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Biomedical subjects

E D Bigler

Publications and source records attributed to E D Bigler.

At least 19 recordsLinked to original sources
PubMed1995

Trauma-induced degenerative changes in brain injury: a morphometric analysis of three patients with preinjury and postinjury MR scans.

Three patients with pretraumatic and posttraumatic brain injury (TBI) MR imaging of the brain are presented. Two patients had moderate to severe injury, whereas the third patient sustained a mild injury. Using imaging software to conduct morphometric analyses, quantitative neuropathologic change was ascertained in each TBI patient. Each case was compared quantitatively to preinjury scans as well as to an age-matched control group. For the moderately to severely injured patients, extensive degenerative changes were found throughout the various cortical structures and the cerebellum, whereas most midbrain and brainstem measures did not demonstrate significant change. For these two patients, the most significant changes occurred within the ventricular system, where generalized ventricular dilation was observed post-TBI. In the mild case, no significant anatomic changes were evident. These case studies demonstrate the use of quantitative methods for examining the structural basis of TBI sequelae.

Adult↗
PubMed1995

Ventricular dilation, cortical atrophy, and neuropsychological outcome following traumatic brain injury.

Day-of-injury computed tomographic scans were compared with postinjury magnetic resonance imaging of 38 patients with traumatic brain injury. Ventricles and several white and gray matter structures were measured. Results demonstrated significant changes in ventricular sizes and all measures of white matter. Changes in gray matter were nonsignificant, except in the putamen/globus pallidus. Patients were grouped according to ventricular change, and neuropsychological outcome was examined. The group with the highest ventricular change had significantly lower memory scores but did not show significant differences on tests of intellectual functioning. A three-dimensional image analysis was performed to enhance visualization of the injured brain.

Adult↗
PubMed1995

Quantitative volumetric analysis of brain MR: normative database spanning 5 decades of life.

PURPOSE: To present a normative volumetric database, spanning 5 decades of life, of cerebrospinal fluid, subarachnoid cerebrospinal fluid, total brain volume, total ventricular volume (component ventricular volumes of lateral, temporal horn, and third and fourth ventricles) and estimates of white and gray matter, based on a multispectral segmentation of brain MR. This database is presented as a reference for future studies comparing pathologic states. METHOD: One hundred ninety-four healthy subjects, ranging in age from 16 to 65 years, received standard axial intermediate- and T2-weighted spin-echo MR images. Multispectral segmentation and volume analysis were performed using ANALYZE. RESULTS: Normative volumetric estimates, both uncorrected and corrected for differences in total intracranial volume, were obtained for all subjects and presented by decade and sex. Age-related cerebrospinal fluid changes were evident for both male and female subjects. Most gender differences were eliminated by correction for differences in total intracranial volume. Standard and fast spin-echo acquisition methods gave comparable volume estimates. Total brain volume measurements from MR compare favorably with data from large autopsy series. CONCLUSION: Although there may be limitations to generalizations, these normative data tables can provide a comparison index for contrasting pathologic groups with a normative sample.

Adolescent↗
PubMed1994

Corpus callosum surface area across the human adult life span: effect of age and gender.

This magnetic resonance (MR) imaging study analyzed and provides normative data on the midsagittal surface area of the corpus callosum (CC) across the human adult life span in 200 normal volunteers. Using MR imaging scans, CC midsagittal surface area was quantified, along with midsagittal intracranial surface area and total intracranial volume (measures of cranial size). Results demonstrate that when head size is controlled, no major changes associated with normal aging are evident in the CC during the more active years of adult life span (up through 65). Overall, females had significantly larger CC relative to total intracranial volume. Results are discussed in terms of potential gender differences in CC size and the clinical application of this normative data.

Adolescent↗
PubMed1994

Day of injury CT scan as an index to pre-injury brain morphology.

This study compared the ventricle-to-brain ratio (VBR) of the day-of-injury (DOI) computerized tomogram (CT) in traumatic brain-injured (TBI) patients with post-injury (2 months or greater) magnetic resonance (MR) VBRs in the same patients and in medical control subjects. The DOI VBR did not differ significantly from the medical controls, but both (DOI and medical control VBR) differed significantly from post-injury VBR. Additionally, a case study is presented wherein MR imaging studies were obtained prior to TBI so that a direct comparison of pre-injury to DOI to post-injury changes could be made. In this case the pre-injury and DOI VBRs were within approximately 9% of each other. In contrast, the post-injury VBR demonstrated over a 100% increase in comparison to either the pre-injury or DOI scan. This case and another case are illustrated using three-dimensional image analysis to represent ventricular change over time. These cases, along with the similarity of the DOI VBR with the medical controls, suggests that the DOI VBR can be utilized as an estimate or index of pre-injury ventricle/brain morphology. This will permit the use of DOI CT data for within-subject designs in TBI research that examines the course of degenerative changes over time.

Adolescent↗
PubMed1993

Fornix degeneration and memory in traumatic brain injury.

Fornix-to-brain ratios (FBR) based on postinjury magnetic resonance (MR) studies were calculated on a group of 27 female traumatic brain injury (TBI) patients and 18 female medical controls by taking the widest aspect of the fornix at the level of the anterior horns and third ventricle and determining a fornix surface area. The FBR was significantly reduced in the TBI group (FBR = 0.1121) as compared to the normal control group (FBR = 0.1766). Despite these significant FBR findings indicating prominent atrophic changes of the fornix in TBI patients, the FBR did not relate systematically to neuropsychological outcome. These findings clearly indicate fornix vulnerability in TBI and that current quantitative MR methods are sensitive enough to detect such changes. However, fornix degeneration constitutes only one of many contributing factors to the anatomic basis of TBI-induced cognitive disturbances, as fornix atrophy did not relate systematically to neuropsychological outcome.

Adolescent↗
PubMed1992

Degenerative changes in traumatic brain injury: post-injury magnetic resonance identified ventricular expansion compared to pre-injury levels.

Magnetic resonance (MR) scans obtained 42 days and 10 months post-injury were compared to scans obtained in similar planes three months prior to injury. In comparison to pre-injury scans, post-injury MR scan analysis demonstrated significant ventricular volume increase which is considered a measure of the degree of diffuse axonal injury. Most important, the trauma induced degenerative effects appeared to be quite complete by 42 days post-injury as there was little further degeneration that occurred between the 6 week and 10 month post-injury scans. This study demonstrates that in humans the majority of gross trauma-induced degenerative changes are complete by 6 weeks post-trauma.

Adult↗
PubMed1992

The neurobiology and neuropsychology of adult learning disorders.

The area of adult learning disabilities is reviewed from a neurobiological and neuropsychological perspective. The seminal contributions of Galaburda's neuroanatomic studies, Duffy's neurophysiologic findings, and recent magnetic resonance imaging studies have illustrated various possible pathophysiologic bases in dyslexia and are reviewed along with other neurobehavioral disorders that may coexist with learning disorders. Neuropsychological assessment methods in evaluating learning disabilities are reviewed and test results in a case of traumatically induced dyslexia are compared to those obtained in three adults with residual developmental dyslexia. The problems associated with treatment of adult learning disorders are discussed in the context of brain plasticity and recovery of function from the perspective of a brain-injury model. Lastly, the basis common to neurologic factors subserving learning disability and emotional dysfunction is explored.

Adult↗
PubMed1991

Short- and long-term psychological status following stroke. Short form MMPI results.

Indices of self-reported depression and psychological adjustment after stroke were evaluated using a short form of the MMPI. Patients with poststroke periods of 2 to 6 and 7 to 24 months were selected, and indices of general intellectual functioning and lesion size/location were obtained. Despite similar levels of intellectual functioning and lesion parameters, the longer duration group showed significantly higher depression scores and significant (T greater than 70) elevations on several other clinical scales of the MMPI. In contrast, the mean overall profile of the short-duration group was roughly within normal limits. These findings have implications for the clinical assessment and treatment of stroke patients and long-term psychological adjustment after stroke.

Adaptation, Psychological↗
PubMed1990

Basic relations among lesion laterality, lesion volume and neuropsychological performance.

Although it is widely accepted that lesion size is an important determinant of severity of deficit, difficulties in the quantification of lesion size and the absence of a theoretical model of how lesion volume combines with lesion locus to produce deficits have inhibited the development of methodological and statistical procedures for studying naturally occurring lesions in humans. We propose such a unified model and apply it to the analysis of neuropsychological performance in a sample of patients with naturally occurring unilateral lesions. The analysis suggests that a statistical interaction between lesion size and laterality may be an important determinant of neuropsychological deficit.

Adult↗
PubMed1990

Neuropsychology and malingering: comment on Faust, Hart, and Guilmette (1988)

Faust, Hart, and Guilmette (1988) recently reported on the inability of neuropsychologists to detect malingering in children who were asked to "fake bad" on a battery of neuropsychological measures. Because of methodological issues, implications of their research are not generalizable to the actual clinical setting. Limitations of the questionnaire format in detecting factitious results are discussed along with the inherent bias of such a research design to overinterpret pathology. The competency of the clinical neuropsychologist judges and their selection process are questioned. Last, some guidelines are offered for future research dealing with the issue of detection of malingering in neuropsychological practice.

Child↗
PubMed1990

Quantitative assessment of covariation between neuropsychological function and location of naturally occurring lesions in humans.

Studies of localization of brain function in humans depend on analysis of covariation between the location of naturally occurring lesions and measures of neuropsychological ability. Such an analysis presents two problems: how to represent numerically the infinite variety of lesion locations, sizes, and shapes; and how to assess covariation between the location measure and performance. We present a mathematical model of lesion location and its relationship with performance. To demonstrate its utility, the model is applied to a sample of 53 patients with naturally occurring brain lesions who were administered a standard battery of neuropsychological tests. Importance functions derived for the neuropsychological measures generally conform to expectations. Sensory and motor abilities were localized correctly within the contralateral hemispheres, and language functions were localized in the left frontal region. Lesion location accounts for substantially more variation in performance than does lesion volume, with location accounting for more than 50% for some left-hemisphere functions.

Brain↗
PubMed1990

Attention deficit disorder and the mediating effect of age on academic and behavioral variables.

Seventy-nine children, independently diagnosed as having attention deficit disorder (ADD) with or without hyperactivity and ranging in age from 6 years, 0 months, to 12 years, 11 months, were administered the Wechsler Intelligence Scale for Children-Revised (WISC-R), the Wide Range Achievement Test (WRAT), and the Child Behavior Checklist (CBC). Multiple regression analyses indicated a significant multiple correlation between age and achievement variables (R = 0.42, p = 0.003) and age and behavioral (CBC) variables (R = 0.55, p = 0.01). Post hoc analyses indicated that much of this variance was accounted for by a significant negative association between age and Full Scale IQ-WRAT Arithmetic difference scores, and significant positive correlations between age and scores on the Social Withdrawal and Uncommunicative scales from the CBC. A nonparametric chi-square analysis indicated that older children with ADD are significantly more likely (p = 0.037) than younger ADD children to have a discrepancy of 15 or more points between IQ and math achievement scores. Results suggest that older ADD children are more likely than younger ADD children to experience academic and socioemotional difficulties.

Achievement↗
PubMed1990

The relationship between continuous performance tasks and neuropsychological tests in children with attention-deficit hyperactivity disorder.

We examined the relationship between measures of sustained attention and impulsivity, as obtained by computerized continuous performance tasks of the Gordon Diagnostic System and a battery of intellectual, achievement, and neuropsychological tests. Subjects were 119 boys (between the ages of 6 yr., 0 mo. and 12 yr., 11 mo.), diagnosed with Attention-deficit Hyperactivity Disorder, using DSM-III or DSM-III--R criteria. Only two measures, the number of correct responses for Vigilance and Distractibility tasks, correlated consistently with other measures (e.g., intellectual measures, the WRAT--R Arithmetic subtest, Beery Test of Visual and Motor Integration, and various sensory-motor variables from the Halstead-Reitan Neuropsychological Battery). The results suggest a unique contribution of continuous performance tasks in the measurement of attention, in a population of children with ADHD, which is not assessed by more traditional tests.

Attention↗
PubMed1989

Rey-Auditory Verbal Learning and Rey-Osterrieth Complex Figure Design performance in Alzheimer's disease and closed head injury.

Performance on the Rey-Auditory Verbal Learning (R-AVL) and Rey-Osterrieth Complex Figure Design (R-O CFD) tests was examined in patients (N = 94) with dementia of the Alzheimer's type (DAT) and closed head injury (CHI). On the R-AVL, DAT patients demonstrated considerably greater impairment than CHI patients, along with a flat learning/retention curve that showed negligible improvement with repeated trials, recency effects only, and an excessive number of word intrusions (confabulation) on the recognition trial. CHI patients demonstrated both a recency and primacy effect along with improvement over repeated trials (positive slope learning curve). Both groups demonstrated impairment R-O CFD recall; the DAT group again displayed substantially greater copying and recall deficits. Clinical guidelines are given for the use of the R-AVL and R-O CFD for these two patient populations.

Adult↗
PubMed1989

Handedness and language among the mentally retarded: implications for the model of pathological left-handedness and gender differences in hemispheric specialization.

The relationship between handedness and language was examined among 238 mentally retarded subjects representing the four DSM III classification ranges of mental retardation. Language ability was found to be significantly related to handedness, with an increased prevalence of left-handedness among those individuals with language deficits. In addition, both expressive and receptive language ability interacted with gender, with the main effects of each language variable being stronger for females than males. Although no main effects were found for severity of retardation, a significant interaction was found between severity and gender. Results support the model of pathological left-handedness and are discussed within the context of this theory, as well as with regard to gender differences in cerebral lateralization of language and cognitive functioning.

Adolescent↗