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Biomedical subjects

D L Na

Publications and source records attributed to D L Na.

At least 19 recordsLinked to original sources
PubMed2006

Deafferentation-disconnection neglect induced by posterior cerebral artery infarction.

OBJECTIVE: To investigate patients with posterior cerebral artery (PCA) infarctions to learn whether hemispatial neglect is more frequent and severe after right than left PCA infarction; whether visual field defects (VFDs) influence the presence or severity of hemispatial neglect; and the anatomic loci of lesions that are associated with hemispatial neglect. METHODS: The authors recruited 45 patients with PCA infarction that involved only the occipital lobe or the occipital lobe plus other areas served by the PCA. All subjects received seven neglect tests within 2 months after onset. RESULTS: Overall, the frequency of hemispatial neglect was 42.2%. The frequency did not significantly differ between the right (48.0%) and left (35.0%) PCA groups, but the severity of hemispatial neglect was significantly greater in the right group. VFD alone did not influence the frequency or severity of neglect after controlling other variables. Isolated occipital lesions were rarely associated with hemispatial neglect, and it was only the occipital plus splenial lesion that significantly influenced the frequency and severity of neglect. CONCLUSIONS: This study suggests that after excluding such confounding factors as aphasia or hemiplegia, neglect frequency does not differ between the right and left posterior cerebral artery (PCA) groups, but the severity of neglect is greater after right PCA infarctions; even in the acute stage of PCA infarction; visual field defect from an isolated occipital lesion does not cause hemispatial neglect; and the injury to both the occipital lobe and the splenium of the corpus callosum is important for producing hemispatial neglect with PCA infarction.

Adult↗
PubMed2005

Glucose metabolism in early onset versus late onset Alzheimer's disease: an SPM analysis of 120 patients.

The aims of this cross-sectional study were (i) to compare the overall glucose metabolism between early onset and late onset Alzheimer's disease in a large sample of patients; and (ii) to investigate the pattern of glucose metabolism as a function of dementia severity in early onset versus late onset Alzheimer's disease, using a statistical parametric mapping (SPM) analysis. Subjects consisted of four groups: 74 patients with early onset Alzheimer's disease, 46 patients with late onset of the disease, and two control groups age matched to each patient group. All the subjects underwent 2-[(18)F]fluoro-2-deoxy-d-glucose (FDG)-PET under the same scanning conditions. Severity of dementia was rated with the Clincial Dementia Rating (CDR). Voxel-based SPM99 was used for statistical analyses. Overall glucose hypometabolism of early onset Alzheimer's disease patients was much greater in magnitude and extent than that of late onset patients, though both groups were similar in dementia severity: the early onset group showed more severe hypometabolism in parietal, frontal and subcortical (basal ganglia and thalamus) areas. When the decline of glucose metabolism was compared as a function of CDR stage, the slope was steeper in early onset than in late onset Alzheimer's disease. The rapid decline occurred at CDR 0.5-1 in the early onset group, whereas similar changes occurred at CDR 2-3 in the late onset group. The greater hypometabolism in early onset than in late onset patients is required to reach the same severity of dementia, probably reflecting greater functional reserve in younger than in older subjects. Alternatively, the metabolic decline curve suggests that the early onset patients may take a more rapid course in the reduction of glucose metabolism than the late onset patients.

Age of Onset↗
PubMed2005

Pattern of glucose hypometabolism in frontotemporal dementia with motor neuron disease.

Frontotemporal dementia (FTD) often coexists with motor neuron disease (MND). To characterize glucose hypometabolism in patients with FTD with MND (FTD/MND), the authors compared the glucose metabolism of 8 patients with FTD/MND with that of 29 patients with FTD. All of the patients with FTD/MND showed glucose hypometabolism only in the frontal area, whereas most patients with FTD had hypometabolism in the frontal and temporal areas. FTD/MND also showed a more symmetric pattern of glucose hypometabolism than FTD.

Aged↗
PubMed2005

Correlation of ventricular asymmetry with metabolic asymmetry in frontotemporal dementia.

BACKGROUND AND PURPOSE: The clinical presentation of frontotemporal dementia (FTD) is often asymmetrical in terms of both its clinical features and atrophy on MRI. Asymmetry in the lateral ventricle size on structural neuroimaging in FTD patients may have clinical significance. However, this has not been systematically investigated yet. This study compares the ventricular asymmetry seen on MRI with that of the asymmetric glucose metabolism using FDG-PET in patients with FTD. METHODS: Nineteen FTD patients who underwent both brain MRI and FDG-PET were retrospectively selected. As control groups, 23 and 11 age and sex-matched healthy normal subjects underwent either brain MRI or FDG-PET, respectively. The ventricular asymmetry index (VAI) was obtained in two ways: by visual rating (VAI-V) and by measuring the lateral ventricular volumes (VAI-ROI). The hemispheric asymmetry of the glucose metabolism on FDG-PET (MAI) was assessed in three ways: 1) by visual rating (MAI-V), 2) by counting the FDG activity of each hemisphere on normalized and smoothed PET images (MAI-ROI) and 3) by counting the number of voxels with significant hypometabolism based on statistical parametric mapping results (MAI-SPM). RESULTS: The VAIs on MRI (VAI-V and VAI-ROI) were highly correlated, as were the MAIs (MAI-V, MAI-ROI, and MAI-SPM) on FDG-PET. More importantly, the VAIs on MRI and the MAIs on FDG-PET showed high correlation. CONCLUSIONS: Ventricular asymmetry in FTD patients was common (78.9%) and there was a high correlation between the ventricular structural asymmetry and the hemispheric metabolic asymmetry. Therefore, it would be reasonable to interpret that the hemisphere with larger ventricle on MRI in FTD patients is undergoing a more active degenerative process.

Adult↗
PubMed2004

Attentional bias induced by viewing actual or illusory movements.

OBJECTIVE: To learn to which portions of a line normal subjects would attend when watching this line actually moving or when perceiving movement even in the absence of actual movement, an illusory movement. METHODS: Twenty normal subjects watched a computer monitor on which either lines or dots moved to the right or left. They also watched stationary lines, which appeared to be moving to the left or right because the background was moving in the opposite direction. While watching these lines or dots, their eye movements were monitored to determine the position of fixation. RESULTS: Overall, subjects fixated on the side of the line that was in the direction of real or illusory movement. In the actual movement condition, leftward motion induced more of an attentional bias than rightward motion. In the illusory movement condition, however, rightward illusory movement condition induced more of an attentional bias than leftward movement. CONCLUSIONS: Objects moving leftward or rightward primarily activate the contralateral hemisphere. This hemispheric activation may induce a contralateral overt orienting response that is reflected by eccentric eye fixation. Treatments of neglect, such as caloric vestibular stimulation, may alter an attentional bias by inducing the illusion of movement.

Adult↗
PubMed2004

The Character-line Bisection Task: a new test for hemispatial neglect.

A failure to report or respond to stimuli presented in a portion of space is termed hemispatial neglect. Line bisection and line cancellation are two of the tests used most commonly to assess for neglect. Perhaps, because neglect can be induced by a variety of deficits, neither of these tests used alone is as sensitive as both used together. Hence, the primary purpose of this study was to assess the sensitivity, reliability and validity of a new test called the Character-line Bisection Task (CLBT) that combines features of both the bisection and cancellation tests. Since local attention and language are primarily mediated by and activate the left hemisphere, our second goal was to learn if the CLBT and especially the letter version induce a greater rightward bias than the solid-line bisection task. Eighty patients with acute right hemisphere stroke and 81 controls performed the CLBT that consists of two subtests, the Letter-line and Star-line Bisection tasks. All subjects also completed four conventional tests for neglect (Standard solid-line bisection, line cancellation, Star Cancellation, and figure copying). In the bisection tasks both patients and controls bisected to the right with the CLBT than with the solid-line bisection task, suggesting the CLBT induces asymmetrical hemispheric activation. This enhanced rightward deviation with the CLBT was the same for the Letter-line and Star-line Bisection tasks. In regard to sensitivity, we defined the presence of neglect syndrome based on a total score derived from performance of controls on all six tests. This total score detected 55 (68.8%) patients with neglect. Within this group, the Letter-line and Star-line tasks diagnosed neglect in 50 and 48 patients, respectively, resulting in the highest sensitivities (90.9, 87.3%) of the six tests. Thus, the CLBTs demonstrated higher sensitivities than the other commonly used neglect tests and these new tests can be useful for the detection and quantification of unilateral neglect.

Adult↗
PubMed2002

Influence of final search direction on tactile line bisection in normal subjects.

BACKGROUND: Many variables influence the tactile bisection performance of normal subjects. Of these, studies that investigated the starting point effect have reported inconsistent results. OBJECTIVE: To determine if the final search direction rather than the initial search direction (starting point) may have an effect on tactile bisection performance, especially when subjects are making multiple searches. METHODS: The authors divided the experiment into single- and multiple-search tasks. Thirty-two blindfolded normal subjects were asked to indicate the midpoint of a rod after a one-way search (single-search task) or after two or more one-way searches (multiple-search task). In each task, the subject started on either end of the horizontally placed rods. The same procedure was also conducted with rods oriented vertically or radially. Therefore, there were six conditions (two starting points x three orientations). RESULTS: In the single-search task, there was a significant effect of starting point or movement direction in all six conditions, with biases occurring toward the starting point from the true midpoint (this is termed the "overshoot phenomenon"). In the multiple-search task, however, there was no significant effect of the starting point in all six conditions. Rather, biases depended on the final movement direction in five of the six conditions, occurring toward the starting point of the final search. CONCLUSION: Future research is needed to understand the mechanism of the overshoot phenomenon in tactile bisection by normal subjects and how the overshoot phenomenon influences patients with neglect.

Adult↗
PubMed2002

Nonconvulsive status epilepticus presenting as a subacute progressive aphasia.

We report a 62-year-old man with non-convulsive status epilepticus (NCSE) presenting as a progressive aphasia that developed insidiously over 5 weeks. On video-EEG monitoring, aggravation of the aphasia coincided with occurrence of seizure activities arising from the left fronto-temporal area. Brain MRI was noncontributory but a fluorodeoxyglucose-PET scan revealed a hypometabolism in the left anterior temporal area. Following anticonvulsant treatment, aphasia recovered gradually over several weeks despite prompt resolution of epileptic discharges on EEG. Our patient's findings, gradual onset of isolated aphasia with gradual resolution after initiation of treatment, may differ from previously reported cases with aphasic status epilepticus because their aphasia showed abrupt onset and rapid resolution with anticonvulsant medication.

Brain↗
PubMed2002

Serial diffusion-weighted MR Imaging in delayed postanoxic encephalopathy. A case study.

We report a case of delayed postanoxic encephalopathy (DPE) studied with serial diffusion weighted imaging five times in a one-year period along with apparent diffusion coefficient (ADC) map as well as ADC values of periventricular white matter. Compared to the normal value, the ADC values of the white matter were initially low on the three (0.68 +/- 0.08 x 10(-3) mm(2)/s) and seven-week images (0.67 +/- 0.08 x 10(-3) mm(2)/s) but gradually recovered to the normal range on the four, six, and twelve-month images (0.78 +/- 0.05, 0.80 +/- 0.05 and 0.87 +/- 0.11 x 10(-3) mm(2)/s, respectively). Among the several pathogenetic mechanisms associated with DPE, these serial changes may be consistent with cytotoxic edema, from apoptosis, triggered by hypoxia.

Activities of Daily Living↗
PubMed2001

Alpha-1 antichymotrypsin and alpha-2 macroglobulin gene polymorphisms are not associated with Korean late-onset Alzheimer's disease.

Alzheimer's disease (AD) is a multifactorial disorder with possible involvement of several genetic and environmental factors. For late-onset AD (LOAD), the epsilon4 allele of apolipoprotein E (APOE) has been identified as a major susceptible gene. However, the observation that APOE epsilon4 accounted for approximately one half of the genetic variance of LOAD prompted many researchers to undertake genome surveys to identify other susceptible genes. Recently, several candidate genes such as alpha-1 antichymotrypsin (ACT) and alpha-2 macroglobulin (A2M) were reported to be associated with LOAD. To evaluate the possible association between these genes and LOAD in Korean population, we genotyped ACT A/T and A2M 5-bp deletion (exon 18) polymorphisms in 89 LOAD cases and 50 age-matched healthy controls. The frequencies of ACT A and A2M 5-bp deletion alleles in LOAD and controls were 0.39 vs. 0.37, and 0.05 vs. 0.05, respectively. Although APOE epsilon4 clearly showed higher frequency in LOAD (0.34) than that in controls (0.09), giving an odds ratio of 5.14 (95% confidence interval, 2.31-11.76), neither ACT nor A2M showed statistically significant difference between LOAD and controls regardless of APOE carrier status. Our results do not support previously reported association of ACT and A2M with LOAD, at least in Korean population.

Aged↗
PubMed2001

A compulsive collecting behavior following an A-com aneurysmal rupture.

Hoarding behavior associated with focal brain injury is rarely reported. The authors report a 46-year-old man with pathologic collecting behavior after a left orbitofrontal and caudate injury from an aneurysmal rupture of anterior communicating artery. His hoarding, an impulse control disorder or an ego-syntonic compulsion, was restricted to one specific item (toy bullet). Treatments with sertraline or fluoxetine were not effective for the hoarding.

Brain↗
PubMed2001

Functional magnetic resonance imaging during pantomiming tool-use gestures.

The purpose of this study was to identify the functional fields activated in relation to gestural movements. Using functional magnetic resonance imaging (fMRI), we mapped brain activity in ten right-handed, normal volunteers during activation and control tasks. The activation condition consisted of pantomiming tool-use gestures with either the left hand or right hand, whereas the control condition comprised repetitive, oppositional movements between thumb and index finger. Activated cortical regions were highly lateralized to the left hemisphere during pantomiming of tool use regardless of hand used. Praxis with either hand commonly activated the superior parietal lobule, supplementary motor area, premotor area of the left hemisphere, and cerebellar vermis. However, minimal activation occurred in the inferior parietal lobule, which has been known to be a critical area for praxis generation. Compared with left-hand praxis, right-hand praxis exhibited additional activation in the left putamen and posterior part of the left inferior temporal region. Our findings concur with neuropsychological observations that the left hemisphere in right-handers mediates programming and executing skilled movements and that, within the left hemisphere, praxis is predominantly subserved by the parietal lobe, supplementary motor area, and premotor area. However, unlike previous lesion studies, the results of our fMRI study suggested that the superior parietal lobule more likely than the inferior parietal lobule play an important role in gesture production.

Adult↗
PubMed2001

Line quadrisection errors in normal subjects.

Many studies have investigated line bisection behaviors in normal individuals and patients with hemispatial neglect. However, little is known about what happens when subjects attempt to fractionate line into more than two equal components (e.g., line quadrisection). Thirty right handed normal subjects were asked to place a mark either 25% (left quadrisection) or 75% (right quadrisection) of the distance along on a 240 mm line. On average, they placed the left quadrisection mark significantly to the left (- 4.2+/-6.7 mm) from the true quadrisection point but they were relatively accurate on the right quadrisection task (1.0+/-6.7 mm). However, comparison of actual quadrisection performances with those of expected performance based on subjective midpoint disclosed that both right and left quadrisection marks deviate toward each end of the line. Individual data analysis also support this trend because majority of subjects showed the lateral deviation in either or both quadrisection tasks. Therefore, in the left quadrisection task the pseudoneglect (leftward bias) in bisection and the lateral bias are additive, resulting in a robust left lateral deviation, whereas in the right quadrisection, these two biases nullify each other, resulting in accurate performance.

Adolescent↗
PubMed2001

Contralesional directional hypermetria associated with line bisection-specific ipsilesional neglect.

Patients with contralesional neglect from right hemisphere injuries often fail to be aware of or respond to visual stimuli in the left hemispace. In contrast, other patients with right hemisphere damage rarely demonstrate behavior consistent with task-specific ipsilesional neglect (IN). We performed a series of experiments in a patient with IN on a line bisection task after a right frontal infarct. When asked to perform horizontal limb movements without visual feedback, the patient showed a leftward directional hypermetria. Similar performance was also observed during a representational production of a given distance without sensory input. These results suggest that IN is induced by a directional hypermetria resulting from disruption of the motor-intentional system.

Aged↗