensory cortex passed through the known corticospinal tract pathway to the pons. It seems that the weakness of this patient recovered due to the recovery of the damaged corticospinal tracts.